Biogenic Synthesis of Photosensitive Magnesium Oxide Nanoparticles Using Citron Waste Peel Extract and Evaluation of Their Antibacterial and Anticarcinogenic Potential

Background Magnesium oxide nanoparticles (MgONPs) have been fabricated by several approaches, including green chemistry approach due to diverse application and versatile features. Objectives The current study aimed to prepare a convenient, biocompatible, and economically viable MgONPs using waste citron peel extract (CP-MgONPs) to evaluate their biological applications. Methods The CP-MgONPs were synthesized by a sustainable approach from extract of waste citron peel both as capping and reducing agents without use of any hazardous material. The physicochemical features of formed CP-MgONPs were determined by sophisticated analytical and microscopic techniques. The biogenic CP-MgONPs were examined for their antibacterial, anticarcinogenic, and photocatalytic attributes. Results A prominent absorption peak in the UV-Vis spectra at 284 nm was the distinguishing characteristic of the CP-MgONPs. The scanning electron microscopy (SEM) reveals polyhedral morphology of nanoparticles with slight agglomeration of CP-MgONPs. The CP-MgONPs exerted excellent antibacterial potencies against six bacterial strains. The CP-MgONPs displayed significant susceptibility towards E. coli (20.72 ± 0.33 mm) and S. aureus (19.52 ± 0.05 mm) with the highest inhibition zones. The anticancer effect of CP-MgONPs was evaluated against HepG2 (IC50 : 15.3 μg·mL−1) cancer cells and exhibited potential anticancer activity. A prompt inversion of cellular injury manifested as impairment of the integrity of the cell membrane, apoptosis, and oxidative stress was observed in treated cells with CP-MgONPs. The biosynthesized CP-MgONPs also conducted successful photocatalytic potential as much as MgO powder under the UV-light using acid orange 8 (AO-8) dye. The degradation performance of CP-MgONPs showed over 94% photocatalytic degradation efficiency of acid orange 8 (AO-8) dyes within a short time. Conclusions Outcomes of this research signify that biogenic CP-MgONPs may be advantageous at low concentrations, with positive environmental impacts.


Introduction
Nowadays, research has its emphasis on green chemistry and necessitates more work to incorporate sustainable practices in order to manufacture desired products and eventually minimize and eliminate waste materials generated [1].Green synthesis has garnered enormous scrutiny as an efcient, enduring, and environmental benign approach for creating plethora of nanomaterials.Te industrial revolution of the 21 st century is said to have been sparked by the marvels of contemporary medicine [2].Te use of nanomaterial loaded with pharmaceuticals such as phytochemicals, vitamins, and hyaluronic acids has emerged as an intriguing substitute [3].Plant and plant waste are valuable source of myriad bioactive compounds including favonoids, terpenoids, alkaloids, steroids, carbohydrates, and acids [4].Tese plant phytoconstituents act as capping agents and natural bioreductants of metal/metal oxide ions, thereby sterically stabilizing nanomaterials by reduction through direct molecular interaction [5].Scientifc analysis has shown that large volumes of bio-wastes produced from fruit and vegetable peels, which are a rich source of several biocomponents, are neglected, ultimately putting market vendors in risky circumstances [6].A feasible approach of reducing bio-waste can be established through its application in the production of advantageous nanomaterials [7].Te uprising of metal-based nanomaterials represents a major advancement in nanotechnology towards the development of superior commodities.Recently, iron, silver, and gold nanoparticles with potent antibacterial and water remediation properties have been successfully prepared from peels of fruits and vegetables as well as their bagasse [8].However, carbon nanostructures developed from these agricultural wastes have been used in the industrial sector to create materials with excellent electrical conductivity and photocatalytic activity, which are used in the production of green fuels, energy storage devices, and water purifcation systems [9].Te most valuable metal-based nanomaterials prepared by the green approaches include silver, gold, zinc, magnesium, copper, iron, and their respective oxides [10].Te signifcant interest in them emanates from their admissible physicochemical features and wide variety of agricultural, food, medical, and industrial use [11].Ag, Au, Cu, and ZnO nanoparticles were studied extensively in pharmaceutical industry for their versatile physicochemical features and diverse biomedical applications [12].However, their accumulation in the body makes them often associated with substantial toxicity risk.Unlike all other nanoparticles, MgO nanoparticles are extremely biocompatible, commercially feasible, and stable in harsh environments [13].MgONPs have distinctive features including a high refractive index, strong corrosion resistance, and superior thermal and poor electrical conductivity [14].It also has a persistent interaction with botanical constituents to generate nanoparticles due to high surface area and highly reactive edges.Tese characteristics give MgONPs access to various domains, including catalysis, electronics, additives, ceramics, photochemical products, drug synthesis, agricultural commodities, sensors, antimicrobial materials, and adsorbents [15].Tey also function exceptionally well as adsorbents for eliminating chemical contaminants from wastewater and this beneft increases with decreasing MgO size [16].Teir unique biocompatibility and physicochemical stability have made them an excellent nanocarrier.Tey beneft from having a high degree of ionization, photocatalytic abilities, and efcient endurance to elevated temperatures [17].Notably, the FDA has recognized MgONPs as a safe, convenient alternative with strong antibacterial properties [18].
Conventionally, synthesis of MgONPs has been accomplished by a variety of physical and chemical techniques, including chemical precipitation, thermal decomposition, sol-gel, chemical vapor deposition, and combustion [19].Tese techniques often need several processing stages, pH control, high temperature and pressure, pricey equipment, and hazardous chemicals and generate numerous side products that may be harmful to the ecosystem.Tus, there is a constant need to develop greener way that is energy-efcient, economical, and ecologically friendly to avoid hazardous chemicals in nanoparticle synthesis [20].To triumph over these challenges, natural products (botanicals, bacteria, fungi, lichens, agricultural waste, etc.) ofer great resources for the phytogenic production of metal/metal oxide nanomaterials.Te accessibility, environmental friendliness, safety, and overall nontoxicity of biomasses of natural products make them a desirable choice for the fabrication of MgO nanoparticles [21].Numerous types of phytochemicals are contained in these natural products that function as a reductants and chemical stabilizers in the formation of metal/metal oxide nanostructures [15].
Citrus medica (citron) has commercially been cultivated in many countries especially in tropical and subtropical regions.Its fruit peel, pulp, and seeds have applications in traditional medicine to cure abdominal colic, digestive issues, and piles.Citron fruits are akin to large lemons in appearance, with a thick skin and little pulp content.Te culinary industry uses it extensively in a variety of items, such as cakes, confections, marmalades, soft drinks, and dairy products [22].However, the processing of citron fruit for these items produces larger percentage of byproducts (peels, seeds, leaves, and stems) compared to that achieved of temperate fruits, which are often discarded as agricultural trash [23].About one third of the fruit that is removed after harvesting is made up of citron peels.. Te literature survey has revealed that citron peel contains a considerable amount of bioactive components, including phenolic, favonoids essential oil (EO), carotenoids, and compounds with diverse cross section of functional groups (carbonyl, carboxyl, ketones, and aldehyde groups) that can be exploited for diferent purposes [24].Also, the peels of citron have exhibited highest antioxidant and antibacterial activity in contrast to seeds and pulp [25].Te agricultural industry can proft from these waste streams since these bioactive compounds can be efective reductants, stabilizers, and capping agents during the synthesis of metal oxide nanomaterials.Previous research work has addressed the formation of copper oxide, gold, silver, and selenium nanomaterials from the juice, seed oil, fruit waste peel, and leaf of C. medica, respectively [26][27][28][29][30]. Hence, considering the rich chemoprofle and medicinal properties of citron peel, it was postulated that using peels to make nanoparticles would produce nanomaterials with medicinal attributes that would be benefcial for the biological system.Te present study was intended to biosynthesize MgONPs using aqueous extract of citron peel, characterize them, and evaluate their antibacterial and anticancer activities.In addition, the presynthesized CP-MgONPs were also examined for photocatalytic ability.protocol with a few minor modifcations [31].To put it briefy, 100 mL of aqueous citron peel extract was infused with 150 mL of freshly prepared magnesium nitrate (1.0 mM) solution, followed by dropwise addition of 10 mL of NaOH (1.0 M) at 80 °C, and the mixture was continuously stirred for 6 h on a magnetic stirrer at 600 rpm.Te pale yellow to yellowish-brown color transition functioned as a signal for the production of nanoparticles.Te precipitate of generated CP-MgONPs was then collected by the centrifugation of reaction mixture at 5000 rpm for 15 min.Te dried CP-MgONPs were obtained by calcining the precipitate at 400 °C in a furnace after it had been repeatedly cleaned of impurities with ethanol.

Characterization of MgO Nanoparticles.
Various modern strategies were employed for the characterization and identifcation of presynthesized CP-MgONPs.Te formation of CP-MgONPs was initially carried out by visual observation based on color change.Te optical characteristic of synthesized CP-MgONPs was studied using UV-Vis absorption spectrophotometer (SM 7504 Uniscope, China) between 200 and 800 nm wavelength.Te existence of functional moieties in the biosynthesized CP-MgONPs was performed by Fourier transform infrared (FTIR) spectroscopy with a 4000 to 400 cm −1 scanning range (FTIR: Nicolet ™ iS50, Termo Fisher Scientifc, USA).Crystallinity and phase purity of the produced nanoparticles were ascertained from their X-ray difraction (XRD) pattern over 2θ range of 20−80 °(XRD, Rigaku DMAX-IIIC, Texas, USA) ftted with Cu Kα source and λ � 1.54056 Å at room temperature.Zeta potential measurements were measured using a particle size analyzer that relies on laser scattering light (NS 3000, Zetasizer, Malvern Instruments Ltd, Malvern, UK).Te microstructure, surface topography, size, and elemental content of the CP-MgONPs were examined using a scanning electron microscope (SEM: JSM-7660F JEOL, Yokogushi, Japan) outftted with an energy-dispersive X-ray (EDX) analyzer at a 15 kV accelerating voltage.Te transmission electron microscopy with a point resolution of 0.45 nm (TEM JEM-ARM200F-G) at a 200 kV accelerating voltage was applied to measure the particle size and their dissemination using ImageJ software.Te thermal integrity of CP-MgONPs was accessed by thermogravimetric analysis using TA instrument Q series ™ thermal analyzer (Q600-DSC/ TGA, Champaign County, USA).  [33].In brief, 100 μL of aliquots of bacterial culture (10 6 cfu/mL) was laid on agar plates to form a smooth lawn and allowed to stand for 10 min.A hole (well) with a diameter of 8 mm was punched using a sterilized cork borer in the media containing agar plate and labeled.After then, 50 μL aliquot of nanoparticle solution (25 μg•mL −1 ) was added into each well on all plate and allowed to stand in the biosafety chamber for 1 h to ensure that the test samples are evenly spaced within the agar, followed by incubation for 24 h at 37 °C.Millimeters (mm) were applied to express the diameter of the growth inhibition zone of bacteria and noted.Te test was executed in triplicates and the Statistical Package for the Social Sciences (SPSS, 20.0 software version) was adapted to statistically estimate the pooled data.Gentamicin was administrated as positive control and dimethyl sulfoxide (DMSO) was negative control for the study.

Minimum Inhibitory Concentration (MIC)
Determination of Biogenic CP-MgONPs.Te lowest possible amount of an antimicrobial agent required for preventing microbial growth after 24 h of incubation period is known as the MIC [34].Te efectiveness of biogenic CP-MgONPs in restricting pathogenic growth was assessed by selecting the optimal concentration of CP-MgONPs that had a signifcant antibacterial efect at 2500 μg•mL −1 .Tis concentration was then used for determining the MIC in 96-well plates by employing the microbroth dilution procedure [35].Te initial concentration (2500 μg•mL −1 ) of nanoparticles was aseptically diluted two-fold by pouring 100 μL of the sterile CP-MgONPs into 100 μL of tryptic soy broth in a well plate to establish a concentration of 1250 μg•mL −1 .Te entire procedure was repeated multiple times to acquire diferent doses (625 μg•mL −1 , 312 μg•mL −1 ), and a 312-fold dilution of initial CP-MgONPs concentration (2500 μg•mL −1 ) was created aseptically by pouring 100 μL of the standardized suspension of bacteria (10 6 cfu/mL, OD 640nm = 0.1) into the both plates and wells, which were then incubated for whole day at 37 °C.After overnight incubation, the OD of the plates has been determined at 640 nm absorbance wavelength on a microplate reader, to establish the lowest inhibitory concentration required to prevent the bacterial cell growth.
2.6.4.Time-Kill Kinetics Assay.Time-kill kinetics assays serve a purpose in understanding the interaction that occurs between microorganisms and antimicrobials.Tis assay demonstrates a dose or time-dependent test impact of antimicrobials on various pathogens.It diferentiates between bacteriostatic and bactericidal antimicrobial drugs.Te time-kill kinetics measurements of CP-MgONPs towards the bacteria under investigation were assessed using an altered time-kill kinetics procedure [36].Te fabricated CP-MgONPs were reconstituted in DMSO to achieve various concentrations (2.5 − 0.01 mg•mL −1 ) in order to estimate the time.Te well plates containing 100 μL of TSB were loaded with various doses of CP-MgONPs, followed by addition of 100 μL of bacterial culture into the each wells and incubated at 37 °C.After every hour, OD was measured and noted.A graph plotted between optical density vs time was used to assess the killing time kinetics that represent the cell response to the nanoparticle exposure.

Evaluation of Morphological
Changes in E. coli and S. aureus.Te morphological alterations of the E. coli and S. aureus treated with presynthesized CP-MgONPs were observed by SEM.Te CP-MgONPs-treated bacterial strains were segmented into pieces (5-10 mm) and they were then mounted for 1 h on a glass slide in phosphate-bufered saline solution with 3% glutaraldehyde.Te treated tissues were then dried using carbon dioxide and ethanol.Te dehydrated tissues were positioned on the aluminium stubs using a gold-palladium coated silver pan and morphology of the bacteria was observed at a 15 kV voltage of acceleration under SEM.

Cytotoxicity Evaluation of the Biogenic CP-MgONPs.
Te antiproliferative behaviour of biogenic CP-MgONPs on Hep2, OLO 205, and SH-SY5Y cancer cells was examined by MTT assay adapted from previously reported method with minor modifcation [37].Briefy, cells were cultured (1 × 10 4 cells/well) with 80% confuence for 24 h in a 96-well plate.After seeding for 24 h period, cells went through exposure to diferent concentrations of CP-MgONPs (25, 50, 75, 100, 125, and 150 μg•mL −1 ) and incubated for extra 24 h.Ten, each well was flled with 10 μL of MTT (5 mg•mL −1 in PBS) solution, and the mixture was incubated for 4 h more at 37 °C to develop the color.Te reaction was stopped and the blue formazan crystals were dissolved by adding an equivalent amount of DMSO to the every well.Finally, a microplate reader was implemented to record the absorbance of the reaction mixture at 570 nm wavelength.Te cell viability was determined by applying the given equation and IC 50 values were then computed.(1) 2.7.1.Cytomorphological Analysis.Te vulnerable, cultivated Hep2 cells were planted at a 1 × 10 5 cells/well density onto a 12-well chamber plate and kept in a humid environment with continuous fow of CO 2 (5%) for 12 h at 37 °C.Te seeded cells were then administrated with CP-MgONPs (100 μg•mL −1 in distilled water) and incubated for 24 h.Te PBS was utilized twice to rinse cells after incubation and cytomorphological alterations in treated and untreated cells were seen and captured on camera under phase-contrast inverted microscope at 24 and 48 h.

Acridine Orange/Ethidium Bromide (AO/EB) Staining.
Te degree of apoptosis induced by CP-MgONPs in Hep2 cancerous cells was evaluated by dual AO/EB fuorescent labelling [38].Te cultivated Hep2 cells (1 × 10 5 cells/well) were seeded in a 12-well plate and placed in a humid environment at 37 °C with a steady supply of CO 2 (5%) for 12 h.Ten, the seeded cells received treatment with CP-MgONPs along with their corresponding IC 50 values and incubated for an entire day at 37 °C.Later, the cells were exposed to 50 μL of an AO/EB dye mixture and were monitored under fuorescence microscope to detect any signs of apoptotic cell death.

Intracellular ROS Detection and Quantifcation.
ROS was assessed by obeying the procedure described by Wang and Roper [39].Briefy, 6 well plates were plated with cultured Hep2 cells and then CP-MgONPs at an IC 50 concentration were administrated for an entire day.Afterward, 10 μM of DCFH-DA solution was poured into the treated and untreated seeded cells and kept for incubation for half an hour at 37 °C.Te extent of production of ROS in treated and untreated cells was determined through a fuorescent spectrophotometer.Subsequently, trypsinized CP-MgONPs-treated cancer cells were collected separately in Eppendorf tubes wrapped in aluminium foil for the estimation of ROS.Te cells were then administered with 25 M of DCFH-DA solution and allowed to incubate for 45 min at 37 °C.Te fuorescence intensity in relation to excitation and emission wavelengths was measured by Fluorolog-FL3-11 spectrofuorometer.

Oxidative Stress Factors.
After being cultured in fasks (75 cm 2 ), the Hep2 cells were exposed for 24 h to CP-MgONPs at an IC 50 dose.Cells were collected in ice-cold PBS at 4 °C after being treated and rinsed with PBS.Te cells were then lysed with lysis bufer that included Na 2 EDTA (1 mM), Triton (1%), NaCl (150 mM), Tris-HCl (20 mM, pH 7.5), and Na 4 O 7 P 2 (2.5 mM).Te supernatant from the centrifugation of the lysed cell homogenate for 10 min at 10,000 rpm was applied to measure the oxidative stress markers.Te estimation of many indicators of liver oxidative stress including LPO, GPx, SOD, catalase, and nonenzymatic antioxidant GSH was performed by obeying standard procedures [40].

Evaluation of Mitochondrial Membrane Potential (MMP or ΔΨm).
Oxidative stress results in the inactivation of the mitochondrial membrane potency and consequent loss of function.Te mitochondrial membrane potential loss in Hep2 cells treated with CP-MgONPs was evaluated using rhodamine 123, a fuorescent indicator that preferentially deposits within the mitochondria based on membrane potential [41].In brief, Hep2 cells (5 × 10 5 cells/well) have been introduced onto 6 well plates and incubated for 12 h at 37 °C under a constant CO 2 (5%) fow.Later, the Hep2 cells were exposed for 24 h to CP-MgONPs at an IC 50 concentration.Following PBS wash, cells were fxed for 10 min in 4% paraformaldehyde and 70% ethanol.Subsequently, 50 μL solution of rhodamine 123 (10 μg/mL) was poured into each well and held for half an hour.After repeated PBS washes to remove excessive dye, cells were examined at 20 × resolution on a fuorescence microscope.Furthermore, the treated and untreated cells were trypsinized for quantifcation and separated into in Eppendorf tubes wrapped in aluminium foil, followed by addition of rhodamine 123 and keeping the mixture at 37 °C for 45 min.Finally, the fuorescence intensity and its associated wavelengths of excitation and emission were then recorded on a FL311-Fluorolog spectrofuorometer.Later, the secondary antibody coupled to horseradish peroxidase (HRP) was applied and left aside at room temperature for 2 h after the primary antibodies were removed.Te enhanced chemiluminescence (ECL) solution was used to visualize the protein band, and ImageJ software was used for quantifcation [43].
2.8.Photocatalytic Activity.Heterogeneous photocatalysis was used to assess the potential of CP-MgONPs for the removal of dye from wastewaters.Acid orange-8 (AO-8) dye was used to examine the photocatalytic efcacy of the CP-MgONPs.A homemade photoreactor was used to conduct the photocatalytic process, and it was furnished with a 250 W Osram mercury lamp with high pressure to provide UV radiation.A glass Pyrex beaker with a magnetic stirring rod constituted the reactor and the light source is situated over the beaker.Te Pyrex glass beaker and the light were placed 20 cm apart.Te photocatalytic reactor was enclosed in a box to avoid lethal radiation.Briefy, 80 mg of CP-MgONPs was dispersed in 100 mL aqueous solution of AO-8 2.50 mg/ 250 mL.Prior to UV illumination exposure, the suspension was magnetically agitated in the dark for 30 min to ensure that the mixture was properly homogeneous and that the absorption equilibrium was reached.After certain time intervals of irradiation, a given volume (4 mL) of the reaction mixture has been gathered and fltered through 0.22 μm Millipore membranes and then the solution was centrifuged for 10 min at 5000 rpm to extract photocatalyst particle suspensions.Te irradiated AO-8 solution was eventually examined using UV-Vis spectrophotometer, scanned in 200-800 nm UV-visible range and then monitored at λ max 480-490 nm wavelength [44].Te following calculation was applied to ascertain the percentage of photocatalytic degradation: Te degradation's rate constant, k, was established utilizing the equation from the frst-order plot: ln (A 0 /A) � kt, where initial dye absorbance is represented by A 0 , and dye solution absorbance is denoted by A after irradiation of UV light.

Statistical Analysis.
Te data disclosed were based on the means of three independent replicates.Te data were statistically estimated by statistical software program SPSS v17.Te analysis of the average variation among the treatments was done with a t-test or analysis of variance (ANOVA).Te HSD Tukey test then ensued at p < 0.05.

Spectrophotometric Characterization of CP-MgONPs.
Te phytochemical components found in the citron waste peels were recognized as a helpful ingredient for producing CP-MgONPs.Citron peel-mediated magnesium oxide nanoparticles (CP-MgONPs) were created when the aqueous magnesium ions were reduced by the citron peel extract.Te color alteration from pale yellow to yellowish-brown was the frst evidence of the formation of presynthesized CP-MgONPs during the integration of aqueous citron peel extract and Mg(NO 3 ) 2 .6H 2 O. Te triggering of vibrations of surface plasmon led to emergence of yellowish-brown, which is a hallmark of MgONPs having ʎ max values between 260 and 300 nm in the visible domain [45].Te size, morphologies, nature, well distribution, particle-to-particle distance, and the surrounding medium of the formed nanoparticles all had a signifcant impact on the SPR absorbance [46].Te biosynthesized MgONPs have tendency to be smaller in size at less than 300 nm SPR values; however, the anisotropy increases with SPR over 300 nm, as described by Jeevanandam et al. [47].In the current study, the optical characteristics of citron peel-mediated synthesized CP-MgONPs were measured between 200 and 800 nm wavelength range and UV-Vis spectra of CP-MgONPs exhibited a sharp plasmon resonance band at 284 nm (Figure 1(a)), indicating the presence of nanoscale particles.Te fndings presented were consistent with those published by Hassan et al. [48], Abdallah et al. [49], and Nguyen et al. [50].Tese investigations demonstrated that the most signifcant bands of MgONPs prepared from Rhizopus oryzae, Tecoma stans (L.), and Rosmarinus ofcinalis L occurred at 282, 281 nm, and 250 nm, respectively.Further, there was a noticeable absorption band at 290 nm in chemically synthesized MgONPs [51], suggesting the bioactive components found in the citron extract were efective at reducing, capping, and stabilizing.Te absorption spectra of biogenic NPs were calculated by applying Tauc's relation, (αh]) 2 = B(hυ-Eg), to determine the band gap energy of CP-MgONPs.In this equation "α" denoted the absorption coefcient and "B" represents a constant.Te term hѵ represents the photon energy and Eg signifes the band energy.Te band gap of presynthesized CP-MgONPs was determined as the linear portion of the curve between (αh]) 2 and (h]).Te estimated amount of band gap energy was 4.62 eV for CP-MgONPs as depicted in Figure 1(b).Te value of band gap is aligning with previously reported literature, and it might be associated with the quantum confnement efect [52].
In this investigation, an extracellular approach was employed since it was more feasible and resulting nanomaterials were easy to purify.Numerous components found in the hydroextract of citron peels function as reductants and the nanoparticle biosynthesis was conducted in alkaline medium as it promotes the reduction ability of functional moieties and avoids nanoparticle aggregation [53].It further aids in the stabilization and capping of nanoparticles by interacting with the amine functions of proteins that are attached to the surfaces and their residual amino acids.

6
Bioinorganic Chemistry and Applications Te double function of the plant biomass as a reductant and capping agent of the anchored functional moieties on the CP-MgONPs surface was recognized by FTIR analysis in the wavelength range of 4000 − 400 cm −1 (Figures 2(a) and 2(b)).Te FTIR spectrum of biogenic CP-MgONPs exhibited bands at 3432, 2923, 1637, 1398, 1346, 1068, 673, and 887 cm −1 (Figure 2(a)) that correspond to O-Hstretching for alcohols, C-H stretching for alkane, C=C stretching for di-substituted (cis), O-H bending for carboxylic acid, O-H bending for alcohols, C-O stretching for primary alcohols, strong C=C bending for di-substituted (cis) alkenes, and strong C=C bending for vinylidene (alkene), respectively, suggesting the existence of several bioactive metabolites such as phenolics, favonoids, tannins, and carbohydrates adsorbed on the surface of NPs [54].Te active functional moieties in these metabolites are essential for the preparation and stability of CP-MgONPs.Moreover, the FTIR spectrum of CP-MgONPs also showed two absorption peaks at 635 cm −1 and 495 cm −1 that were associated with the MgO vibrations, suggesting the MgO nanoparticle formation [55].Various peaks were observed at 447, 510, 582, and 670 cm −1 which were linked to the CP-MgONPs vibrations.Te shift observed in various peaks of biosynthesized CP-MgONPs in contrast to citron peel extract may be due to interaction of MgO vibrations with functional groups of citron peels extracts.
Generally, the activity profle of nanoparticles is often linked to various features such as size, shape, and distribution.Tus, it has signifcance to assess the size and morphology of the formed nanoparticle.Te SEM micrograph of biosynthesized CP-MgONPs displayed polyhedral shape with agglomeration that may be possibly caused by electrostatic attraction of MgONPs as described by Pugazhendhi et al. [56].Te formed nanoparticle has an average diameter of 38.7 nm, and its particle size dispersion is shown in Figure 3(a).It is intriguing to note that almost all the CP-MgONPs were uniformly disseminated and encompassed by polyphenol biocomponent layer, providing evidence that the CP-MgONPs were capped and distributed by the biocomponents present in citron peel extract.Te elemental composition of CP-MgONPs was examined using energy scattering spectroscopy (EDX).Te EDX chart demonstrated the excellent purity of the presynthesized CP-MgONPs containing Mg and O ions, demonstrating that CP-MgONPs had been successfully produced by exploiting the metabolites of citron peel aqueous extract.Also, the occurrence of two peaks for Mg and O at 0.5-1.5 keV range of bending energies supports the successful MgO formation (Figure 3(b)).Te EDX spectrum showed prominent signals for magnesium and oxygen with mean percentage of 38.47% and 45.79%, respectively.Te existence of carbon (C) peak signal with mean 15.74% as well as weaker peaks for hydrogen (H), chloride (Cl), sodium (Na), and potassium (K) might be due to the presence of bioactive components binding to the surface of presynthesized CP-MgONPs  220), (311), and (222), respectively.Te observed peaks illustrated crystallographic structure and were easily assigned to diferent MgO cubic phase crystal planes devoid of any secondary peak signal, signifying the purity of the presynthesized CP-MgONPs.Te intensity and angular location of the peaks were compared with data and matched those in the reference standard fle (JCDPS No. 75-0447), confrming the emergence of cubic phase of MgO [57].Te size of biogenic CP-MgONPs can be determined according to sharp XRD peak width (200) positioned at a 2θ value of 42.351 °by applying Scherrer's equation.Te fndings revealed that the average crystal size of biogenic CP-MgONPs was 38.7 nm as per XRD analysis.Te green accomplished MgONPs prepared with diferent bioactive metabolites have demonstrated a comparable XRD pattern [48,58].
Furthermore, the thermal stability and oxygen functionality of the caped green biogenic CP-MgONPs were examined by thermogravimetric analysis (TGA).Te thermogram of the CP-MgONPs revealed three identical and constant phases of weight loss (Figure 4(d)).Te initial stage of disintegration takes place between ambient temperature and 180 °C with a weight loss of 2.16%, indicating that watercontaining contaminants have been eliminated from the CP-MgONPs.Te removal of water and water-related impurities was symbolized by wide endothermic peak at around 160 °C with 2.16% of weight loss, while the 5.32% weight decrease in 8 Bioinorganic Chemistry and Applications the second stage was observed between 180 and 552 °C and was associated with breakdown of organic molecules (phenolics and favonoids) that function as capping/reducing agents for the CP-MgONPs.Te appearance of two broad peaks at 240 and 365 °C suggested that the nature of reaction was endothermic at that point.Tis outcome was consistent with that of the FTIR spectra, whereas the third and last phase of decomposition involves disintegration of CP-MgONPs at an elevated temperature between 553 and 800 °C and results in 2.86% of weight reduction.Te percentage purity of biosynthesized CP-MgONPs was estimated to be 92.31% and a comparable TGA range was reported in a previous study for a one-pot crystalline MgONPs synthesis [59].

Antibacterial Activity of Biosynthesized CP-MgONPs.
Antibacterial resistance continues to be a major barrier to controlling of infectious diseases in medical systems, animal husbandry, and the food manufacturing sector.1).However, E. coli, K. pneumoniae, and S. aureus were found to be Ampicillin-resistant, whereas S. pneumoniae and B. cereus were found to be Ampicillinsusceptible.All six strains of pathogen tested in this investigation exhibited sensitivity to the antibiotics Amikacin, Gentamicin, Augmentin, Ciprofoxacin, and Norfoxacin.However, all the applied bacterial strains were resistant to Cefotaxime antibiotic, with the exception of P. aeruginosa.Tus, the result revealed that the highly efcient antibiotics were Augmentin, Gentamicin, Amikacin, Ciprofoxacin, and Norfoxacin, whereas Ampicillin and Cefalexin were the most resisted antibiotics (Table 1).Te antibacterial potency of the biosynthesized CP-MgONPs was examined against six microbial strains utilizing the difusion technique in an agar well.Varied doses (25, 250, 500, and 2500 μg•mL −1 ) of CP-MgONPs were prepared and applied.Te antimicrobial efect exerted by biosynthesized CP-MgONPs that inhibit the proliferation of microorganism was discernible as a distinct inhibition zone as depicted in Figure 5(A).Using 2500 μg•mL −1 concentration as a standard, the biogenic CP-MgONPs showed signifcant activity towards all the used pathogenic strains as demonstrated by Table 2. Te CP-MgO-NPs showed potent susceptibility to E. coli and S. aureus with highest inhibition zones of 20.72 ± 0.33 mm and 19.52 ± 0.05 mm, respectively, at 2500 μg•mL −1 concentration (Figure 5  .On the other hand, K. pneumoniae and S. pneumoniae treated with biogenic CP-MgONP showed moderate growth inhibition, with inhibition zones of 14.24 ± 0.09 mm and 13.92 ± 0.01 mm, respectively.Tus, the biosynthesized CP-MgONPs exhibited good sensitivity response towards the both Gram-positive and Gram-negative bacteria at four diferent doses.Te inhibitory diameter zone widened with the rise in CP-MgONPs doses towards each tested strain of bacteria, suggesting the antibacterial efect is dependent on dose.10 Bioinorganic Chemistry and Applications Te observed antibacterial efect might be the result of nanoparticles entering bacterial cells and inhibiting their growth.Te small size and morphology of biosynthesized CP-MgONPs as well as the profle of the biologically active components found in the biomass of citron peel extract could be the responsible factors for their penetration and consequently the potent antibacterial efect.Previous studies have also demonstrated that MgONPs have dose-dependent inhibitory efects on wide range of pathogenic bacteria [60][61][62].Tese fndings can also be partially attributed to the smallest MgONPs, which have an average diameter of 32-39 nm and have been demonstrated to have potent inhibitory efects against several Gram-negative bacteria in other studies [18].Considering that the MgONPs that were created before have substantial bactericidal properties as a result of the utilization of P. guajava leaves [63], C. sinensis leaves [64], S. costus roots [65], and so on, it is reasonable to conclude that produced MgONPs are a useful bioresource with antibacterial properties that may fnd use in the biomedical feld and other relevant felds.Te precise mechanism behind MgONPs' ability to limit bacterial growth continues to be unresolved, despite the fact that several potential theories have been put forth.Generally, it has been believed that magnesium cations from MgONPs adhered to the negatively charged cell wall of bacteria, which then broke it down, leading to leading denaturing of proteins and ultimately dying of cells [66].Te adherence of magnesium cations to the cell wall conduces to a rise in envelope protein precursors, which in turn promotes a disruption of the proton motive force and inevitably cell demise.It has also been found that MgONPs have the ability to breach the plasma and outer membranes, which depletes intracellular ATP [67].Another hypothesis that has been proposed is that oxygen and silver interact with sulfhydryl moieties on the cell wall to form R-S-S-R bonds, which stop the cell from breathing and force it to die [68].Moreover, recent study evidence has indicated that MgONPs may have antimicrobial efects on microorganisms by accelerating the release of ROS, which causes intracellular material to escape through membranes, harming DNA and proteins, and releasing cellular content, and eventually causing cell death [69].From the results presented in Table 2 and Figure 5, it is apparent that superior antibacterial potential of CP-MgONPs increases with concentration.Similar results were recently reported by Yoon et al. who established that increasing the dosage of formed MgONPs improved their antibacterial activity towards E. coli [70].Das et al. also demonstrated the dose-dependent efectiveness of MgONPs towards the diferent strains of pathogens [71]. Te antibacterial potential of the presynthesized CP-MgONPs was also evaluated by the minimum inhibitory concentration (MIC) method to ascertain the least dosage of CP-MgONPs that can limit the development of bacteria.Te outcome demonstrated that 625 μg•mL −1 was the lowest concentration of CP-MgONPs required to efectively stop E. coli and S. aureus from growing, whereas the lowest inhibitory concentration for B. cereus and P. aeruginosa was achieved at 0.64 μg•mL −1 .Te MIC of CP-MgONPs needed to hinder the growth of K. pneumoniae and S. pneumoniae was 0.78 μg•mL −1 and 0.88 μg•mL −1 , respectively.However, minimum bactericidal concentration (MBC) for B. cereus, E. coli, K. pneumonia, S. aureus, S. pneumonia, and P. aeruginosa was found to be 1.74, 1025, 1.96, 1012, 2.11, and 1.89 μg•mL −1 , respectively.Te lowest (most efective) concentration of CP-MgONPs was found 1.74 μg•mL −1 in the MBC test against the B. cereus.Te values of MIC and MBC for biogenic CP-MgONPs are shown in Table 3.
However, the ability of test microbial strains to endure at varied concentrations of biosynthetic CP-MgONPs was assessed by the growth analysis measurements and tracked over the time at 640 nm optical density.Figure 6(a) illustrates that at 2500 μg•mL −1 of CP-MgONPs, the growth of E. coli, S. aureus, B. cereus, and P. aeruginosa was completely inhibited, but P. aeruginosa and B. cereus bacterial strains exhibited evidence of growth up until the second hour.Te pathogenic strain was still adjusting to the medium when a sharp drop was detected in growth trajectory.An efective inhibition was noticed at 1.25 mg•mL −1 concentration.Te cellular activity has been noticed in E. coli from 0 h to the 1 st h.Following that, a spiraling phase was seen between 2 nd hour and 4 th hour, showing that that CP-MgONPs had disrupted metabolic performance, whereas a stagnant phase was noticed at the 5 th hour that ultimately brought about the dying phase at 6 th hour (Figure 6(b)) [72].Figure 6(c), which represents the Gram-positive pathogenic strain S. aureus, and Figure 6(d), which represents the Gram-negative pathogenic strain P. aeruginosa, respectively, indicate the infuence of time on their survival at various concentrations of CP-MgONPs.
Te bactericidal efects of CP-MgO-NPs, including cell and membrane damage, may be caused by an electrochemical interaction between LPS and Mg 2+ ions or oxidative stress brought on by the spontaneous production of ROS and RNS free radicals.Furthermore, the most susceptible strains were discovered to be E. coli and S. aureus and they were tracked for morphological alterations under SEM (Figure 7).Te results obtained revealed that the shape and size of selected bacterial strains were dramatically changed after the treatment with biogenic CP-MgONPs (Figures 7(c) and 7(f )).Te presynthesized CP-MgONPs can instantly infltrate the peptidoglycan layer of the E. coli and S. aureus cell membrane, rupturing it and allowing components to fow out, killing the pathogenic cell (Figures 7(c) and 7(f )).A positive control for the contrast was chosen to be the pathogenic cells that were not treated (Figures 7(a) and 7(d)).

Anticancer Activity.
Te anticancer activity of biogenic CP-MgONPs was assessed by MTT assay on three cancer cell lines (Hep2, SH-SY5Y, and COLO 205) and results showed that all the cancer cell lines treated with CP-MgONPs had lower cell viability except Hep2.Te IC 50 values of CP-MgONPs were found to be 28.4 μg•mL −1 , 98.3 μg•mL −1 , and 138.4 μg•mL −1 for 24 h, while 15.3 μg•mL −1 , 74 μg•mL −1 , and 96.1 μg•mL −1 for Hep2, SH-SY5Y, and COLO 205 cancer cells, respectively, after 48 h of treatment (Figure 8(A)).Based on the cell viability data, Hep2 cells were found to be Bioinorganic Chemistry and Applications most sensitive with low values of IC 50 and chosen for more research to understand the precise mechanism of action of CP-MgONPs.Te Hep2 cells treated with CP-MgONPs showed growth inhibition as well as telltale signs of cell death as cell contraction, chromatin condensation, membrane blebbing, and rounding up of nuclei in the cytomorphological analysis (Figure 8(B)-(a)-(c)).Unlike the untreated group, that exhibited a population of cells with a high cell density and characteristic epithelial shaped cells.Te cellular absorption of CP-MgONPs through macropinocytosis may have enhanced the formation of ROS, which triggered the apoptotic cascade and provoked cell death as the likely cause of the morphological alterations.On the other hand, the AO/EB double staining clearly    Te probable apoptotic pathway is caused by a rise in ROS levels, which also initiates the pathological alterations such as oxidation of proteins, lipid peroxidation, infammatory conditions, and destruction of DNA.Similar results from a previous study showing that MgO and silica nanoparticles caused delayed apoptosis among human colon cancer (HT-29) cells were reported [73].Most anticancer medications enhance apoptosis in cancerous cells by amending the antioxidant and oxidant status levels.As a result, the levels of ROS species in Hep2 cells exposed to CP-MgONPs were estimated by DCFH-DA staining.It was discovered that the green fuorescence intensity was found to be higher in Hep2 cells administrated with CP-MgONPs than in untreated ones, indicating the high content of ROS in treated cells (Figure 8(B)-(g)-(i)), whereas spectrofuorometric analysis was employed to measure the ROS content in CP-MgONPs-administrated Hep2 cells, and the fndings revealed that intensity had increased by 68%, displaying that the apoptotic action of CP-MgONPs on Hep2 cancer cells causes a rise in ROS level and its accumulation.In addition, the quantity of antioxidant enzymes such LPO, SOD, GSH, GPx, and catalase as well as oxidant producers like LPO was utilized for assessing the damage produced by oxidative stress in Hep2 cancerous cells after treatment with CP-MgONPs.Te results revealed that the MDA levels were 1.2 times higher in CP-MgONPs-treated Hep2 cells in contrast to control group.On the other hand, a decline in the functioning of natural defensive enzyme as well as depletion of nonenzymatic levels of catalase, GPx, SOD, and GSH was observed by 1.2, 2.7, 2.9, and 0.61 times, respectively, in CP-MgONPs-treated Hep2 cells as compared to control group (Figure 9(A)-(a)-(b)).Tese fndings align with a previously disclosed work on ZnONPs-treated HepG2 cells that claimed that alterations in antioxidant/oxidant levels were responsible for the induction of apoptosis [74].After inducing apoptosis, one of the most essential intracellular processes is the perturbation of mitochondrial membrane potential (MMP).Since mitochondria are the major cell structure responsible for producing ROS, any situation that depletes antioxidants or leads to an overabundance of ROS will activate mitochondrial damage.Loss of MMP, a crucial component of apoptosis, has been caused by the rise in ROS levels [75].Te infuence of CP-MgONPs on the MMP loss was assessed by rhodamine 123 staining in this study.Rhodamine 123 with high green fuorescence is a lipophilic cationic dye that exhibits intense green fuorescence may easily pass through undamaged mitochondria and accumulate considerably in their inner membrane.CP-MgONPs-treated Hep2 cells exerted low intensity of green fuorescence of MMP, but high levels of green fuorescence were noticed in untreated cells implying healthy Te two principal signaling channels by which apoptosis is normally initiated are intrinsic and extrinsic signaling pathways, which are controlled by caspases 8 and 9, respectively.Te extrinsic mediated apoptosis pathway is commenced by interaction between receptors of membrane and external ligand like FAS, followed by binding with adapter proteins related to death motif in the intracellular receptor section.Procaspase 8 is recruited by this deathinducing signaling complex (DISC), which then triggers the stimulation of caspase 8 [77].Once caspase 8 is activated, it initiates the cascade signaling that eventually leads to cell demise by activating other caspases of execution like caspase 3, while the intrinsic route is activated by an increase in ROS content and eventually causes cytochrome C to be expelled and MMP to fail continuously.Te enzymes pro-caspase 9, apoptotic protease activating factor 1 (Apaf-1), and dATP combine with the liberated cytosolic cytochrome C to form an apoptosome complex [78].More than a hundred receptors, including lamins, PARP, and several DNA-related proteins that detect and activate signals for breaks in DNA strands, are cleaved by active caspase 3 after it has been triggered by the apoptosome complex through a downstream signaling cascade.PARP is broken by the active caspase 3, and broken segment of PARP is one of the indicators of apoptosis [79].To comprehend the underlying molecular process in CP-MgONPs-treated Hep2 cells inducing apoptosis, the expression of caspase 3, caspase 8, caspase 9, PARP, and lamin was evaluated.It was noticed that Hep2 cells treated with CP-MgONPs exhibited alleviated manifestation of active caspases-3, 8, and 9, PARP, and lamin with the increase in concentration of CP-MgONPs (Figure 10(a)).Te densitometry estimation showed fold enhancement in the manifestation of active caspases-3, 8, and 9, PARP, and lamin by 4.1, 1.9, 3.8, 2.5, and 1.1, respectively, after 24 h in CP-MgONPs-administrated Hep2 cells in contrast to control cells at 60 μg•mL −1 concentrations (Figure 10(b)).Tese results demonstrated that CP-MgONP-induced Hep2 cell death involves both intrinsic and extrinsic apoptotic mechanisms.Comparable outcomes were noted in green synthesized silver nanoparticles prepared from A. calamus by Nakkala et al. [80].

Photocatalytic Activity.
Te photocatalytic efect of biogenic CP-MgONPs produced from citron waste peel extract was tested by degradation of AO-8 dye by photocatalysis under UV light irradiation for 150 min at ambient temperature.After UV light exposure, the absorption peaks' intensity steadily declines over time without altering their positions, and there exists a direct correlation between concentration and dye degradation absorbance.Figure 11(a Bioinorganic Chemistry and Applications process used under UV light irradiation.Te extent of AO-8 dye decoloration was monitored throughout time intervals in both presence and absence of presynthesized CP-MgONPs.It was interesting to note that the UV light barely degraded the AO-8 dye at all, proving that it cannot be degraded by UV light alone.However, the AO-8 dye was almost completely degraded (94%) in the presence of the biogenic CP-MgONPs (Figure 11(b)).Te kinetics of AO-8 dye degradation was commonly described using the Langmuir-Hinshelwood model, and the rate constant was calculated using following equation: where R, C, t, K, and k represent the dye discoloration rate (mg/1 min), dye concentration (mg/l), dye illumination time, adsorption coefcient (l/mg), and rate constant (mg/l min).An extremely diluted solution will have a minuscule concentration (C) and formula would be as under: where K app represents the apparent rate constant.
Te photodegradation process of AO-8 dye represented by 1 st order kinetics graph is illustrated in Figure 11(c) and plotting ln (C o /C) against time produced a straight line whose slope matched the 1 st order rate constant.Te computed regression coefcient (R 2 ) and apparent rate constant (k app ) for the presynthesized CP-MgONPs were found to be 0.9769 and 0.0274 min −1 , respectively.Te results attained were consistent with the literature that has been published [81].Te decolorization of presynthesized CP-MgONPs was allowed after 150 min of treatment in the photocatalysis of AO-8 dye. Figure 11(d) illustrates the AO-8 dye discoloration reaction mechanism.Electron-hole (e − /h + ) pairs are produced when photons of an appropriate wavelength fall on the presynthesized CP-MgONPs [82].
When UV light was applied to the photocatalyst, elevation of electrons (e − ) from the valence band (VB) to the conduction band (CB) would occur and these electrons interact with the photocatalyst surface to produce superoxide ions (O −2 ).Te generated superoxide was protonated to HOO• radicals which then interact with e − and holes (h + ) in the valence band to produce H 2 O 2 .Simultaneously, HOO• radicals react with free water to create H 2 O and OH − Te degradation of dyes was mainly triggered by the fragmentation of the in situ produced H 2 O 2 into two * OH/ OH − .On the contrary, the photogenerated photons h + vb might be trapped on catalyst surface, exchanging charge with the OH− ions that are there or with the surface that has H2O adsorbed to it to generate OH * active species as illustrated below: Te decrease in photogeneration efciency may be due to recombination caused by photogenerated e − /h + not being able to reach their proper locations.Te structural and morphological features would afect the photocatalytic performance since the photocatalytic activity was enabled across the surface of the MgO nanoparticles during their Scheme 1: Extraction, synthesis, characterization, and biological application of biogenic CP-MgONPS using waste peels of citron.
Bioinorganic Chemistry and Applications formation.Te highly crystalline and homogeneous MgO nanoparticles may facilitate efcient photodegradation by lowering the recombination rate of photogenerated e − /h + pairs [83].Te efcient AO-8 dye degradation indicates that CP-MgONPs can act as an efcient photocatalyst to break down organic dyes when exposed to UV radiation.Te CP-MgONPs' reusability as a photocatalyst in the AO-8 dye decomposition procedure was also investigated.Prior to being used for each cycle, the nanoparticles were carefully rinsed three times in a centrifuge.Tree times the photodegradation method has been carried out with comparable circumstances, and degradation outcomes for frst, second, and third cycles showed 94%, 83%, and 72% of AO-8 dye degradation, respectively.Te results demonstrated that the formed CP-MgONPs have excellent reusability and photostability.Prior study has shown almost similar pattern of photocatalytic potential for gold nanoparticle obtained from orange peel extract [84].
Tus, the potential biological applications of formed CP-MgONPs make them an appropriate choice of switching out for nanoparticles made chemically.Additionally, these CP-MgONPs could be used as antimicrobial and anticancer agent, which would ofer a potential remedy for the current crisis.However, in vitro and in vivo research is necessary to learn about their biological characteristics and potential applications.Te whole study has been summarized as graphical abstract (Scheme 1).We frmly believe that in the near future, utilization of wastes peels from diferent citrus plants for the synthesis of nanomaterials will open new way for variety of biomedical applications as nanodrugs [85].More research is still needed to comprehend and identify the exact molecular process by which plants generate MgONPs so that their size and form may be more efectively regulated.Te processes underlying the prolonged toxicity, difusion, absorption, and excretion of these nanoparticles are currently very little understood.

Conclusion
In conclusion, this study clearly ofers afordable, environmentally benign, and simple reproducible strategy for the synthesis of morphologically distinct CP-MgONPs by employing citron waste peels as reducing, capping, and stabilizing agents.Te biosynthesized CP-MgONPs were comprehensively characterized by advanced spectroscopic (UV-Vis, FTIR, and XRD) and modern microscopic (SEM, EDX, and TEM) techniques.Te FTIR result identifes numerous phytochemicals involved in the reduction of ions, leading to CP-MgONPs formation.Biosynthesized CP-MgONPs were found to be well-dispersed, relatively stable, and comparatively smaller in size and shape and attached to an organic layer that included favonoids in the reaction mixture.Te SEM monographs showed that average diameter of formed CP-MgONPs was 34.45-52.13nm range with polyhedral shape.Te biosynthesized CP-MgONPs demonstrated antibacterial and anticancer potential in signifcant levels in a dose-dependent manner.Te explored CP-MgONPs exerted potent antibacterial efectiveness towards particular Gram-negative and Gram-positive strains of bacteria.Although the biogenic CP-MgONPs showed toxicity at higher doses, they exerted outstanding efcacy (almost destroyed 95% of cells) against Hep2 cell line, indicating that they might be the potential alternative for killing the cancer cells at optimum doses.Furthermore, the as-prepared CP-MgONPs showed efcient degradation ability against AO-8 dye in the presence of UV irradiation and about 94% of dye was degraded within 150 min.Tus, the CP-MgONPs can be employed as multifaceted therapeutics for diverse biological and biotechnological applications.Teir biomedical properties and application can be further investigated using in vitro and in vivo studies.

Figure 6 :
Figure 6: Impact of time on survival of (a) each tested bacterial strain at 2.5 mg•mL −1 CP-MgONPs concentration.Impact of time on survival of bacterial strains in 1.25 mg•mL −1 CP-MgONPs concentration on (b) E. coli, (c) S. aureus, and (d) P. aeruginosa.

Figure 7 :
Figure 7: SEM images of (a, d) untreated, (b, e) treated with citron peel extract, and (c, f ) treated with biogenic CP-MgO-NPs representing reshaped E. coli and S. aureus.

Figure 8 :Figure 10 :Figure 9 :
Figure 8: (A) IC 50 values of CP-MgONPs for Hep2, SH-SY5Y, and COLO 205 cancer cells at multiple points in time of 24 and 48 h.(B) Images of Hep2 cells at ×200 magnifcation acquired by phase-contrast microscopy: (b, c) alterations in cytomorphology and growth inhibition, (e, f ) AO/EB stained cells showing apoptotic, and (h, i) DCFH-DA stained cells showing the ROS level efect of synthesized CP-MgO-NPs on the Hep2 cells, at multiple points in time of 24 and 48 h.(a, d, g) Control.

Figure 11 :
Figure 11: (a) Absorbance spectra of degraded AO-8 dye solution, (b) the C/Co vs time interval graph for the biogenic CP-MgONPs, (c) frst-order kinetics graph for the photodegradation of the AO-8 dye, and (d) schematic demonstrating the photocatalytic degradation process of AO-8 dye in presence of biogenic CP-MgONPs.

Table 1 :
Evaluation of antibiogram resistance profles of the tested bacterial strains.

Table 2 :
) indicate the mean ± standard deviation of the bacterial growth inhibition zone diameter data in triplicates for each concentration produced by biogenically synthesized CP-MgO-NPs on the tested bacterial strains.Te values with the same alphabetic superscript in each concentration column were not statistically diferent from each other.
Te value (mm) of mean zones of inhibition produced after treatment with as-synthesized CP-MgO-NPs using citron (Citrus medica) peel extract.