Characterization of Film for Medical Textiles Application

The presented research focuses on the development and characterization of fi lm made from lime peel extracts; well-known for its anti-oxidant and antimicrobial properties. The study includes preparation of fi lm using the solution casting technique and characterization tests including IR spectroscopy, X-ray diff raction, and thermal behaviour through diff erential scanning calorimetry (DSC) and through thermogravimetric analysis (TGA). The fi lm is also analysed for its antibacterial properties. Several functional groups are identifi ed for the diff erent molecules such as cellulose, hemicellulose and lignin, and some polyphenolic compounds such as fl avonoids. The fi lm shows excellent antimicrobial properties against E. Coli and S. Aureus strains.


Introduction
Lime is a fruit being yellowish green in colour and contains a large quantity of vitamin C.Many authors have reported that lime peel extracts have active components such as avonoid and limonene which act as antioxidant, anti-obesity as well as anti-carcinogenic agents and also show a tendency to inhibit tumor growth [1,2].In addition to vitamin C, carotenoids, avonoids, limonoids, phenolic acids are also present in the lime peels which are also bene cial to human health [3][4][5][6][7].e bioactive components are responsible for di erent biological functions, including anti-oxidative, anti-in ammatory, antibacterial, antiallergic, antiviral, anti-proliferative, anti-mutagenic, and anti-carcinogenic activities within the human body [8][9][10][11].Consumption of foods rich in avonoids is essential for preventing several degenerative pathologies, including cardiovascular diseases, atherosclerosis, cataract and several forms of cancer [12].  1) molecules present in the citrus peel are mainly responsible for antibacterial and antioxidant activities and stabilising the free radicals involved in oxidative processes of various reactions taking place inside the human body [15].All the above studies relate to possibilities of using lime peel extracts during various healthcare-related applications.ere has been no work reported so far in the direction of developing polymeric lm from lime peel's extract and its behaviour.So in this paper an attempt has been made to develop the polymeric lm from lime peel's extract and characterise the newly-developed lm in terms of functional group identi cation, thermal behaviour, X-ray diffraction and antibacterial activity.is approach is of interest due to probable wound-care and tissue engineering applications where polymers having antimicrobial properties show several advantages.

Materials and experimental procedure
e materials used for developing the lm are lime peels.Lime peels are extracted from fresh limes that can be purchased from the local markets or local gardens of Jalandhar, India.en lime peels' extract i.e. liquid from the lime peels are collected on a plastic surface by cold pressing of the fresh lime peel.ebrous matrixes are isolated from the lime peel extracts by pressing the plastic surface on a rubbery surface through a manual mechanical process.en 100 mg of brous matrix is dissolved in 10 ml of methylene chloride at room temperature with 65±2% relative humidity in a test tube (Figure 2).e time period required for the dissolution of brous matrix in methylene chloride is much less.A erwards the solution is spread on a petri dish for air-drying for a minimum of 8 hours.Finally a yellowish lm of 1 mm thickness being non-transparent in nature is prepared (Figure 2).In a similar way, 150 mg, 200 mg and 250 mg of brous matrix are each dissolved in 10 ml of methylene chloride in three di erent test tubes giving lms of 1.5 mm, 2 mm and 2.5 mm respectively.

FTIR Spectroscopy (Fourier Transformation
Infrared Spectroscopy) Perkin Elmer (Spectrum BX) FTIR was used for identifying the chemical groups within the lms.A total of 100 scans per sample were taken with a resolution of 4 cm -1 within the frequency range of 400 cm -1 to 4000 cm -1 in the transmission mode.

Wide -Angle X-ray Diff raction
Wide-angle X-ray di raction was carried out using the Panalytical (PW 3040/ 60 X'pert PRO) system.CuKα radiation was used with a wavelength 0.15421 nm.X ray scattering was registered on the equator between 2θ = 2° to 60°.

Thermal analysis
e TGA curves were recorded on an EXSTAR6000 (TG/DTA 6300) instrument at a heating rate of 10°C/min from 25°C to 600°C.e DSC curve was recorded on a Mettler Toledo (DSC 823 e ) instrument at a heating rate 10°C/min from 25°C to 150°C.

Antibacterial activity
e antibacterial activity of the lm was analysed using the standard test method using the shake ask test in accordance with GB 15979-2002 Hygienic Standard for disposable sanitary products.e test culture comprising of E. Coli (a gram negative) and S. Aureus (a gram positive) incubated in a nutrient broth (composed of animal extracts supplied from Himedia Laboratories Pvt.Ltd ® ) was diluted with 0.3 mM phosphate bu er (sterile) to give a working concentration of 1.5-3.0X 105 CFU/ml.Following this, each lm was transferred to a ask containing 50 ml of the working dilution under constant stirring at 190 rpm for one hour.e inoculated plates were incubated at 37°C for 24 hours and the viable cells were counted.
e antimicrobial activity was expressed in % reduction of the bacteria, obtained by comparing the total of viable bacterial cells in the test specimen compared to the control (working dilution without lm).e antimicrobial activity was calcuusing the following equation [16]: where A the total number of surviving cells (CFU/ ml) in the test sample a er the speci ed exposure time and B the zero exposure time before the addition of the specimen for determining A.

Functional Group Identifi cation
From Figure 3, the most intense band at 3435 cm -1 was assigned to the stretching of OH groups of the carbohydrates and those of lignin [17].e signal at 2901 cm -1 is caused by asymmetrical and symmetrical stretching vibrations of the C-H groups.e band at 1803 cm -1 was assigned to the carbonyl (C=O) stretching.It follows from analysis of the literature [18,19] on the IR spectra of lm containing avonoids that the carbonyl group bands had the following vibration frequencies such as 1603 and 1631 cm -1 being the characteristic peaks of the hesperidin types of avonoid.e C-H bending is available at wave number 1454 cm -1 for querecetin type of avonoid.Other typical absorption bands [20] characteristics of pure cellulose are those at wave numbers 1030, 907, 3029-3059 cm -1 .

XRD Analysis
e XRD spectrum of the lm is shown in Figure 4. e X-ray di raction spectrum exhibited a number of well-de ned crystalline peaks as expected for natural organic materials [21,22].Crystallinity is a measure of the amount of crystalline material with respect to the entire amount of polymer material.A crystallinity parameter that was determined using the standard method [23] was 16%.Using the equation [24], L = (kλ)/β cosθ, the crystallite size (L) of the cellulose-I crystal present in the lm was found to be 7 nm at 2θ = 23 °.Where, k is a constant (0.89), β is the peak's full width at half-maximum and λ is the wavelength of radiation.However, the presented lm is a mixture of cellulose and di erent polyphenolic compounds.As seen from Figure 5, the crystalline peaks are noticeable between 2θ = 12° to 2θ = 23° which corresponds to the crystallographic plane family of cellulose-I and another set of peaks appear between 2θ = 30° to 2θ = 52° which may be due to the presence of qurecetin types of avonoid [25,26].According to Chen Run, who described in his PhD thesis [27,28] that the second set of peaks may be due to the presence of hesperetin, rutin types of avonoids [28].

Thermal analysis
e occurrence of chain scission is clearly demonstrated by TGA.If the polymer undergoes degradation, its weight will decrease.TGA and DSC curves of the lm are shown in Figure 5. Corresponding to the weight loss on TGA curves, at least four main thermal events can be clearly distinguished up to 600°C.In the cases of TGA curves [29], the rst weight loss step below 105°C refers to the volatile components and physically adsorbed water molecules within the samples.e main mass losses are associated with the biomass decomposition, essentially to its three main components (hemicelluloses, cellulose and lignin).
e second step from 150 to 265°C can be attributed to decomposition of hemicelluloses.e third decomposition process between 265 and 372°C was associated with the degradation of cellulose [30].Finally, the carbon-carbon linkage [31] between lignin structural units was cleaved within the temperature range from 372 to 570°C.e endothermic peak at 10°C/min rate of heating (Figure 5b) was observed perhaps due to the presence of various volatile oils and physically adsorbed moisture in the sample.e lm is predominantly amorphous which indicates a lesser number of crystals present in the lm.So there is no signi cant melting peak, as shown in the DSC curve.

Antibacterial behaviour
e antibacterial e ect of lm prepared from lime peels' extract with di erent bacterial species in terms of reduction of bacterial count is shown in Table 2  All the samples were very e ective against both test bacteria with a reduction of over 83% for E. Coli and 94% for S. aureus, thus indicating excellent antibacterial properties.e reason behind the antibacterial property may be due to the presence of di erent avonoids and other polyphenolic compounds present in the lm which is also identi ed in the FTIR and XRD results.
4 Conclusions e lm was successfully produced from lime peels' extract.e various active ingredients such as avonoids of rutin, hesperitin and qurecetin were identied using the FTIR method and XRD technique.All the avonoid molecules had very good antioxidant and antibacterial activities.e XRD technique revealed the crystalinity index of the material as 16%.
e thermal behaviour of the material was studied by DSC and TG-DTA techniques.e thermal stability was established with respect to the decompositions of the various constituent elements.
e antibacterial activities of the lms were found to be excellent against E. Coli and S. aureus. is work could yield bene cial outcomes in terms of the development of wound dressing and healthcare materials, and it could act as an e ective method for recycling solid residual wastes, a potential cause of environmental pollution.
*Mean value of three replicates.