Synthesis of cellulose based amino acid functionalized nano-biocomplex: Characterization, antifungal activity, molecular docking and hemocompatibility

Highlights

• Synthesis of new formulation of zinc nano-biocomplex based on oxidized functionalized cellulose.

• Full characterization of zinc nano-biocomplex was performed.

• The antifungal activity of this new complex against Aspergillus spp was promising as well as Hemocompatibility.

• Density Functional Theory and the computational calculation complex were carried out.

Abstract

In this study, amino acid functionalized nano-biocomplex based on cellulose was prepared to avoid use of traditional antifungal agents which easy resist by fungi. Dialdehyde cellulose (DAC) was functionalized via glycine (Gly), where the functionalized cellulose complex (DAC/Gly) was carried out via green method using Zinc salt. The produced nano-biocomplex (DAC/Gly/Zn) was characterized using FTIR, XRD, SEM, EDX, UV–vis and computational DFT. The computational calculation of DAC/Gly and DAC/Gly/Zn by DFT/ B3LYP/6−31 G (d) basis sets was studied. Molecular docking study of composite against fungal protein PDB (3K4Q) and PDB (1KS5) showed interaction energy score (-5.0, -4.2) Kcal/mol with short bond length (2.8 Å, 1.6 Å) for DAC/Gly and DAC/Gly/Zn, respectively. In the context, the mean particle size of DAC/Gly/Zn is 151 nm. Antifungal activity of towards Aspergillus niger, A. terreus, A. flavus And A. fumigatus was evaluated. Results illustrated that DAC/Gly/Zn has antifungal activity higher than DAC/Gly. Inhibition zones of DAC/Gly/Zn (10 mg/mL) towards A.niger, A. terreus, A. flavus and A. fumigatus were 27.3, 8.9, 16.9 and 23.4 nm, while as MICs were 0.156, 2.5, 0.312 and 0.078 mg/mL respectively. Moreover, DAC/Gly/Zn exhibited non-hemolytic effect on human RBCs at concentrations up to 2.5 mg/mL. Consequently, DAC/Gly/Zn is a promising nano-biocomplex as antifungal agent.

Introduction

The resistance of microbes to antimicrobial agent is increased day by day. Moreover, the secondary infection is recorded usually after long term of antibiotics treatment with fungi. Fungal infections significantly increased in the last two decades, with high rates of mortality, especially in immunodeficiency patients (Chang et al., 2017). Pathogenic fungi invade more than 1.2 billion individuals overall the world with at least 1.7 million deaths / year (Gaffi G.P, 2013; Campoy and Adrio, 2017; Chang et al., 2017). Mortality of fungal pathogens becomes equal to drug-resistant Mycobacterium tuberculosis and exceeds malaria (Brown et al., 2012). Invasive fungal infections for human are candidiasis and aspergillosis (Schmiedel and Zimmerli, 2016). The recent annual incidence of invasive aspergillosis, candidiasis, and mucormycosis is over 300,000, 750,000, and 10,000 cases, respectively (Bongomin et al., 2017). The occurrence of invasive aspergillosis, a fatal systemic fungal infection, has increased drastically over the past few decades, and the death toll has risen by more than 300 % (McNeil et al., 2001). Invasive aspergillosis is predominantly caused by Aspergillus fumigatus, although other Aspergillus species, such as Aspergillus flavus, Aspergillus niger, and Aspergillus terreus, also may be involved (Walsh et al., 2008). Aspergillus spores usually enter the lower respiratory tract of the host via inhalation. Other areas where the infection can originate include the sinuses, gastrointestinal (GI) tract, and skin. Symptoms of infection include fever, cough, dyspnea, chest pain and sputum. Invasive aspergillosis can spread to other organs, including the skin, heart and brain (Aula et al., 2014). The widespread use of antifungal drugs leads to produce fungal strains resistant to most of antifungal agents (Pfaller, 2012). Recently, most of pathogenic fungi become resistant to drugs as well as bacteria. Therefore, it must be explore new antifungal agents based on modern biotechnology to control of drug resistant fungi. The new generations of antibiotics are dealing with bacterial infections in general not for fungal infections. Some nano-metals are characterized as antifungal e.g. copper, silver, zinc and slenium etc. However the safety profiles of the effective concentration of these metals usually not fit with human being (Patra et al., 2018; El-Naggar et al., 2020; Hashem et al., 2021). Consequently, zinc is characterized with highly safety profile as well biocompatible and used as drug for treated mineral deficiency (Stoimenov et al., 2002; Brayner et al., 2006). The drug carrier strategies may be playing an important role in increasing of the drug efficiency and activity (Rasoulzadeh and Namazi, 2017). Cellulose is one of lignocellulosic material production, it is widely available and renewable polymers in nature for thousands of years for human basic needs such as drug carrier, sensors, hydrogel, pharmaceuticals, biotechnology and medicine (Dacrory et al., 2018a). Although, cellulose is a naturally existing biopolymer characterized by its renewability, biocompatibility, biodegradability, nontoxicity, low cost and environmentally friendly (Kamala et al., 2019), but it cannot be used as it is because it insoluble in polar solvents due to its inter and intra-molecular hydrogen bonds (Dacrory et al., 2019b). So, it should be chemically modified as a useful way to improve its chemical and physical properties and to extend the range of their uses (Khattab et al., 2019; Akl et al., 2020). Periodate oxidation as a most widely method to modified cellulose to a corresponding dialdehyde cellulose by specifically cleaving the C2–C3 bond of the 1,4-glucan unit (Li et al., 2011; DACRORY et al., 2019a). Mild oxidation of cellulose leads to selective cleavage of the C2-C3 bond in the pyranose ring of the cellulose chain, and converts two hydroxyl groups OH in positions 2, 3 into two aldehyde groups producing ring-opened (Dacrory, 2021). In recent years, dialdehyde polysaccharides have received an increasing attention as an ideal crosslinking agent whose aldehyde groups CO can crosslink with NH₂ of amino acid by Schiff’s base interaction (Guo et al., 2014). Additionally, the conjugation of biopolymer with amino acid leads to increase of its availability and functionality (Basta et al., 2016; Hasanin et al., 2019; Ibrahim et al., 2019; Hasanin and Moustafa, 2020; Abu-Elghait et al., 2021). Thus, this work aimed to prepare new formulation of functionalized dialdyde cellulose based on amino acid with zinc in nanoscale via green method to use as effective antifungal agent. Additionally, molecular docking and computational calculation was investigated for this new formulation to show the binding modes of interaction between the synthesized compounds and microbial protein.