Biotechnology Research at Amrita Vishwa Vidyapeetham

An electrochemical immunosensing platform capable of detecting Immunoglobulin G (IgG) concentration as low as femtograms was developed based on signal amplification strategy. The immunosensing platform was fabricated using self-assembled monolayers (SAM) of 11- mercaptoundecanoic acid (MUDA) on a gold disc electrode. The covalent immobilization of antibody was achieved through the bonding of a carboxyl group of MUDA and amino group of antibody using [1-ethyl-3-(3-dimethylaminopropyl) carbodiimide] (EDC) and N-hydroxysuccinimide (NHS) chemistry. The formation of SAM and antibody immobilization was analyzed using cyclic voltammetry and electrochemical impedance spectroscopy. The gold nanoparticles conjugated with horseradish peroxidase-labeled secondary antibodies were used as nanolabels, to increase the sensitivity and catalytic efficiency of the immunosensor. The sandwich immunocomplex formed on the electrode surface produced an electrocatalytic response through the reduction of hydrogen peroxide in the presence of thionin. The fabricated immunosensor exhibited two linear ranges that included IgG concentrations of 10 fg mL−1 to 0.1 ng mL−1 and 0.1 to 100 ng mL−1 respectively.

Background: Chitin is the main component of fungal, protozoan and helminth cell wall. Theyhelp to maintain the structural and functional characteristics of these organisms. The chitin wall is dynamicand is repaired, rearranged and synthesized as the cells develop. Active synthesis can be noticedduring cytokinesis, laying of primary septum, maintenance of lateral cell wall integrity and hyphal tipgrowth. Chitin synthesis involves coordinated action of two enzymes namely, chitin synthase (that laysnew cell wall) and chitinase (that removes the older ones). Since chitin synthase is conserved in differenteukaryotic microorganisms that can be a ‘soft target’ for inhibition with small molecules. Whenchitin synthase is inhibited, it leads to the loss of viability of cells owing to the self- disruption of thecell wall by existing chitinase.Methods: In the described study, small molecules from plant sources were screened for their ability tointerfere with hyphal tip growth, by employing Hyphal Tip Burst assay (HTB). Aspergillus niger wasused as the model organism. The specific role of these small molecules in interfering with chitin synthesiswas established with an in-vitro method. The enzyme required was isolated from Aspergillus nigerand its activity was deduced through a novel method involving non-radioactively labelled substrate. Theactivity of the potential lead molecules were also checked against Candida albicans and Caenorhabditiselegans. The latter was adopted as a surrogate for the pathogenic helminths as it shares similarity withregard to cell wall structure and biochemistry. Moreover, it is widely studied and the methodologies arewell established.Results: Out of the 11 compounds and extracts screened, 8 were found to be prospective. They werealso found to be effective against Candida albicans and Caenorhabditis elegans.Conclusion: Purified Methyl Ethyl Ketone (MEK) Fraction1 (F1) of Coconut (Cocos nucifera) ShellExtract (COSE) was found to be more effective against Candida albicans with an IC50 value of 3.04μg/mL and on L4 stage of Caenorhabditis elegans with an IC50 of 77.8 μg/mL.