Nirmal Prabhakar

Electrochemical determination of M. tuberculosis antigen based on Poly(3,4-ethylenedioxythiophene) and functionalized carbon nanotubes hybrid platform

An electrochemical DNA aptasensor for the detection of Mycobacterium tuberculosis (M. tb) antigen MPT64, was developed using Poly(3,4-ethylenedioxythiophene) (PEDOT) doped with carbon nanotubes (CNTs). The biotinylated aptamer was immobilized onto streptavidin attached to -COOH functionalized CNTs via streptavidin-biotin interaction. Various characterization studies as FT-IR, FE-SEM, EIS and DPV were done to validate each fabrication step of the aptasensor. Optimization studies related to aptamer concentration and response time were performed. The electrochemical signal generated from the aptamer-target molecule interaction was monitored electrochemically by differential pulse voltammetry in the presence of [Fe(CN)6]3-/4- as a redox probe. The aptasensor exhibited limit of detection of 0.5±0.2fgmL-1 within 15min with stability of 27 days at 4°C and reusability of 7 times after repeated regeneration with 50mM NaOH. The potential application of the aptasensor was established by spike-in studies to obtain recovery in between (88-95)%.

Acetylcholinesterase immobilised eggshell membrane-based optical biosensor for organophosphate detection

The development of an optical biosensor for the determination of malathion based on acetylcholinesterase (AChE) inhibition using Ellman’s reagent is reported. The AChE has been immobilised onto the eggshell membrane (ESM) using glutaraldehyde as a cross-linking agent. Scanning Electron Microscopic (SEM) studies and Fourier Transformed Infra-Red (FTIR) characterisations have been carried out to affirm the successful immobilisation of AChE onto the ESM. Under optimum conditions, the developed biosensor estimated the pesticide concentration in the range of 0.1–50 ng/mL with a limit of detection (LOD) of 0.1 ng/mL within 30 min. Parameters affecting the biosensor response such as concentration of enzyme, substrate and inhibition time were optimised. The stability and reusability of the AChE/ESM sensor have been observed as 31 days at 4°C and two times, respectively.