Zeolites-AuNPs assembled interface towards amperometric biosensing of spermidine

- Sensing methodology to detect the spermidine (Spmd) is reported.
- Electrochemical tests using zeolites-gold nanoparticles (AuNPs) modified gold (Au) electrode were performed.
- Analytical applications of the biosensor for determination of Spmd contents in real fish samples.

Detection of the spermidine level (Spmd) present in a sample is a sensible indication of the standard of foodstuffs. A new biosensing electrode having polyamine oxidase (PAO) as the biorecognition element immobilized on the surface of chitosan (CHIT)/zeolites-gold nanoparticles (AuNPs) modified gold (Au) electrode was prepared and applied for determination of Spmd contents in fish homogenates. Zeolite nanocrystals and AuNPs were synthesized via hydrothermal and biological (using Ocimum sanctum leaf extracts) routes respectively and hybrids of zeolites-AuNPs were synthesized by high temperature calcination. Transmission Electron Microscopy (TEM) was used to determine the size of AuNPs and their efficient impregnation onto zeolites was confirmed by Energy Dispersive X-ray (EDX) Spectroscopy studies. Thus synthesized zeolites-AuNPs hybrids, when used with chitosan (CHIT/zeolites-AuNPs), offered a porous structure with high surface area having an activated surface for attaching. This retains the enzyme along with better electron transport properties. Electrochemical Impedance Spectroscopy (EIS) and Scanning Electron Microscopy (SEM) were used to confirm the modification of Au electrode with PAO loaded CHIT/zeolites-AuNPs composite film. Cyclic voltammetry (CV) was used to study the activity of the immobilized PAO electrochemically. Under optimum conditions, the proposed electrochemical sensor showed wide linearity ranging from 0.2-200 μM and a detection limit (LOD) of 0.1 μM (S/N = 3) with favorable reproducibility and stability.

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