An optical biosensor based on stacked immobilisation of MBTH
reagent in sol–gel/BA hybrid film and HRP enzyme in chitosan film
was successfully developed in this study. Hybridisation of sol–gel
with hydrophobic monomer BA could reduce the porosity of the
sol–gel film and thus reducing the leaching tendency of hydrophilic
MBTH reagent from the pure sol–gel film. This optical biosensor had
linear response from 0.2 mM to 4.0 mM (R2 = 0.9908) with detection
limit of 0.17 mM and demonstrated good reproducibility and recovery.
The biosensor developed was comparable with the standard
method, HPLC for the determination of capsaicin concentration in
chilli sample.