Carbon nanotubes — chitosan nanobiocomposite for immunosensor

Carboxylic group functionalized single walled (SW) and multi walled (MW) carbon nanotubes (CNT) have been incorporated into biopolymer matrix of chitosan (CH) to fabricate nanobiocomposite film onto indium–tin–oxide (ITO) coated glass plate for co-immobilization of rabbit-immunoglobulin (r-IgGs) and bovine serum albumin (BSA) to detect ochratoxin-A (OTA). The results of electrochemical studies reveal that presence of both CNT results in increased electro-active surface area of CH leading to enhanced electron transport in these nanobiocomposites. Moreover, in CH–SWCNT and CH–MWCNT nanobiocomposites the availability of NH2/OH group in CH and surface charged CNT also increases loading of the r-IgGs resulting in enhanced electron transport responsible for improved sensing characteristics. Compared to BSA/r-IgGs/CH–MWCNT/ITO immunoelectrode, electrochemical response studies of BSA/r-IgGs/CH–SWCNT/ITO immunoelectrode carried out as a function of OTA concentration exhibits improved linearity as 0.25–6 ng/dL, detection limit as 0.25 ng/dL, response time as 25 s, and sensitivity as 21 μA ng dL− 1 cm− 2 with the regression coefficient as 0.998.