A H2O2 biosensor based on the modification of graphite electrode with toluidine blue modified MWCNTs was developed by H. Ju and co workers. HRP was immobilized with the aid of CS for sensing H2O2 with a good stability and reproducibility. Qian and Yang developed a mediator free amperometric biosensor for H2O2. HRP was crosslinked with composite film SU11274 PKI-SU11274 using GA. Sanchez et al. reported the fabrication of MWCNTs/polysulfone biocomposite membrane, which allows the incorporation of HRP enzyme by phase inversion technique. This biocomposite membrane was used for the construction of a H2O2 biosensor. Qu et al. took the combined advantages of CNTs and nano Fe3O4 to prepare a magnetic CNTs/nano Fe3O4 composite by co precipitation. It exhibited higher electrocatalytic activity toward the redox processes of H2O2.
They also introduced CS into the bulk of the composite by co precipitation to immobilize GOx covalently to make an amperometric glucose sensor. Choi et al. constructed a highly sensitive and stable amperometric PXD101 ethanol biosensor based on the immobilization of ADH within a thin composite film of CNTs titania Nafion. Due to the mesoporous nature of this composite film, the present ethanol biosensor exhibited remarkably fast response time and wide linear response range. Santos et al. constructed an amperometric ethanol biosensor based on co immobilization of ADH and Methylene Blue on MWCNTs through the cross linking with GA and agglutination with mineral oil. The amperometric response of this biosensor showed an excellent operational stability and wide linear response range.
Cai and coworkers fabricated a nanocomposite by the functionalization of SWCNTs with poly for ethanol biosensor. Immobilization of ADH onto the modified electrode showed electrocatalytic activity toward the oxidation of ethanol with a good stability, reproducibility, and higher biological affinity. Liu and Cai developed an ethanol biosensor based on the nanocomposites of positively charged PDDA wrapped SWCNTs. The negatively charged ADH was immobilized on the nanocomposites via the charge interaction and this biosensor provided a good electrocatalytic activity toward the oxidation of ethanol with a good stability, reproducibility, and high biological affinity. Yang et al. reported the modification of gold electrodes by self assembling the positively charged Pt nanoparticle MWCNTs CS and negatively charged poly salt for a sensitive cholesterol biosensor.
MWCNTs were dispersed in the Pt nanoparticle doped CS solution to obtained Pt CNTs CHIT material. Cholesterol oxidase was immobilized onto the modified electrode surface using GA. Tang et al. developed an amperometric glutamate biosensor based on self assembly of glutamate dehydrogenase and poly dendrimer encapsulated platinum nanoparticles onto carboxylic acid group functionalized MWCNTs. The modified electrode showed electrocatalytic activity toward the oxidation of glutamate with a good reproducibility and high sensitivity. Lin,s group fabricated a simple and inexpensive choline biosensor based on the immobilization of choline oxidase, ChO and HRP bienzymes onto MWCNTs modified GCE using LBL assembly technique.