One step electrodeposition of multi-walled carbon nanotubes-chitosan for Quaternary Ammoniums Compounds biosensor

Quaternary Ammoniums Compounds (QACs) are biocide disinfectants used in the food industry to decontaminate and prevent the spread of infection. For example, milk tanks can be decontaminated with benzalkonium chloride (BAC) and/or dimethyldidecylammonium chloride (DDAC). The presence of QAC residues in rinsing water after cleaning and disinfection procedures and in milk products is monitored in industry with commercial tests, which are not sensitive enough.

An enzymatic sensor for the detection of QACs was obtained for the first time. We have developed a simple electrochemical method for the immobilization of acetylcholinesterase (AChE). It was based on the covalent bonding of AChE to a multiwall carbon nanotube (c-MWNT)-cross-linked chitosan (Chi) modified glassy carbon screen-printed electrode (SPE) [1]. The AChE activity was inhibited in the presence of QACs, which induced a change in the measured current.

The native structure of the immobilized enzyme AChE was preserved on this composite film, because of the excellent biocompatibility and non-toxicity of chitosan. This film was elaborated by one-step electrodeposition on a glassy carbon screen-printed electrode (GC).

Incorporation of functionalized multiwalled carbon nanotubes (c-MWCNT) into a chitosan film promoted electron transfer reaction and enhanced the electrochemical response.

Glutaraldehyde (GA) was used as cross-linker to covalently bind the AChE, and efficiently prevented leakage of the enzyme from the film.

A sensitive voltammetric sensor was optimized for the rapid detection of QACs (eg. DDAC) in milk [2]. This biosensor is a promising new tool for QACs analysis.

1. Du, D., et al., Amperometric detection of triazophos pesticide using acetylcholinesterase biosensor based on multiwall carbon nanotube–chitosan matrix. Sensors and Actuators B: Chemical, 2007. 127(2): p. 531-535.
2. Zhai, C., et al., Acetylcholinesterase biosensor based on chitosan/prussian blue/multiwall carbon nanotubes/hollow gold nanospheres nanocomposite film by one-stepelectrodeposition. Biosensors and Bioelectronics, 2013. 42: p. 124-130.