Acetylcholinesterase Liquid Crystal Biosensor Based on Modulated Growth of Gold Nanoparticles for Amplified Detection of Acetylcholine and Inhibitor

Abstract

A novel acetylcholinesterase (AChE) liquid crystal (LC) biosensor based on enzymatic growth of gold nanoparticles (Au NPs) has been developed for amplified detection of acetylcholine (ACh) and AChE inhibitor. In this method, AChE mediates the hydrolysis of acetylthiocholine (ATCl) to form thiocholine, and the latter further reduces AuCl(4)(-) to Au NPs without Au nanoseeds. This process, termed biometallization, leads to a great enhancement in the optical signal of the LC biosensor due to the large size of Au NPs, which can greatly disrupt the orientational arrangement of LCs. On the other hand, the hydrolysis of ATCl is inhibited in the presence of ACh or organophosphate pesticides (OPs, a AChE inhibitor), which will decrease the catalytic growth of Au NPs and, as a result, reduce the orientational response of LCs. On the basis of such an inhibition mechanism, the AChE LC biosensor can be used as an effective way to realize the detection of ACh and AChE inhibitors. The results showed that the AChE LC biosensor was highly sensitive to ACh with a detection limit of 15 μmol/L and OPs with a detection limit of 0.3 nmol/L. This study provides a simple and sensitive AChE LC biosensing approach and offers effective signal enhanced strategies for the development of enzyme LC biosensors.

Assembly of carbon nanotubes on a nanoporous gold electrode for acetylcholinesterase biosensor design

“…These impurities are far more potent anti-cholinesterase agents, which inhibit free and immobilized AChE in a concentration-dependent manner [32,33]. This phenomenon was also observed by others [34,35]. With increasing the malathion concentration, the produced current of ATCl on the AChE-MWCNT-CA-NPG electrode decreases (Fig.…”

Fluorescein-5-isothiocyanate-conjugated protein-directed synthesis of gold nanoclusters for fluorescent ratiometric sensing of an enzyme–substrate system

“…For example, hydrogen peroxide (H 2 O 2 )-, thiolcholine-, nicotinamide adenine dinucleotide (NAD)-, and dopamine-catalyzed growth of AuNPs increases the intensity of localized SPR. These phenomena are well suited for probing oxidase , acetylcholineesterase (Liao et al, 2012;Pavlov et al, 2005), NAD + -dependent dehydrogenase (Zhang et al, 2011), and tyrosinase systems.…”

Liquid crystal sensor for the detection of acetylcholine using acetylcholinesterase immobilized on a nanostructured polymeric surface

“…We hypothesized that the enzyme-linked surface treated with carbofuran would not react with ACh, which would then induce a uniform orientation of 5CB because of the lack of topographical change. We incubated the AChE-linked surface with carbofuran dissolved in acetonitrile and DI water in a 1:9 [20,28]. The incubation time of the inhibitor was 25 min to minimize any effects of irreversible reaction, prevent detachment of the inhibitor from the active site of enzyme, and to save detection time [5].…”

“…Recently, Liao et al exploited a LC-based biosensor for amplified detection of ACh and an AChE inhibitor by introduction of a bio-metallization process onto the surface upon which the LC aligns [20]. After immobilizing AChE on the glass substrate, modified by a thiethoxysilybutylaldehyde/N, N-dimethyl-N-octadecyl(3-aminopropyl)trimethoxysilyl chloride, they detected the presence of ACh or an organophosphate pesticide by immersing the surface with a mixture of HAuCl 4 and acetylthiocholine (ATCI).…”