A signal on an electrochemiluminescence (ECL) biosensor using β-cyclodextrin (CD) functionalized graphitic carbon nitride (g-C3N4) as the luminophore was constructed for sensitive organophosphate pesticides (OPs) detection based on the enzyme inhibition of OPs, showing that the consumption of coreactant triethylamine (Et3N) decreased with a lessening of the acetic acid (HAc) in situ generated by enzymatic reaction.

A glassy carbon electrode (GCE) was modified with a nanocomposite consisting of tetraoctylammonium bromide (TOAB), C60 fullerene, and palladium nanorods (PdNRs). The PdNRs were hydrothermally prepared and had a typical width of 20 ± 2 nm. The nanocomposite forms stable films on the GCE and exhibits a reversible redox pair for the C60/C60− system while rendering the surface to be positively charged. The modified GCE was applied to fabricate an electrochemical biosensor for detecting acetylcholinesterase (AChE) by measurement of the amount of thiocholine formed from acetylthiocholine, best at a working voltage of −0.19 V (vs. SCE). The detection scheme is based on (a) measurement of the activity of ethyl paraoxon-inhibited AChE, and (b) measurement of AChE activity after reactivation with pralidoxime (2-PAM). Compared to the conventional methods using acetylthiocholine as a substrate, the dual method presented here provides data on the AChE activity after inhibition and subsequent reactivation, thereby yielding credible data on reactivated enzyme activity. The linear analytical range for AChE activity extends from 2.5 U L−1 to 250 kU·L−1, and the detection limit is 0.83 U L−1.

•One-dimensional Pd–Au NWs were synthesized.•An ECL biosensor was fabricated for AChE detection based on dual biomarkers for the first time.•The method of dual biomarkers can achieve credible and accurate evaluation for AChE activity.•Pd–Au NWs and AChE–ChOx remarkably amplify the ECL response.One-dimensional Pd–Au nanowires (Pd–Au NWs) were prepared and applied to fabricate an electrochemiluminescence (ECL) biosensor for the detection of acetylcholinesterase (AChE) activity. Compared with single-component of Pd or Au, the bimetallic nanocomposite of Pd–Au NWs offers a larger surface area for the immobilization of enzyme, and displays superior electrocatalytic activity and efficient electron transport capacity. In the presence of AChE and choline oxidase (ChOx), acetylcholine (ATCl) is hydrolyzed by AChE to generate thiocholine, then thiocholine is catalyzed by ChOx to produce H2O2in situ, which serves as the coreactant to effectively enhance the ECL intensity in luminol-ECL system. The detection principle is based on the inhibited AChE and reactivated AChE as dual biomarkers, in which AChE was inhibited by organophosphorus (OP) agents, and then reactivated by obidoxime. Such dual biomarkers method can achieve credible evaluation for AChE activity via providing AChE activity before and after reactivation. The liner range for AChE activity detection was from 0.025 U L−1 to 25 KU L−1 with a low detection limit down to 0.0083 U L−1.

An ultrasensitive electrochemical glucose biosensor has been developed by depositing C60-fullerene functionalized with tetraoctylammonium bromide (C60-TOAB+) on the surface of a glassy carbon electrode (GCE). The glucose-binding protein concanavalin A (Con A) was then linked to the surface. Binding of glucose by Con A affects the electroactivity of the reversible redox couple C60/C60−, and this finding forms the basis for a quantitative glucose assay over the 10 to 10 mM concentration range and with a lower detection limit of 3.3 nM (at an S/N ratio of 3). The sensitivity of this sensor allowed glucose to be determined in saliva. This biosensor possesses excellent selectivity, outstanding reproducibility and good long-term stability.

•PTCA and Au NPs functionalized Ru(dcbpy)32+ exhibited greatly enhanced ECL signal.•MoS2 NF as new ECL quencher could efficiently quench ECL signal of Ru complex.•The new ECL biosensor exhibited good performance for the detection of Con A.A novel signal-off electrochemiluminescence (ECL) biosensor was constructed for concanavalin A (Con A) detection based on the ECL quenching of Ru complex by MoS2 nanoflower (MoS2 NF). In brief, PTCA-Ru-Au NPs as matrix was dropped on the electrode to immobilize phenoxy dextran (DexP) through π-π interaction, where 3,4,9,10-perylenetetracarboxylic acid (PTCA) and Au nanoparticles (Au NPs) could greatly increase the luminous efficiency of Tris (2,2′-bipyridyl-4,4′-dicarboxylato) ruthenium(II) (Ru(dcbpy)32+). Then, DexP as recognition element was bonded with Con A via specific carbohydrate-Con A interaction. Finally, the MoS2 NF-multi-walled carbon nanotubes (MWCNT)-DexP as quenching probe of ECL signal was combined with Con A to successfully fabricate a sandwich type ECL biosensor. Importantly, MoS2 NF as a new ECL quencher showed high ECL quenching efficiency toward Ru complex. Under the optimum detection conditions, a wide liner range of 1.0 pg/mL to 100 ng/mL was achieved with relatively low detection limit of 0.3 pg/mL.

A signal on an electrochemiluminescence (ECL) biosensor using β-cyclodextrin (CD) functionalized graphitic carbon nitride (g-C3N4) as the luminophore was constructed for sensitive organophosphate pesticides (OPs) detection based on the enzyme inhibition of OPs, showing that the consumption of coreactant triethylamine (Et3N) decreased with a lessening of the acetic acid (HAc) in situ generated by enzymatic reaction.