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Abstract: This work described a highly sensitive amperometric biosensor for organophosphates (OPs) pesticides based on immobilization of acetylcholinesterase (AChE) on multiwall carbon nanotubes (MWCNTs)-β-cyclodextrin (β-CD) composite modified glassy carbon electrode. The synthesized composite through polymer wrapping strategy has been characterized by attenuated total reflection Fourier-transform infrared spectra (ATR-FTIR) measurement and scanning electron microscopy (SEM) images. Due to the good dispersibility and porous structures of MWCNTs-β-CD composite, the resulting surface provided a favorable microenvironment for acetylcholinesterase biosensor fabrication and maintained the bioactivity of AChE for screening of OPs exposure. MWCNTs promoted electron-transfer reactions at a lower potential and catalyzed the electro-oxidation of thiocholine, thus increasing detection sensitivity. Based on the inhibition of OPs on the AChE activity, using dimethoate as a model compound, the inhibition of dimethoate was proportional to its concentration ranging from 0.01 to 2.44 and 2.44 to 10.00μM, with a detection limit was 2nM (S/N=3). The developed biosensor exhibited good reproducibility and acceptable stability, thus providing a new promising tool for analysis of enzyme inhibitors. [Copyright &y& Elsevier]

[Display omitted] • Hydroquinone-mediated OPECT biosensing strategy was developed. • ZnSe/Bi 2 MoO 6 heterojunction was employed as photoactive material. • Sensitive and selective detection of FTO protein was achieved. • Hemin catalyzed the oxidation of ZnSe and hydroquinone by H 2 O 2 was employed to achieve signal suppression. • Rhein and perfluorohexane sulfonate inhibited FTO protein activity. Organic photoelectrochemical transistor (OPECT) biosensing is a new concept that combines photoelectrochemical and organic electrochemical transistor biosensing. It reduces background noise and combines both signal amplification for low abundance biomolecule detection. In this work, an OPECT biosensor for the detection of fat mass and obesity-associated protein (FTO) was constructed, in which ZnSe/Bi 2 MoO 6 was chosen as the gate material, hm6ARNA (containing N6-methyladenine RNA sequence) as the target molecule, and hydroquinone as the electron donor. Under FTO oxidation induced RNA demethylation, the formation of hemin loaded with G-quadruplex on the electrode surface was triggered. With the catalysis of hemin-based DNAzyme towards the oxidation reaction caused by H 2 O 2 towards hydroquinone and ZnSe, the electron donor was consumed and ZnSe was oxidized in situ to form SeO 2 which reduced the photo-anodic response. The variation of the gate effectively gated the state of the channel polymer thus producing different channel current responses, a process that was closely related to the content of FTO. In addition, the effects of rhein and potassium perfluorohexanesulfonate on FTO activity were also investigated in this experiment, with IC 50 values of 10.62 μM, 31.28 mg/L respectively. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) are an emerging type of porous crystalline polymers that are built by light elements (typically H, B, C, N, O and Si) via organic covalent bonds. Currently, COFs have been exploited for biomedical application due to their unique properties, such as structural diversity, intrinsic stability, ordered porosity, tailor-made functions, and excellent adsorption features. In particular, COFs are increasingly popular in the construction of biosensors for the detection of various disease biomarkers, and have been extended to the clinical applicability for early diagnostics, medication instruction and prognostic monitoring of diseases. In this review, we mainly summarize the recent advances on COFs-based biosensors for the assay of disease biomarkers with clinical applications. According to the features of molecular structure, disease biomarkers are classified into four categories, including small biological ions/molecules, proteins, nucleic acids, and cancer cells/exosomes. Impressively, COFs-based biosensors present a bright prospect in clinical diagnosis of diseases in both hospital-end and household-end utilization. • Progress on COFs-based biosensors for the assay of disease biomarkers is summarized. • Four categories of disease biomarkers are mainly discussed with the clinical applications. • COFs-based biosensors exhibit excellent sensitivity and anti-interference in diseases diagnosis. • The challenges of COFs-based biosensors are also put forward. [ABSTRACT FROM AUTHOR]