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In this work, we designed a facile and label-free electrochemical biosensor based on intrinsic topological insulator (TI) Bi 2 Se 3 and peptide for the detection of immune checkpoint molecules. With topological protection, Bi 2 Se 3 could have robust surface states with low electronic noise, which was beneficial for the stable and sensitive electron transport between electrode and electrolyte interface. The peptides are easily synthesized and chemically modified, and have good biocompatibility and bioavailability, which is a suitable candidate as the recognition units for immune checkpoint molecules. Therefore, the peptide/Bi 2 Se 3 was developed as a suitable working electrode for the electrochemical biosensor. The basic performance of the designed peptide/Bi 2 Se 3 biosensor was investigated to determine the Anti-HA Tag Antibody and PD-L1 molecules. The linear detection range was from 3.6 × 10−10 mg mL−1 to 3.6 × 10−5 mg mL−1, and the detection limit was 1.07 × 10−11 mg mL−1. Moreover, the biosensor also displayed good selectivity and stability. [Display omitted] • Sensitive electrochemical biosensors combined with topological materials and peptides. • High-quality and large-scale topological crystal with few defects as electrodes. • Effective recognition units of peptides for the immune checkpoint. • A large detection range, good selectivity and stability with low detection limit of the sensing assay. • Excellent discernment in the complicated serum environment for clinical application. [ABSTRACT FROM AUTHOR]

A large-size Bi2Se3 tape electrode (BTE) was prepared by peeling off a 2 × 1 × 0.5 cm high-quality single crystal. The feasibility of using the flexible BTE as an efficient bioplatform to load Au nanoparticles and probe DNA for HIV-1 DNA electrochemical sensing was explored. Differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) show that the resultant biosensor has a wide linear range from 0.1 fM to 1 pM, a low detection limit of 50 aM, excellent selectivity, reproducibility and stability, and is superior to the pM DNA detection level of Pt-Au, graphene-AuNPs hybrid biosensors. This outstanding performance is attributed to the intrinsic surface state of Bi2Se3 topological insulator in facilitating electron transfer. Therefore, BTE electrochemical biosensor platform has great potential in the application for sensitive detection of DNA biomarkers. [ABSTRACT FROM AUTHOR]

• Novel C 2 N based electrode for Hydrogen Evolution Reaction (HER). • C 2 N based electrode has an excellent stability for HER. • Pt coated C 2 N shows a Tafel slope of 53 mV/dec and an overpotential 33 mV. In this work, a novel catalyst based on holey nitrogenated graphene (C 2 N) was developed for hydrogen evolution reaction (HER). C 2 N nanosheets were deposited on Fluorine doped Tin Oxide substrate by using a facile drop-coating method. Electrochemical tests indicated that C 2 N based work electrode exhibited excellent stability in acidic environment. To improve its catalytic performance, various noble-metal nanoparticles were deposited on the surface of C 2 N using physical vapor deposition, including Au, Cu, Co, Ni and Pt. The size most particles was observed to be 3–5 nm, which was beneficial for catalyst reaction. Among those samples with different metal particles, Pt coated C 2 N multi-catalysts exhibited an overpotential of 33 mV and Tafel slope of 53 mV/dec, which outperformed other metal particles, and also pure Pt particles or C 2 N nanosheets without metallic particles, demonstrating its great potential of multi-catalyst Pt/C 2 N for HER application. [ABSTRACT FROM AUTHOR]