Highly sensitive electrochemical peptide-based biosensor for marine biotoxin detection using a bimetallic platinum and ruthenium nanoparticle-tethered metal-organic framework modified electrode.

Saxitoxin (STX) is a highly toxic small-molecule cyanotoxin that is water-soluble, stable in acidic media, and thermostable. STX is hazardous to human health and the environment in ocean, thus it is an important to detect it at very low concentrations. Herein, we developed an electrochemical peptide-based biosensor for the trace detection of STX in different sample matrix utilizing differential pulse voltammetry (DPV) signal. We synthesized the nanocomposite of zeolitic imidazolate framework-67 (ZIF-67) decorated bimetallic platinum (Pt) and ruthenium (Ru) nanoparticles (Pt-Ru@C/ZIF-67) using impregnation method. The nanocomposite modified with screen-printed electrode (SPE) was subsequently used to detect STX in the range of 1-1,000 ng mL-1, with a detection limit (LOD) of 26.7 pg mL-1. The developed peptide-based biosensor is highly selective and sensitive towards STX detection, thus it represents a promising strategy for the development of novel portable bioassay for monitoring various hazardous molecules in aquatic food chains.

Fine-tuning of MXene-nickel oxide-reduced graphene oxide nanocomposite bioelectrode: Sensor for the detection of influenza virus and viral protein.

Influenza viruses can cause epidemics through inter-human transmission, and the social consequences of viral transmission are incalculable. Current diagnostics for virus detection commonly relies on antibodies or nucleic acid as recognition reagent. However, a more advanced and general method for the facile development of new biosensors is increasing in demand. In this study, we report the fabrication of an ultra-sensitive peptide-based nanobiosensor using a nickel oxide (NiO)-reduced graphene oxide (rGO)/MXene nanocomposite to detect active influenza viruses (H1N1 and H5N2) and viral proteins. The sensing mechanism is based on the signal inhibition, the specific interaction between H1N1 (QMGFMTSPKHSV) and H5N1 (GHPHYNNPSLQL) binding peptides anchored on the NiO-rGO/MXene/glassy carbon electrode (GCE) surface and the viral surface protein hemagglutinin (HA) is the critical factor for the decrease in the peak current of the sensor. In this strategy, the NiO-rGO/MXene nanocomposite results in synergistic signal effects, including electrical conductivity, porosity, electroactive surface area, and active site availability when viruses are deposited on the electrode. Based on these observations, the results showed that the developed nanobiosensor was capable of highly sensitive and specific detection of their corresponding influenza viruses and viral proteins with a very low detection limit (3.63 nM of H1N1 and 2.39 nM for H5N1, respectively) and good recovery. The findings demonstrate that the proposed NiO-rGO/MXene-based peptide biosensor can provide insights for developing a wide range of clinical screening tools for detecting affected patients.