Advances in phage display based nano immunosensors for cholera toxin

Nanozyme and bifunctional nanobody-based colorimetric-SERS dual-mode Immunosensor for microcystin-LR detection

Microcystin-LR (MC-LR), a potent cyanotoxin in freshwater, poses a risk of severe liver damage and other health issues, making its detection vital. However, the detection capabilities of conventional antibodies are constrained, which limited their use in immunoassays. In this work, we designed a new bifunctional nanobody, named A2.3-SBP (comprised of nanobody and streptavidin binding peptide), capable of binding with MC-LR and streptavidin. Based on A2.3-SBP and Fe3O4@Au-Pt nanozyme, we introduced an enzyme-free immunosensor that operated in microplate with colorimetric and surface-enhanced Raman scattering (SERS) detection modes. The dual-mode assay showed color changes and SERS intensity directly correlating to MC-LR concentrations with a range from 1.0 to 500 ng/mL and a limit of detection of 0.26 and 0.032 ng/mL, respectively. This strategy eliminated the need for complex enzymatic reactions and realized dual-signal detection of MC-LR in 96 water samples (0.03 μg/kg) within 30 min, suggesting its potential in drinking water detection.

Breaking barriers in electrochemical biosensing using bioinspired peptide and phage probes

Electrochemical biosensing continues to advance tirelessly, overcoming barriers that have kept it from leaving research laboratories for many years. Among them, its compromised performance in complex biological matrices due to fouling or receptor stability issues, the limitations in determining toxic and small analytes, and its use, conditioned to the commercial availability of commercial receptors and the exploration of natural molecular interactions, deserved to be highlighted. To address these challenges, in addition to the intrinsic properties of electrochemical biosensing, its coupling with biomimetic materials has played a fundamental role, among which bioinspired phage and peptide probes stand out. The versatility in design and employment of these probes has opened an unimaginable plethora of possibilities for electrochemical biosensing, improving their performance far beyond the development of highly sensitive and selective devices. The state of the art offers robust electroanalytical biotools, capable of operating in complex samples and with exciting opportunities to discover and determine targets regardless of their toxicity and size, the commercial availability of bioreceptors, and prior knowledge of molecular interactions. With all this in mind, this review offers a panoramic, novel, and updated vision of both the tremendous advances and opportunities offered by the combination of electrochemical biosensors with bioinspired phage and peptide probes and the challenges and research efforts that are envisioned in the immediate future.