Oxygen vacancies boosted vanadium doped ZnO nanostructures-based voltage-switchable binary biosensor

The development of a reliable non-enzymatic multi-analyte biosensor is remained a great challenge for biomedical and industrial applications. In this prospective, rationally designed electrode materials having voltage switchable electrocatalytic properties are highly promising. Here, we report vanadium doped ZnO engineered nanostructures (Zn_1-xV_xO where 0 ≤ x ≤ 0.1) which exhibit voltage switchable electrocatalytic properties for accurate measurements of glucose and hydrogen peroxide. Microstructures and chemical analysis show that the oxygen vacancies in the material can be tuned by controlling the stoichiometric ratios which play key role for voltage dependent measurements of different analytes. The developed Zn_1-xV_xO nanostructures exhibit outstanding sensing ability for binary analytes with a high selectivity, low detection limit, thermal stability and long-term stability. The Zn_0.9V_0.1O/glassy carbon (GC) electrode shows 3-fold increase in reproducible sensitivity for both glucose (655.24μA mM^-1cm^-2) and H₂O₂(13309.37μA mM^-1cm^-2) as compared to the pristine ZnO/GC electrode. Moreover, the electrode also shows good response for human blood serum and commercially available samples. The results demonstrate that defect engineering is a promising route for the development of cost-effective non-enzymatic multi-analyte sensors for practical applications.

Self-Assembled Chromogenic Polymeric Nanoparticle-Laden Nanocarrier as a Signal Carrier for Derivative Binary Responsive Virus Detection

In the current biosensor, the signal generation is limited to single virus detection in the reaction chamber. An adaptive strategy is required to enable the recognition of multiple viruses for diagnostics and surveillance. In this work, a nanocarrier is deployed to bring specific signal amplification into the biosensor, depending on the target viruses. The nanocarrier is designed using pH-sensitive polymeric nanoparticle-laden nanocarriers (PNLNs) prepared by sequential nanoprecipitation. The nanoprecipitation of two chromogens, phenolphthalein (PP) and thymolphthalein (TP), is investigated in three different solvent systems in which PNLNs demonstrate a high loading of the chromogen up to 59.75% in dimethylformamide (DMF)/dimethyl sulfoxide (DMSO)/ethanol attributing to the coprecipitation degree of the chromogens and the polymer. The PP-encapsulated PNLNs (PP@PNLNs) and TP-encapsulated PNLNs (TP@PNLNs) are conjugated to antibodies specific to target viruses, influenza virus A subtype H1N1 (IV/A/H1N1) and H3N2 (IV/A/H3N2), respectively. After the addition of anti-IV/A antibody-conjugated magnetic nanoparticles (MNPs) and magnetic separation, the enriched PNLNs/virus/MNPs sandwich structure is treated in an alkaline solution. It demonstrates a synergy reaction in which the degradation of the polymeric boundary and the pH-induced colorimetric development of the chromogen occurred. The derivative binary biosensor shows feasible detection on IV/A with excellent specificities of PP@PNLNs on IV/A/H1N1 and TP@PNLNs on IV/A/H3N2 with LODs of 27.56 and 28.38 fg mL^-1, respectively. It intrigues the distinguished analytical signal in human serum with a variance coefficient of 25.8% and a recovery of 93.6-110.6% for one-step subtype influenza virus detection.