One-step synthesis of triethanolamine-capped Pt nanoparticle for colorimetric and electrochemiluminescent immunoassay of SARS-CoV spike proteins

One-pot synthesis of multifunctional sliver nanoparticles with controlled size for sensitive colorimetric and electrochemiluminescent immunoassay of SARS-CoV-2

Silver nanoparticles (AgNPs) have great potential in a broad range of applications because of their biochemical functionality, unique physical and optical properties. However, it is still a great challenge to synthesize small-size AgNPs with good stability and high performance for biosensors. In this work, triethanolamine and polyacrylic acid modified AgNPs (TEOA@AgNPs-PAA) with controllable size and high catalytic activity for sensitive detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are reported. Monodisperse TEOA@AgNPs-PAA are prepared by the one-pot synthesis using the TEOA and PAA as reducing agent and surfactant, respectively. The size of TEOA@AgNPs-PAA (the average size of 8.65 nm) is 6 times smaller than that of the TEOA@AgNPs (52 ± 1.5 nm) without PAA. The as-prepared TEOA@AgNPs-PAA possess catalytic activity and present mimicking property of horseradish peroxidase, which are employed to fabricate colorimetric biosensors by catalyzing the reaction between H2O2 and 3,3',5,5'-tetramethylbenzidine (TMB) to produce blue oxTMB for sensitive detection of SARS-CoV-2 spiking proteins. Significantly, the small-size TEOA@AgNPs-PAA can catalyze electroreduction process of K2S2O8 to enhance the cathodic ECL signal, and their surface cap abundant TEOA molecules, which can also act as a coreactant to enhance the anodic ECL of Ru(bpy)32+. Under optimal conditions, the fabricate immunosensors for anodic and cathodic ECL determination of SARS-CoV-2 present the detection limits of 9.2 fg/mL and 14.3 fg/mL (S/N = 3), respectively. This work exhibits a promising novel strategy for the development of multifunctional AgNPs as an efficient sensing platform for the clinical diagnosis and biosensing application.

Multi-modal nanoprobe-enabled biosensing platforms: a critical review

Nanomaterials show great potential for applications in biosensing due to their unique physical, chemical, and biological properties. However, the single-modal signal sensing mechanism greatly limits the development of single-modal nanoprobes and their related sensors. Multi-modal nanoprobes can realize the output of fluorescence, colorimetric, electrochemical, and magnetic signals through composite nanomaterials, which can effectively compensate for the defects of single-modal nanoprobes. Following the multi-modal nanoprobes, multi-modal biosensors break through the performance limitation of the current single-modal signal and realize multi-modal signal reading. Herein, the current status and classification of multi-modal nanoprobes are provided. Moreover, the multi-modal signal sensing mechanisms and the working principle of multi-modal biosensing platforms are discussed in detail. We also focus on the applications in pharmaceutical detection, food and environmental fields. Finally, we highlight this field's challenges and development prospects to create potential enlightenment.