A Novel Label-Free Electrochemical Immunosensor for the Detection of Thyroid Transcription Factor 1 Using Ribbon-like Tungsten Disulfide-Reduced Graphene Oxide Nanohybrids and Gold Nanoparticles.

Thyroid transcription factor 1 (TTF1) is an important cancer-related biomarker for clinical diagnosis, especially for carcinomas of lung and thyroid origin. Herein, a novel label-free electrochemical immunosensor was prepared for TTF1 detection based on nanohybrids of ribbon-like tungsten disulfide-reduced graphene oxide (WS2-rGO) and gold nanoparticles (AuNPs). The proposed immunosensor employed H2O2 as the electrochemical probe because of the excellent peroxidase-like activity of ribbon-like WS2-rGO. The introduction of AuNPs not only enhanced the electrocatalytic activity of the immunosensor, but also provided immobilization sites for binding TTF1 antibodies. The electrochemical signals can be greatly amplified due to their excellent electrochemical performance, which realized the sensitive determination of TTF1 with a wide linear range of 0.025-50 ng mL-1 and a lower detection limit of 0.016 ng mL-1 (S/N = 3). Moreover, the immunosensor exhibited high selectivity, good reproducibility, and robust stability, as well as the ability to detect TTF1 in human serum with satisfactory results. These observed properties of the immunosensor enhance its potential practicability in clinical applications. This method can also be used for the detection of other tumor biomarkers by using the corresponding antigen-antibody complex.

Highly electrocatalytic biosensor based on Hemin@AuNPs/reduced graphene oxide/chitosan nanohybrids for non-enzymatic ultrasensitive detection of hydrogen peroxide in living cells.

A non-enzymatic and highly electrocatalytic H2O2 biosensor was proposed by using a novel electrode composed of hemin-capped biomineralized gold nanoparticles (Hem@AuNPs), reduced graphene oxide (rGO) and chitosan (CS). Owing to the excellent electrocatalytic activity of Hem@AuNPs and great conductivity of rGO, this developed biosensor is capable of ultrasensitive measuring H2O2 in real-time. In addition, the introduction of CS resulted in a film on the electrode, which can enhance the stability by protecting the biosensor from external disturbances. Taking advantages of the peroxidase-like activities of the nanohybrids, the developed electrode exhibited outstanding electrochemical performance toward H2O2 with high selectivity, fast response, superior sensitivity and good stability. More importantly, the lower determination limit of 9.3 nM and wider linear ranges of 5 orders of magnitude enable this biosensor to detect H2O2 releasing from living Hela cells accurately. This work provides tremendous potential for real-time monitoring the secretion of H2O2 in living cells.