Label-Free and Ultrasensitive Electrochemiluminescent Immunosensor Based on Novel Luminophores of Ce2Sn2O7 Nanocubes.

In this research article, a novel and simple label-free electrochemiluminescence (ECL) immunosensor using cerium stannite (Ce2Sn2O7) nanocubes as brand-new ECL emitters has been suggested for the first time. Ce2Sn2O7 nanocubes prepared by a simple hydrothermal method displayed bright ECL emission, promising biocompatibility, low noxiousness, and perfect stability. On comparison of ECL and photoluminescence (PL) spectra, a surface-state mechanism was proposed to be involved in the ECL emission. After aminofunctionalization with 3-aminopropyltriethoxysilane (APTES), Ce2Sn2O7 could be decorated with gold nanoparticles through Au-NH2 covalent linkage, which yielded Au@Ce2Sn2O7 nanocomposites and further enhanced the ECL emission. To confirm the proposed immunosensor feasibility, carcinoembryonic antigen (CEA) was employed as an exemplary analyte. Based on the abovementioned points, our fabricated immunosensor improved the ECL performance to CEA concentrations in a linear range of 0.001-70 ng/mL with a low limit of detection of 0.53 pg/mL (S/N = 3). With outstanding stability, reproducibility, and specificity, this method is expected to be an innovative one for sensitive analyses of CEA and other biomarkers in real samples.

Electrochemiluminescence behaviour of silver/ZnIn2S4/reduced graphene oxide composites quenched by Au@SiO2 nanoparticles for ultrasensitive insulin detection.

Herein, an effective electrochemiluminescence resonance energy transfer (ECL-RET) immunosensing strategy was proposed using silver/ZnIn2S4/reduced graphene oxide composites (Ag/ZnIn2S4/RGO) as the ECL donor and gold decorated silicon dioxide nanoparticles (Au@SiO2 NPs) as the ECL acceptor. ZnIn2S4 nanosheets (NSs), which exhibited strong ECL emission in the presence of potassium persulfate (K2S2O8) with ECL spectral band at 370-720 nm, were in situ grew on the RGO surface (ZnIn2S4/RGO) by a facile one-step hydrothermal method. Integrating with the morphological and electrical superiorities of RGO and AgNPs, the ECL emission of ZnIn2S4 at 551 nm was dramatically enhanced. Moreover, Au@SiO2 NPs whose UV-vis absorption spectra at 450-650 nm were firstly fabricated as a matched ECL acceptor for Ag/ZnIn2S4/RGO. Due to the fine spectral overlap between the ECL emission spectra of ZnIn2S4 NSs and the absorption spectra of Au@SiO2 NPs, efficient ECL quenching was induced for the sensitive responses and accurate quantification of insulin in real samples. Given the excellent linearity performed in 0.1 pg/mL - 80 ng/mL and the low detection limit achieved at 0.034 pg/mL (S/N = 3), the highly-efficient ECL-RET immunosensor holds splendid potential in detecting insulin and other biomarkers in human serum for the early diagnostics of serious diseases.

Electrochemiluminescence behaviour of silver/silver orthophosphate/graphene oxide quenched by Pd@Au core-shell nanoflowers for ultrasensitive detection of insulin.

Herein, a highly efficient electrochemiluminescence resonance energy transfer (ECL-RET) immunosensor was established for ultrasensitive insulin detection. Silver/silver orthophosphate/graphene oxide composites (Ag/Ag3PO4/GO) were prepared as sensing platform for capture-antibody (Ab1) incubation. Ag3PO4 is a novel ECL donor whose emission could be remarkably enhanced by the synergetic assistance of GO with Ag NPs. Notably, GO presented excellent electrical conductivity and ultrahigh specific surface area to improve the loading capacity Ab1 and Ag3PO4, and Ag NPs with fine biocompatibility and catalytic property could immobilize Ab1 via Ag-N bond and further hasten the electron transfer to catalyze the generation of SO4•- radicals for boosting the ECL emission of donor. To establish a new ECL-RET system, Pd@Au core-shell nanoflower was prepared as a suitable ECL acceptor which could immobilize the detection-antibody (Ab2). Due to the fine spectral overlap, Pd@Au nanoflower could significantly quench the ECL emission of Ag3PO4, causing distinct decreases in ECL intensity. The proposed ECL-RET immunosensor exhibited sensitive response to insulin in a linear range of 0.0001-80 ng/mL with a low detection limit of 0.02 pg/mL (S/N = 3), it not only provides a reliable tool for insulin detection in diagnostics of diabetes, but also lights up a new avenue for designing effective ECL-RET pairs in bioanalysis.