Sulfur Regulated Boron Nitride Quantum Dots Electrochemiluminescence with Amplified Surface Plasmon Coupling Strategy for BRAF Gene Detection

Because boron nitride quantum dots (BN QDs) have a wider gap (5.0-6.0 eV) than other QDs, the edge configurations, chemical functionalities, and heteroatom dopants can decrease and regulate the band gap of BN QDs, thereby ameliorating the QDs' properties. Now, the precise control and regulation of BN QDs are still at an early stage and is a challenging task. Therefore, we used thiourea and l-cysteine as different sulfur precursors to regulate the BN QDs' optoelectronic properties in this study. It is interesting that two kinds of S-regulated BN QDs present significantly different electrochemiluminescence (ECL) properties and electro-optical activity. Furthermore, a ratiometric and enzyme-free ECL sensing mode is constructed with the amplified surface plasmon coupled-ECL (SPC-ECL) strategy. The proposed DNA sensor can quantify the BRAF gene from 1 pmol/L to 1.5 nmol/L with a limit of detection (LOD) of 0.3 pmol/L. The change of BN QDs' ECL signal was easily observed with a smartphone camera. This work for the first time provides insight into the role of sulfur regulation in enhancing ECL efficiency and the electro-optical activity of BN QDs.