Surface plasmon-enhanced electrochemiluminescence of P, N-doped carbon dots for ultrasensitive detection of BRAF gene

Carbon dots (CDs) have shown enormous potential as electrochemiluminescence (ECL) probes for biosensing and bioimaging applications due to their ease of synthesis and modification, high biocompatibility, stable optical and electrochemical properties. However, the mild ECL emission of CDs often restricts their practical applications. Herein, an ECL biosensor for mutant BRAF gene determination was proposed based on the surface plasmon resonance-enhanced ECL (SPR-ECL) between asymmetrically modified amine-gold nanodendrites (am-AuNDs) and phosphorus (P) and nitrogen (N) co-doped CDs (PNCDs). Compared to the N-doped CDs (NCDs), PNCDs exhibited an 8-fold enhanced ECL because of the larger atom size and higher electron-donating ability of P atom compared to N. Due to the surface plasmon resonance effect of am-AuNDs and proper distance controlled by catalytic hairpin assembly (CHA), the ECL signal of PNCDs was remarkably improved based on a nonradiative energy transfer between PNCDs and the am-AuNDs. The as-constructed SPR-ECL biosensor performed well for the detection of mutant B-type Raf kinase (BRAF) gene with high sensitivity, stability and accuracy in the range from 0.5 pM to 2000 pM with a limit of detection (LOD) of 0.34 pM. This work would open a new avenue to boost the ECL performance of carbon nanomaterials for practical applications, especially for bioanalysis and diagnostics.