Multipath Regulation Including Size Tuning, Surface State Modification, and Self-Feedback Mechanism Construction Induced High Electrochemiluminescence of Ultrasmall Bi₂Sn₂O₇ Nanoparticles

Here, through size adjustment, surface state modification, and construction of novel self-feedback mechanism (SFM), ultrasmall Bi₂Sn₂O₇ nanoparticles (u-BSO NPs, about 3.54 nm) with excellent electrochemiluminescence (ECL) properties were reported. In the confined ultrasmall volume, the quantum size effect endowed u-BSO NPs with higher surface energy, increased specific surface area, and enhanced electron transfer capabilities compared with bulk Bi₂Sn₂O₇ (b-BSO), which turned on obvious ECL emission. Meanwhile, surface state modifications originated from oxygen vacancies (Ov) contributed to narrower band gap and induced higher concentration and ion diffusion kinetics of coreactant by more positive surface charge, which obviously facilitated the ECL emission. More interestingly, the u-BSO NPs themselves also exhibited strong catalytic activity for reducing the enriched coreactant S₂O₈^2- to accelerate the coreaction efficiency. And the formed ECL SFM further enhanced the ECL performance. Then, the u-BSO NPs were applied to fabricate an ECL biosensor for detecting <i>Vibrio parahaemolyticus</i> (VP)-16S rDNA with a low detection limit of 10.39 aM. A strand displacement amplification and "Locked" fuel chain-mediated entropy-driven circuit (SDA-L-EDC) strategy was proposed, which solved the weaknesses of signal leakage and low target concentration of traditional EDC, achieving more efficient and sensitive detection. Therefore, the strategy of lighting up the ECL of a nonluminous nanomaterial by size adjustment and enhancing ECL emission by surface state modulation and ECL SFM construction can be extended to the study of other nanostructures, providing valuable insights for the development of new ECL emitters and broader application.