Abstract:

Bovine serum albumin(BSA)-modified spin-labeled near-infrared fluorescence gold nanoparticles as bimodal molecular probe was designed and synthesized. Glutathione capped gold nanoparticles(GSH-AuNPs) was synthesized and modified by BSA, the BSA modified fluorescent gold nanoparticles conjugates(GSH-AuNPs@BSA) was spin-labeled by paramagnetic nitroxide radical and gave a spin-labeled conjugate GSH-AuNPs@BSA-TEMPO. The introduction of BSA to the conjugate was to further modify the surface of GSH-AuNPs in order to enhance the intrinsic fluorescence of GSH-AuNPs, and to facilitate the spin labeling. GSH-AuNPs@BSA-TEMPO itself was a weak fluorescent conjugate and showed strong ESR signal properties. Reducing the paramagnetic functional group TEMPO in the as-prepared conjugates to its counterpart hydroxylamine by ascorbic acid, both Off-on fluorescence increase and On-off ESR decrease are observed, showing concentration related bimodal response to ascorbic acid(AA).)

Key words: Near-infrared fluorescent AuNPs, Molecular probe, Nitroxide free radical, Spin-labeled