Sensitive and Selective Detection of Antibiotic D-Penicillamine Based on a Dual-Mode Probe of Fluorescent Carbon Dots and Gold Nanoparticles.

This paper reported a dual-mode probe for D-penicillamine on the basis of pH-mediated gold nanoparticles aggregation and fluorescence resonance energy transfer (FRET) from carbon dots. D-penicillamine is a zwitterionic compound and has different forms depending on specific pH ranges. The thiol group of D-penicillamine has high affinity towards the surface of gold nanoparticles and can replace other surface ligands. When pH values were close to its isoelectrical point (pH(I)), the D-penicillamine capped gold nanoparticles aggregated through hydrogen bonding or electrostatic interactions, resulting in the releasing of carbon dots from gold nanoparticles. The dual-mode probe consisted of fluorescent carbon dots and gold nanoparticles, and the fluorescence of carbon dots was quenched by the attached gold nanoparticles due to the FRET. Then, the fluorescence can be recovered in presence of D-penicillamine due to the gold nanoparticles aggregation in specific pH range. Under the optimum conditions, the probe has linear response for D-penicillamine in the 0.25-1.5 µM concentration range with a detection limit of 0.085 µM. This method provides a potential application in sensitive detection of D-penicillamine.

Sensitive detection and imaging of endogenous peroxynitrite using a benzo[d]thiazole derived cyanine probe.

Peroxynitrite is a short-lived endogenous reactive species and plays important roles in many physiological and pathological processes. In this work, we synthesized a near-infrared probe based on the structure of benzothiazole derived cyanine for determination of peroxynitrite (ONOO-). The designed probe specifically reacted with ONOO- through oxidative cleavage of conjugated C˭C double bonds and generating the non-fluorescent product. Meanwhile, the characteristic absorption of the probe at 630 nm greatly decreased after reaction with ONOO-, accompanied by drastic color change from bright blue to green yellow, which exhibited a distinct visual feature. It was demonstrated that the probe could be used to measure ONOO- in a dose-response manner and had a detection limit lower as 26 nM. Furthermore, the probe Cy-SN was applied for the imaging of endogenous ONOO- in living cells by confocal microscopy, which showed good cell permeability and low cytotoxicity. Successful application of probe for exogenous colorimetric detection and endogenous fluorescence imaging of ONOO- is suggesting its great potential applications in biological analysis.