Soft surface-enhanced fluorescence sensing platform based on oil-in-water emulsion stabilized by Brust-Schiffrin silver nanoparticles

Pickering emulsions enhance the fluorescence signal intensity of fluorophores by facilitating the assembly of nanoparticles at the oil-water interface. Here we present a soft bio-sensor for trypsin based on oil-in-water Pickering emulsions stabilized by Silver\Thiols core-shell Nanoparticles covalently conjugated with albumin labeled with fluorescein isothiocyanate (FITC). Trypsin was added at seven different concentrations to cleave the albumin-FITC, and the resulting fluorescent signals were measured both as colloidal dispersions and as Pickering emulsions. The results suggest that fluorescent signal intensities are significantly higher from the Pickering emulsions compared with their equivalent colloidal dispersions with trypsin linearity of 1 ng/mL-1 × 10⁶ ng/mL and limit of detection (LOD) of 0.94 ng/mL. This study highlights the superiority of Pickering emulsions to detect trypsin compared to colloidal dispersions, owing to the assembly of the nanoparticles at the interface of the oil and water phase. These findings suggest that Pickering emulsions may serve as effective soft Metal-Enhanced Fluorescence based biosensors.