Green synthesis of gold nanoparticle/gelatin/protein nanogels with enhanced bioluminescence/biofluorescence.

Here we report the green synthesis of gelatin/protein hybrid nanogels containing gold nanoparticles (AuNPs) that collectively exhibit metal-enhanced luminescence/fluorescence (MEL/MEF). The gelatin/protein nanogels, prepared by genipin cross-linking of preformed gelatin/protein polyion complexes (PICs), exhibited sizes ranging between 50 and 200 nm, depending on the weight ratio of gelatin and protein. These nanogels serve as reducing and stabilizing agents for the AuNPs, allowing for nucleation in a gel network that exhibits colloidal stability and MEL/MEF. AuNP/gelatin/HRP and AuNP/gelatin/LTF nanogels presented an ~11-fold enhancement of bioluminescence in an HRP-luminol system and a ~50-fold fluorescence enhancement when compared to free LTF in cell uptake experiments. These hybrid nanogels show promise for optically enhanced diagnosis and other therapeutic applications.