Highly photostable nanogels for fluorescence-based theranostics

A novel photo-crosslinkable nanogel is prepared from a biodegradable polymer template with intrinsic photoluminescence and high photostability.The fluorescent nanogels display excellent biodegradability and cytocompatibility owed to the facile synthesis scheme involving a solvent-and surfactant-free onepot reaction,derived entirely from biocompatible monomers citric acid,maleic acid,L-cysteine,and poly(ethylene glycol).The resultant nanogels are less than 200 nm in diameter with a narrow size distribution and monodispersity,and demonstrate long-term structural stability in biological buffer for two weeks.To gauge potential in theranostic applications,the fluorescent nanogels were surface functionalized with biologically active RGD peptides and encapsulated with active anti-cancer drug Doxorubicin,resulting in a pH-responsive controlled drug release in acidic pH resembling tumor environments.The strong fluorescence of the nanogels enabled tracking of targeted drug delivery,showing that drug-loaded nanogels homed into the cytoplasmic regions of prostate cancer cells to significantly induce cell death.These photo-crosslinkable and biodegradable nanogels pose as a strong candidate for theranostic medicine,demonstrating versatile functionalization,high stability in biological buffers,and capacity for real-time fluorescence-based monitoring of targeted drug delivery.