Polyacrylamide Nanoparticles with Visible and Near-Infrared Autofluorescence

Nowadays, self-fluorescent materials such as quantum dots are widely studied and applied in biomedical field. However, the biggest obstacle is biocompatibility. Here, a novel autofluorescent nanoparticle is constructed by crosslinking polyacrylamide nanoparticles (PAANPs) that contain epsilon-poly-L-lysine with glutaraldehyde (named fPAANPs). The nanoparticle has a mean size of about 16 nm, a zeta potential of about + 16 mV, and strong visible and near-infrared autofluorescence. The nanoparticle can be efficiently internalized into cells with high biocompatibility, the LC50 of which in RAW264.7, HepG2, and Hepa1-6 cells is 6, 9, and 7.5 mg mL(-1), respectively. The nanoparticle shows no visible impact on the mice vitality even at a high intravenously administered dose (126 mg kg(-1)). The autofluorescence of fPAANPs shows high stability, persistence, allowing long-term dynamic imaging for 25 d in subcutaneous injections and 18 d in xenograft tumors in mice. The nanoparticle thus provides a self-traceable nanomaterial that can be exploited as drug carrier and potential photodynamic therapy photosensitizer.