Characterization of Target effect of Nano-hydrogel by Near-infrared Fluorescent Quantum Dots

Nano-hydrogel is one of the most promising drug carrier for its sensitivity to environmental stimulus. For in vivo optical imaging of nano-hydrogel, the development of novel contrast agents with near-infrared (NIR) fluorescence is especially important. Poly-N-isopropylacrylamide-co-acrylic acid (PNIPA-co-AA) nano-hydrogel was synthesized by precipitation polymerization method. The regulation on the size and lower critical solution temperature (LCST) of the hydrogel nanoparticles were intensively studied. Semiconductor nanocrystals CdHgTe were grown in aqueous solution and then labeled PNIPA-co-AA. PNIPA-co-AA nano-hydrogel has a least diameter distribution around 50 nm and a tunable lower critical solution temperature (LCST) from 35 to 45degC, which made it to have site-specific effect. The nanocrystals were approximately 5 nm in diameter and have a broad fluorescence peak in the NIR spectra range (750 nm). Nanocrystals CdHgTe coated PNIPA-co-AA has good NIR fluorescence sensitivity. The NIR fluorescence of the nanocrystals together with the target effect of PNIPA-co-AA makes them particularly attractive candidates for in vivo imaging and drug pharmacokinetics studies.