In Situ Synthesis of CuS Nanoparticle-Doped Poly(N-isopropylacrylamide)-Based Microgels for Near-Infrared Triggered Photothermal Therapy

Poly(N-isopropylacrylamide)-co-(acrylic acid) (pNIPAm-co-AAc) microgels incorporated with CuS nano particles (CuSNPs) were synthesized and employed for near infrared (NIR) triggered photothermal killing of cancer cells. Cu2+ was enriched in the microgels through deprotonation of the pNIPAm-co-AAc microgels at high solution pH. CuSNPs were subsequently generated within the pNIPAm-co-AAc microgels upon exposure to heat and S2-. The solution of hybrid microgels showed an absorption peak in the NIR region (similar to 1000 nm). After demonstrating that the hybrid microgels were not cytotoxic, we showed that NIR excitation of the hybrid microgels could be used to kill HeLa cells. Almost 90% of the HeLa cells were killed when incubated with 400 mu g/mL of the hybrid microgels and exposed to 808 nm laser light with a power density of 2 W/cm(2) for 10 min. While these materials show promise for photothermal therapy, they can also be incorporated into a hydrogel matrix that can be triggered to release small molecule drugs upon exposure to NIR wavelengths.