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 nanoparticles (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 (∼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 μg/mL of the hybrid microgels and exposed to 808 nm laser light with a power density of 2 W/cm2 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.