Dopamine-conjugated CuS/chitosan nanocomposite for targeted photothermal drug delivery: In vitro cytotoxicity study to establish bio-compatibility

Abstract The Near-Infrared (NIR) photothermal therapy is used in biomedical applications like anti-cancer and anti-microbial treatments. In a biological system, NIR has deep penetrating ability without harmful side effects. The present work utilizes this property as a trigger in drug delivery applications. The ability of the drug to be released from the composite on application of NIR is examined. Nanospheres of covellite copper sulphide (CuS) with chitosan (CS) as base was synthesized by chemical method. Dopamine was conjugated to the CuS/CS system so that the CuS/CS would act as a nano drug carrier. NIR responsive behaviour of CuS is an ideal photothermal trigger to facilitate the release of the encapsulated drug. The encapsulation of dopamine in the composite was confirmed by FTIR and HRTEM analysis. The composite was further studied by X-ray diffraction technique and thermogravimetric analysis for the structural analysis and thermal stability. The NIR absorption showed the significant plasmonic peak of CuS. The dopamine@CuS/CS nanocomposite was introduced into a dialysis bag and the release of the drug through NIR triggering from the carrier was studied. Cytotoxicity/cell viability assay using MTT and cell cycle assay using flow cytometry were conducted separately for CuS nanoparticles and dopamine@CuS/CS nanocomposite in A549 (lung), L132 (cervical-derived) and SH-SY5Y (neuronal) cells. The viability of the cells and their cell cycle were not affected indicating the carrier as well as the nanocomposite are non-toxic. Thus, this photo-controlled technique is an ideal method to control and manage the targeted release of encapsulated drugs that are non-toxic especially in the context of neurodegenerative diseases.