Browsing by Author "Govindachar, DM"

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    Engineering of Tripeptide-Stabilized Gold Nanoclusters with Inherent Photosensitizing Property for Bioimaging and Photodynamic Therapy
    (ACS Sustainable Chem. Eng, 2023-01) Santhakumar, H; Nair, RV; Govindachar, DM; Periyasamy, G; Jayasree, RS
    Gold nanoclusters have the characteristics of small size, unique optical properties, and eco-friendly synthesis that make them promising candidates for biomedical applications, especially for bioimaging. However, their inherent photochemical activity and therapeutic efficiency are largely unknown and remain unexplored. Here, we report a simple one-step green synthesis procedure for the preparation of two tripeptide-stabilized silver-doped gold nanoclusters (TPGNCs) and their photodynamic therapeutic effect on cancer cells and simultaneous imaging. The custom-designed tripeptides were used for the preparation of silver-doped gold nanoclusters with enhanced fluorescence emission. These TPGNCs exhibited strong red fluorescence with high quantum yield, large Stokes shift, good photostability, and excellent biocompatibility toward normal cells. TPGNCs imparted minimum dark toxicity toward breast cancer cells. These TPGNCs exhibited appreciable photosensitization to generate ROS within the cancer cells triggering loss of mitochondrial membrane potential, leading to apoptotic cell death. The photosensitizing ability of TPGNCs will be a new avenue in the area of photoinduced cancer therapy with negligible side effects.
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    Luminescent Gold Nanorod to enhance the NIR emission of Photosensitizer for Targeted Cancer Imaging and Dual therapy: Experimental and Theoretical Approach.
    (Chemistry:A European Journal., 2019-11) Nair, RV; Nair, LV; Govindachar, DM; Santhakumar, H; Nazeer, SS; Rekha, CR; Shenoy, SJ; Periyasamy, G; Jayasree, RS
    The strong plasmon absorption in the near‐infrared (NIR) region render gold nano rods (GNR) amenable for biomedical applications, particularly for photo‐thermal therapy. However, these nanostructures have not been explored for their imaging potential because of their weak emission profile. In this study, the weak fluorescence emission of GNR is tuned to match with the absorption of a photosensitizer molecule (PS), and the energy transfer from GNR to PS enhances emission profile of GNR‐PS combination. GNR complexes generally quench the fluorescence emission of nearby chromophores. However, in the present study, through a competition of energy transfer, the complex retains or rather enhances the fluorescence. The excitation dependent energy transfer has been explained experimentally and theoretically using DFT calculations and CIE chromaticity diagram and power spectrum. The final GNR‐PS complex modified for tumor specificity serves as an excellent organ specific theranostic probe for bioimaging and dual modal therapy, both in vitro and in vivo. Principal component analysis designates photodynamic therapy as a better candidate than the photothermal therapy for long term efficacy, in vivo.