Luminescent Gold Nanorods To Enhance the Near‐Infrared Emission of a Photosensitizer for Targeted Cancer Imaging and Dual Therapy: Experimental and Theoretical Approach

Abstract

Strong plasmon absorption in the near‐infrared (NIR) region renders gold nanorods (GNRs) amenable for biomedical applications, particularly for photothermal 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 GNRs is tuned to match that of the absorption of a photosensitizer (PS) molecule, and energy transfer from the GNR to PS enhances the emission profile of the GNR–PS combination. GNR complexes generally quench the fluorescence emission of nearby chromophores. However, herein, the complex retains or rather enhances the fluorescence through competition in energy transfer. Excitation‐dependent energy transfer has been explained experimentally and theoretically by using DFT calculations, the 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 therapy both in vitro and in vivo. Principal component analysis designates photodynamic therapy a better candidate than that of photothermal therapy for long‐term efficacy in vivo.

A nanoarchitecture of a gold cluster conjugated gold nanorod hybrid system and its application in fluorescence imaging and plasmonic photothermal therapy

“…In order to develop a hybrid nanomaterial, parental materials such as gold nanorods (GNRs) and glutathione stabilized gold clusters (GQCs) were synthesized as per the optimized protocol reported by our group. 31,32,38,39 The broad fluorescence emission in the NIR range around 750 nm (Fig. S1a†) is attributed to the glutathione cluster, Au33 as reported earlier.…”

“…24–26 To impart additional properties and/or to decrease the toxicity, different coatings such as polymers, bifunctional molecules, dye molecules and biomolecules have been explored. 27–32 Apart from these, coating with other metal nano particles (SiO 2 , Pt, and Fe) has also been established. 33–37…”

NIR-II-responsive AuNRs@SiO2–RB@MnO2nanotheranostic for multimodal imaging-guided CDT/PTT synergistic cancer therapy

“…[1][2][3][4][5] Nanomaterials are commonly used in photothermal and photodynamic studies, especially in the field of photothermal therapy (PTT). 3,[6][7][8][9] In PTT, a photothermal agent produces hyperthermia under near-infrared (NIR) irradiation to effectively achieve tumor ablation. [10][11][12] PTT leads to cell damage and enhances the activity of other therapeutic processes based on the increase in temperature.…”

Asialoglycoprotein receptor targeted optical and magnetic resonance imaging and therapy of liver fibrosis using pullulan stabilized multi-functional iron oxide nanoprobe

“…In vivo optical imaging of mice was performed using the Xenogen IVIS spectrum in vivo optical imaging system having excitation filters in the range 430–780 nm and emission filters in the range 500–800 nm 29 , 30 . A series of images are acquired with different combinations of excitations and emissions in the above range.…”