Tunable NIR Absorption Property of a Dithiolene Nickel Complex: A Promising NIR-II Absorption Material for Photothermal Therapy

Abstract

Exogenous photothermal agents absorbing in the second near-infrared optical window (NIR-II, 1000−1700 nm) have received much attention due to their use in noninvasive photothermal therapy. A small quantity of organic NIR-II photothermal agents have been exploited, and the development of organic NIR-II photothermal materials is an urgent need for biological applications. In this study, we designed and synthesized three dithiolene nickel(II) complexes with different ligands bis(phenyl) dithiolene for NiBD-Ph, bis(fluorenyl) dithiolene for NiBD-Fl, and bis(carbazolyl) dithiolene for NiBD-Czand investigated their photophysical properties. These complexes exhibited ligand-dependent NIR absorption performance, centered at 854 nm for NiBD-Ph, 942 nm for NiBD-Fl, and 1010 nm for NiBD-Cz, respectively. NiBD-Cz is wrapped in ethylene oxide/propylene oxide block copolymer (F-127) through a hydrophilic− hydrophobic interaction to form water-soluble NiBD-Cz/F-127 nanoparticles (NiBD-Cz NPs), and the absorption peak of NiBD-Cz NPs are red-shifted to 1036 nm. NiBD-Cz NPs exhibit good dispersibility in water, robust photostability, and a high photothermal conversion efficiency (PCE) of 63.6% under 1064 nm laser irradiation, which is the highest PCE among metal bis(dithiolene) complexes up to now. The high PCE makes it possible to achieve better photothermal treatment effects even at low concentrations and under low-power laser irradiation.

NIR‐II absorbing organic nanoagents for photoacoustic imaging and photothermal therapy

“…In addition, Chen et al used bis(fluorenyl) dithiolene as the ligand to construct nickel (II) dithiolene complex SM5. [45] They used amphiphilic Pluronic F127 to formulate SM5-based ONAs as spherical nanoparticles with a size of 67 nm (Figure 4e). However, only in vitro NIR-II PTT was conducted on a cellular level (HeLa cells) despite the high photothermal conversion efficiency (PTCE) of SM5-based ONAs (Figure 4f,g).…”

“…In addition, Chen et al. used bis(fluorenyl) dithiolene as the ligand to construct nickel (II) dithiolene complex SM5 [45] . They used amphiphilic Pluronic F127 to formulate SM5‐based ONAs as spherical nanoparticles with a size of 67 nm (Figure 4e).…”

“…(g) Live/dead staining for the demonstration of the PTT effect against HeLa cells. Reproduced with permission [45] . Copyright 2021, American Chemical Society.…”

Revealing the synergetic interaction between amino and carbonyl functional groups and their effect on the electronic and optical properties of carbon dots

“…In recent years several comprehensive studies to further the understanding of the role of surface functional groups in the electronic and optical properties of CDs have been conducted based on computational and experimental studies. 9,11–15 This knowledge significantly broadens the potential application of CDs in various applications, such as energy conversion, catalysis, and biomedicine. 16–20 For example, as is well known, the absorption peaks of CDs are mainly in the UV and visible light regions.…”

Nickel Complexes Bearing ONS Chelating Ligands: A Promising Contender for In Vitro Cytotoxicity Effects on Human Pancreatic Cancer MIA-PaCa-2 Cells

“…The development of novel metal complexes for better anticancer activity having lesser side effects is a common concern of chemists. After the discovery of cisplatin, many other reports have been published with concern of anticancer activities. − It has been found that many nickel complexes have shown excellent anticancer activities and sometimes even better than the well-known anticancer drug cisplatin. Sobiesiak et al synthesized nickel complexes bearing thiosemicarbazone-derived ligands which were analyzed for anticancer activity against K562 cells, HeLa cells, and human umbilical vein endothelial cells (HUVECs) by the MTT assay and found better toxicity toward HUVECs under identical reaction conditions .…”