NIR-Absorbing Mesoporous Silica-Coated Copper Sulphide Nanostructures for Light-to-Thermal Energy Conversion

Abstract

Plasmonic nanostructures, featuring near infrared (NIR)-absorption, are rising as efficient nanosystems for in vitro photothermal (PT) studies and in vivo PT treatment of cancer diseases. Among the different materials, new plasmonic nanostructures based on Cu2−xS nanocrystals (NCs) are emerging as valuable alternatives to Au nanorods, nanostars and nanoshells, largely exploited as NIR absorbing nanoheaters. Even though Cu2−xS plasmonic properties are not linked to geometry, the role played by their size, shape and surface chemistry is expected to be fundamental for an efficient PT process. Here, Cu2−xS NCs coated with a hydrophilic mesoporous silica shell (MSS) are synthesized by solution-phase strategies, tuning the core geometry, MSS thickness and texture. Besides their loading capability, the silica shell has been widely reported to provide a more robust plasmonic core protection than organic molecular/polymeric coatings, and improved heat flow from the NC to the environment due to a reduced interfacial thermal resistance and direct electron–phonon coupling through the interface. Systematic structural and morphological analysis of the core-shell nanoparticles and an in-depth thermoplasmonic characterization by using a pump beam 808 nm laser, are carried out. The results suggest that large triangular nanoplates (NPLs) coated by a few tens of nanometers thick MSS, show good photostability under laser light irradiation and provide a temperature increase above 38 °C and a 20% PT efficiency upon short irradiation time (60 s) at 6 W/cm2 power density.

Assembling Near-Infrared Dye on the Surface of Near-Infrared Silica-Coated Copper Sulphide Plasmonic Nanoparticles

“…Synthesis of Cu 2-x S@MSS-based nanoparticles. Cu 2-x S@MSS NPs with an average size of 52 nm (σ% 8, Figure 1 b) were obtained by the multistep approach [ 37 ], as described in the experimental section. Specifically, the first stage of synthesis in organic solvent provided Cu 2-x S NPs of nearly 10 nm (σ% 15, Figure 1 a), followed by ligand shell “reconstructuring” by OA and Olam treatment, phase transfer in water, where a lipophilic interaction of the CTAB surfactant with the alkyl chain of the ligands at the NP surface occurred, and finally in situ growth of a uniform MSS around Cu 2-x S NP by sol–gel reaction of TEOS precursor under an alkaline environment.…”

“…In this work, NIR-absorbing plasmonic NPs in the form of copper sulphide NPs (with the general formula Cu 2-x S) are used as a viable material [ 36 ]. These plasmonic NPs have some advantages over noble metals because they are less expensive and more stable upon exposure to light [ 37 ]. Because their LSPR band covers the second (II)-NIR window (i.e., from 1000 to 1700 nm), they have a potential for biomedical applications [ 38 , 39 ].…”

Biomimetic Keratin-Coated Gold Nanoparticles for Photo-Thermal Therapy in a 3D Bioprinted Glioblastoma Tumor Model

“…Both AuNRs and AuBPs exhibit higher photo-thermal efficiency and absorption in the first biological window (700–900 nm), where tissue absorption is low, showing higher light penetration (1–2 cm). In addition, ongoing studies are devoted to developing innovative biomimetic NPs made with different chemical compositions, such as Ag [ 5 ] and CuS [ 31 , 32 ]. This crucial aspect enables the overcoming of several critical issues [ 33 ] and the tackling of new nanomedicine challenges, such as exploiting the synergistic effects of chemotherapeutic agents and PTT.…”

Recent Advances in Copper-Based Organic Complexes and Nanoparticles for Tumor Theranostics

“…Several studies successfully implemented copper for efficient bone regeneration [ 57 ] and anti-inflammatory therapy [ 58 ]. Copper-based nanoparticles also found their place in chemodynamic [ 59 ] and photothermal therapy [ 60 ].…”