Engineering of copper sulfide mediated by phototherapy performance

Copper sulfide based phototherapy, including photothermal therapy and photodynamic therapy, is an emerging minimally invasive treatment of tumor, which the light was converted to heat or reactive oxygen to kill the tumor cells. Compared with conventional chemotherapy and radiation therapy, Cu2-x S based phototherapy is more efficient and has fewer side effects. However, considering the dose-dependent toxicity of Cu2-x S, the performance of Cu2-x S based phototherapy still cannot meet the requirement of the clinical application to now. To overcome this limitation, engineering of Cu2-x S to improve the phototherapy performance by increasing light absorption has attracted extensive attention. For better guidance of Cu2-x S engineering, we outline the currently engineering method being explored, including (1) structural engineering, (2) compositional engineering, (3) functional engineering, and (4) performance engineering. Also, the relationship between the engineering method and phototherapy performance was discussed in this review. In addition, the further development of Cu2-x S based phototherapy is prospected, including smart materials based phototherapy, phototherapy induced immune microenvironment modulation et al. This review will provide new ideas and opportunities for engineering of Cu2-x S with better phototherapy performance. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Probing Bidirectional Plasmon-Plasmon Coupling-Induced Hot Charge Carriers in Dual Plasmonic Au/CuS Nanocrystals

Heterostructured Au/CuS nanocrystals (NCs) exhibit localized surface plasmon resonance (LSPR) centered at two different wavelengths (551 and 1051 nm) with a slight broadening compared to respective homostructured Au and CuS NC spectra. By applying ultrafast transient absorption spectroscopy we show that a resonant excitation at the respective LSPR maxima of the heterostructured Au/CuS NCs leads to the characteristic hot charge carrier relaxation associated with both LSPRs in both cases. A comparison of the dual plasmonic heterostructure with a colloidal mixture of homostructured Au and CuS NCs shows that the coupled dual plasmonic interaction is only active in the heterostructured Au/CuS NCs. By investigating the charge carrier dynamics of the process, we find that the observed interaction is faster than phononic or thermal processes (< 100 fs). The relaxation of the generated hot charge carriers is faster for heterostructured nanocrystals and indicates that the interaction occurs as an energy transfer (we propose Landau damping or interaction via LSPR beat oscillations as possible mechanisms) or charge carrier transfer between both materials. Our results strengthen the understanding of multiplasmonic interactions in heterostructured Au/CuS NCs and will significantly advance applications where these interactions are essential, such as catalytic reactions.

In Situ Partial Sulfidation for Preparing Cu/Cu2−xS Core/Shell Nanorods with Enhanced Photocatalytic Degradation

Herein, we report an approach to prepare Cu/Cu2−xS core/shell nanorods by in situ sulfidation of copper nanorods. Firstly, copper nanorods with tunable longitudinal surface plasmon resonances were synthesized by a seed-mediated method using Au nanoparticles as seeds. A convenient in situ sulfidation method was then applied to convert the outermost layer of Cu nanorods into Cu2−xS, to increase their stability and surface activity in photocatalytic applications. The thickness of Cu2−xS layer can be adjusted by controlling the amount of S source. The Cu/Cu2−xS core/shell nanorods exhibits two characteristic surface plasmon resonances located in visible and near-infrared regions, respectively. The photocatalytic performances of Cu nanorods and their derivatives were evaluated by measuring the degradation rate of methyl orange dyes. Compared with Cu nanorods, the Cu/Cu2−xS core/shell nanorods demonstrate more than a 13.6-fold enhancement in the degradation rate at 40 min. This work suggests a new direction for constructing derivative nanostructures of copper nanorods and exploring their applications.

Dual Plasmonic Au-Cu2-x S Nanocomposites: Design Strategies and Photothermal Properties

Coupling two different materials to create a hybrid nanostructured system is a powerful strategy for achieving synergistically enhanced properties and advanced functionalities. In the case of Au and Cu_2-x S, their combination on the nanoscale results in dual plasmonic Au-Cu_2-x S nanocomposites that exhibit intense photon absorption in both the visible and the near-infrared spectral ranges. Their strong light-absorbing properties translate to superior photothermal transduction efficiency, making them attractive in photothermal-based applications. There are several nanostructure configurations that are possible for the Au-Cu_2-x S system, and the successful fabrication of a particular architecture often requires a carefully planned synthetic strategy. In this Minireview, the different synthetic approaches that can be employed to produce rationally designed Au-Cu_2-x S nanocomposites are presented, with a focus on the experimental protocols that can lead to heterodimer, core-shell, reverse core-shell, and yolk-shell configurations. The photothermal behavior of these materials is also discussed, providing a glimpse of their potential use as photothermally active agents in therapeutic and theranostic applications.

Synthesis of hybrid Au-Ag2S-Cu2-xS nanocrystals with disparate interfacial features

Hybrid nanocrystals (NCs) with multiple components and junctions have attracted considerable attention due to their promising synergistic properties. In particular, great attention has been paid to the manipulation of buried multijunction heterointerfaces because they are closely related to the surface energy and carrier transfer of NCs. However, heterointerfaced NCs are usually constructed by sequential step-by-step pathways, and buried interfaces can only be formed along a given direction, resulting in the one and only spatial orientation of multiple interfaces. In this work, we demonstrate two types of Au-Ag₂S-Cu_2-xS NCs with disparate interfacial features. Specifically, the first type (Type I) is prepared through a routine two-step method and shows that Au domain close to the Ag₂S-Cu_2-xS interface; another type (Type II) is achieved by a facile one-pot synthesis procedure and contains Au domain with an interphase only with the Ag₂S domain, far from the Cu_2-xS domain. More importantly, type II NCs could not be formed through other traditional strategies and an underlying mechanism of formation is developed by monitoring the evolution process. Au@Ag core-shell NCs, metastable Au@Ag₂S NCs and Janus Au-Ag₂S NCs are formed successively before the Cu_2-xS domain appears. We speculate that the Au@Ag₂S intermediate plays an essential role in building the final complex nanostructure. We expect that such a simple and facile one-pot method will be used to fabricate additional asymmetric multicomponent NCs with distinctive interfacial features and promising potential applications.

Growth behavior of Au/Cu2−xS hybrids and their plasmon-enhanced dual-functional catalytic activity

The growth behavior of Au/Cu_2−xS hybrids was investigated, and the obtained half-shell Au(nanospheres)/Cu_2−xS exhibited dual-plasmon enhanced bifunctional catalytic activity.

Generating plasmonic heterostructures by cation exchange and redox reactions of covellite CuS nanocrystals with Au3+ ions

We demonstrate the fabrication of various types of heterostructures, including core-shells and dimers. This is achieved by reacting platelet-shaped covellite (CuS) nanocrystals (NCs) with Au³⁺ ions under various reaction conditions: the exposure of CuS NCs to Au³⁺ ions, in the presence or in the absence of ascorbic acid (AA), leads to the formation of CuS@Au core-shell nanostructures; the reaction of CuS NCs with Au³⁺ ions in the presence of oleylamine (OM) leads to the formation of CuS@Au₂S; the presence of both OM and AA leads to the formation of Au/CuS dimers. Depending on which condition is chosen, either cation exchange (CE) between gold and copper ions is predominant (leading to amorphous Au₂S) or the reduction of Au³⁺ leads to the nucleation of metallic Au domains (which are operated by the AA). In the heterostructures achieved by CE, the Au₂S shell is almost entirely amorphous, and can be converted to polycrystalline upon electron beam irradiation. Finally, when both oleylamine and AA are present in the reaction environment, Au/CuS dimers are formed due to the reduction of Au³⁺ to metallic Au domains which nucleate on top of the CuS seeds. The experimental dual plasmonic bands of the CuS@Au core-shells and Au/CuS dimers are in agreement with the theoretical optical simulations. The procedures described here enable the synthesis of core-shell nanostructures with tunable localized surface plasmon resonances (LSPRs) in the near-infrared (NIR) region, and of plasmonic metal/semiconductor heterostructures with LSPRs in both the NIR and the visible regions.

Localized Surface Plasmon Resonance in Semiconductor Nanocrystals

Localized surface plasmon resonance (LSPR) in semiconductor nanocrystals (NCs) that results in resonant absorption, scattering, and near field enhancement around the NC can be tuned across a wide optical spectral range from visible to far-infrared by synthetically varying doping level, and post synthetically via chemical oxidation and reduction, photochemical control, and electrochemical control. In this review, we will discuss the fundamental electromagnetic dynamics governing light matter interaction in plasmonic semiconductor NCs and the realization of various distinctive physical properties made possible by the advancement of colloidal synthesis routes to such NCs. Here, we will illustrate how free carrier dielectric properties are induced in various semiconductor materials including metal oxides, metal chalcogenides, metal nitrides, silicon, and other materials. We will highlight the applicability and limitations of the Drude model as applied to semiconductors considering the complex band structures and crystal structures that predominate and quantum effects that emerge at nonclassical sizes. We will also emphasize the impact of dopant hybridization with bands of the host lattice as well as the interplay of shape and crystal structure in determining the LSPR characteristics of semiconductor NCs. To illustrate the discussion regarding both physical and synthetic aspects of LSPR-active NCs, we will focus on metal oxides with substantial consideration also of copper chalcogenide NCs, with select examples drawn from the literature on other doped semiconductor materials. Furthermore, we will discuss the promise that LSPR in doped semiconductor NCs holds for a wide range of applications such as infrared spectroscopy, energy-saving technologies like smart windows and waste heat management, biomedical applications including therapy and imaging, and optical applications like two photon upconversion, enhanced luminesence, and infrared metasurfaces.

Diversified copper sulfide (Cu2-xS) micro-/nanostructures: a comprehensive review on synthesis, modifications and applications

As a significant metal chalcogenide, copper sulfide (Cu_2-xS, 0 < x < 1), with a unique semiconducting and nontoxic nature, has received significant attention over the past few decades. Extensive investigations have been employed to the various Cu_2-xS micro-/nanostructures owing to their excellent optoelectronic behavior, potential thermoelectric properties, and promising biomedical applications. As a result, micro-/nanostructured Cu_2-xS with well-controlled morphologies, sizes, crystalline phases, and compositions have been rationally synthesized and applied in the fields of photocatalysis, energy conversion, in vitro biosensing, and in vivo imaging and therapy. However, a comprehensive review on diversified Cu_2-xS micro-/nanostructures is still lacking; therefore, there is an imperative need to thoroughly highlight the new advances made in function-directed Cu_2-xS-based nanocomposites. In this review, we have summarized the important progress made in the diversified Cu_2-xS micro-/nanostructures, including that in the synthetic strategies for the preparation of 0D, 1D, 2D, and 3D micro-/nanostructures (including polyhedral, hierarchical, hollow architectures, and superlattices) and in the development of modified Cu_2-xS-based composites for enhanced performance, as well as their various applications. Furthermore, the present issues and promising research directions are briefly discussed.

Recent advances in the rational design of copper chalcogenide to enhance the photothermal conversion efficiency for the photothermal ablation of cancer cells

Three rational designs and the mechanism for copper chalcogenide to enhance the heat conversion efficiency were discussed.