Copper Sulfide Nanocrystals Research Articles

Atomic‐Thin 2D Copper Sulfide Nanocrystals with over 94% Photothermal Conversion Efficiency as Superior NIR‐II Photoacoustic Agents

Atomic‐Thin 2D Copper Sulfide Nanocrystals with over 94% Photothermal Conversion Efficiency as Superior NIR‐II Photoacoustic Agents

A multifunctional nanotheranostic agent based on Lenvatinib for multimodal synergistic hepatocellular carcinoma therapy with remarkably enhanced efficacy

Lenvatinib (LT), a first-line molecular targeted therapeutic drug for hepatocellular carcinoma (HCC), has been replacing the status of Sorafenib (SF) as the clinically preferred and irreplaceable treatment for a decade. To overcome the low drug utilization and limited single efficacy of LT, ultrasmall copper sulfide nanocrystals (Cu2-xS NCs), and ultrasmall gold nanoparticle (AuNPs) were evenly wrapped into galactosamine conjugated poly(lactide-co-glycolide) (PLGA) as the drug delivery nanoparticles (CAL@PG) by nanoprecipitation. The CAL@PG NPs exhibited excellent stability under physiological conditions, whereas they released LT rapidly in the unique tumor microenvironment (TME) and high temperature, which could be provided by the near-infrared-II (NIR-II) photothermal effect of Cu2-xS NCs. Moreover, the temperature elevation, regenerated hydrogen peroxide (H2O2), and lower pH of TME could substantially boost the reaction potency of copper Fenton-like chemistry. More importantly, this combined therapy significantly improved the efficacy of LT, provided a multifunctional LT delivery system, and enriched the nanoparticle-augmented multimodal synergistic HCC therapy modality.

Electrochemical lithium doping of Cu2−xS nanocrystal assemblies for tuning their near infrared absorbance

The characteristic NIR of copper sulfide nanocrystals (Cu2−xS NCs) assemblies based on the LSPR can be controlled by exploiting monovalent lithium ions through electrochemical methods.

Reusable Cu2-xS-modified masks with infrared lamp-driven antibacterial and antiviral activity for real-time personal protection

Disposable surgical masks are widely used by the general public since the onset of the coronavirus outbreak in 2019. However, current surgical masks cannot self-sterilize for reuse or recycling for other purposes, resulting in high economic and environmental costs. To solve these issue, herein we report a novel low-cost surgical mask decorated with copper sulfide (Cu2-xS) nanocrystals for photothermal sterilization in a short time (6 min). With the spun-bonded nonwoven fabrics (SNF) layer from surgical masks as the substrate, Cu2-xS nanocrystals are in-situ grown on their surface with the help of a commercial textile adhesion promoter. The SNF-Cu2-xS layer possesses good hydrophobicity and strong near infrared absorption. Under the irradiation with an infrared baking lamp (IR lamp, 50 mW cm−2), the surface temperature of SNF-Cu2-xS layer on masks can quickly increase to over 78 °C, resulting from the high photothermal effects of Cu2-xS nanocrystals. As a result, the polluted masks exhibit an outstanding antibacterial rate of 99.9999% and 85.4% for the Escherichia coli (E.coli) and Staphylococcus aureus (S. aureus) as well as the inactivation of human coronavirus OC43 (3.18-log10 decay) and influenza A virus A/PR/8/34 (H1N1) (3.93-log10 decay) after 6 min irradiation, and achieve rapid sterilization for reuse and recycling. Therefore, such Cu2-xS-modified masks with IR lamp-driven antibacterial and antiviral activity have great potential for real-time personal protection.

Stoichiometric Doping of Highly Coupled Cu2–xS Nanocrystal Assemblies

The hole density of individual copper sulfide nanocrystals (Cu2-xS NCs) is determined from the stoichiometric mismatch (x) between copper and sulfide atoms. Consequently, the electronic properties of the material vary over a range of x. To exploit Cu2-xS NCs in devices, assemblies of NCs are typically required. Herein, we investigate the influence of x, referred to as the stoichiometric doping effect, on the structural, optical, electrical, and thermoelectric properties of electronically coupled Cu2-xS NC assemblies. The doping process is done by immersing the solid NC assemblies into a solution containing a Cu(I) complex for different durations (0-10 min). As Cu+ gradually occupied the copper-deficient sites of Cu2-xS NCs, x could be controlled from 0.9 to less than 0.1. Consequently, the near-infrared (NIR) absorbance of Cu2-xS NC assemblies changes systematically with x. With increasing x, electrical conductivity increased and the Seebeck coefficient decreased systematically, leading to the maximal thermoelectric power factor from a film of Cu2-xS NCs at an optimal doping condition yielding x = 0.1. The physical characteristics of the Cu2-xS NC assemblies investigated herein will provide guidelines for exploiting this emerging class of nanocrystal system based on doping.

Greatly improved NIR shielding performance of CuS nanocrystals by gallium doping for energy efficient window

In this work, gallium doped copper sulfide (Ga-doped CuS) nanocrystals were prepared using a solvothermal method. The effects of Ga doping on the crystal structures, chemical composition, morphology, optical properties and thermal performance of copper sulfide (CuS) were investigated. The Ga-doped CuS nanocrystals had a hexagonal structure comparable to that of pure CuS. The Cu+/Cu2+ ratio first decreased and then increased with increasing Ga3+ doping. Both CuS and Ga-doped CuS exhibited nanoplate and nanorod morphologies. The visible transmittance of the Ga-doped CuS films was in the range of 61–77.1%. Importantly, the near-infrared (NIR) shielding performance of the films can be tuned by adjusting the concentration of the Ga dopant. The NIR shielding value of the optimal Ga-doped CuS film was 72.4%, which was approximately 1.5 times as high as that of the pure CuS film. This can be ascribed to the enhanced plasmonic NIR absorption that resulted from an increase in the hole concentration after doping with Ga3+ ions. In the thermal performance test, the Ga-doped CuS film lowered the interior temperature of the heat box by 9.1 °C. Therefore, the integration of good visible transmittance and high NIR shielding performance make the Ga-doped CuS nanocrystals a promising candidate for energy-efficient window coatings.

Synthesis of flower and biconcave shape CuS: Enhancement of super-capacitance properties via Ni–CuS nanocomposite formation

Copper sulphide nanocrystals (NCs) and their derivatives are rapidly gaining attention of researchers due to wide variety of exciting physical properties. These properties can be further tuned by varying morphology and incorporation of suitable elements. Here, we report a simple and facile method for the synthesis of hierarchical flower shape CuS containing 30–40 nm thick nanosheets and Ni–CuS nanocomposite with varying molar ratio of Ni to CuS. It is observed that the formation of hierarchical flower shape of CuS is significantly depend on the type of sulfur source and metal to sulfur precursor ratio. The incorporation of uniformly decorated nickel particles on CuS micro flowers increased electrochemically active sites leading to better ion diffusion kinetics. Further, the specific capacitance value of Ni–CuS (molar ratio of 0.6:1) reflected significant enhancement, more than three times (464.03 F/g at 2 A/g), than the pure CuS (132.89 F/g at 2 A/g) submicron flowers with excellent cyclic stability.

Insights into Nucleation and Growth of Colloidal Quaternary Nanocrystals by Multimodal X-ray Analysis.

Copper chalcogenide nanocrystals find applications in photovoltaic inks, bio labels, and thermoelectric materials. We reveal insights in the nucleation and growth during synthesis of anisotropic Cu2ZnSnS4 nanocrystals by simultaneously performing in situ X-ray absorption spectroscopy (XAS) and small-angle X-ray scattering (SAXS). Real-time XAFS reveals that upon thiol injection into the reaction flask, a key copper thiolate intermediate species is formed within fractions of seconds, which decomposes further within a narrow temperature and time window to form copper sulfide nanocrystals. These nanocrystals convert into Cu2ZnSnS4 nanorods by sequentially incorporating Sn and Zn. Real-time SAXS and ex situ TEM of aliquots corroborate these findings. Our work demonstrates how combined in situ X-ray absorption and small-angle X-ray scattering enables the understanding of mechanistic pathways in colloidal nanocrystal formation.

Copper Sulfide Nanoassemblies for Catalytic and Photoresponsive Eradication of Bacteria from Infected Wounds.

Bovine serum albumin (BSA)-encapsulated copper sulfide nanocrystals (CuS NCs) were prepared by heating an alkaline solution containing copper ions and BSA without an additional sulfur source. At a high BSA concentration (0.8 mM), nanoassembly of the as-formed CuS NCs occurs to form BSA-CuS NCs as a result of the formation of BSA gel-like structures. In addition to their intrinsic photothermal properties, the BSA-CuS NCs possess rich surface vacancies and thus exhibit enzyme-like and photodynamic activities. Spontaneous generation of hydrogen peroxide (H2O2) led to the in situ formation of copper peroxide (CPO) nanodots on the BSA-CuS NCs to catalyze singlet oxygen radical generation. The antimicrobial response was enhanced by >60-fold upon NIR laser irradiation, which was ascribed to the combined effect of the photodynamic and photothermal inactivation of bacteria. Furthermore, BSA-CuS NCs were transdermally administered onto a methicillin-resistant Staphylococcus aureus-infected wound and eradicated >99% of bacteria in just 1 min under NIR illumination due to the additional peroxidase-like activity of BSA-CuS NCs, transforming H2O2 at the infection site into hydroxyl radicals and thus increasing the synergistic effect from photodynamic and photothermal treatment. The BSA-CuS NCs exhibited insignificant in vitro cytotoxicity and hemolysis and thus can serve as highly biocompatible bactericides in preclinical applications to effectively eradicate bacteria.

Lenvatinib and Cu2-xS nanocrystals co-encapsulated in poly(D,L-lactide-co-glycolide) for synergistic chemo-photothermal therapy against advanced hepatocellular carcinoma.

Lenvatinib (LT) is gradually replacing sorafenib as an alternative targeted drug against advanced hepatocellular carcinoma (HCC). However, the anticancer effects of LT are still limited because of its low cytotoxicity, multidrug resistance (MDR), and tumor relapse. Herein, we constructed a smart biophotonic nanoplatform to overcome the barriers preventing high performance. LT and copper sulfide nanocrystals (Cu2-xS NCs) with excellent photothermal properties in the near-infrared-II (NIR-II) zone were co-encapsulated in poly(D,L-lactide-co-glycolide) (PLGA) through nanoprecipitation. Both in vitro and in vivo evaluations demonstrated that Cu2-xS NCs enhanced the anticancer efficacy of LT, without recurrence. In addition, the presence of copper ions could allow glutathione (GHS) to be consumed and oxygen to be produced, likely suppressing the expression of P-glycoprotein (P-gp) and overcoming the issue of MDR relating to LT. More importantly, synergistic chemo-photothermal therapy with LT and Cu2-xS NCs was more effective than any single therapy or theoretical combination. This nanoplatform is promising for advancing future LT-based treatment strategies for HCC therapy.

Seeded Growth Combined with Cation Exchange for the Synthesis of Anisotropic Cu2-x S/ZnS, Cu2-x S, and CuInS2 Nanorods.

Colloidal copper(I) sulfide (Cu2–xS) nanocrystals (NCs) have attracted much attention for a wide range of applications because of their unique optoelectronic properties, driving scientists to explore the potential of using Cu2–xS NCs as seeds in the synthesis of heteronanocrystals to achieve new multifunctional materials. Herein, we developed a multistep synthesis strategy toward Cu2–xS/ZnS heteronanorods. The Janus-type Cu2–xS/ZnS heteronanorods are obtained by the injection of hexagonal high-chalcocite Cu2–xS seed NCs in a hot zinc oleate solution in the presence of suitable surfactants, 20 s after the injection of sulfur precursors. The Cu2–xS seed NCs undergo rapid aggregation and coalescence in the first few seconds after the injection, forming larger NCs that act as the effective seeds for heteronucleation and growth of ZnS. The ZnS heteronucleation occurs on a single (100) facet of the Cu2–xS seed NCs and is followed by fast anisotropic growth along a direction that is perpendicular to the c-axis, thus leading to Cu2–xS/ZnS Janus-type heteronanorods with a sharp heterointerface. Interestingly, the high-chalcocite crystal structure of the injected Cu2–xS seed NCs is preserved in the Cu2–xS segments of the heteronanorods because of the high-thermodynamic stability of this Cu2–xS phase. The Cu2–xS/ZnS heteronanorods are subsequently converted into single-component Cu2–xS and CuInS2 nanorods by postsynthetic topotactic cation exchange. This work expands the possibilities for the rational synthesis of colloidal multicomponent heteronanorods by allowing the design principles of postsynthetic heteroepitaxial seeded growth and nanoscale cation exchange to be combined, yielding access to a plethora of multicomponent heteronanorods with diameters in the quantum confinement regime.

Quaternized chitosan-assisted in situ synthesized CuS/cellulose nanofibers conductive paper for flexible electrode

Cellulose nanofibers (CNF) are considered to be a potential substrate of energy material for energy storage devices due to the foldable, lightweight, recyclable and environmentally friendly feature. However, the energy materials tend to distribute unevenly or fall off from CNF easily, resulting in the decrease of the devices’ overall performance. Here, for the first time, we used quaternized chitosan (QCS) as stabilizer and adhesive to in situ synthesize and deposite copper sulfide nanocrystals (CuS-NCs) on CNF and further obtained the conductive paper for flexible supercapacitors. In the presence of QCS, CuS-NCs deposited in situ on CNF can be capped and stabilized by the QCS molecular chains for uniform distribution, which is conducive to the capacitive behavior and electrochemical stability of composite paper. The result shows that the specific capacitance of the composite paper was as high as 314.3 F/g at a current density of 1 A/g, a high rate capacitance of 252.6 F/g was achieved even at a high current density of 10 A/g. It reveals that the composite paper exhibited better electrochemical performance than many other CuS-based electrode materials for supercapacitor. More importantly, the composite paper performed well in various folding state without changing much electrochemical performance. Therefore, this work provides a novel strategy to in situ fabricate paper-based electrode for next-generation flexible energy-storage system.

Morphology and composition-controllable synthesis of copper sulfide nanocrystals for electrochemical reduction of CO2 to HCOOH

Electrochemical conversion of CO2 into value-added chemicals such as formic acid (HCOOH) has gained tremendous interests. Sulfide-derived copper has been shown recently to be selective for HCOOH production. However, the rich composition and morphology variation of copper sulfides on their electrochemical CO2 reduction have yet to be investigated. Herein, we report a simple ethylene glycol solvothermal route to synthesize copper sulfides nanocrystals, with their morphology and composition varied by tuning the Cu/S feed ratio and reaction temperatures. When being applied to the electrochemical reduction of CO2 to HCOOH, CuS nanoflowers exhibited high Faradic efficiency (~52%) due to its high S content and specific morphology, compared to their more Cu-rich counterparts.

Gold nanoparticles functionalized with 4,4’-dithiobiphenyl blended with CuS in PMMA for switching memory devices

A switching memory device based on functionalized gold nanoparticles (AuNPs) and hexagonal copper sulfide nanocrystals (CuS), finely blended in polymethylmethacrylate matrix (PMMA), is herein presented. A two-electrode sandwich architecture has been implemented using aluminum top and bottom electrodes and a polymeric insulating layer based on PMMA/AuNPs/CuS. The device showed memory storage capabilities suitable for (Read Only Memory) ROM applications and behaves as a typical Write-Once, Read-Many-times (WORM) device. The results obtained with the blend containing AuNPs and/or CuS were compared with pure PMMA. By a voltage ramp in the range ± 9 V, it was possible to permanently change the electrical resistance between the electrodes yielding an ON/OFF current ratio above 105 with long-term stability over the whole experiment duration (30 days).

Biodegradable hollow mesoporous organosilica-based nanosystems with dual stimuli-responsive drug delivery for efficient tumor inhibition by synergistic chemo- and photothermal therapy

Engineering gated porous nanocarriers with multi-stimuli-response is rather fascinating for efficient tumor chemotherapy owing to the avoidance of premature drug leakage and the accurate control of site-specific drug delivery. Herein, a phase-change material (PCM) as a stimuli-responsive ‘‘gate-keeper’’ and copper sulfide (CuS) nanocrystal as a photothermal agent were introduced into biodegradable hollow mesoporous organosilica nanoparticles (HMONs) to construct a multifunctional nanosystem for dual stimuli-responsive drug delivery. The capping of PCM on HMONs enabled the prevention of drug leakage and the temperature-responsive drug release manner, and the reducing-responsive biodegradability of disulfide-hybridized HMONs allowed the tumor microenvironment (TME)-sensitive drug release. With the aid of the near-infrared (NIR)-thermal conversion of CuS nanocrystals, the prepared nanosystem could not only realize both endogenous and external stimuli-triggered drug release, but also achieve synergistic effects of chemo- and photothermal therapy for tumor inhibition. In result, such biocompatible and biodegradable PCM-gated HMONs@CuS nanosystem achieved effective delivery of doxorubicin (DOX) and precise drug release at tumor site, and exhibited remarkable in vitro and in vivo tumor inhibition efficacy by combination of chemotherapy and photothermal therapy, showing great prospect in tumor treatment.

Structural properties of sulfur copper (CuS) nanocrystals grown by chemical bath deposition

In this paper, we present preliminary results in the synthesis of copper sulfide (CuS) nanocrystals, applying the Chemical Bath Deposit technique and subsequent thermal treatment at 1000 °C in air atmosphere. The crystalline growth is systematically performed at two different reaction temperatures of 20 °C and 90 °C. The powders are investigated by applying the techniques of Scanning Electron Microscopy (SEM), Fourier-Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and differential scanning calorimetry (DSC). SEM images showed morphology with crystalline conglomerates on the surfaces, and energy dispersive spectrometry (EDX) spectra shows of Cu, S and O elements. The materials show surface morphological differences associated with the temperature of the crystalline growth and the effect of temperature thermal treatment on texture, grain size, and grain boundaries. XRD identifies a hexagonal phase in CuS20 and CuS90 samples, as well as the transition to CuS(s)→CuO(s). The grain for size for the 20 °C and 90 °C is ∼3.7-5.7 nm, and ∼14.2–35.2 nm respectively. The FTIR analysis shows bands identified with the CO32- and OH− ions located at range ∼1000−2000 cm-1 which was generated by thiourea hydrolysis. These bands decrease with thermal treatment up to disappear completely. The DSC plots show the changes associated with the structural transition of CuS(s)→ CuO(s). This structural behavior is associated with the thermal stability properties of the CuS and CuO.

In situ thermal fabrication of copper sulfide-polymer hybrid nanostructures for tunable plasmon resonance.

Here, a novel strategy for fabricating plasmonic-polymer hybrid nanostructures via the in situ thermal synthesis of copper sulfide (CuS) nanocrystals within poly(N-vinyl caprolactam)-based microgels is presented. In particular, the carboxyl groups inside the microgels enriched Cu2+ ions via electrostatic interaction, which further facilitated the nucleation inside the microgel matrix. The increase in nanocrystals' sizes with more added precursors indicated nanocrystals' continuous growth. The plasmon resonances in CuS nanocrystals were obtained due to the high-density free carriers in the covellite CuS. Both the sizes and the plasmon resonances of the as-synthesized CuS nanocrystals could be modulated by adjusting the amount of precursor. The fabricated hybrid nanostructures possessed good temperature responsivity, adjustable loading capacity, good colloidal stability, and pH dependent plasmon resonance. Furthermore, effective photothermal conversion performance was obtained under the illumination of a 980 nm NIR laser for controlling the phase transition of microgels, revealing promising potential in remotely controlled release of drugs.

Ligand assisted tunability of morphological and optical properties of copper sulfide nanocrystals

Crystal structure and morphology-controlled synthesis of copper sulfide (Cu2-xS) nanocrystals (NCs) through a single (specific) synthesis route is highly complex due to the non-stoichiometric composition of the copper sulfide system. In this work, solution processed hot injection method was employed to synthesize Cu2-xS NCs with hierarchical morphology. Precise control of the morphology (tunable) and optical properties of Cu2-xS NCs was demonstrated by simple synthesis strategy with the use of less hazardous capping ligands. Copper sulfide NCs with tunable morphologies were successfully synthesized by using different capping ligands such as oleic acid and oleylamine without the aid of any post treatment. The morphological analysis shows that the synthesized NCs exist in hierarchical structures such as nanospheres that are composed of hexagonal interconnected nanoflakes, truncated octahedral nanostructures, nanorods and spherical nanoparticles. EDX analysis reveals the chemical composition of prepared nanocrystals and the results are in good agreement with the XRD results. Optical properties of synthesized Cu2-xS NCs were analyzed through the absorption spectra and by the evaluation of optical band gap energy. The results of absorption spectroscopy reveal the band-gap tunability in Cu2-xS NCs. FTIR analysis confirms the surface passivation of capping ligands that lead to the controlled synthesis of Cu2-xS NCs.

Sulfur-Mediated Mechanochemical Synthesis of Spherical and Needle-Like Copper Sulfide Nanocrystals with Antibacterial Activity

In the present study, a quick and environmentally friendly approach has been developed for the synthesis of CuS nanocrystals of different shape with antibacterial activity. The process is completed...

Glycosylated Copper Sulfide Nanocrystals for Targeted Photokilling of Bacteria in the Near‐Infrared II Window

AbstractPhotothermal and photodynamic therapies are established as alternative approaches to combating bacterial infections; however, the heat and reactive oxygen species generated by the photoagents act on both normal and bacterial cells. A targeting strategy is thus required to minimize side effects and enhance the antibacterial efficiency. Glycoconjugates specifically interacting with bacterial lectins have emerged as a new class of materials for targeting bacteria. In this paper, galactosylated plasmonic copper sulfide nanocrystals (Cu2−xS NCs) are used to target Pseudomonas aeruginosa via galactose–LecA interactions and kill the bacteria by simultaneous photothermal and photodynamic therapy. Galactosylated Cu2−xS NCs are obtained by functionalizing the nanocrystals with tri‐thiogalactoside glycoclusters. The excellent specificity of galactosylated nanoparticles toward LecA with a LecA‐deficient P. aeruginosa strain as the control is first demonstrated. Afterward, a laser in the near‐infrared II window is used to kill the bacteria, and the critical role of targeted binding in efficient killing of bacteria is highlighted. This approach can be readily generalized to the targeting of other pathogens which have highly specific carbohydrate‐binding lectins.