Copper sulfide nanostructures: synthesis and biological applications

Neurotoxicity and Developmental Neurotoxicity of Copper Sulfide Nanoparticles on a Human Neuronal In-Vitro Test System

Nanoparticles (NPs) are becoming increasingly important novel materials for many purposes, including basic research, medicine, agriculture, and engineering. Increasing human and environmental exposure to these promising compounds requires assessment of their potential health risks. While the general direct cytotoxicity of NPs is often routinely measured, more indirect possible long-term effects, such as reproductive or developmental neurotoxicity (DNT), have been studied only occasionally and, if so, mostly on non-human animal models, such as zebrafish embryos. In this present study, we employed a well-characterized human neuronal precursor cell line to test the concentration-dependent DNT of green-manufactured copper sulfide (CuS) nanoparticles on crucial early events in human brain development. CuS NPs turned out to be generally cytotoxic in the low ppm range. Using an established prediction model, we found a clear DNT potential of CuS NPs on neuronal precursor cell migration and neurite outgrowth, with IC50 values 10 times and 5 times, respectively, lower for the specific DNT endpoint than for general cytotoxicity. We conclude that, in addition to the opportunities of NPs, their risks to human health should be carefully considered.

Effect of PVP Molecular Weights on the Synthesis of Ultrasmall Cus Nanoflakes: Synthesis, Properties, and Potential Application for Phototheranostics

Copper sulfide nanoparticles (CuS) hold tremendous potential for applications in photothermal therapy (PTT) and photoacoustic imaging (PAI). However, the conventional chemical coprecipitation method often leads to particle agglomeration issues. To overcome this challenge, we utilized polyvinylpyrrolidone (PVP) as a stabilizing agent, resulting in the synthesis of small PVP-CuS nanoparticles named PC10, PCK30, and PC40. Our study aimed to investigate how different molecular weights of PVP influence the nanoparticles' crystalline characteristics and essential properties, especially their photoacoustic and photothermal responses. While prior research on PVP-assisted CuS nanoparticles has been conducted, our study delves deeper into this area, providing insights into optical properties. Remarkably, all synthesized nanoparticles exhibited a crystalline structure, were smaller than 10 nm, and featured an absorbance peak at 1020 nm, indicating their robust photoacoustic and photothermal capabilities. Among these nanoparticles, PC10 emerged as the standout performer, displaying superior photoacoustic properties. Our photothermal experiments demonstrated significant temperature increases in all cases, with PC10 achieving an impressive efficiency of 51%. Moreover, cytotoxicity assays revealed the nanoparticles' compatibility with cells, coupled with an enhanced incidence of apoptosis compared to necrosis. These findings underscore the promising potential of PVP-stabilized CuS nanoparticles for advanced cancer theranostics.

Chitosan/copper sulfide nanoparticles (CS/CuSNPs) hybrid fibers with improved mechanical and photo-thermal conversion properties via tuning CuSNPs' morphological structures

Conventional textiles are inadequate for maintaining warmth in extremely cold conditions. Therefore, the development of photo-thermal fibers for personal thermal management textiles has emerged as an urgent need. Herein, novel chitosan/copper sulfide nanoparticles (CS/CuSNPs) hybrid fibers with photo-thermal function were fabricated successfully. Significantly, our study demonstrated that the tensile and photo-thermal conversation properties of the CS/CuSNPs hybrid fibers could be effectively regulated by altering the CuSNPs` morphological structures. Compared with other CuSNPs (tube-like, sphere-like, and flower-like), the plate-like CuSNPs with smooth surfaces and uniform nanometer size played a significant role by scattering incident light in the fibers as a secondary light source for CuSNPs absorbance. Thus, under IR light irradiation at a power density of 1.0 W/cm2, the surface temperature of CS/0.1 wt% plate-like CuSNPs hybrid fibers sharply increased by 27.6 °C, which was more than 4 times of the pure CS fibers. And the breaking strength and initial modulus of CS/0.1 wt% plate-like CuSNPs hybrid fibers increased by more than 18.37 and 6.88 % compared with the nascent CS fibers. This study develops a novel and effective strategy to tune the photo-thermal and tensile properties of CS hybrid fibers without incorporating more content or additives.

Plasmonic porous micro- and nano-materials based on Au/Ag nanostructures developed for photothermal cancer therapy: challenges in clinicalization

Photothermal therapy (PTT) has developed in recent decades as a relatively safe method for the treatment of cancers. Recently, various species of gold and silver (Au and Ag) nanostructures have been developed and investigated to achieve PTT due to their highly localized surface plasmon resonance (LSPR) effect. Concisely, the collective oscillation of electrons on the surface of Au and Ag nanostructures upon exposure to a specific wavelength (depending on their size and shape) and further plasmonic resonance leads to the heating of the surface of these particles. Hence, porous species can be equipped with tiny plasmonic ingredients that add plasmonic properties to therapeutic cargoes. In this case, a precise review of the recent achievements is very important to figure out to what extent plasmonic photothermal therapy (PPTT) by Au/Ag-based plasmonic porous nanomedicines successfully treated cancers with satisfactory biosafety. Herein, we classify the various species of LSPR-active micro- and nano-materials. Moreover, the routes for the preparation of Ag/Au-plasmonic porous cargoes and related bench assessments are carefully reviewed. Finally, as the main aim of this study, principal requirements for the clinicalization of Ag/Au-plasmonic porous cargoes and their further challenges are discussed, which are critical for specialists in this field.

Plasmonic and Photothermal Effects of CuS Nanoparticles Biosynthesized from Acid Mine Drainage with Potential Drug Delivery Applications

In this work, the plasmonic and photothermal effects of CuS nanoparticles biosynthesized from acid mine drainage (AMD) were studied. CuS were formed by delivering the H2S generated by a sulfidogenic bioreactor to an off-line system containing the AMD. The precipitates collected after contact for an hour were washed and physico-chemically characterized, showing a nanoparticle with a mean diameter of 33 nm, crystalline nature and semiconductor behavior with a direct band gap of 2.2 eV. Moreover, the CuS nanoparticles exhibited localized surface plasmonic resonance in the near infrared range, with a high absorption band centered at 973 nm of wavelength, which allowed an increase in the temperature of the surrounding media under irradiation. Finally, the cytotoxicity of the CuS nanoparticles as well as their potential use as part of drug delivery platforms were investigated.

Evolving approaches in glioma treatment: harnessing the potential of copper metabolism modulation

The key properties and high versatility of metal nanoparticles have shed new perspectives on cancer therapy, with copper nanoparticles gaining great interest because of the ability to couple the intrinsic properties of metal nanoparticles with the biological activities of copper ions in cancer cells. Copper, indeed, is a cofactor involved in different metabolic pathways of many physiological and pathological processes. Literature data report on the use of copper in preclinical protocols for cancer treatment based on chemo-, photothermal-, or copper chelating-therapies. Copper nanoparticles exhibit anticancer activity via multiple routes, mainly involving the targeting of mitochondria, the modulation of oxidative stress, the induction of apoptosis and autophagy, and the modulation of immune response. Moreover, compared to other metal nanoparticles (e.g. gold, silver, palladium, and platinum), copper nanoparticles are rapidly cleared from organs with low systemic toxicity and benefit from the copper's low cost and wide availability. Within this review, we aim to explore the impact of copper in cancer research, focusing on glioma, the most common primary brain tumour. Glioma accounts for about 80% of all malignant brain tumours and shows a poor prognosis with the five-year survival rate being less than 5%. After introducing the glioma pathogenesis and the limitation of current therapeutic strategies, we will discuss the potential impact of copper therapy and present the key results of the most relevant literature to establish a reliable foundation for future development of copper-based approaches.

Electronic Properties of Transition and Alkaline Earth Metal Doped CuS: A DFT Study

CuS is a unique semiconductor with potential in optoelectronics. Its unusual electronic structure, including a partially occupied valence band, and complex crystal structure with an S-S bond offer unique opportunities and potential applications. In this work, the use of doping to optimize the properties of CuS for various applications is investigated by density functional theory (DFT) calculations. Among the dopants studied, Ni, Zn, and Mg may be the most practical due to their lower formation energies. Doping with Fe, Ni, or Ca induces significant distortion, which may be beneficial for achieving materials with high surface areas and active states. Significantly, doping alters the conductor-like behavior of CuS, opening a band gap by increasing bond ionicity and reducing the S-S bond covalency. Thus, doping CuS can tune the plasmonic properties and transform it from a conductor to an intrinsic fluorescent semiconductor. Ni and Fe doping give the lowest band gaps (0.35 eV and 0.39 eV, respectively), while Mg doping gives the highest (0.86 eV). Doping with Mg, Ca, and Zn may enhance electron mobility and charge separation. Most dopants increase the anisotropy of electron-to-hole mass ratios, enabling device design that exploits directional-dependence for improved performance.

Development of hierarchical copper sulfide-carbon nanotube (CuS-CNT) composites and utilization of their superior carrier mobility in efficient charge transport towards photodegradation of Rhodamine B under visible light

In this work, the synthesis of visible light sensitive copper sulfide (CuS) nanoparticles and their composites with carbon nanotubes (T-CuS) via a solvothermal technique is reported. The synthesized nanoparticles (NPs) and their composites were significantly characterized by powder X-ray diffraction (PXRD), scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-vis spectroscopy, photoluminescence (PL) spectroscopy and thermogravimetric analysis (TGA). The effect of carbon nanotubes (CNTs) on the crystallinity, microstructures, photo-absorption, photo-excitation, thermal stability and surface area of CuS was investigated. The current-voltage (I vs. V) characteristics of both CuS and T-CuS based Schottky diodes were measured to determine the charge transport parameters like photosensitivity, conductivity, mobility of charge carriers, and transit time. The photocatalytic performance of bare CuS and T-CuS in the decomposition of Rhodamine B dye was studied using a solar simulator. The T-CuS composite showed higher photocatalytic activity (94%) compared to bare CuS (58%). The significance of charge carrier mobility in transferring photo-induced charges (holes and electrons) through complex networks of composites and facilitating the photodegradation process is explained. Finally, the reactive species responsible for the Rhodamine B degradation were also identified.

Challenges and advances for glioma therapy based on inorganic nanoparticles

Glioma is one of the most serious central nervous system diseases, with high mortality and poor prognosis. Despite the continuous development of existing treatment methods, the median survival time of glioma patients is still only 15 months. The main treatment difficulties are the invasive growth of glioma and the obstruction of the blood-brain barrier (BBB) to drugs. With rapid advancements in nanotechnology, inorganic nanoparticles (INPs) have shown favourable application prospects in the diagnosis and treatment of glioma. Due to their extraordinary intrinsic features, INPs can be easily fabricated, while doping with other elements and surface modification by biological ligands can be used to enhance BBB penetration, targeted delivery and biocompatibility. Guided glioma theranostics with INPs can improve and enhance the efficacy of traditional methods such as chemotherapy, radiotherapy and gene therapy. New strategies, such as immunotherapy, photothermal and photodynamic therapy, magnetic hyperthermia therapy, and multifunctional inorganic nanoplatforms, have also been facilitated by INPs. This review emphasizes the current state of research and clinical applications of INPs, including glioma targeting and BBB penetration enhancement methods, in vivo and in vitro biocompatibility, and diagnostic and treatment strategies. As such, it provides insights for the development of novel glioma treatment strategies.

Recent Development of Nanomaterials for Transdermal Drug Delivery

Nano-engineered medical products first appeared in the last decade. The current research in this area focuses on developing safe drugs with minimal adverse effects associated with the pharmacologically active cargo. Transdermal drug delivery, an alternative to oral administration, offers patient convenience, avoids first-pass hepatic metabolism, provides local targeting, and reduces effective drug toxicities. Nanomaterials provide alternatives to conventional transdermal drug delivery including patches, gels, sprays, and lotions, but it is crucial to understand the transport mechanisms involved. This article reviews the recent research trends in transdermal drug delivery and emphasizes the mechanisms and nano-formulations currently in vogue.

Mechanochemical synthesis of non-stoichiometric copper sulfide Cu1.8S applicable as a photocatalyst and antibacterial agent and synthesis scalability verification

An effort to prepare different non-stoichiometric Cu_xS_y compounds starting from elemental precursors using mechanochemistry was made in this study. However, out of the 7 stoichiometries tested, it was only possible to obtain three phases: covellite CuS, chalcocite Cu₂S and digenite Cu_1.8S and their mixtures. To obtain the digenite phase with the highest purity, the Cu : S stoichiometric ratio needed to be fixed at 1.6 : 1. The reaction between copper and sulfur was completed within a second range, however, milling was performed for up to 15 minutes until the equilibrium in phase composition between digenite and covellite was reached. The possibility of preparing the product in a 300 g batch by eccentric vibratory milling in 30 minutes was successfully verified at the end. The estimated crystallite sizes for the digenite Cu_1.8S obtained via lab-scale and scalable experiments were around 12 and 17 nm, respectively. The obtained products were found to be efficient photocatalysts under visible light irradiation in the presence of hydrogen peroxide, being capable of the complete degradation of the Methyl Orange dye in a concentration of 10 mg L^-1 in 2 hours. Finally, the antibacterial potential of both lab-scale and large-scale industrial products was proven and, regardless of the manufacturing scale, the nanoparticles retained their properties against bacterial cells.

Recent advances in metal sulfide nanoparticle-added bionanocomposite films for food packaging applications

Metal sulfide nanoparticles have recently attracted much attention due to their unique physical and functional properties. Metal sulfide nanoparticles used as optoelectronic and biomedical materials in the past decades are promising for making functional nanocomposite films due to their low toxicity and strong antibacterial activity. Recently, copper sulfide and zinc sulfide nanomaterials have been used to produce food packaging films for active packaging. Metal sulfide nanoparticles added as nanofillers are attracting attention in packaging applications due to their excellent potential to improve mechanical, barrier properties, and antibacterial activity. This review covers the fabrication process and important applications of metal sulfide nanoparticles. The development of metal sulfides reinforcing mainly copper sulfide and zinc sulfide nanomaterials as multifunctional nanofillers in bio-based films for active packaging applications has been comprehensively reviewed. As the recognition of metal sulfide nanoparticles as a functional filler increases, the development and application potential of active packaging films using them is expected to increase.

Photo-Stimuli-Responsive CuS Nanomaterials as Cutting-Edge Platform Materials for Antibacterial Applications

Photo-stimuli-responsive therapeutic nanomaterials have gained widespread attention as frontline materials for biomedical applications. The photoactivation strategies are classified as single-modality (based on either reactive oxygen species (ROS)-based photodynamic therapy (PDT), hyperthermia-based photothermal therapy (PTT)), or dual-modality (which combines PDT and PTT). Due to its minimal invasiveness, phototherapy has been extensively applied as an efficient therapeutic platform for many diseases, including skin cancers. However, extensive implementation of phototherapy to address the emergence of multidrug-resistant (MDR) bacterial infections remains challenging. This review focuses on copper sulfide (CuS) nanomaterials as efficient and cost-effective PDT and PTT therapeutic nanomaterials with antibacterial activity. The features and merits of CuS nanomaterials as therapeutics are compared to those of other nanomaterials. Control of the dimensions and morphological complexity of CuS nanomaterials through judicious synthesis is then introduced. Both the in vitro antibacterial activity and the in vivo therapeutic effect of CuS nanomaterials and derivative nanocomposites composed of 2D nanomaterials, polymers, metals, metal oxides, and proteins are described in detail. Finally, the perspective of photo-stimuli-responsive CuS nanomaterials for future clinical antibacterial applications is highlighted. This review illustrates that CuS nanomaterials are highly effective, low-toxic, and environmentally friendly antibacterial agents or platform nanomaterials for combatting MDR bacterial infections.