Correlating semiconductor nanoparticle architecture and applicability for the controlled encoding of luminescent polymer microparticles

Luminophore stained micro- and nanobeads made from organic polymers like polystyrene (PS) are broadly used in the life and material sciences as luminescent reporters, for bead-based assays, sensor arrays, printable barcodes, security inks, and the calibration of fluorescence microscopes and flow cytometers. Initially mostly prepared with organic dyes, meanwhile luminescent core/shell nanoparticles (NPs) like spherical semiconductor quantum dots (QDs) are increasingly employed for bead encoding. This is related to their narrower emission spectra, tuneability of emission color, broad wavelength excitability, and better photostability. However, correlations between particle architecture, morphology, and photoluminescence (PL) of the luminescent nanocrystals used for encoding and the optical properties of the NP-stained beads have been rarely explored. This encouraged us to perform a screening study on the incorporation of different types of luminescent core/shell semiconductor nanocrystals into polymer microparticles (PMPs) by a radical-induced polymerization reaction. Nanocrystals explored include CdSe/CdS QDs of varying CdS shell thickness, a CdSe/ZnS core/shell QD, CdSe/CdS quantum rods (QRs), and CdSe/CdS nanoplatelets (NPLs). Thereby, we focused on the applicability of these NPs for the polymerization synthesis approach used and quantified the preservation of the initial NP luminescence. The spectroscopic characterization of the resulting PMPs revealed the successful staining of the PMPs with luminescent CdSe/CdS QDs and CdSe/CdS NPLs. In contrast, usage of CdSe/CdS QRs and CdSe QDs with a ZnS shell did not yield luminescent PMPs. The results of this study provide new insights into structure-property relationships between NP stained PMPs and the initial luminescent NPs applied for staining and underline the importance of such studies for the performance optimization of NP-stained beads.

Photo-excitable zinc sulfide nanoparticles: A theranostic nanotool for cancer management

OBJECTIVES

Zinc sulfide nanoparticles (ZnS NPs), as one of the quantum dots less than 10 nm, possess unique size-dependent autofluorescence. Excitation of their valence electrons by energy higher than the bandgap reveals the ZnS NPs' inherited photocatalysis with additive cytotoxic consequences of reactive oxygen species (ROS) release. Coupling the cytotoxicity of photoactivated ZnS NPs with their autofluorescence would be a novel theranostic modality, combating superficially accessible carcinoma.

MATERIAL AND METHODS

After synthesizing and characterization of ZnS NPs, we verified their photocatalysis and electron donation upon UV excitation in degrading organic dye and DNA cleavage, respectively. We then tested the efficacy of UV-activated ZnS NPs to induce ROS-dependent apoptosis in squamous cell carcinoma and breast cancer cell lines.

RESULTS

The energetic electron-hole pairs generated upon UV excitation of ZnS NPs with the consequent cascade of ROS release revealed potent apoptotic cancer cell deaths, compared with single treatment modalities of nonexcited nanoparticles and UV. Moreover, the inherited luminescence of ZnS NPs enabled visualization of their predominant intracytoplasmic uptake with tracking of their cellular response.

CONCLUSION

The intensified luminescence and the fortified cytotoxicity of photoactivated ZnS NPs enhance their theranostic qualifications, boosting their antitumorigenic use.

Chiral Materials: Progress, Applications, and Prospects

Chirality is a universal phenomenon in molecular and biological systems, denoting an asymmetric configurational property where an object cannot be superimposed onto its mirror image by any kind of translation or rotation, which is ubiquitous on the scale from neutrinos to spiral galaxies. Chirality plays a very important role in the life system. Many biological molecules in the life body show chirality, such as the "codebook" of the earth's biological diversity-DNA, nucleic acid, etc. Intriguingly, living organisms hierarchically consist of homochiral building blocks, for example, l-amino acids and d-sugars with unknown reason. When molecules with chirality interact with these chiral factors, only one conformation favors the positive development of life, that is, the chiral host environment can only selectively interact with chiral molecules of one of the conformations. The differences in chiral interactions are often manifested by chiral recognition, mutual matching, and interactions with chiral molecules, which means that the stereoselectivity of chiral molecules can produce changes in pharmacodynamics and pathology. Here, the latest investigations are summarized including the construction and applications of chiral materials based on natural small molecules as chiral source, natural biomacromolecules as chiral sources, and the material synthesized by design as a chiral source.

Experimental and DFT studies on the structural and optical properties of chitosan/polyvinyl pyrrolidone/ZnS nanocomposites

Chitosan/Polyvinyl pyrrolidone (CS/PVP) semi-natural polymeric blend involving gradient concentrations of ZnS nanoparticles (ZnS-NPS) was prepared via a simple casting method. In conjunction with computational density functional theory approaches (DFT), prepared samples were characterized by UV/Vis spectrophotometric studies and Fourier transform infrared measurements (FTIR) to take into account a detailed description of the different reaction mechanisms within the polymeric matrices. To conduct all calculations, the Becke three-parameter hybrid functional (B3LYP) correlation function used with the electron core potential basis set LANL2DZ was used. A detailed study of different reaction regimes was studied and reaction via Oxygen was observed to be preferred and compatible with that of the experimental data. UV/vis. Absorption experimental data were used to calculate the optical energy gap using the Mott-Davis equation and observed data was found to follow an indirect transition route.

Light driven Aspergillus niger-ZnS nanobiohybrids for degradation of methyl orange

Inorganic-microbial hybrid systems have potential to be sustainable, efficient and versatile chemical synthesis platforms by integrating the light-harvesting properties of semiconductors with microbial cells. Here, we demonstrate light-driven photocatalytic semiconducting Aspergillus niger cells-ZnS nanoparticles for enhanced removal of the dye methyl orange. Chemically synthesized ZnS nanoparticles exhibited a zinc blende pattern in X-ray diffraction, had a dimension of 20-90 nm with a band gap (E_bg) of 3.4 eV at 1.83 × 10¹⁸ photons/second. Biologically synthesized ZnS nanoparticles of 40-90 nm showed a hexagonal pattern in the X-ray powder diffraction spectra with an E_bg 3.7 eV at 1.68 × 10¹⁸ photons/second. At a methyl orange (MO) concentration of 100 mg/L, dosage of 0.5 × 10⁵ mol catalyst and pH 4, a 97.5% and 98% removal efficiency of MO was achieved in 90 min and 60 min for, respectively, chemically and biologically synthesized ZnS nanobiohybrids in the presence of UV-A light. The major degradation products of photocatalysis for chemically synthesized ZnS nanobiohybrids were naphtholate (C₁₀H₇O m/z 143) and hydroquinone (C₉H₅m/z 113). For the biologically synthesized ZnS nanobiohybrids, the degradation products were hydroquinone (C₉H₅m/z 113) and 2-phenylphenol (C₁₂H₁₀O m/z 170).

Low recombination rates and improving charge transfer as decisive conditions for high current densities and fill factors in ZnS complex systems

The growth of ZnS photoelectrodes on ZnO particles identified as ZnO/ZnS(ZC + TAA) by the microwave-assisted hydrothermal method showed excellent photovoltaic parameters of J_SC = 1.2 mA cm^-2 and FF = 0.66, even compared to ZnS(ZC + TAA) used as a reference sample with J_SC = 0.15 mA cm^-2 and FF = 0.52. A careful analysis indicates that the better charge transfer and the higher resistance to recombination present in the ZnO/ZnS(ZC + TAA) samples were the origin of the best photovoltaic behavior. These assertions are supported by a set of samples synthesized from different precursors resulting in different crystal structures, which can be directly associated with current densities and fill factors. All aspects about synthesis and optical/electronic parameters associated with structural features will be available in this article.

Chitosan nanocomposites with CdSe/ZnS quantum dots and porphyrin

Water-soluble nanocomposites based on CdSe/ZnS quantum dots (QDs) and hydrophobic tetraphenylporphyrin (TPP) molecules passivated by chitosan (CS) have been formed. Magnetic circular dichroism (MCD) spectra evidence TPP presence in both monomeric and agglomerated forms in the nanocomposites. The nanocomposites demonstrate more pronounced singlet oxygen generation compared to free TPP in CS at the same concentration due to the intracomplex Förster resonance energy transfer (FRET) with a 45% average efficiency.

An efficient and magnetically recoverable g-C3N4/ZnS/CoFe2O4 nanocomposite for sustainable photodegradation of organic dye under UV-visible light illumination

Effective improvement of an easily recoverable photocatalyst is equally vital to its photocatalytic performance from a practical application view. The magnetically recoverable process is one of the easiest ways, provided the photocatalyst is magnetically strong enough to respond to an external magnetic field. Herein, we prepared graphitic carbon nitride nanosheet (g-C₃N₄), and ZnS quantum dots (QDs) supported ferromagnetic CoFe₂O₄ nanoparticles (NPs) as the gC₃N₄/ZnS/CoFe₂O₄ nanohybrid photocatalyst by a wet-impregnation method. The loading of CoFe₂O₄ NPs in the g-C₃N₄/ZnS nanohybrid resulted in extended visible light absorption. The ferromagnetic g-C₃N₄/ZnS/CoFe₂O₄ nanohybrid exhibited better visible-light-active photocatalytic performance (97.11%) against methylene blue (MB) dye, and it was easily separable from the aqueous solution by an external bar magnet. The g-C₃N₄/ZnS/CoFe₂O₄ nanohybrid displayed excellent photostability and reusability after five consecutive cycles. The favourable band alignment and availability of a large number of active sites affected the better charge separation and enhanced photocatalytic response. The role of active species involved in the degradation of MB dye during photocatalyst by g-C₃N₄/ZnS/CoFe₂O₄ nanohybrid was also investigated. Overall, this study provides a facile method for design eco-friendly and promising g-C₃N₄/ZnS/CoFe₂O₄ nanohybrid photocatalyst as applicable in the eco-friendly dye degradation process.

GSH-ZnS Nanoparticles Exhibit High-Efficiency and Broad-Spectrum Antiviral Activities via Multistep Inhibition Mechanisms

Despite the good biocompatibility and antibacterial activity of zinc sulfide nanoparticles (ZnS NPs), whether they possess antiviral activity is still unclear. Here, GSH-modified ZnS NPs (GSH-ZnS NPs) were synthesized and their significant antiviral activity was demonstrated using the Arteriviridae family RNA virus, porcine reproductive and respiratory syndrome virus (PRRSV), as a model. Mechanistically, GSH-ZnS NPs were shown to reduce PRRSV-induced ROS production to prevent PRRSV multiplication, with no activating effect on the interferon (IFN) signal pathway, the first defense line against virus infection. Furthermore, isobaric tags for relative and absolute quantification (iTRAQ)-based quantitative proteomic analysis of GSH-ZnS NP-treated cells revealed the involvement of numerous crucial proteins in virus proliferation, with vitronectin (VTN) being confirmed as an efficient PRRSV antagonist here. Furthermore, GSH-ZnS NPs were found to have potent antiviral effects on the Herpesviridae family DNA virus, pseudorabies virus (PRV), the Coronaviridae family positive-sense RNA virus, porcine epidemic diarrhea virus (PEDV), and the Rhabdoviridae family negative-stranded RNA virus, vesicular stomatitis virus (VSV), indicating their broad-spectrum antiviral activity against viruses from different families with various genome types. Overall, GSH-ZnS NP is a prospective candidate for the development of antiviral nanomaterials and may serve as a model for investigation of potential host restriction factors in combination with proteomics.

High Refractive-Index Hybrids Consisting of Water-Soluble Matrices with Bipyridine-Modified Polyhedral Oligomeric Silsesquioxane and Lanthanoid Cations

We report high refractive-index (RI) films composed of polyhedral oligomeric silsesquioxane (SSQ) matrices and various lanthanoid cations. The SSQ matrices were constructed from octaammonium SSQ by connecting with bipyridine dicarboxylic acid, which is expected to capture cations. By modulating the feed ratio between SSQ and dicarboxylic acid, the series of the SSQ matrices were obtained with variable cross-linking ratios among the SSQ units. Thin transparent films were able to be prepared through the drop-casting method with the aqueous mixtures containing SSQ matrices and various kinds of lanthanoid salts up to 40 wt %. From RI measurements, it was revealed that the increase of the amount of the metal ion can significantly lift up the RI values. In particular, critical losses of Abbe numbers, which theoretically have the trade-off relationship toward increases in RI values, were hardly detected. This effect could be obtained by cation assembly in local spots that are assisted by SSQ.

Dopamine-induced photoluminescence quenching of bovine serum albumin-capped manganese-doped zinc sulphide quantum dots

The direct detection of dopamine (DA) in human body fluids is a great challenge for medical diagnostics of neurological disorders like Parkinson's disease, Alzheimer's disease, senile dementia, and schizophrenia. In this work, a simple and turn off luminescence sensing of DA based on bovine serum albumin (BSA)-capped manganese-doped zinc sulphide quantum dots (Mn:ZnS/BSA QDs) is developed. The Mn:ZnS/BSA QDs were synthesized by a chemical co-precipitation method. Due to the special interaction of DA with BSA and metal ions, Mn:ZnS/BSA QDs can serve as an effective sensing platform for DA. The luminescence of Mn:ZnS/BSA QDs decreased linearly with increasing concentration of DA in the range from 6.6 to 50.6 nM. The limit of detection is 2.02 nM. The driving force for the luminescence quenching is partly provided by ground-state complex formation of QDs with DA. The photo-induced electron transfer from the conduction band of QDs to oxidized dopamine (quinone) also favors quenching. The Mn:ZnS/BSA QDs are barely interfered with by other competing biomolecules except catecholamine neurotransmitter like epinephrine. Moreover, this method is used in the analysis of DA-spiked human serum and human urine samples and good recovery percentages are found. To assess the utility of the developed sensor, paper strip assay was also successfully conducted. Graphical abstract.

Understanding the role of zinc dithiocarbamate complexes as single source precursors to ZnS nanomaterials

Zinc sulfide is an important wide-band gap semi-conductor and dithiocarbamate complexes [Zn(S₂CNR₂)₂] find widespread use as single-source precursors for the controlled synthesis of ZnS nanoparticulate modifications. Decomposition of [Zn(S₂CNⁱBu₂)₂] in oleylamine gives high aspect ratio wurtzite nanowires, the average length of which was increased upon addition of thiuram disulfide to the decomposition mixture. To provide further insight into the decomposition process, X-ray absorption spectroscopy (XAS) of [Zn(S₂CNMe₂)₂] was performed in the solid-state, in non-coordinating xylene and in oleylamine. In the solid-state, dimeric [Zn(S₂CNMe₂)₂]₂ was characterised in accord with the single crystal X-ray structure, while in xylene this breaks down into tetrahedral monomers. In situ XAS in oleylamine (RNH₂) shows that the coordination sphere is further modified, amine binding to give five-coordinate [Zn(S₂CNMe₂)₂(RNH₂)]. This species is stable to ca. 70 °C, above which amine dissociates and at ca. 90 °C decomposition occurs to generate ZnS. The relatively low temperature onset of nanoparticle formation is associated with amine-exchange leading to the in situ formation of [Zn(S₂CNMe₂)(S₂CNHR)] which has a low temperature decomposition pathway. Combining these observations with the previous work of others allows us to propose a detailed mechanistic scheme for the overall process.

Room-Temperature Synthesis of ZnS Nanoparticles Using Zinc Xanthates as Molecular Precursors

Molecular precursors are suitable starting compounds for preparation of semiconductor nanoparticles (NPs), which allow for control of atomic ratio, composition, monodispersity, and particle size of nanoscaled metal sulfides/oxides. In the present study, we carried out a one-pot synthesis of ZnS NPs in aqueous triethanolamine medium at room temperature, from molecular precursor zinc xanthate as a source of both Zn²⁺ and S^2- ions. Furthermore, we compared the products obtained from zinc ethylxanthate (Zn(C₂H₅OCS₂)₂) and zinc amylxanthate (Zn(C₅H₁₁OCS₂)₂). The as-prepared ZnS NPs were found to crystallize in cubic phase, which usually forms at low temperatures, with the dimension dependent on the xanthate precursor used. The long carbon-chain xanthate Zn(C₅H₁₁OCS₂)₂ gave spherically shaped NPs with an average diameter of 19 nm, while the NPs that originated from zinc ethylxanthate had a mean size of ~26 nm. Both nanomaterials had surface sulfur vacancies that extended their absorption spectra toward the visible region and reduced the band gap. This allowed both materials to demonstrate photocatalytic performance under visible-light irradiation. Photodegradation of methylene blue over newly prepared ZnS NPs was tested under visible light, demonstrating efficiency of 50%-60% after 180 min.

Green polymeric nanomaterials for the photocatalytic degradation of dyes: a review

Pure and drinkable water will be rarer and more expensive as the result of pollution induced by industrialisation, urbanisation and population growth. Among the numerous sources of water pollution, the textile industry has become a major issue because effluents containing dyes are often released in natural water bodies. For instance, about two years are needed to biodegrade dye-derived, carcinogenic aromatic amines, in sediments. Classical remediation methods based upon physicochemical reactions are costly and still generate sludges that contain amine residues. Nonetheless, recent research shows that nanomaterials containing biopolymers are promising to degrade organic pollutants by photocatalysis. Here, we review the synthesis and applications of biopolymeric nanomaterials for photocatalytic degradation of azo dyes. We focus on conducting biopolymers incorporating metal, metal oxide, metal/metal oxide and metal sulphide for improved biodegradation. Biopolymers can be obtained from microorganisms, plants and animals. Unlike fossil-fuel-derived polymers, biopolymers are carbon neutral and thus sustainable in the context of global warming. Biopolymers are often biodegradable and biocompatible.

To what extent do polymeric stabilizers affect nanoparticles characteristics?

Colloidal synthesis of nanoparticles using polymeric stabilizers as a template of a structure directing agent provided a plethora of opportunities in fabricating nanoparticles (NPs) with controlled size, shape, composition and structural characteristics. To understand the complete potency of polymeric stabilizers during the synthesis of nanoparticles, the relationship between polymer characteristics such as structure, molecular weight and concentration and nanoparticles characteristics is discussed in depth. This review portrays the use of polymers to attain nanostructured materials via covalent and non-covalent approaches. These polymers can also serve as surfaces modifier as well as the growth regulators during the synthesis of nanomaterials. The effect provided by polymers that directs the formation of nanomaterials into desired forms is otherwise hard to achieve. We especially spotlight on the approaches for tuning the characteristic properties of nanoparticles via cautious choice of the polymer system with special focus to stimuli-responsive polymers. This review mainly focusses on answering the main challenging question; what is the ideal polymeric stabilizer system to obtain specific morphology, size and phase structure of nanoparticles? Such vital information will enable rational design of nanoparticles to meet specific needs for different applications.

A Raman spectral probe on polar w-ZnS nanostructures and surface optical phonon modes in nanowires

In the present study, different morphologies of ZnS nanostructures have been synthesized through a hydrothermal method and their Raman spectral modes are investigated. Raman scattering from surface optical (SO) modes has been seen and identified as a strange shoulder band of LO at 340 cm-1 in nanowires (NWs) with a hexagonal wurtzite structure of ZnS in air medium. X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques have been used to confirm the hexagonal phase and the modulation in the surface during the growth process, which causes the translational symmetry breaking to activate the SO mode. The appearance of a strong SO mode in NWs has been obviously confirmed by the frequency downshift of the SO mode in different dielectric media with dielectric constants ranging from 1 to 2.56. The SO phonon mode shift due to the roughness in the NW faces has been estimated from the wave-vector that activates the SO mode and an approximate dielectric continuum (DC) model has been used to understand the SO modes in NWs. The surface perturbation responsible for the activation of the SO mode has been estimated and is compared with the surface modulation along the growth axis of the NW from the TEM images.

Formation of highly ordered micro fillers in polymeric matrix by electro-field-assisted aligning

Nanocomposites composed by polymeric matrix with micro/nano fillers have drawn lots of attention since their dramatic properties beyond pristine polymers. The spatial distribution of the micro/nano fillers in the polymeric matrix determines the final desired properties of the nanocomposites, thus deserves to investigate. Here, we proposed an effective method of assembling the micro/nano fillers to pre-designed patterns within the polymeric matrix by AC-electro-field-assisted aligning. By pre-designed AC electric fields which could be dynamically controllable, the distribution of microparticles (acting as fillers) in the matrix was tuned to various patterns related to the electric fields, such as linear alignment and circular alignment. The field-oriented particles chains could act as endoskeletal structures, showing unique properties (i.e., mechanical, optical, and anisotropic properties) beyond those of the conventional composites with randomly distributed particles.

Nanocomposites composed by polymeric matrix with micro/nano fillers have drawn lots of attention since their dramatic properties beyond pristine polymers.

Graphene Oxide/ZnS:Mn Nanocomposite Functionalized with Folic Acid as a Nontoxic and Effective Theranostic Platform for Breast Cancer Treatment

Nanoparticle-based cancer theranostic agents generally suffer of poor dispersability in biological media, re-agglomeration over time, and toxicity concerns. To address these challenges, we developed a nanocomposite consisting of chemically-reduced graphene oxide combined with manganese-doped zinc sulfide quantum dots and functionalized with folic acid (FA-rGO/ZnS:Mn). We studied the dispersion stability, Doxorubicin (DOX) loading and release efficiency, target specificity, internalization, and biocompatibility of FA-rGO/ZnS:Mn against folate-rich breast cancer cells, and compared to its uncoated counterpart (rGO/ZnS:Mn). The results indicate that DOX is adsorbed on the graphene surface via π⁻π stacking and hydrophobic interaction, with enhanced loading (~35%) and entrapment (~60%) efficiency that are associated to the chelation of DOX and surface Zn2+ ions. DOX release is favored under acidic conditions reaching a release of up to 95% after 70 h. Membrane integrity of the cells assessed by Lactate dehydrogenase (LDH) release indicate that the surface passivation caused by folic acid (FA) functionalization decreases the strong hydrophobic interaction between the cell membrane wall and the edges/corners of graphene flakes. Chemotherapeutic effect assays reveal that the cancer cell viability was reduced up to ~50% at 3 µg/mL of DOX-FA-rGO/ZnS:Mn exposure, which is more pronounced than those obtained for free DOX at the same doses. Moreover, DOX-rGO/ZnS:Mn did not show any signs of toxicity. An opposite trend was observed for cells that do not overexpress the folate receptors, indicating that FA functionalization endows rGO/ZnS:Mn with an effective ability to discriminate positive folate receptor cancerous cells, enhancing its drug loading/release efficiency as a compact drug delivery system (DDS). This study paves the way for the potential use of functionalized rGO/ZnS:Mn nanocomposite as a platform for targeted cancer treatment.

Time-Resolved Photoluminescence Microscopy for the Analysis of Semiconductor-Based Paint Layers

In conservation, science semiconductors occur as the constituent matter of the so-called semiconductor pigments, produced following the Industrial Revolution and extensively used by modern painters. With recent research highlighting the occurrence of various degradation phenomena in semiconductor paints, it is clear that their detection by conventional optical fluorescence imaging and microscopy is limited by the complexity of historical painting materials. Here, we illustrate and prove the capabilities of time-resolved photoluminescence (TRPL) microscopy, equipped with both spectral and lifetime sensitivity at timescales ranging from nanoseconds to hundreds of microseconds, for the analysis of cross-sections of paint layers made of luminescent semiconductor pigments. The method is sensitive to heterogeneities within micro-samples and provides valuable information for the interpretation of the nature of the emissions in samples. A case study is presented on micro samples from a painting by Henri Matisse and serves to demonstrate how TRPL can be used to identify the semiconductor pigments zinc white and cadmium yellow, and to inform future investigations of the degradation of a cadmium yellow paint.

Facile synthesis of bovine serum albumin conjugated low-dimensional ZnS nanocrystals

We present a facile synthesis of bovine serum albumin (BSA) conjugated low-dimensional ZnS nanocrystals. The experimental parameters such as effects of BSA concentration and precursor vol ratios of Zn:S on the formation of ZnS nanoparticles in BSA matrix were investigated. The ZnS crystalline sizes of 1.9, 1.8 and 1.6nm were obtained by using the BSA concentrations of 1×10^-4, 5×10^-4 and 10×10^-4g/mL, respectively, with a fixed Zn:S vol ratio of 1:1. The ZnS samples prepared from 1:10 and 10:1 vol ratios of Zn:S at BSA concentration of 5×10^-4g/mL shows the crystalline sizes of ZnS are 2.1 and 1.5nm, respectively. FT-IR analysis suggests that the prepared ZnS nanoparticles might be conjugated through the interactions of hydroxyl and amine groups present in BSA. We evaluate the cytotoxicity of the prepared ZnS nanoparticles, the THP-1 cells showed a good viability (>88%) for all the prepared ZnS samples. The plausible mechanism for the formation of ZnS-BSA composite has also been discussed.

Nanomaterials made of non-toxic metallic sulfides: A systematic review of their potential biomedical applications

Metallic sulfides involve the chemical bonding of one or more sulfur atoms to a metal. Metallic sulfides are cheap, abundant semiconductor materials that can be used for several applications. However, an important and emerging use for non-toxic metallic sulfides in biomedical applications has arisen quickly in the medical field. In this systematic review, the available data from electronic databases were collected according to PRISMA alignments for systematic reviews. This review shows that these metallic sulfides could be promising for biomedical uses and applications. This systematic review is focused primarily on the following compounds: silver sulfide, copper sulfide, and iron sulfide. The aim of this review was to provide a quick reference on synthesis methods, biocompatibility, recent advances and perspectives, with remarks on future improvements. The toxicity of metallic sulfides depends directly on the cytotoxicity of their interactions with cells and tissues. Metallic sulfides have potential biomedical applications due to their antibacterial properties, uses in imaging and diagnostics, therapies such as photothermal therapy and chemotherapy in tumors and cancer cells, drug delivery and the fabrication of biosensors for the sensitive and selective detection of moieties, among others. Although current evidence about metallic sulfide NPs is promising, there are still several issues to be addressed before these NPs can be used in biomedicine. The current review is a brief but significant guide to metallic sulfides and their potential uses in the biomedical field.