Biomedical Applications of Silver Nanoparticles: An Up-to-Date Overview

In vitro and in vivo assessments of inspired Ag/80S bioactive nanocomposites against carbapenem-resistant Klebsiella pneumoniae

In 2017 the World Health Organization listed carbapenem-resistant K. pneumoniae as a critical priority for developing a novel antimicrobial agent. Here we report on our investigation of the antibacterial efficacy of silver nanoparticles (AgNPs), confined to a mesostructured material and designated as an Ag/80S bioactive nanocomposite, against carbapenem-resistant K. pneumoniae. Results from a textural analysis indicate a 7.5 nm mesopore size and 307.6 m²/g surface area for Ag/80S. UV-Vis spectrum and transmission electron microscope images of Ag/80S revealed a uniform AgNP size distribution with an approximately 3.5 nm average. ICP-MS analysis demonstrated a significantly higher silver content in TSB (a protein-rich environment) compared to ultrapure water, suggesting a controllable release of Ag/80S and thus designated as the inspired Ag/80S. Minimum inhibitory concentration (MIC) values against 16 K. pneumoniae isolates ranged from 0.25 to 0.5% (2.5 to 5.0 mg/ml). NIH 3T3 fibroblast viability at 0.25% exceeded 80% and at 0.5% just under 70%, suggesting low cytotoxicity. Mechanistic study results indicate that the inspired Ag/80S attached to and deformed bacterial cells and induced a time-dependent accumulation of reactive oxygen species, leading to bacterial death. Further, inspired Ag/80S significantly extended median survival time in a Caenorhabditis elegans animal model infected with carbapenem-resistant K. pneumoniae ATCC BAA-1705. Combined, we found a novel Ag/80S which could prevent aggregation of AgNP and control its release via a specific environment for medical use against carbapenem-resistant K. pneumoniae.

One-Pot Reducing Agent-Free Synthesis of Silver Nanoparticles/Nitrocellulose Composite Surface Coating with Antimicrobial and Antibiofilm Activities

Nitrocellulose with silver nanoparticle (AgNP/NC) composite was prepared in situ using Ag(CH₃CO₂) and nitrocellulose without any reducing agent. The composite materials synthesized were spray coated onto glass substrates to obtain thin films. The AgNPs/NC composites were characterized by ultraviolet-visible, Fourier transform infrared, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The antimicrobial activity of AgNPs/NC composite was investigated by tube method and time-kill kinetic studies against three microbial species, including Pseudomonas aeruginosa (ATCC 27853), Staphylococcus aureus (ATCC 25923), and Candida albicans (ATCC 10231). The antibiofilm activities were qualitatively determined against all three organisms. Prepared AgNPs/NC films exhibited good antimicrobial activity and significant inhibition of biofilm development against all three microbial species. The effective dispersion of AgNPs/NC in biofilm was responsible for the significant antibiofilm activity of the prepared material. The reported AgNPs/NC composite can be used as coating additive in bacteriocidal paint which can be applied onto surfaces such as in healthcare environments.

Developmental exposure to silver nanoparticles leads to long term gut dysbiosis and neurobehavioral alterations

Due to their antimicrobial properties, silver nanoparticles (AgNPs) are used in a wide range of consumer products that includes topical wound dressings, coatings for biomedical devices, and food-packaging to extend the shelf-life. Despite their beneficial antimicrobial effects, developmental exposure to such AgNPs may lead to gut dysbiosis and long-term health consequences in exposed offspring. AgNPs can cross the placenta and blood–brain-barrier to translocate in the brain of offspring. The underlying hypothesis tested in the current study was that developmental exposure of male and female mice to AgNPs disrupts the microbiome–gut–brain axis. To examine for such effects, C57BL6 female mice were exposed orally to AgNPs at a dose of 3 mg/kg BW or vehicle control 2 weeks prior to breeding and throughout gestation. Male and female offspring were tested in various mazes that measure different behavioral domains, and the gut microbial profiles were surveyed from 30 through 120 days of age. Our study results suggest that developmental exposure results in increased likelihood of engaging in repetitive behaviors and reductions in resident microglial cells. Echo-MRI results indicate increased body fat in offspring exposed to AgNPs exhibit. Coprobacillus spp., Mucispirillum spp., and Bifidobacterium spp. were reduced, while Prevotella spp., Bacillus spp., Planococcaceae, Staphylococcus spp., Enterococcus spp., and Ruminococcus spp. were increased in those developmentally exposed to NPs. These bacterial changes were linked to behavioral and metabolic alterations. In conclusion, developmental exposure of AgNPs results in long term gut dysbiosis, body fat increase and neurobehavioral alterations in offspring.

Multifunctional hybrid nanoplatform based on Fe3O4@Ag NPs for nitric oxide delivery: development, characterization, therapeutic efficacy, and hemocompatibility

The combination of Fe₃O₄@Ag superparamagnetic hybrid nanoparticles and nitric oxide (NO) represents an innovative strategy for a localized NO delivery with a simultaneous antibacterial and antitumoral actions. Here, we report the design of Fe₃O₄@Ag hybrid nanoparticles, coated with a modified and nitrosated chitosan polymer, able to release NO in a biological medium. After their synthesis, physicochemical characterization confirmed the obtention of small NO-functionalized superparamagnetic Fe₃O₄@Ag NPs. Antibacterial assays demonstrated enhanced effects compared to control. Bacteriostatic effect against Gram-positive strains and bactericidal effect against E. coli were demonstrated. Moreover, NO-functionalized Fe₃O₄@Ag NPs demonstrated improved ability to reduce cancer cells viability and less cytotoxicity against non-tumoral cells compared to Fe₃O₄@Ag NPs. These effects were associated to the ability of these NPs act simultaneous as cytotoxic (necrosis inductors) and cytostatic compounds inducing S-phase cell cycle arrest. NPs also demonstrated low hemolysis ratio (<10%) at ideal work range, evidencing their potential for biomedical applications. Targeted and hemocompatible nitric oxide-releasing multi-functional hybrid nanoparticles for antitumor and antimicrobial applications.

SiO2-Ag Composite as a Highly Virucidal Material: A Roadmap that Rapidly Eliminates SARS-CoV-2

COVID-19, as the cause of a global pandemic, has resulted in lockdowns all over the world since early 2020. Both theoretical and experimental efforts are being made to find an effective treatment to suppress the virus, constituting the forefront of current global safety concerns and a significant burden on global economies. The development of innovative materials able to prevent the transmission, spread, and entry of COVID-19 pathogens into the human body is currently in the spotlight. The synthesis of these materials is, therefore, gaining momentum, as methods providing nontoxic and environmentally friendly procedures are in high demand. Here, a highly virucidal material constructed from SiO2-Ag composite immobilized in a polymeric matrix (ethyl vinyl acetate) is presented. The experimental results indicated that the as-fabricated samples exhibited high antibacterial activity towards Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) as well as towards SARS-CoV-2. Based on the present results and radical scavenger experiments, we propose a possible mechanism to explain the enhancement of the biocidal activity. In the presence of O2 and H2O, the plasmon-assisted surface mechanism is the major reaction channel generating reactive oxygen species (ROS). We believe that the present strategy based on the plasmonic effect would be a significant contribution to the design and preparation of efficient biocidal materials. This fundamental research is a precedent for the design and application of adequate technology to the next-generation of antiviral surfaces to combat SARS-CoV-2.

Combined NMR and Computational Study of Cysteine Oxidation during Nucleation of Metallic Clusters in Biological Systems

The widespread biomedical applications of silver and gold nanoparticles (AgNPs and AuNPs, respectively) prompt the need for mechanistic evaluation of their interaction with biomolecules. In biological media, metallic NPs are known to transform by various pathways, especially in the presence of thiols. The interplay between metallic NPs and thiols may lead to unpredictable consequences for the health status of an organism. This study explored the potential events occurring during biotransformation, dissolution, and reformation of NPs in the thiol-rich biological media. The study employed a model system evaluating the interaction of cysteine with small-sized AgNPs and AuNPs. The interplay of cysteine on transformation and reformation pathways of these NPs was experimentally investigated by nuclear magnetic resonance (NMR) spectroscopy and supported by light scattering techniques and transmission electron microscopy (TEM). As the main outcome, Ag- or Au-catalyzed oxidation of cysteine to cystine was found to occur through generation of reactive oxygen species (ROS). Computational simulations confirmed this mechanism and the role of ROS in the oxidative dimerization of biothiol during NPs reformation. The obtained results represent valuable mechanistic data about the complex events during the transport of metallic NPs in thiol-rich biological systems that should be considered for the future biomedical applications of metal-based nanomaterials.

Recent research and progress of biodegradable zinc alloys and composites for biomedical applications: Biomechanical and biocorrosion perspectives

Biodegradable metals (BMs) gradually degrade in vivo by releasing corrosion products once exposed to the physiological environment in the body. Complete dissolution of biodegradable implants assists tissue healing, with no implant residues in the surrounding tissues. In recent years, three classes of BMs have been extensively investigated, including magnesium (Mg)-based, iron (Fe)-based, and zinc (Zn)-based BMs. Among these three BMs, Mg-based materials have undergone the most clinical trials. However, Mg-based BMs generally exhibit faster degradation rates, which may not match the healing periods for bone tissue, whereas Fe-based BMs exhibit slower and less complete in vivo degradation. Zn-based BMs are now considered a new class of BMs due to their intermediate degradation rates, which fall between those of Mg-based BMs and Fe-based BMs, thus requiring extensive research to validate their suitability for biomedical applications. In the present study, recent research and development on Zn-based BMs are reviewed in conjunction with discussion of their advantages and limitations in relation to existing BMs. The underlying roles of alloy composition, microstructure, and processing technique on the mechanical and corrosion properties of Zn-based BMs are also discussed.

Noble Metal Nanomaterials for NIR-Triggered Photothermal Therapy in Cancer

It is of great significance to develop anticancer therapeutic agents or technologies with high degree of specificity and patient compliance, while low toxicity. The emerging photothermal therapy (PTT) has become a new and powerful therapeutic technology due to its noninvasiveness, high specificity, low side effects to normal tissues and strong anticancer efficacy. Noble metal nanomaterials possess strong surface plasmon resonance (SPR) effect and synthetic tunability, which make them facile and effective PTT agents with superior optical and photothermal characteristics, such as high absorption cross-section, incomparable optical-thermal conversion efficiency in the near infrared (NIR) region, as well as the potential of bioimaging. By incorporating with various functional reagents such as antibodies, peptides, biocompatible polymers, chemo-drug and immune factors, noble metal nanomaterials have presented strong potential in multifunctional cancer therapy. Herein, the recent development regarding the application of noble metal nanomaterials for NIR-triggered PTT in cancer treatment is summarized. A variety of studies with good therapeutic effects against cancer from impressive photothermal efficacy of noble metal nanomaterials are concluded. Intelligent nanoplatforms through ingenious fabrication showing potential of multifunctional PTT, combined with chemo-therapy, immunotherapy, photodynamic therapy (PDT), as well as simultaneous imaging modality are also demonstrated.

Metal-Immobilized Micellar Aggregates of a Block Copolymer from a Mixed Solvent for a SERS-Active Sensing Substrate and Versatile Dip Catalysis

Here, we have reported micellar aggregations of an amphiphilic block copolymer in mixed solvent and their subsequent use as a template for the fabrication of a very dense, tunable metal nanoparticle-decorated surface for SERS and flexible dip catalysis applications. A silver nanoparticle-immobilized layer on silicon substrates shows excellent SERS (surface-enhanced Raman scattering)-based sensing performance for model analyte rhodamine B up to 10^-6 M concentration with a well-defined calibration curve. Furthermore, a facile approach to the preparation of metal NP-immobilized BCP membranes as efficient dip catalyst for two model reactions (the reduction of nitrophenol and the Suzuki-Miyaura reaction of iodobenzene or 2,7-diiodofluorene with phenyl boronic acid) is also demonstrated. The Ag NP-decorated film exhibits high efficiency and extensive reusability in a prototype reaction such as the reduction of nitrophenol by sodium borohydride with a very high turnover number, >126 (for a single use), whereas the Pd NP-immobilized film also has a high, ∼100%, reaction yield and extensive reusability and applicable for different aromatic systems. This work provides a new platform for the design and synthesis of a functionalizable, flexible, and highly mechanically stable dip catalyst which is highly demanded in the catalytic production of value-added chemicals and environmental applications such as wastewater treatment.

Aloe Vera-Mediated Te Nanostructures: Highly Potent Antibacterial Agents and Moderated Anticancer Effects

Cancer and antimicrobial resistance to antibiotics are two of the most worrying healthcare concerns that humanity is facing nowadays. Some of the most promising solutions for these healthcare problems may come from nanomedicine. While the traditional synthesis of nanomaterials is often accompanied by drawbacks such as high cost or the production of toxic by-products, green nanotechnology has been presented as a suitable solution to overcome such challenges. In this work, an approach for the synthesis of tellurium (Te) nanostructures in aqueous media has been developed using aloe vera (AV) extracts as a unique reducing and capping agent. Te-based nanoparticles (AV-TeNPs), with sizes between 20 and 60 nm, were characterized in terms of physicochemical properties and tested for potential biomedical applications. A significant decay in bacterial growth after 24 h was achieved for both Methicillin-resistant Staphylococcus aureus and multidrug-resistant Escherichia coli at a relative low concentration of 5 µg/mL, while there was no cytotoxicity towards human dermal fibroblasts after 3 days of treatment. AV-TeNPs also showed anticancer properties up to 72 h within a range of concentrations between 5 and 100 µg/mL. Consequently, here, we present a novel and green approach to produce Te-based nanostructures with potential biomedical applications, especially for antibacterial and anticancer applications.

Folate Receptors' Expression in Gliomas May Possess Potential Nanoparticle-Based Drug Delivery Opportunities

Brain cancer effected around estimated 23 890 adults and 3540 children under the age of 15 in 2020. The chemotherapeutic agents that are already approved by the FDA for brain cancer are proving to be not highly effective because of the interference from the tumor microenvironment as well as their own toxicities. Added to this is the impedance presented by the extremely restrictive permeability of the blood brain barrier (BBB). Targeted nanoparticulate drug delivery systems offer a good opportunity to traverse the BBB and selectively target the tumor cells. Folate receptors are found to be one of the most useful targets for drug delivery to the brain. Hence, this Mini-Review discusses the folate receptors and their application in the treatment of brain cancers using targeted nanoparticles.

Silver Nanoparticles for a Colorimetric Determination of Putrescine and Cadaverine in Biological Samples

A convenient and uncomplicated scheme has been projected for the quantitative determination of essential diamines putrescine (PUT) and cadaverine (CAD) via sodium dodecyl sulfate protected silver nanoparticles (SDS-AgNPs). This scheme is based on the chemical interaction of a SDS-AgNPs probe with PUT and CAD, leading to a color change from yellow to red or reddish brown. The interaction was investigated through different techniques such as using a UV-visible spectrophotometer, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), dynamic light scattering spectroscopy (DLS) and the zeta potential. Both amines possess a close resemblance in structure (except for the addition of one more methylene group in CAD), and no any distinguishable color change was noted. However, the maximum absorption band at 580 and 600 nm was demonstrated for PUT and CAD correspondingly. The methodical response was observed at absorption ratios of 580/410 and 600/410 nm, with the linear regression within 4 - 12 and 6 - 14 μg/mL for PUT and CAD. The detection limits calculated for both the diamines PUT and CAD were 0.333 and 1.638 μg/mL. The scheme was successfully applied for determinations in biological samples, including spiked blood plasma and urine. Putrescine exhibited % recovery within 95.717 - 105.200%, while cadaverine was within 95.940 - 105.109%, respectively. The scheme was reproducible and precise with inter-day RSD (n = 5) within 1.126, 0.018% and the intraday RSD (n = 5) was within 0.005, 0.002% for PUT and CAD, respectively.

Multifunctional Hydroxyapatite/Silver Nanoparticles/Cotton Gauze for Antimicrobial and Biomedical Applications

Medical textiles have played an increasingly important protection role in the healthcare industry. This study was aimed at improving the conventional cotton gauze for achieving advanced biomedical specifications (coloration, UV-protection, anti-inflammation, and antimicrobial activities). These features were obtained by modifying the cotton gauze fabrics via in-situ precipitation of hydroxyapatite nanoparticles (HAp NP), followed by in-situ photosynthesis of silver (Ag) NPs with ginger oil as a green reductant with anti-inflammation properties. The HAp-Ag NPs coating provides good UV-protection properties. To further improve the HAp and Ag NPs dispersion and adhesion on the surface, the cotton gauze fabrics were modified by cationization with chitosan, or by partial carboxymethylation (anionic modification). The influence of the cationic and anionic modifications and HAp and Ag NPs deposition on the cotton gauze properties (coloration, UV-protection, antimicrobial activities, and water absorption) was thoroughly assessed. Overall, the results indicate that chemical (anionic and cationic) modification of the cotton gauze enhances HAp and Ag NPs deposition. Chitosan can increase biocompatibility and promotes wound healing properties of cotton gauze. Ag NP deposition onto cotton gauze fabrics brought high antimicrobial activities against Candida albicans, Gram-positive and Gram-negative bacteria, and improved UV protection.

Interaction mechanism of plant-based nanoarchitectured materials with digestive enzymes of termites as target for pest control: Evidence from molecular docking simulation and in vitro studies

The integration of nanotechnology for efficient pest management is gaining momentum to overcome the challenges and drawbacks of traditional approaches. However, studies pertaining to termite pest control using biosynthesized nanoparticles are seldom. The present study aims to highlight the following key points: a) green synthesis of AgNPs using Glochidion eriocarpum and their activity against wood-feeding termites, b) testing the hypothesis that AgNPs diminish digestive enzymes in termite gut through in silico analysis. The green synthesis route generated spherical PsAgNPs in the size range of 4-44.5 nm exhibiting higher thermal stability with minimal weight loss at 700 °C. The choice and no-choice bioassays confirmed strong repellent (80.97%) and antifeedant activity of PsAgNPs. Moreover, PsAgNPs exposure caused visible morphological changes in termites. Molecular docking simulation indicated possible attenuation of endoglucanase and bacteria-origin xylanase, digestive enzymes from termite gut, through partial blocking of the catalytic site by AgNPs. Altogether, our preliminary study suggests promising potentials of PsAgNPs for pest management in forestry and agriculture sectors to prevent damages to living trees, wood, crops, etc. As sustainable pest management practices demand low risk to the environment and biodiversity therefore, we recommend that more extensive studies should be performed to elucidate the environmental compatibility of PsAgNPs.

Edible mushroom (Flammulina velutipes) as biosource for silver nanoparticles: from synthesis to diverse biomedical and environmental applications

The current study reports advanced, ecofriendly and biosynthesized silver NPs for diverse biomedical and environmental applications using Flammulina velutipes as biosource. In the study, a simple aqueous extract of F. velutipes was utilized to reduce the AgNO₃ into stable elemental silver (Ag⁰) at a nanometric scale. The NPs had average size of 21.4 nm, spherical morphology, and were highly stable and pure. The characterized nanoparticles were exploited for a broad range of biomedical applications including bacteriocidal, fungicidal, leishmanicidal, in vitro antialzheimer's, antioxidant, anti-diabetic and biocompatibility studies. Our findings showed that F. velutipes mediated AgNPs exhibited high activity against MDR bacterial strains and spore forming fungal strains. All the tested urinary tract infection bacterial isolates, were resistant to non-coated antibiotics but by applying 1% of the synthesized AgNPs, the bactericidal potential of the tested antibiotics enhanced manifolds. The NPs also exhibited dose-dependent cytotoxic potential against Leishmania tropica with significant LC₅₀ of 248 μg ml^-1 for promastigote and 251 μg ml^-1 for amastigote forms of the parasite. Furthermore, promising antialzheimer and antidiabetic activities were observed as significant inhibition of α-amylase, α-glucosidase, acetylcholinesterase (AChE) and butrylcholineterase (BChE) were noted. Moreover, remarkable biocompatible nature of the particles was found against human red blood cells. The biosynthesized AgNPs as photocatalyst, also resulted in 98.2% degradation of indigo carmine dye within 140 min. Owing to ecofriendly synthesis, biosafe nature and excellent physicochemical properties F. velutipes AgNPs can be exploited as novel candidates for multifaceted biomedical and environmental applications.

Nanotoxic Effects of Silver Nanoparticles on Normal HEK-293 Cells in Comparison to Cancerous HeLa Cell Line

Purpose

Biomimetic approaches for the synthesis of silver nanoparticles (AgNPs) had created a substantial impression among the research community that focuses on nano-bio interactions. In this study, an eco-friendly method using Rhizophora apiculata aqueous leaf extract as a reductant-rich hydrosol was followed to synthesize AgNPs and test its cytotoxicity.

Methods

To optimise the parameters for the synthesis of AgNPs, central composite design based on response surface methodology was used. The particles synthesized at a nano-scale were characterized in our previously published report. The present report further characterizes the nanoparticles by X-ray diffraction, SEM and TEM at varying sites and magnifications. The characterized AgNPs were tested for their cytotoxic effects on HEK-293 and HeLa cells.

Results

The cytotoxicity on the cell lines was dose-dependent. At a concentration of 2.5 μL/mL of the AgNPs-containing hydrosol, 100% inhibition of HEK-293 cells and 75% inhibition of the HeLa cells were observed. The IC₅₀ value for AgNPs on HEK-293 was 0.622 µL/mL (12.135 ng), whereas, for HeLa cells, it was 1.98 µL/mL (38.629 ng).

Conclusion

The nanoparticles were three-fold toxic towards the HEK-293 cells in comparison to the HeLa cells. Therefore, the therapeutic index is low for R. apiculata derived AgNPs on HeLa cells when tested in comparison with the HEK-293 cells. The nanotoxicity profile of the synthesized AgNPs seems more prominent than the nanotherapeutic index. According to our knowledge, this is the first-ever report on the optimization of synthesis of AgNPs using response surface methodology and identifying the therapeutic index of mangrove leaf-derived AgNPs.

Repurposed Drugs, Molecular Vaccines, Immune-Modulators, and Nanotherapeutics to Treat and Prevent COVID-19 Associated with SARS-CoV-2, a Deadly Nanovector

The deadly pandemic, coronavirus disease 2019 (COVID-19), caused due to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has paralyzed the world. Although significant methodological advances have been made in the field of viral detection/diagnosis with 251 in vitro diagnostic tests receiving emergency use approval by the US-FDA, little progress has been made in identifying curative or preventive therapies. This review discusses the current trends and potential future approaches for developing COVID-19 therapeutics, including repurposed drugs, vaccine candidates, immune-modulators, convalescent plasma therapy, and antiviral nanoparticles/nanovaccines/combinatorial nanotherapeutics to surmount the pandemic viral strain. Many potent therapeutic candidates emerging via drug-repurposing could significantly reduce the cost and duration of anti-COVID-19 drug development. Gene/protein-based vaccine candidates that could elicit both humoral and cell-based immunity would be on the frontlines to prevent the disease. Many emerging nanotechnology-based interventions will be critical in the fight against the deadly virus by facilitating early detection and enabling target oriented multidrug therapeutics. The therapeutic candidates discussed in this article include remdesivir, dexamethasone, hydroxychloroquine, favilavir, lopinavir/ritonavir, antibody therapeutics like gimsilumab and TJM2, anti-viral nanoparticles, and nanoparticle-based DNA and mRNA vaccines.

Impact of Zero-Valent Iron on Freshwater Bacterioplankton Metabolism as Predicted from 16S rRNA Gene Sequence Libraries

The application of zero-valent iron particles (ZVI) for the treatment of heavily polluted environment and its biological effects have been studied for at least two decades. Still, information on the impact on bacterial metabolic pathways is lacking. This study describes the effect of microscale and nanoscale ZVI (mZVI and nZVI) on the abundance of different metabolic pathways in freshwater bacterial communities. The metabolic pathways were inferred from metabolism modelling based on 16S rRNA gene sequence data using paprica pipeline. The nZVI changed the abundance of numerous metabolic pathways compared to a less influencing mZVI. We identified the 50 most affected pathways, where 31 were related to degradation, 17 to biosynthesis, and 2 to detoxification. The linkage between pathways was two times higher in nZVI samples compared to mZVI, and was specifically higher considering the arsenate detoxification II pathway. Limnohabitans and Roseiflexus were linked to the same pathways in both nZVI and mZVI. The prediction of metabolic pathways increases our knowledge of the impacts of nZVI and mZVI on freshwater bacterioplankton.

Intradermal administration of green synthesized nanosilver (NS) through film-coated PEGDA microneedles for potential antibacterial applications

Skin infections caused by pathogens, including bacteria, fungi and viruses, are difficult to completely eliminate through standard topical administration, owing to the restricted drug permeation into the epidermis layer. Herein, we developed a poly(ethylene glycol) diacrylate (PEGDA) microneedle patch with surface coating of a nanosilver (NS) encapsulated gelatin/sucrose film for antibacterial applications, by virtue of enhanced skin permeation by microneedle penetration and efficient drug delivery through rapid film dissolving. NS was facilely synthesized through a green process based on the bioinspired crystallization of ionic state silver in the presence of a silk fibroin (SF) template. A gelatin/sucrose polymeric film encapsulating NS was dressed on the surface of the mold cavity, and film-coated PEGDA (PEGDA/film-NS) microneedles were subsequently fabricated through standard ultraviolet (UV) light-induced polymerization. To demonstrate their advantages for therapeutic applications, the physicochemical properties of the as-developed microneedles were characterized in terms of their morphology, composition, mechanical strength, etc. Moreover, rapid NS release from PEGDA@film-NS microneedles driven by the aqueous environment was demonstrated under physiological conditions. Additionally, such film-coated microneedles exhibited good mechanical strength for skin penetration, and their antibacterial activity against Gram-positive bacteria (Staphylococcus epidermidis and Staphylococcus aureus) as well as Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) was verified using bacterial suspension in vitro. Altogether, such a minimally invasive strategy exhibited good potential for realizing a broad-spectrum antibacterial effect, which may provide a practical methodology for the management of polymicrobial skin infection during clinical trials.

Antimicrobial efficacy of silver nanoparticles against Candida albicans: A systematic review protocol

INTRODUCTION

Denture-induced stomatitis is one form of candidiasis. It is characterised as inflammation and erythema of the oral mucosa underneath the denture-bearing areas and clinically classified into three types according to severity. Denture hygiene, appropriate mouth rinses and the use of antifungal therapy are commonly used to treat the condition, but new technologies are emerging that may assist in its treatment.

AIM

The aim of this systematic review is to determine if silver nanoparticles inhibit the growth of Candida Albicans when included in acrylic dentures and in different denture liners.

METHODOLOGY

A protocol was developed and published on PROSPERO (Registration No: CRD42019145542) and with the institutional ethics committee (Registration No: BM20/4/1). The protocol includes all aspects of a systematic review namely: selection criteria, search strategy, selection methods using predetermined eligibility criteria, data collection, data extraction, critical appraisal of included studies, and the intended statistical analyses such as calculating risk ratios (RR) for dichotomous outcomes and presented at 95% confidence intervals, a meta-analysis, if possible or a narrative report as needed.

EXPECTED RESULTS

With rigorous inclusion criteria set and databases identified for searching, appropriate clinical and laboratory studies may be obtained but the results and its interpretation and translation into clinical practice may be a challenge as these depend on the quality of the research.

Cytotoxicity against human breast carcinoma cells of silver nanoparticles biosynthesized using Capsosiphon fulvescens extract

Targeting cancer cells with small nanoparticles is a novel and promising approach to cancer therapy. Breast cancer is the most common cancer afflicting women worldwide. In the present study, silver nanoparticles (AgNPs) were synthesized using the aqueous extract of the marine alga Capsosiphon (C.) fulvescens, and the cytotoxicity and anti-cancer activities of the nanoparticles against MCF-7 breast cancer cells were analyzed. Nanoparticle formation was confirmed by solution color change and UV-Vis spectroscopy. The size and distribution of the C. fulvescens-biosynthesized silver nanoparticles (CfAgNPs) were then examined using various analytical methods; the particle size was around 20-22 nm and spherical in shape with no agglomeration. Cytotoxicity analysis revealed that the inhibitory concentration (IC₅₀) of CfAgNPs was 50 μg/ml. MCF-7 cell viability decreased with increasing concentrations of CfAgNPs. MCF-7 cells were evaluated for morphological changes before and after treatment with the CfAgNPs; cells treated with C. fulvescens aqueous algal extract (without CfAgNPs) showed irregular confluent aggregates with round polygonal cells, similar to the untreated control. Tamoxifen- (TMX) and CfAgNPs-treated cells show significant morphological changes. An apoptosis study was conducted using 4',6-diamidino-2-phenylindole (DAPI) staining, in which CfAgNP-treated MCF-7 cells generated bright blue fluorescence and shortened, disjointed chromatin was evident; control cells displayed less bright fluorescence. Flow cytometry analysis revealed that the percentage of cells in late apoptosis was high following treatment with TMX (77.2%) and CfAgNP (74.6%). A novel anti-cancer agent, developed by generating silver nanoparticles from C. fulvescens extract, showed strong cytotoxic activity against MCF-7 cells.

First principle simulation of coated hydroxychloroquine on Ag, Au and Pt nanoparticles

From the first month of the COVID-19 pandemic, the potential antiviral properties of hydroxychloroquine (HCQ) and chloroquine (CQ) against SARS-CoV-2 suggested that these drugs could be the appropriate therapeutic candidates. However, their side effects directed clinical tests towards optimizing safe utilization strategies. The noble metal nanoparticles (NP) are promising materials with antiviral and antibacterial properties that can deliver the drug to the target agent, thereby reducing the side effects. In this work, we applied both the quantum mechanical and classical atomistic molecular dynamics approaches to demonstrate the adsorption properties of HCQ/CQ on Ag, Au, AgAu, and Pt nanoparticles. We found the adsorption energies of HCQ/CQ towards nanoparticles have the following trend: PtNP > AuNP > AuAgNP > AgNP. This shows that PtNP has the highest affinity in comparison to the other types of nanoparticles. The (non)perturbative effects of this drug on the plasmonic absorption spectra of AgNP and AuNP with the time-dependent density functional theory. The effect of size and composition of NPs on the coating with HCQ and CQ were obtained to propose the appropriate candidate for drug delivery. This kind of modeling could help experimental groups to find efficient and safe therapies.

Transcriptomic responses to silver nanoparticles in the freshwater unicellular eukaryote Tetrahymena thermophila

Currently, silver nanoparticles (AgNPs) are being increasingly used as biocides in various consumer products and if released in the environment they can affect non-target organisms. Therefore, understanding the toxicity mechanism is crucial for both the design of more efficient nano-antimicrobials and for the design of nanomaterials that are biologically and environmentally benign throughout their life-cycle. Here, the ciliate Tetrahymena thermophila was used to elucidate the mechanisms of action of AgNPs by analysing the gene expression profile by RNA-seq and the transcriptomic effects of AgNPs were compared to those induced by soluble silver salt, AgNO₃. Exposure to AgNPs at sublethal concentrations for 24 h induced phagocytosis, transport pathways, response to oxidative stress, glutathione peroxidase activity, response to stimulus, oxidation-reduction, proteolysis, and nitrogen metabolism process. Based on gene set enrichment analysis (GSEA), some biological processes appeared targets of both toxicants. In addition to many similarities in affected genes, some effects were triggered only by NPs, like phagocytosis, glutathione peroxidase activity, response to stimulus, protein phosphorylation and nitrogen metabolism process. This research provides evidence that AgNPs compared to AgNO₃ at the same concentration of dissolved silver ions dysregulate a higher number of cellular pathways. These findings confirm that AgNPs can induce toxicity not only due to soluble silver ions released from the particles but also to particle intrinsic features.

Studies on Molecular Interactions between Bovine β-Lactoglobulin and Silver Nanoparticles

BACKGROUND

Silver Nanoparticles (AgNPs) were found to modulate the fibrillation of Bovine Β-Lactoglobulin (BLG).

OBJECTIVE

To gain an insight regarding the mechanism of BLG aggregation modulation by AgNPs at molecular level, studies on the interactions between BLG and AgNPs were carried out.

METHODS

Protein-ligand interactions were studied based on Trp fluorescence quenching (at four different temperatures), synchronous and three-dimensional fluorescence and circular dichroism spectroscopy (far-UV and near-UV).

RESULTS

Protein-nanoparticles association constant was in the range of 106 -1010 M-1 and the quenching constant was determined as ~107 M-1. Ground state complexation between the protein and nanoparticles was predicted. Change in polarity surrounding the Trp residue was not detected by synchronous and three-dimensional fluorescence spectroscopy. AgNPs caused a global change in the secondary and tertiary structure of the protein as revealed from far-UV and near-UV CD spectroscopy. Enthalpy driven complexation between the protein and nanoparticles indicates the involvement of hydrogen bonding and/or van der Waals interactions.

CONCLUSION

Modulation of BLG aggregation by AgNPs is due to strong binding of the nanoparticles with BLG, which also causes structural perturbations of the protein.

Endocytosed silver nanoparticles degrade in lysosomes to form secondary nanoparticle structures during expression of autophagy genes in osteogenic cells

Silver nanoparticles (AgNPs) are increasingly used in combination with biomaterials, such as bone grafts, to provide antimicrobial properties. Our research focused on the cytotoxic and intracellular uptake mechanism of AgNPs on osteogenic cells, and the affected gene expression of osteoblasts exposed to AgNPs. Osteoblast cells were found to be relatively resistant to AgNP exposure, compared to osteoclasts, with a higher IC₅₀ and fewer adverse morphological features. AgNPs were endocytosed within lysosomes, which resulted in the secondary internal formation of curved Ag^O nano-chains assemblies within the cytosol. Furthermore, osteoblasts demonstrated an oxidative stress response, with autophagic cell death mechanisms, as indicated from qRT²-PCR analysis, with sustained upregulation of the protective gene Heme Oxygenase 1 reaching 86-fold by 48 hours (10 μg/mL). The internalization and fate of AgNPs in osteogenic cells, and the resulting impact on gene expression over time provide further understanding of the nanotoxicity mechanism of AgNPs.

Architectured Therapeutic and Diagnostic Nanoplatforms for Combating SARS-CoV-2: Role of Inorganic, Organic, and Radioactive Materials

Although extensive research is being done to combat SARS-CoV-2, we are yet far away from a robust conclusion or strategy. With an increased amount of vaccine research, nanotechnology has found its way into vaccine technology. Researchers have explored the use of various nanostructures for delivering the vaccines for enhanced efficacy. Apart from acting as delivery platforms, multiple studies have shown the application of inorganic nanoparticles in suppressing the growth as well as transmission of the virus. The present review gives a detailed description of various inorganic nanomaterials which are being explored for combating SARS-CoV-2 along with their role in suppressing the transmission of the virus either through air or by contact with inanimate surfaces. The review further discusses the use of nanoparticles for development of an antiviral coating that may decrease adhesion of SARS-CoV-2. A separate section has been included describing the role of nanostructures in biosensing and diagnosis of SARS-CoV-2. The role of nanotechnology in providing an alternative therapeutic platform along with the role of radionuclides in SARS-CoV-2 has been described briefly. Based on ongoing research and commercialization of this nanoplatform for a viral disease, the nanomaterials show the potential in therapy, biosensing, and diagnosis of SARS-CoV-2.

Rapid green synthesis of non-cytotoxic silver nanoparticles using aqueous extracts of 'Golden Delicious' apple pulp and cumin seeds with antibacterial and antioxidant activity

Abstract

A simple, facile and rapid microwave irradiated system was applied to synthesize silver nanoparticles using 'Golden Delicious' apple pulp (Malus domestica) and cumin (Cuminum cyminum) seed extracts. The phytosynthesized AgNPs were characterized by Ultraviolet–Visible Spectroscopy (UV–vis), Fourier transform infrared (FTIR), X-ray Diffraction (XRD) Transmission Electron Microscopy (TEM) and Zeta sizer analysis. In the study, the presence of face-centered cubic crystalline structured metallic silver in AgNPs from apple and cumin extracts and the monodisperse nature of AgNPs with the size distribution range of 5.46–20 nm and 1.84–20.57 nm were confirmed, respectively. This study established an efficient green synthesis approach that created so far, the smallest silver nanoparticles by using these two extracts. According to the results obtained, AgNPs synthesized using both extracts were non-toxic against L929 mouse fibroblast cells, while they were effective against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria with a greater effect on S. aureus. Moreover, AgNPs synthesized through cumin extract exhibited a higher ABTS scavenging ability (96.43 ± 0.78% at 160 μg/mL) in comparison to apple pulp extract mediated AgNPs, while both AgNPs showed lower activity for DPPH (27.84 ± 0.56% and 13.12 ± 0.32% from cumin seed and apple pulp extracts, respectively). In summary, our results suggest the green non-cytotoxic AgNPs synthesized in this study could be a promising template for further biological and clinical applications.

Graphical abstract

Silver Nanocolloids Loaded with Betulinic Acid with Enhanced Antitumor Potential: Physicochemical Characterization and In Vitro Evaluation

Betulinic acid (BA), a natural compound with various health benefits including selective antitumor activity, has a limited applicability in vivo due to its poor water solubility and bioavailability. Thus, this study focused on obtaining a BA nano-sized formulation with improved solubility and enhanced antitumor activity using silver nanocolloids (SilCo and PEG_SilCo) as drug carriers. The synthesis was performed using a chemical method and the physicochemical characterization was achieved applying UV-Vis absorption, transmission electron microscopy (TEM), Raman and photon correlation spectroscopy (PCS). The biological evaluation was conducted on two in vitro experimental models-hepatocellular carcinoma (HepG2) and lung cancer (A549) cell lines. The physicochemical characterization showed the following results: an average hydrodynamic diameter of 32 nm for SilCo_BA and 71 nm for PEG_SilCo_BA, a spherical shape, and a loading capacity of 54.1% for SilCo_BA and 61.9% for PEG_SilCo_BA, respectively. The in vitro assessment revealed a cell type- and time-dependent cytotoxic effect characterized by a decrease in cell viability as follows: (i) SilCo_BA (66.44%) < PEG_SilCo_BA (72.05%) < BA_DMSO (75.30%) in HepG2 cells, and (ii) SilCo_BA (75.28%) < PEG_SilCo_BA (86.80%) < BA_DMSO (87.99%) in A549 cells. The novel silver nanocolloids loaded with BA induced an augmented anticancer effect as compared to BA alone.

Graphene-assisted preparation of large-scale single-crystal Ag(111) nanoparticle arrays for surface-enhanced Raman scattering

Surface plasmon resonance (SPR) of metal nanostructures has broad application prospects in the fields of sensing, energy, catalysis and optics. This paper reports a graphene-assisted method for preparing large-scale single-crystal Ag(111) nanoparticle (NP) arrays based on the ion implantation technique. By surface periodic patterning treatment and annealing of the implanted sample, regularly arranged Ag NPs can be prepared on the sample surface. A new application for graphene is proposed, that is, as a perfect barrier layer to prevent metal atoms from evaporating or diffusing. All the Ag NPs show (111) crystal orientation. Besides, the Ag atoms are covered by graphene immediately when they precipitate from the substrate, which can prevent them from being oxidized. On the basis of this structure, as one of the applications of the metal SPR, we have measured the surface-enhanced Raman scattering effect and found that the G peak of the Raman spectrum of the graphene achieved about 20 times enhancement.

Optoelectronic properties of highly porous silver oxide thin film

Abstract

In this paper, we report oxidation time effect on highly porous silver oxide nanowires thin films fabricated using ultrasonic spray pyrolysis and oxygen plasma etching method. The NW’s morphological, electrical, and optical properties were investigated under different plasma etching periods and the number of deposition cycles. The increase of plasma etching and oxidation time increases the surface roughness of the Ag NWs until it fused to form a porous thin film of silver oxide. AgNWs based thin films were characterized using X-ray diffraction, scanning electron microscope, transmission electron microscope, X-ray photoemission spectroscopy, and UV–Vis spectroscopy techniques. The obtained results indicate the formation of mixed mesoporous Ag2O and AgO NW thin films. The Ag2O phase of silver oxide appears after 300 s of oxidation under the same conditions, while the optical transparency of the thin film decreases as plasma etching time increases. The sheet resistance of the final film is influenced by the oxidation time and the plasma application periodicity.

Graphic abstract

Silver-Deposited Nanoparticles on the Titanium Nanotubes Surface as a Promising Antibacterial Material into Implants

The main disadvantage of the implants is the associated infections. Therefore, in the long term, the possibility of improving the antibacterial capacity of different types of implants (dental, orthopedic) is being researched. The severity of the problem lies in the increasing bacterial resistance and finding appropriate alternative treatments for infectious diseases, which is an important research field nowadays. The purpose of this review is to draw a parallel between different studies analyzing the antibacterial activity and mechanism of silver nanoparticles (NP Ag) deposited on the titanium nanotubes (NTT), as well as the analysis of the NP Ag toxicity. This review also provides an overview of the synthesis and characterization of TiO2-derived nanotubes (NT). Thus, the analysis aims to present the existing knowledge to better understand the NP Ag implants benefits and their antibacterial activity.

Environmental exposures and the etiopathogenesis of Alzheimer's disease: The potential role of BACE1 as a critical neurotoxic target

Alzheimer's disease (AD) is a major public health crisis due to devastating cognitive symptoms, a lack of curative treatments, and increasing prevalence. Most cases are sporadic (>95% of cases) after the age of 65 years, implicating an important role of environmental factors in disease pathogenesis. Environmental neurotoxicants have been implicated in neurodegenerative disorders including Parkinson's Disease and AD. Animal models of AD and in vitro studies have shed light on potential neuropathological mechanisms, yet the biochemical and molecular underpinnings of AD-relevant environmental neurotoxicity remain poorly understood. Beta-site amyloid precursor protein cleaving enzyme 1 (BACE1) is a potentially critical pathogenic target of environmentally induced neurotoxicity. BACE1 clearly has a critical role in AD pathophysiology: It is required for amyloid beta production and expression and activity of BACE1 are increased in the AD brain. Though the literature on BACE1 in response to environmental insults is limited, current studies, along with extensive AD neurobiology literature suggest that BACE1 deserves attention as an important neurotoxic target. Here, we critically review research on environmental neurotoxicants such as metals, pesticides, herbicides, fungicides, polyfluoroalkyl substances, heterocyclic aromatic amines, advanced glycation end products, and acrolein that modulate BACE1 and potential mechanisms of action. Though more research is needed to clearly understand whether BACE1 is a critical mediator of AD-relevant neurotoxicity, available reports provide convincing evidence that BACE1 is altered by environmental risk factors associated with AD pathology, implying that BACE1 inhibition and its use as a biomarker should be considered in AD management and research.

Antimicrobial and biological effects of polyaniline/polyvinylpyrrolidone nanocomposites loaded with silver nanospheres/triangles

Two Ag–PANI/PVP nanocomposites were prepared using in situ integration of AgNPs during oxidative aniline polymerization, accelerated by the presence of PVP, which as well minimized the risk of particle agglomeration and macroscopic precipitation.

Silver nanoparticles doped with silver cations and stabilized with maleic acid copolymers: specific structure and antimicrobial properties

The specificity of the structure of polymer complexes of silver nanoparticles and silver cations is revealed, and the additive antimicrobial effect of the system components is shown.

A proposed insight into the anti-viral potential of metallic nanoparticles against novel coronavirus disease-19 (COVID-19)

BACKGROUND

Over the last ten months since December 2019, the world has faced infectious emerging novel coronavirus disease-2019 (COVID-19) outbreaks that had a massive global impact affecting over 185 countries.

MAIN BODY

Emerging novel COVID-19 is a global health emergency on a pandemic scale that represents a terror to human health through its ability to escape anti-viral measures. Such viral infections impose a great socioeconomic burden, besides global health challenges. This imposes a pressing need for the development of anti-viral therapeutic agents and diagnostic tools that demonstrate multifunctional, target-specific, and non-toxic properties. Nanotheranostics is regarded as a promising approach for the management of different viral infections. Nanotheranostics facilitates targeted drug-delivery of anti-viral therapeutics as well as contributing to the development of diagnostic systems. Multifunctional metallic nanoparticles (NPs) have emerged as innovative theranostic agents that enable sustainable treatment and effective diagnosis. Here we have reviewed current advances in the use of theranostic metallic NPs to fight against COVID-19, and discussed the application as well as limitations associated with nanotechnology-based theranostic approaches.

CONCLUSION

This review verified the potential use of some metal-based NPs as anti-viral nanotheranostic agents. Metal-based NPs could act as carriers that enable the sustainable and targeted delivery of active anti-viral molecules, or as diagnostic agents that allow rapid and sensitive diagnosis of viral infections.

A facile microwave-assisted synthesis of Ag@SiO2 nanoparticles for Raman spectroscopy

A microwave-assisted synthesis of 90 nm ± 10 nm Ag@SiO₂ nanospheres for Raman spectroscopy.

Green synthesis of silver nanoparticles using soluble soybean polysaccharide and their application in antibacterial coatings

In the present work, a facile and green synthesis approach for the production of monodispersed, small-sized (2.9 ± 0.7 nm) and stable silver nanoparticles (AgNPs) using soluble soybean polysaccharide (SSPS) was reported. SSPS was used as the reducing and stabilizing agent. The obtained SSPS-stabilized AgNPs (SA) were characterized by UV-vis absorption spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy and transmission electron microscopy. The antimicrobial activity of the SA colloidal dispersion (SACD) was evaluated based on the growth kinetics of bacteria E. coli and S. aureus. Afterwards, the colloidal dispersion was applied as a coating material to Kraft paper. The SACD-coated Kraft paper exhibited excellent antimicrobial activity against above bacteria strains and P. aeruginosa. The effects of SACD coating on surface wettability, barrier property and microstructure of the Kraft paper were also studied. The results suggested that the SSPS-stabilized AgNPs have great potential in antibacterial applications.

Probabilistic modelling of nanobiomaterial release from medical applications into the environment

Nanobiomaterials (NBMs) are currently being tested in numerous biomedical applications, and their use is expected to grow rapidly in the near future. Many different types of nanomaterials are employed for a wide variety of different applications. Silver nanoparticles (nano-Ag) have been investigated for their antibacterial, antifungal, and osteoinductive properties to be used in catheters, wound healing, dental applications, and bone healing. Polymeric nanoparticles such as poly(lactic-co-glycolic acid) (PLGA) are mainly studied for their ability to deliver cancer drugs as the body metabolizes them into simple compounds. However, most of these applications are still in the development stage and unavailable on the market, meaning that information on possible consumption, material flows, and concentrations in the environment is lacking. We thus modeled a realistic scenario involving several nano-Ag and PLGA applications which are already in use or likely to reach the market soon. We assumed their full market penetration in Europe in order to explore the prospective flows of NBMs and their environmental concentrations. The potential flows of three application-specific composite materials were also examined for one precise application each: Fe₃O₄PEG-PLGA used in drug delivery, MgHA-collagen used for bone tissue engineering, and PLLA-Ag applied in wound healing. Mean annual consumption in Europe, considering all realistic and probable applications of the respective NBMs, was estimated to be 5,650 kg of nano-Ag and 48,000 kg of PLGA. Mean annual consumption of the three application-specific materials under the full market penetration scenario was estimated to be 4,000 kg of Fe₃O₄PEG-PLGA, 58 kg of MgHA-collagen, and 24,300 kg of PLLA-Ag. A probabilistic material-flow model was used to quantify flows of the NBMs studied from production, through use, and on to end-of-life in the environment. The highest possible worst-case predicted environmental concentration (wc-PEC) were found to occur in sewage sludge, with 0.2 µg/kg of nano-Ag, 400 µg/kg of PLGA, 33 µg/kg of Fe₃O₄PEG-PLGA, 0.007 µg/kg of MgHA-collagen, and 2.9 µg/kg of PLLA-Ag. PLGA exhibited the highest concentration in all environmental compartments except natural and urban soil, where nano-Ag showed the highest concentration. The results showed that the distribution of NBMs into different environmental and technical compartments is strongly dependent on their type of application.

Therapeutic strategies and potential implications of silver nanoparticles in the management of skin cancer

Skin cancer (SC) is the most common carcinoma affecting 3 million people annually in the United States and millions of people worldwide. It is classified as melanoma SC (MSC) and non-melanoma SC (NMSC). NMSC represents approximately 80% of SC and includes squamous cell carcinoma and basal cell carcinoma. MSC, however, has a higher mortality rate than SC because of its ability to metastasize. SC is a major health problem in the United States with significant morbidity and mortality in the Caucasian population. Treatment options for SC include cryotherapy, excisional surgery, Mohs surgery, curettage and electrodessication, radiation therapy, photodynamic therapy, immunotherapy, and chemotherapy. Treatment is chosen based on the type of SC and the potential for side effects. Novel targeted therapies are being used with increased frequency for large tumors and for metastatic disease. A scoping literature search on PubMed, Google Scholar, and Cancer Registry websites revealed that traditional chemotherapeutic drugs have little effect against SC after the cancer has metastasized. Following an overview of SC biology, epidemiology, and treatment options, this review focuses on the mechanisms of advanced technologies that use silver nanoparticles in SC treatment regimens.