Current Knowledge of Silver and Gold Nanoparticles in Laboratory Research-Application, Toxicity, Cellular Uptake

Nanomaterials for Photothermal Antimicrobial Surfaces

Microbial infection diseases are a major threat to human health and have become one of the main causes of mortality. The search for novel antimicrobial strategies is an important challenge for the scientific community, considering also the constant increase of antimicrobial resistance and the rise of new diseases. Among the new strategies to combat microbial infections, the photothermal effect seems to be one of the most promising. Hyperthermia is an effective and broad spectrum strategy for the removal of microbial infections. Among all of the strategies to reduce the diffusion of microbial infections, the preparation of antimicrobial surfaces seems of primary importance. In many cases, in fact, an infection can be diffused through surfaces just by touching them, or by inoculating microbes through an internalizable device, such as an implant, a prosthesis, or a catheter. In this review, we will summarize the recent advances in the preparation of photothermal antibacterial surfaces.

Next-Generation Cardiac Interfacing Technologies Using Nanomaterial-Based Soft Bioelectronics

Cardiac interfacing devices are essential components for the management of cardiovascular diseases, particularly in terms of electrophysiological monitoring and implementation of therapies. However, conventional cardiac devices are typically composed of rigid and bulky materials and thus pose significant challenges for effective long-term interfacing with the curvilinear surface of a dynamically beating heart. In this regard, the recent development of intrinsically soft bioelectronic devices using nanocomposites, which are fabricated by blending conductive nanofillers in polymeric and elastomeric matrices, has shown great promise. The intrinsically soft bioelectronics not only endure the dynamic beating motion of the heart and maintain stable performance but also enable conformal, reliable, and large-area interfacing with the target cardiac tissue, allowing for high-quality electrophysiological mapping, feedback electrical stimulations, and even mechanical assistance. Here, we explore next-generation cardiac interfacing strategies based on soft bioelectronic devices that utilize elastic conductive nanocomposites. We first discuss the conventional cardiac devices used to manage cardiovascular diseases and explain their undesired limitations. Then, we introduce intrinsically soft polymeric materials and mechanical restraint devices utilizing soft polymeric materials. After the discussion of the fabrication and functionalization of conductive nanomaterials, the introduction of intrinsically soft bioelectronics using nanocomposites and their application to cardiac monitoring and feedback therapy follow. Finally, comments on the future prospects of soft bioelectronics for cardiac interfacing technologies are discussed.

Himalayan lichen biomass for green synthesis of silver nanocolloids: growth kinetics, effect of pH and metal sensing

Lichen is one of the most abundant non-vascular biomasses; however, a systematic study on the application of biomass in nanomaterial synthesis is very limited. In this study, an aqueous lichen extract was obtained from Hypotrachyna cirrhata, one of the most abundant Himalayan lichen biomasses, using a simple cold percolation method. The effects of extract-to-silver nitrate mixing ratio, pH and waiting time on the growth and stability of nanoparticles were systematically explored. The rate constant for bio-reduction was found to be 5.3 × 10-3 min-1. Transmission electron microscopy showed a narrow particle size distribution with a mean particle size of 11.1 ± 3.6 nm (n = 200). The X-ray diffraction and selected area electron diffraction techniques confirmed the formation of cubic crystals. The synthesized colloidal solution showed excellent response to Hg2+ and Cu2+ ions in spiked water samples. The limit of detection and calibration sensitivity for Hg2+ and Cu2+ ions were found to be 1 and 5 mg l-1 and 2.9 × 10-3 and 1.6 × 10-3 units ppm-1, respectively. These findings suggested that spherical silver nanoparticles with a narrow particle size distribution can be synthesized on a laboratory scale using an aqueous H. cirrhata lichen extract, and the colloidal solution can be used for the detection of selected heavy metals in water samples.

Gold Nanoparticles in Neurological Diseases: A Review of Neuroprotection

This review explores the diverse applications of gold nanoparticles (AuNPs) in neurological diseases, with a specific focus on Alzheimer's disease (AD), Parkinson's disease (PD), and stroke. The introduction highlights the pivotal role of neuroinflammation in these disorders and introduces the unique properties of AuNPs. The review's core examines the mechanisms by which AuNPs exert neuroprotection and anti-neuro-inflammatory effects, elucidating various pathways through which they manifest these properties. The potential therapeutic applications of AuNPs in AD are discussed, shedding light on promising avenues for therapy. This review also explores the prospects of utilizing AuNPs in PD interventions, presenting a hopeful outlook for future treatments. Additionally, the review delves into the potential of AuNPs in providing neuroprotection after strokes, emphasizing their significance in mitigating cerebrovascular accidents' aftermath. Experimental findings from cellular and animal models are consolidated to provide a comprehensive overview of AuNPs' effectiveness, offering insights into their impact at both the cellular and in vivo levels. This review enhances our understanding of AuNPs' applications in neurological diseases and lays the groundwork for innovative therapeutic strategies in neurology.

Current Overview of Metal Nanoparticles' Synthesis, Characterization, and Biomedical Applications, with a Focus on Silver and Gold Nanoparticles

Metal nanoparticles (NPs) have garnered considerable attention, due to their unique physicochemical properties, that render them promising candidates for various applications in medicine and industry. This article offers a comprehensive overview of the most recent advancements in the manufacturing, characterization, and biomedical utilization of metal NPs, with a primary focus on silver and gold NPs. Their potential as effective anticancer, anti-inflammatory, and antimicrobial agents, drug delivery systems, and imaging agents in the diagnosis and treatment of a variety of disorders is reviewed. Moreover, their translation to therapeutic settings, and the issue of their inclusion in clinical trials, are assessed in light of over 30 clinical investigations that concentrate on administering either silver or gold NPs in conditions ranging from nosocomial infections to different types of cancers. This paper aims not only to examine the biocompatibility of nanomaterials but also to emphasize potential challenges that may limit their safe integration into healthcare practices. More than 100 nanomedicines are currently on the market, which justifies ongoing study into the use of nanomaterials in medicine. Overall, the present review aims to highlight the potential of silver and gold NPs as innovative and effective therapeutics in the field of biomedicine, citing some of their most relevant current applications.

Comparative oxidative damages induced by silver nanoparticles with different sizes and coatings in Caenorhabditis elegans

Silver nanoparticles (AgNPs) are widely used in many commercial and medical products. Serious concerns are paid on their adverse potentials to the environment and human health. In this study, toxic effects and oxidative stress induced by AgNPs with different sizes and coatings (20 nm AgNPs, 20 nm polyvinylpyrrolidone (PVP) -AgNPs and 50 nm AgNPs) in Caenorhabditis elegans (C. elegans) were investigated. The toxic effects including the shortened lifespan and decreased frequency of head thrashes and body bends of C. elegans were induced in a dose-dependent manner by AgNPs. The reactive oxygen species (ROS) production and the oxidative stress-related indicators including malondialdehyde (MDA) and glutathione (GSH) in nematodes were changed after exposure to three kinds of AgNPs. These effects were the most obvious in a 20 nm PVP-AgNPs exposure group. AgNPs could also induce the expression of genes related to oxidative stress in nematodes. In addition, the up-regulation of mtl-1 and mtl-2 in nematodes might reduce the oxidative damage caused by AgNPs, by using transgenic strains CF2222 and CL2120 nematodes. Metallothionein (MT), an antioxidant, could relieve the oxidative damage caused by AgNPs. These results suggested that 20 nm PVP-AgNPs with a smaller particle size and better dispersion have stronger toxic effects and the oxidative damage to nematodes. Mtl-1 and mtl-2 might be involved in alleviating the oxidative damage caused by AgNPs. Our findings provide clues for the safety evaluation and mechanism information of metal nanoparticles.

Promising renoprotective effect of gold nanoparticles and dapagliflozin in diabetic nephropathy via targeting miR-192 and miR-21

Diabetic nephropathy (DN) is a worldwide issue that eventually leads to end-stage renal failure, with limited therapeutic options. Prior research has revealed that gold nanoparticles (AuNPs) have a substantial antidiabetic impact. In addition, sodium-glucose cotransporter2 (SGLT2) inhibitors, including dapagliflozin (DAPA), had renoprotective impact on DN. Therefore, this research attempted to determine the potential AuNPs and DAPA impacts in ameliorating experimentally DN induction and the underlying mechanisms focusing on miR-192 and miR-21, correlating them with autophagy, apoptosis, fibrosis, and oxidative stress. Diabetes induction was through a single intraperitoneal streptozotocin (55 mg/kg) injection, and rats with diabetes received AuNPs (2.5 mg/kg/day) as well as DAPA (2 mg/kg/day) for 7 weeks as a treatment. AuNPs and DAPA treatment for 7 weeks substantially alleviated DN. AuNPs and DAPA significantly increased catalase (CAT) activity as well as serum total antioxidant capacity (TAC), along with a substantial decline in malondialdehyde (MDA). AuNPs and DAPA treatment alleviated renal fibrosis as they decreased transforming growth factorß1(TGF-ß1) as well as matrix metalloproteinase-2 (MMP-2) renal expression, decreased apoptosis through alleviating the proapoptotic gene (caspase-3) renal expression and increased the antiapoptotic gene (Bcl-2) renal expression, and increased autophagy as they increased LC-3 as well as Beclin-1 renal expression. Autophagy activation, inhibition of apoptosis, and renal fibrosis could be due to their inhibitory impact on miR-192 and miR-21 renal expression. AuNPs and DAPA have a protective effect on DN in rats by targeting miR-192 and miR-21 and their downstream pathways, including fibrosis, apoptosis, autophagy, and oxidative stress.

Ex vivo fluorescence imaging for the identification of rhodamine-labeled bovine serum albumin and chitosan-coated gold and silver nanoparticles

Therapeutic potential and toxic effects of in vivo administered gold nanoparticles (GNPs) and silver nanoparticles (SNP) depend on distribution in tissues. Rhodamine (Rho) labeled bovine serum albumin (BSA) and chitosan (Chi) were prepared by covalent conjugation and were characterized by fluorescence spectral analysis. GNP and SNP were coated with the labeled conjugates of BSA and chitosan by adsorption. The soluble Rho-BSA or Rho-Chi conjugates, uncoated, and conjugate-coated GNP, and SNP were orally administered into 8-week-old rats. After 24 h, rats were euthanized and the liver, kidney, spleen, and thymus were dissected. The tissues were examined ex vivo using a small animal in vivo imaging system. The liver, kidney, and thymus displayed higher fluorescence due to increased accumulation of Rho-BSA or Rho-Chi conjugate-coated nanoparticles (NPs) in the tissues as compared to the spleen where lower fluorescence was noticed. Tissues obtained from rats that were administered Rho-BSA or Rho-Chi conjugate-coated GNP and SNP showed tenfold higher fluorescence intensity as compared to tissues from rats that were given soluble conjugates or NP alone. The results strongly suggest significant tissue distribution of NP following oral administration.

Biogenic Silver Nanoparticles for Targeted Cancer Therapy and Enhancing Photodynamic Therapy

Different conventional therapeutic procedures are utilized globally to manage cancer cases, yet the mortality rate in patients with cancer remains considerably high. Developments in the field of nanotechnology have included novel therapeutic strategies to deal with cancer. Biogenic (green) metallic silver nanoparticles (AgNPs) obtained using plant-mediated protocols are attractive to researchers exploring cancer treatment. Biogenic AgNPs present advantages, since they are cost-effective, easy to obtain, energy efficient, and less toxic compared to chemically and physically obtained AgNPs. Also, they present excellent anticancer abilities thanks to their unique sizes, shapes, and optical properties. This review provides recent advancements in exploring biogenic AgNPs as a drug or agent for cancer treatment. Thus, great attention was paid to the anticancer efficacy of biogenic AgNPs, their anticancer mechanisms, their efficacy in cancer photodynamic therapy (PDT), their efficacy in targeted cancer therapy, and their toxicity.

Multimodal Biomedical Implant with Plasmonic and Simulated Body Temperature Responses

This work presents a novel nanoparticle-based thermosensor implant able to reveal the precise temperature variations along the polymer filaments, as it contracts and expands due to changes in the macroscale local temperature. The multimodal device is able to trace the position and the temperature of a polypropylene mesh, employed in abdominal hernia repair, by combining plasmon resonance and Raman spectroscopy with hydrogel responsive system. The novelty relies on the attachment of the biocompatible nanoparticles, based on gold stabilized by a chitosan-shell, already charged with the Raman reporter (RaR) molecules, to the robust prosthesis, without the need of chemical linkers. The SERS enhanced effect observed is potentiated by the presence of a quite thick layer of the copolymer (poly(N-isopropylacrylamide)-co-poly(acrylamide)) hydrogel. At temperatures above the LCST of PNIPAAm-co-PAAm, the water molecules are expulsed and the hydrogel layer contracts, leaving the RaR molecules more accessible to the Raman source. In vitro studies with fibroblast cells reveal that the functionalized surgical mesh is biocompatible and no toxic substances are leached in the medium. The mesh sensor opens new frontiers to semi-invasive diagnosis and infection prevention in hernia repair by using SERS spectroscopy. It also offers new possibilities to the functionalization of other healthcare products.

Gold nanoparticle intratesticular injections as a potential animal sterilization tool: Long-term reproductive and toxicological implications

This study aimed to evaluate the gold nanoparticles (AuNPs) animal sterilizing potential after intratesticular injections and long-term adverse reproductive and systemic effects. Adult male Wistar rats were divided into control and gold nanoparticle (AuNPs) groups. The rats received 200µL of saline or AuNPs solution (16µg/mL) on experimental days 1 and 7 (ED1 and ED7). After 150 days, the testicular blood flow was measured, and the rats were mated with females. After mating, male animals were euthanized for histological, cellular, and molecular evaluations. The female fertility indices and fetal development were also recorded. The results indicated increased blood flow in the testes of treated animals. Testes from treated rats had histological abnormalities, shorter seminiferous epithelia, and oxidative stress. Although the sperm concentration was lower in the AuNP-treated rats, there were no alterations in sperm morphology. Animals exposed to AuNPs had decreased male fertility indices, and their offspring had lighter and less efficient placentas. Additionally, the anogenital distance was longer in female fetuses. There were no changes in the histology of the kidney and liver, the lipid profile, and the serum levels of LH, testosterone, AST, ALT, ALP, albumin, and creatinine. The primary systemic effect was an increase in MDA levels in the liver and kidney, with only the liver experiencing an increase in CAT activity. In conclusion, AuNPs have a long-term impact on reproduction with very slight alterations in animal health. The development of reproductive biotechnologies that eliminate germ cells or treat local cancers can benefit from using AuNPs.

Intense up-conversion luminescence from Dy3+-doped multi-component telluroborate glass matrix: Role of CuO nanoparticles embedment

This paper reports an intense up-conversion luminescence from Dy³⁺-doped strontium-telluro-alumino-magnesium-borate glasses for the first time. The samples were made via the melt-quenching method and characterized to determine the influence of various CuO nanoparticles contents change on their up-conversion emission traits. Absorption spectral data were used to calculate the Judd-Ofelt intensity parameters. The sample without CuO nanoparticles revealed two intense photoluminescence up-conversion emission peaks at 478 and 570 nm. In addition, CuO nanoparticles-activated sample displayed about 1.4-fold up-conversion emission intensity improvement due to strong light absorption in the visible to the infrared region at 799 nm excitation. The stimulated emission cross-section of the CuO nanoparticles-activated glasses was increased from 102.4 × 10^-23 to 1301.1 × 10^-23 cm² (nearly 10-fold amplification) while the branching ratio was reduced to 66.9%. Thus, CuO nanoparticles as an additive in the current glass matrix enhanced the up-conversion emission and strengthened the associated nonlinear optical properties. CIE 1931 color matching revealed the influence of CuO in modifying the up-conversion color coordinates, thereby improving the white color purity. The achieved up-conversion emission coupled with the color tunability of the proposed glasses may be advantageous for the up-conversion UV tunable laser making.

Ethanol and NaCl-Induced Gold Nanoparticle Aggregation Toxicity toward DNA Investigated with a DNA/GCE Biosensor

Engineered nanomaterials are becoming increasingly common in commercial and consumer products and pose a serious toxicological threat. Exposure of human organisms to nanomaterials can occur by inhalation, oral intake, or dermal transport. Together with the consumption of alcohol in the physiological environment of the body containing NaCl, this has raised concerns about the potentially harmful effects of ingested nanomaterials on human health. Although gold nanoparticles (AuNPs) exhibit great potential for various biomedical applications, there is some inconsistency in the case of the unambiguous genotoxicity of AuNPs due to differences in their shape, size, solubility, and exposure time. A DNA/GCE (DNA/glassy carbon electrode) biosensor was used to study ethanol (EtOH) and NaCl-induced gold nanoparticle aggregation genotoxicity under UV light in this study. The genotoxic effect of dispersed and aggregated negatively charged gold nanoparticles AuNP1 (8 nm) and AuNP2 (30 nm) toward salmon sperm double-stranded dsDNA was monitored by cyclic and square-wave voltammetry (CV, SWV). Electrochemical impedance spectroscopy (EIS) was used for a surface study of the biosensor. The aggregation of AuNPs was monitored by UV-vis spectroscopy. AuNP1 aggregates formed by 30% v/v EtOH and 0.15 mol·L^-1 NaCl caused the greatest damage to the biosensor DNA layer.

Gold Nanoparticles Induced Size Dependent Cytotoxicity on Human Alveolar Adenocarcinoma Cells by Inhibiting the Ubiquitin Proteasome System

Gold nanoparticles (AuNPs) are widely used in biomedicine due to their remarkable therapeutic applications. However, little is known about their cytotoxic effects on the ubiquitin proteasome system (UPS). Herein, the cytotoxicity of different sizes of AuNPs (5, 10, and 80 nm) on the UPS was investigated with a particular focus on deubiquitinating enzymes (DUBs) such as ubiquitin-specific proteases (USP) and ubiquitin carboxyl-terminal hydrolases (UCHL-1) in human alveolar epithelial adenocarcinoma (A549). It was found that all sizes of AuNPs reduced the percentage of viable A549 cells and increased lactate dehydrogenase (LDH) release, measured using the MTT and LDH assays, respectively. Furthermore, the 5 nm AuNPs were found to exhibit greater cytotoxicity than the 10 and 80 nm AuNPs. In addition, apoptosis and necrosis were activated through reactive oxygen species (ROS) generation due to AuNPs exposure. The internalisation of AuNPs in A549 cells increased with increasing particle size (80 > 10 > 5 nm). Interestingly, the expression of USP7, USP8, USP10, and UCHL-1 was significantly (p < 0.001) downregulated upon treatment with 5-30 µg/mL of all the AuNPs sizes compared to control cells. Moreover, the inhibition of these proteins triggered mitochondrial-related apoptosis through the upregulation of poly (ADP-ribose) polymerase (PARP), caspase-3, and caspase-9. Collectively, these results indicate that AuNPs suppress the proliferation of A549 cells and can potentially be used as novel inhibitors of the proteasome.

Nanoparticles for Topical Application in the Treatment of Skin Dysfunctions-An Overview of Dermo-Cosmetic and Dermatological Products

Nanomaterials (NM) arouse interest in various fields of science and industry due to their composition-tunable properties and the ease of modification. They appear currently as components of many consumer products such as sunscreen, dressings, sports clothes, surface-cleaning agents, computer devices, paints, as well as pharmaceutical and cosmetics formulations. The use of NPs in products for topical applications improves the permeation/penetration of the bioactive compounds into deeper layers of the skin, providing a depot effect with sustained drug release and specific cellular and subcellular targeting. Nanocarriers provide advances in dermatology and systemic treatments. Examples are a non-invasive method of vaccination, advanced diagnostic techniques, and transdermal drug delivery. The mechanism of action of NPs, efficiency of skin penetration, and potential threat to human health are still open and not fully explained. This review gives a brief outline of the latest nanotechnology achievements in products used in topical applications to prevent and treat skin diseases. We highlighted aspects such as the penetration of NPs through the skin (influence of physical-chemical properties of NPs, the experimental models for skin penetration, methods applied to improve the penetration of NPs through the skin, and methods applied to investigate the skin penetration by NPs). The review summarizes various therapies using NPs to diagnose and treat skin diseases (melanoma, acne, alopecia, vitiligo, psoriasis) and anti-aging and UV-protectant nano-cosmetics.

Recent Advances in Nanomaterials for Asthma Treatment

Asthma is a chronic airway inflammatory disease with complex mechanisms, and these patients often encounter difficulties in their treatment course due to the heterogeneity of the disease. Currently, clinical treatments for asthma are mainly based on glucocorticoid-based combination drug therapy; however, glucocorticoid resistance and multiple side effects, as well as the occurrence of poor drug delivery, require the development of more promising treatments. Nanotechnology is an emerging technology that has been extensively researched in the medical field. Several studies have shown that drug delivery systems could significantly improve the targeting, reduce toxicity and improve the bioavailability of drugs. The use of multiple nanoparticle delivery strategies could improve the therapeutic efficacy of drugs compared to traditional delivery methods. Herein, the authors presented the mechanisms of asthma development and current therapeutic methods. Furthermore, the design and synthesis of different types of nanomaterials and micromaterials for asthma therapy are reviewed, including polymetric nanomaterials, solid lipid nanomaterials, cell membranes-based nanomaterials, and metal nanomaterials. Finally, the challenges and future perspectives of these nanomaterials are discussed to provide guidance for further research directions and hopefully promote the clinical application of nanotherapeutics in asthma treatment.

Silver nanoparticles suppress forskolin-induced syncytialization in BeWo cells

Opportunities for the exposure of pregnant women to engineered nanoparticles have been increasing with the expanding use of these materials. Therefore, there are concerns that nanoparticles could have adverse effects on the establishment and maintenance of pregnancy. The effects of nanoparticles on the mother and fetus have been evaluated from this perspective, but there is still little knowledge about the effects on placentation and function acquisition, which are essential for the successful establishment and maintenance of pregnancy. Formation of the syncytiotrophoblast is indispensable for the acquisition of placental function, and impairment of syncytialization inevitably affects pregnancy outcomes. Here, we assessed the effect of nanoparticles on placental formation by using forskolin-treated BeWo cells, a typical in vitro model of trophoblast syncytialization. Immunofluorescence staining analysis revealed that silver nanoparticles with a diameter of 10 nm (nAg10) (at 0.156 µg/mL) significantly decreased the proportion of syncytialized BeWo cells, but gold nanoparticles with a diameter of 10 nm did not. Consistently, only nAg10 (at 0.156 µg/mL) significantly suppressed forskolin-induced elevation of CGB and SDC1 mRNA expression levels and human chorionic gonadotropin β production in a dose-dependent manner; these molecules are all markers of syncytialization. Besides, nAg10 significantly decreased the expression of ERVFRD-1, which encodes proteins associated with cell fusion. Moreover, nAg10 tended to suppress the expression of sFlt-1 e15a, a placental angiogenesis marker. Collectively, our data suggest that nAg10 could suppress formation of the syncytiotrophoblast and that induce placental dysfunction and the following poor pregnancy outcomes.

Silver nanoparticles exposure induces developmental neurotoxicity in hiPSC-derived cerebral organoids

Silver nanoparticles (AgNPs) are used in various research fields. Although the neurotoxicity of AgNPs has been explored in animal models and 2D cell-culture models, including human stem cells, these models cannot accurately mimic the development of the human brain. Therefore, the potential mechanisms of AgNPs-induced developmental neurotoxicity in humans are still largely unclear. In this study, cerebral organoids derived from induced pluripotent stem cells were treated with 0.1 μg/mL or 0.5 μg/mL AgNPs for 7 days. At the low concentration (0.1 μg/mL), AgNPs increased the cell proliferation and inhibited the neural apoptosis in the organoids, but impaired the cilium assembly and elongation, which may perturb the cell cycle and induce abnormal cerebral-organoid growth. Conversely, at the high concentration (0.5 μg/mL), AgNPs significantly inhibited cell proliferation and induced apoptosis in cerebral organoids. High-concentration AgNPs reduced the expression and co-localization of the cytoskeleton proteins F-actin, myosin, and tubulin, thereby perturbing neurite growth. In conclusion, AgNPs exposure induces developmental neurotoxic effects in cerebral organoids and is thus a potential congenital risk factor.

In vivo intrinsic atomic interaction infer molecular eco-toxicity of industrial TiO2 nanoparticles via oxidative stress channelized steatosis and apoptosis in Paramecium caudatum

The ecotoxicological effect of after-usage released TiO₂ nanoparticles in aquatic resources has been a major concern owing to their production and utilization in different applications. Addressing the issue, this study investigates the detailed in vivo molecular toxicity of TiO₂ nanoparticles with Paramecium caudatum. TiO₂ nanoparticles were synthesized at a lab scale using high energy ball milling technique; characterized for their physicochemical properties and investigated for their ecotoxicological impact on oxidative stress, steatosis, and apoptosis of cells through different biochemical analysis, flow cytometry, and fluorescent microscopy. TiO₂ nanoparticles; TiO₂ (N15); of size 36 ± 12 nm were synthesized with a zeta potential of - 20.2 ± 8.8 mV and bandgap of 4.6 ± 0.3 eV and exhibited a blue shift in UV-spectrum. Compared to the Bulk TiO₂, the TiO₂ (N15) exhibited higher cytotoxicity with a 24 h LC50 of 202.4 µg/ml with P. Caudatum. The mechanism was elucidated as the size and charge-dependent internalization of nanoparticles leading to abnormal physiological metabolism in oxidative stress, steatosis, and apoptosis because of their influential effect on the activity of metabolic proteins like SOD, GSH, MDA, and catalase. The study emphasized the controlled usage TiO₂ nanoparticles in daily activity with a concern for ecological and biomedical aspects.

Green Synthesis of Silver Nanoparticles Using Populi gemmae Extract: Preparation, Physicochemical Characterization, Antimicrobial Potential and In Vitro Antiproliferative Assessment

Green route is an economic, facile and eco-friendly method, employed for the synthesis of various types of nanoparticles, having it as a starting point biological entity, especially as a plant extract. The present study aims to obtain silver nanoparticles (AgNPs) starting from an ethanolic extract of Populi gemmae (Pg), by adjusting the reaction parameters. The morphological and structural characterization exhibited that both the reaction temperature and the concentration of metal salt, contributes to the obtaining of Pg-AgNPs with adjustable size and shape. The newly synthesized nanoparticles exhibited a good antibacterial activity on Gram-positive bacteria as well as antifungal activity. The in vitro antiproliferative activity of Pg-AgNPs was assessed on two different cancer cell lines (breast cancer cells-MCF7 and lung carcinoma epithelial cells-A549). Results have shown that the green-synthetized Pg-AgNPs_S2 (obtained at 60 °C, using AgNO3 of 5 M) induced a substantial decrease in tumor cell viability in a dose-dependent manner with an IC50 ranging from 5.03 to 5.07 µg/mL on A549 cell line and 3.24 to 4.93 µg/mL on MCF7 cell line.

In vivo bio-distribution and acute toxicity evaluation of greenly synthesized ultra-small gold nanoparticles with different biological activities

Ultra-small gold nanoparticles (Au-NPs) “≤ 10 nm diameters” have potent biomedical applications. Hence, the present study aimed to greenly synthesize ultra-small gold nanoparticles using Egyptian propolis extract. Different biological activities, in vivo bio-distribution and acute toxicity study were assessed. Results revealed that, Egyptian propolis extract can successfully synthesize the highly pure and stable ultra-small Au-NPs with average diameter 7.8 nm. In vitro antimicrobial and antimycobacterial activities revealed the powerful effect of the prepared Au-NPs. Moreover, the cytotoxic effect on human cancer cell lines revealed the potent inhibition of the cancer cells’ proliferation with high reactive oxygen species-mediated apoptosis induction. In vivo bio-distribution and acute toxicity studies were performed (10 and 100 mg/kg doses) in male albino rats. The ultra-small Au-NPs showed low or no toxicity upon using the Au-NPs low dose. The mean area accumulation (%) of the Au-NPs was higher in the liver, kidney, and brain tissues (4.41, 2.96, and 0.3 times, respectively) treated with high Au-NPs dosage compared to those treated with the low dose. Surprisingly, Au-NP accumulation in brain tissue was observed in the glial cells only. Accordingly, the low dose (10 mg/kg) of Au-NPs can be used safely in a variety of biomedical applications.

Molecular Imaging and Nanotechnology-Emerging Tools in Diagnostics and Therapy

Personalized medicine is emerging as a new goal in the diagnosis and treatment of diseases. This approach aims to establish differences between patients suffering from the same disease, which allows to choose the most effective treatment. Molecular imaging (MI) enables advanced insight into molecule interactions and disease pathology, improving the process of diagnosis and therapy and, for that reason, plays a crucial role in personalized medicine. Nanoparticles are widely used in MI techniques due to their size, high surface area to volume ratio, and multifunctional properties. After conjugation to specific ligands and drugs, nanoparticles can transport therapeutic compounds directly to their area of action and therefore may be used in theranostics—the simultaneous implementation of treatment and diagnostics. This review summarizes different MI techniques, including optical imaging, ultrasound imaging, magnetic resonance imaging, nuclear imaging, and computed tomography imaging with theranostics nanoparticles. Furthermore, it explores the potential use of constructs that enables multimodal imaging and track diseases in real time.

Skin interaction, permeation, and toxicity of silica nanoparticles: Challenges and recent therapeutic and cosmetic advances

Silica nanoparticles (SNPs) received more attention with the emergence of nanotechnology with the aim and promise of becoming innovative drug delivery systems. They have been fulfilling this objective with excellence and nowadays they play a central role in biomedical applications. New SNPs application routes are being explored such as the epidermal, dermal, and transdermal routes. With that, novel models of synthesis, functionalization, and applications constantly appear. However, it is essential that such innovations are accompanied by in-depth studies on permeation, biodistribution, metabolization, and elimination of the generated by-products. Such studies are still incipient, if not rare. This article reviews significant findings on SNPs and their skin interactions. An extensive literature review on SNPs synthesis and functionalization methodologies was performed, as well as on the skin characteristics, skin permeation mechanisms, and in vivo toxicity assessments. Furthermore, studies of the past 5 years on the main therapeutic and cosmetic products employing SNPs, with greater emphasis on in vivo and ex vivo studies were included.

Coating-Dependent Neurotoxicity of Silver Nanoparticles-An In Vivo Study on Hippocampal Oxidative Stress and Neurosteroids

Silver nanoparticles (AgNPs) are one of the most widely used nanomaterials. The level of exposure to nanosilver is constantly raising, and a growing body of research highlights that it is harmful to the health, especially the nervous system, of humans. The potential pathways through which nanosilver affects neurons include the release of silver ions and the associated induction of oxidative stress. To better understand the mechanisms underlying the neurotoxicity of nanosilver, in this study we exposed male Wistar rats to 0.5 mg/kg body weight of AgNPs coated with bovine serum albumin (BSA), polyethylene glycol (PEG), or citrate, or to AgNO3 as a source of silver ions for 28 days and assessed the expression of antioxidant defense markers in the hippocampus of the exposed animals after 1 week of spatial memory training. We also evaluated the influence of AgNPs coating on neurosteroidogenesis in the rat hippocampus. The results showed that AgNPs disrupted the antioxidant system in the hippocampus and induced oxidative stress in a coating-dependent manner, which could potentially be responsible for neurodegeneration and cognitive disorders. The analysis of the influence of AgNPs on neurosteroids also indicated coating-dependent modulation of steroid levels with a significant decrease in the concentrations of progesterone and 17α-progesterone in AgNPs(BSA), AgNPs(PEG), and Ag+ groups. Furthermore, exposure to AgNPs or Ag+ resulted in the downregulation of selected genes involved in antioxidant defense (Cat), neurosteroid synthesis (Star, Hsd3b3, Hsd17b1, and Hsd17b10), and steroid metabolism (Ar, Er1, and Er2). In conclusion, depending on the coating material used for their stabilization, AgNPs induced oxidative stress and modulated the concentrations of steroids as well as the expression of genes involved in steroid synthesis and metabolism.

Role of siRNA-based nanocarriers for the treatment of neurodegenerative diseases

Neurodegenerative disorders (NDs) lead to the progressive degeneration of the structural and physiological functions of the central and peripheral nervous systems, resulting in lifelong cognitive and motor dysfunction. Although comprehensive treatment of NDs is lacking, small interfering (si)RNA has shown therapeutic utility in the form of cellular nuclease-driven downregulation of mRNA levels. Various nanotechnologies have been used to modulate crucial physicochemical and biopharmaceutical properties of siRNA to provide protection and to enhance biomembrane interactions, residence times, tissue absorption, and cellular internalization for improved cytoplasm and/or nucleus interactions. In this review, we highlight advances in, and the role of, siRNA-based nanocarriers for the treatment of various NDs.

Green Synthesis of Silver-Peptide Nanoparticles Generated by the Photoionization Process for Anti-Biofilm Application

An alarming increase in antibiotic-resistant bacterial strains is driving clinical demand for new antibacterial agents. One of the oldest antimicrobial agents is elementary silver (Ag), which has been used for thousands of years. Even today, elementary Ag is used for medical purposes such as treating burns, wounds, and microbial infections. In consideration of the effectiveness of elementary Ag, the present researchers generated effective antibacterial/antibiofilm agents by combining elementary Ag with biocompatible ultrashort peptide compounds. The innovative antibacterial agents comprised a hybrid peptide bound to Ag nanoparticles (IVFK/Ag NPs). These were generated by photoionizing a biocompatible ultrashort peptide, thus reducing Ag ions to form Ag NPs with a diameter of 6 nm. The IVFK/Ag NPs demonstrated promising antibacterial/antibiofilm activity against reference Gram-positive and Gram-negative bacteria compared with commercial Ag NPs. Through morphological changes in Escherichia coli and Staphylococcus aureus, we proposed that the mechanism of action for IVFK/Ag NPs derives from their ability to disrupt bacterial membranes. In terms of safety, the IVFK/Ag NPs demonstrated biocompatibility in the presence of human dermal fibroblast cells, and concentrations within the minimal inhibitory concentration had no significant effect on cell viability. These results demonstrated that hybrid peptide/Ag NPs hold promise as a biocompatible material with strong antibacterial/antibiofilm properties, allowing them to be applied across a wide range of applications in tissue engineering and regenerative medicine.

Attenuating Effect of Vitamin E against Silver Nano Particles Toxicity in Submandibular Salivary Glands

Silver nanoparticles (AgNPs) are extensively used in many industries due to their superior antimicrobial properties. However, it is evident from many studies that AgNPs has cytotoxic potential through its effect on excessive formation of reactive oxygen species (ROS). The aim of this study was to examine the toxic effect of AgNPs on the submandibular salivary glands and the attenuating effect of vitamin E, as a natural antioxidant, against this toxicity. Thirty Albino rats were divided into 3 groups (n = 10): control group, AgNPs group receiving 2 mg/kg daily for 28 days, and AgNPs and vitamin E group receiving AgNPs the same as the previous group in addition to vitamin E at a dose of 100 mg/kg. Microscopic, ultrastructural, and cytokeratin immune-reactivity examination of the glands were performed. The AgNPs group showed noticeable degeneration in all structures of the gland as evident in the histological and ultrastructural examination. The AgNPs and vitamin E group revealed an improvement of the glandular elements. A significant increase in cytokeratin immune expression was found after comparison of both groups (p = 0.01). This current study shows that vitamin E has powerful antioxidant properties, which can combat the cytotoxic effect caused by AgNPs. Further studies are deemed necessary to confirm this finding using other immunohistochemical markers, such as myosin and E-cadherin.

Kinetics of Silver Accumulation in Tissues of Laboratory Mice after Long-Term Oral Administration of Silver Nanoparticles

Since ancient times, silver has been known for its pronounced bactericidal, antiviral and fungicidal properties. Currently, nanoparticles of this metal are widely used in the food, light and pharmaceutical industries, as well as in medicine. Silver in any form can have a toxic effect not only on pathogens, but also on healthy cells. The biological activity and bioavailability of silver preparations depend on the degree of their solubility in water. In addition, the maximum permissible concentration of soluble forms of silver is an order of magnitude lower than that of insoluble forms. This makes nanoparticles of silver with a hydrophilic coating that form stable colloidal solutions in aqueous media potentially unsafe objects. In this work, we studied the kinetics of the accumulation of silver nanoparticles with an average size of 34 ± 5 nm stabilized with polyvinylpyrrolidone in the organs of laboratory C57Bl/6 mice. The administration of nanoparticles was carried out orally for 30, 60, 120 and 180 days at the dose of 50 µg/day/animal. All the mice developed and gained weight normally during the experiment. No adverse effects were observed. Determination of the silver content in biological tissues of mammals was accomplished by neutron activation analysis. The masses and concentrations of silver in the brain and its different sections (hippocampus, cerebellum, cortex and remnants), as well as in the lungs, testes, liver, blood, kidneys, spleen and heart, were determined. The injection times at which the accumulation curves reached saturation were established. An extremely high accumulation of silver in the testes was shown at 120 days of administration, and a significant accumulation of silver in the lungs and brain was observed. The accumulation of silver in all parts of the brain except the cortex was significant, and its trend was similar to that in the whole brain.

Effect of size and surface chemistry of gold nanoparticles on their retention in a sediment-water system and Lumbriculus variegatus

With the increased production, usage, and disposal of engineered nanoparticles (ENPs), there is growing concern over the fate of ENPs in the environment, their potential bioavailability and ecotoxicity. It is assumed that bioavailability and uptake into organisms depend on the environmental conditions as well as the physicochemical properties of ENPs, such as particle size or surface coating. A major sink for nanoparticles is expected to be sediments due to sorption and agglomeration processes. Accordingly, this study, investigated how different sizes (5 and 30 nm) and surface coatings of three different AuENPs based on citrate (AuCIT), mercaptoundecanoic acid (AuMUDA), and bovine serum albumin (AuBSA) affected the retention of ENPs in a sediment-water system and subsequent uptake into sediment-dwelling organism Lumbriculus variegatus (L. variegatus). Surface charge was found to be one of the factors affecting retention of the AuENPs in the sediment-water system. More negatively charged AuENPs had a higher mass fraction in the supernatant after 24 h exposure. Furthermore, the stability of AuENPs in the supernatant depended more on their zeta potential than particle size (5 nm vs. 30 nm). The surface coating was found to play an important role in the uptake (after depuration) of Au in L. variegatus, that is, AuBSA > AuCIT > AuMUDA.