The effect of particle size on the cytotoxicity, inflammation, developmental toxicity and genotoxicity of silver nanoparticles

Dual-Drug Delivery by Anisotropic and Uniform Hybrid Nanostructures: A Comparative Study of the Function and Substrate-Drug Interaction Properties

By utilizing nanoparticles to upload and interact with several pharmaceuticals in varying methods, the primary obstacles associated with loading two or more medications or cargos with different characteristics may be addressed. Therefore, it is feasible to evaluate the benefits provided by co-delivery systems utilizing nanoparticles by investigating the properties and functions of the commonly used structures, such as multi- or simultaneous-stage controlled release, synergic effect, enhanced targetability, and internalization. However, due to the unique surface or core features of each hybrid design, the eventual drug-carrier interactions, release, and penetration processes may vary. Our review article focused on the drug's loading, binding interactions, release, physiochemical, and surface functionalization features, as well as the varying internalization and cytotoxicity of each structure that may aid in the selection of an appropriate design. This was achieved by comparing the actions of uniform-surfaced hybrid particles (such as core-shell particles) to those of anisotropic, asymmetrical hybrid particles (such as Janus, multicompartment, or patchy particles). Information is provided on the use of homogeneous or heterogeneous particles with specified characteristics for the simultaneous delivery of various cargos, possibly enhancing the efficacy of treatment techniques for illnesses such as cancer.

Synergistic Effects of Silicate-Platelet Supporting Ag and ZnO, Offering High Antibacterial Activity and Low Cytotoxicity

Silver nanoparticles (AgNPs) are remarkably able to eliminate microorganisms, but induce cytotoxicity in mammalian cells, and zinc oxide nanoparticles (ZnONPs) are considered to have a wide bactericidal effect with weak cytotoxicity. In this study, both zinc oxide nanoparticles and silver nanoparticles were co-synthesized on a nano-silicate platelet (NSP) to prepare a hybrid of AgNP/ZnONP/NSP. Ultraviolet-visible spectroscopy (UV-Vis), X-ray diffraction (XRD), and transmission electron microscopy (TEM) were used to characterize the formation of nanoparticles on the NSP. Synthesized ZnONP/NSP (ZnONP on NSP) was confirmed by the absorption peaks on UV-Vis and XRD. AgNP synthesized on ZnONP/NSP was also characterized by UV-Vis, and ZnONP/NSP showed no interference with synthesis. The images of TEM demonstrated that NSP provides physical support for the growth of nanoparticles and could prevent the inherent aggregation of ZnONP. In antibacterial tests, AgNP/ZnONP/NSP exhibited more efficacy against Staphylococcus aureus (S. aureus) than ZnONP/NSP (ZnONP was synthesized on NSP) and AgNP/NSP (AgNP was synthesized on NSP). In cell culture tests, 1/10/99 (weight ratio) of AgNP/ZnONP/NSP exhibited low cytotoxicity for mammalian cells (>100 ppm). Therefore, AgNP/ZnONP/NSP, containing both AgNP and ZnONP, with both strong antibacterial qualities and low cytotoxicity, showed potentially advantageous medical utilizations due to its antibacterial properties.

Functionalization of 3D Printed Scaffolds Using Polydopamine and Silver Nanoparticles for Bone-Interfacing Applications

The prevention of bacterial colonization and the stimulation of osseointegration are two major requirements for bone-interfacing materials to reduce the incidence of complications and promote the restoration of the patient's health. The present investigation developed an effective, two-step functionalization of 3D printed scaffolds intended for bone-interfacing applications using a simple polydopamine (PDA) dip-coating method followed by the formation of silver nanoparticles (AgNPs) after a second coating step in silver nitrate. 3D printed polymeric substrates coated with a ∼20 nm PDA layer and 70 nm diameter AgNPs proved effective in hindering Staphylococcus aureus biofilm formation, with a 3000-8000-fold reduction in the number of bacterial colonies formed. The implementation of porous geometries significantly accelerated osteoblast-like cell growth. Microscopy characterization further elucidated homogeneity, features, and penetration of the coating inside the scaffold. A proof-of-concept coating on titanium substrates attests to the transferability of the method to other materials, broadening the range of applications both in and outside the medical sector. The antibacterial efficiency of the coating is likely to lead to a decrease in the number of bacterial infections developed after surgery in the presence of these coatings on prosthetics, thus translating to a reduction in revision surgeries and improved health outcomes.

Structural parameters of nanoparticles affecting their toxicity for biomedical applications: a review

Rapidly growing interest in using nanoparticles (NPs) for biomedical applications has increased concerns about their safety and toxicity. In comparison with bulk materials, NPs are more chemically active and toxic due to the greater surface area and small size. Understanding the NPs' mechanism of toxicity, together with the factors influencing their behavior in biological environments, can help researchers to design NPs with reduced side effects and improved performance. After overviewing the classification and properties of NPs, this review article discusses their biomedical applications in molecular imaging and cell therapy, gene transfer, tissue engineering, targeted drug delivery, Anti-SARS-CoV-2 vaccines, cancer treatment, wound healing, and anti-bacterial applications. There are different mechanisms of toxicity of NPs, and their toxicity and behaviors depend on various factors, which are elaborated on in this article. More specifically, the mechanism of toxicity and their interactions with living components are discussed by considering the impact of different physiochemical parameters such as size, shape, structure, agglomeration state, surface charge, wettability, dose, and substance type. The toxicity of polymeric, silica-based, carbon-based, and metallic-based NPs (including plasmonic alloy NPs) have been considered separately.

Osteoimmunomodulatory Nanoparticles for Bone Regeneration

Treatment of large bone fractures remains a challenge for orthopedists. Bone regeneration is a complex process that includes skeletal cells such as osteoblasts, osteoclasts, and immune cells to regulate bone formation and resorption. Osteoimmunology, studying this complicated process, has recently been used to develop biomaterials for advanced bone regeneration. Ideally, a biomaterial shall enable a timely switch from early stage inflammatory (to recruit osteogenic progenitor cells) to later-stage anti-inflammatory (to promote differentiation and terminal osteogenic mineralization and model the microstructure of bone tissue) in immune cells, especially the M1-to-M2 phenotype switch in macrophage populations, for bone regeneration. Nanoparticle (NP)-based advanced drug delivery systems can enable the controlled release of therapeutic reagents and the delivery of therapeutics into specific cell types, thereby benefiting bone regeneration through osteoimmunomodulation. In this review, we briefly describe the significance of osteoimmunology in bone regeneration, the advancement of NP-based approaches for bone regeneration, and the application of NPs in macrophage-targeting drug delivery for advanced osteoimmunomodulation.

Ozonation/UV irradiation of dispersed Ag/AgI nanoparticles in water resources: stability and aggregation

Proliferation of nanoparticles (NPs) as aqueous pollutants is a matter of growing concern today. The aggregation kinetics of colloidal bare silver (Ag, 20.5 nm) and silver iodide (AgI, 15.3 nm) NPs were investigated during ozone/ultraviolet (O₃/UV) oxidation. Dynamic light scattering was applied to monitor the aggregation of NPs, and the z-average of treated samples was considered aggregate diameter. The effect of temperature, pH, and initial concentration of NPs was investigated on the aggregation rate constant and stability ratio. At a short oxidation period of approximately 1 min, the lower stability ratio was achieved for Ag NPs (< 50) than AgI NPs (> 100). Under acidic conditions, the negative surface charge of both NPs was neutralized that resulted in faster aggregation. In contrast, the impact of temperature and initial concentration of NPs on the aggregation rate was different for both NPs, which was due to the type of O₃/UV interaction with the surface of NPs and the thickness of the electrical double layer surrounding the NPs. The aggregation behavior of Ag NPs obeyed diffusion-limited regime, while an intermediate regime between diffusion- and reaction-limited was observed for AgI NP aggregation. The resulting aggregate morphologies showed that the clusters were ramified for Ag and compressed for AgI NPs. Applying the O₃/UV oxidation process for water treatment purposes leads to a significant reduction in aggregation time for inherently unstable Ag and stable AgI toxic NPs from several hours or days to several minutes.

Optimistic and possible contribution of nanomaterial on biomedical applications: A review

Nanomaterials have many advantages over bulk materials, including enhanced surface-to-volume proportion as well as magnetic traits. It has been a steady rise in research with using nanomaterials in various biomedical fields in the past few decades. Constructing nanomaterials has emerged as a leading research primary concern in order to discover specialized biomedical applications. Since, their advantageous properties including chemical stability, non-toxicity, bio - compatibility, relatively high magnetization, and strong magnetic vulnerability, nanoparticles of iron oxide had already influenced implementations in different biomedical fields. Nanomaterials can be divided up into four nanomaterials such as metallic nanomaterials, bimetallic or alloy nanomaterials, metal oxide nanomaterials, as well as magnetic nanomaterials. Hence, the purpose of this review is to conduct such in discussion on emerging advancements in nanomaterials for biomedical, with such a special emphasis upon those options of nanomaterials including metallic nanomaterials: Au and Ag, bimetallic nanomaterials: Fe-Co and Fe-Pt, and metal oxides: TiO₂ and CeO₂. Securing this information gap will result in a better comprehension of the contribution of nanomaterial type and subsequent huge-scale applications in aspects of both their potential and challenges.

Antibiofilm properties of silver nanoparticles incorporated into polymethyl methacrylate used for dental applications

BACKGROUND

Acrylic resins used in dental and biomedical applications do not have antimicrobial properties, their surface is susceptible to colonization of microorganisms.

OBJECTIVE

The aim of this study was to evaluate the antibiofilm properties of silver nanoparticles (AgNPs) deposited in a polymethyl methacrylate (PMMA) surface against a Staphylococcus aureus biofilm.

METHODS

The PMMA was impregnated with AgNPs by using the in-situ polymerization method. To determine the solubility of the incorporated silver (Ag+) atomic absorption spectrophotometry was used (AAS) at 24 h, 48 h, 7 days, and 30 days. Thirty specimens of PMMA with AgNPs and without NP (control group) were assembled in the CDC Biofilm Bioreactor system with a cell suspension of S. aureus. The specimens were removed at 6, 12, 24, 48, and 72 h to determine the viability profile and quantify the Arbitrary Fluorescence Units (AFU).

RESULTS

The AgNPs showed an irregular and quasispherical shape with an average size of 25 nm. AAS analysis demonstrated a low solubility of Ag+. The formation of the S. aureus biofilm increased as the evaluation periods continued up to 72 h. The experimental group showed poor growth, and a decrease in the intensity of the fluorescence demonstrated a statistically significant inhibition of the formation of the biofilm (P < 0.05) in relation to the control group at 6, 12, 24, 48, and 72 h.

CONCLUSION

AgNPs incorporated into PMMA decreased the growth and maturation of S. aureus biofilm.

Advanced bioactive nanomaterials for diagnosis and treatment of major chronic diseases

With the rapid innovation of nanoscience and technology, nanomaterials have also been deeply applied in the medical and health industry and become one of the innovative methods to treat many diseases. In recent years, bioactive nanomaterials have attracted extensive attention and have made some progress in the treatment of some major chronic diseases, such as nervous system diseases and various malignant tumors. Bioactive nanomaterials depend on their physical and chemical properties (crystal structure, surface charge, surface functional groups, morphology, and size, etc.) and direct produce biological activity and play to the role of the treatment of diseases, compared with the traditional nanometer pharmaceutical preparations, biological active nano materials don't exert effects through drug release, way more directly, also is expected to be more effective for the treatment of diseases. However, further studies are needed in the evaluation of biological effects, fate in vivo, structure-activity relationship and clinical transformation of bionanomaterials. Based on the latest research reports, this paper reviews the application of bioactive nanomaterials in the diagnosis and treatment of major chronic diseases and analyzes the technical challenges and key scientific issues faced by bioactive nanomaterials in the diagnosis and treatment of diseases, to provide suggestions for the future development of this field.

Putative adverse outcome pathways for silver nanoparticle toxicity on mammalian male reproductive system: a literature review

BACKGROUND

Adverse outcome pathways (AOPs) are conceptual frameworks that organize knowledge about biological interactions and toxicity mechanisms. They present a sequence of events commencing with initial interaction(s) of a stressor, which defines the perturbation in a biological system (molecular initiating event, MIE), and a dependent series of key events (KEs), ending with an adverse outcome (AO). AOPs have recently become the subject of intense studies in a view to better understand the mechanisms of nanomaterial (NM) toxicity. Silver nanoparticles (Ag NPs) are one of the most explored nanostructures and are extensively used in various application. This, in turn, has increased the potential for interactions of Ag NPs with environments, and toxicity to human health. The aim of this study was to construct a putative AOPs (pAOP) related to reproductive toxicity of Ag NPs, in order to lay the groundwork for a better comprehension of mechanisms affecting both undesired toxicity (against human cell) and expected toxicity (against microorganisms).

METHODS

PubMed and Scopus were systematically searched for peer-reviewed studies examining reproductive toxicity potential of Ag NPs. The quality of selected studies was assessed through ToxRTool. Eventually, forty-eight studies published between 2005 and 2022 were selected to identify the mechanisms of Ag NPs impact on reproductive function in human male. The biological endpoints, measurements, and results were extracted from these studies. Where possible, endpoints were assigned to a potential KE and an AO using expert judgment. Then, KEs were classified at each major level of biological organization.

RESULTS

We identified the impairment of intracellular SH-containing biomolecules, which are major cellular antioxidants, as a putative MIE, with subsequent KEs defined as ROS accumulation, mitochondrial damage, DNA damage and lipid peroxidation, apoptosis, reduced production of reproductive hormones and reduced quality of sperm. These successive KEs may result in impaired male fertility (AO).

CONCLUSION

This research recapitulates and schematically represents complex literature data gathered from different biological levels and propose a pAOP related to the reproductive toxicity induced by AgNPs. The development of AOPs specific to NMs should be encouraged in order to provide new insights to gain a better understanding of NP toxicity.

Green Synthesis of Silver Nanoparticles of Vernonia cinerea Leaf Extract and their In vitro Cytotoxicity Activity against Neuroblastoma SHSY-5Y Cell Lines, Antimicrobial and Antioxidant Studies

BACKGROUND

Green syntheses of silver nanoparticles using plant extracts have potential anti- cancer, antimicrobial, and antioxidant properties, among other aspects. The aim of the present patent study was to synthesize silver nanoparticles (AgNPs) using Vernonia cinerea plant extract.

METHODS

The AgNPs were successfully prepared and characterized using UV-Vis Spectrophotometer, particle size, Zeta potential, Transmission electron microscopy (TEM), Energy-dispersive x-ray analysis (EDAX), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectrometry. The in vitro cytotoxicity study was performed using neuroblastoma SHSY-5Y cell lines. Moreover, antimicrobial and antioxidant activity studies were also performed for AgNPs.

RESULTS

The size of AgNPs determined through the dynamic light scattering (DLS) technique was 49.5 nm and the zeta potential was -36.8 mV. The synthesized AgNPs were checked using UV-Visible spectroscopy at ƛmax 439 nm. The color was changed from green to dark brown, indicating the formation of AgNPs. The TEM study revealed that the nanoparticles were spherical in shape. The XRD pattern of AgNPs produced in this experiment was apparently crystalline. The results of FTIR study revealed that the majority of the obtained peaks correspond to the polyphenols, triterpenoids, and alkaloids which were abundant in the corresponding to the V. cinerea leaf extract and support to the formation of AgNPs. The cytotoxicity effect of the V. cinerea plant extract and biosynthesized AgNPs was found to be dosedependent. From the results of antimicrobial studies, it was reported that the gram negative bacteria were found to be more susceptible compared to the gram positive bacteria. Moreover, the results of antioxidant study revealed that the AgNPs showed good antioxidant activity (77.21%) in comparison to the V. cinerea plant extract (56.13%).

CONCLUSION

Based on the results, it could be concluded that the green synthesized silver nanoparticles showed promising anticancer, antioxidant, and anti-bacterial activities as compared to the plain V. cineria plant extract.

The fabrication and evaluation of silver nanoparticle-based keratin scaffolds

The biotoxicity caused by focus releasing of Ag, which associated with the Ag loading mode, is a problematic issue that need to be solved for practical utilization of the keratin based wound dressing. In this study, keratin/AgNPs blend scaffolds (Ker/Ag) and keratin scaffolds with AgNPs attached on the scaffold's wall surface (Ag@Ker) were prepared. Structure and physical properties of the scaffolds were tested and investigated. In comparison to the Ag@Ker scaffolds, the Ker/Ag scaffolds with uniform dispersion of AgNPs have larger tensile strength and slower degradation rate. Both kind of scaffolds present excellent antibacterial property with 10 μg mL^-1 AgNPs addition, while the Ker/Ag displayed a linear Ag releasing ratio in the first 5-7 days, which is beneficial for obtaining a continuous antibacterial property and avoiding the biotoxicity caused by focus release of Ag. Correspondingly, cytotoxicity assay further reveals that the continuously slow release of Ag of the Ker/Ag scaffolds accelerated the proliferation of cell. Infectious animal models and histological studies showed that the Ker/Ag scaffolds can effectively inhibit the inflammatory response and accelerate epithelialization. Thus, it can be concluded that the Ker/Ag scaffolds with uniform dispersion of AgNPs are more attractive as wound repair materials.

Development of New Health Risk Assessment of Nanoparticles: EPA Health Risk Assessment Revised

The concentration of nanoparticles in the ambient air can lead to induced toxicities; however, it appears that nanoparticles’ unique properties are completely omitted when assessing health risks. This paper aims to enhance the EPA health risk assessment by incorporating two new variables that consider the size of nanoparticles: the toxicity multiplier and the size multiplier. The former considers the qualitative aspect of the size of particles within a concentration, whilst the latter takes into account the effects associated with the number of particles of the specific i-th size distribution interval. To observe the impact of the new variables, a case study was performed. The studied element was cadmium, which was measured using ICP-MS to discover concentrations of size fractions, ranging from <15.1 to <9830 nm. Next, the cadmium concentration is assessed using both the current state-of-the-art method and the proposed method with adjustments. Based on the new approach, the final risk was 1.1 × 10−5, which was almost 24 times higher compared with the current method. The contribution of nanoparticles to the risk value grew from barely 6% to an alarming 88%. Therefore, the enhanced method can lead to more realistic results when assessing the health risks of nanoparticles.

In search of cytotoxic selectivity on cancer cells with biogenically synthesized Ag/AgCl nanoparticles

Green synthesis may be a useful approach to achieve selective cytotoxicity of silver nanoparticles on cancer cells and healthy cells. In this study, the concomitant biosynthesis of silver (Ag)/silver chloride (AgCl) nanoparticles from pineapple peel extracts and their behavior on the breast cancer cell line MCF-7 is shown. Bioreactions were monitored at different temperatures. Fourier-transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-vis), thermogravimetric analysis (TGA), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) techniques were used to characterize nanoparticle development. The breast cancer cell line MCF-7 was used as a test model to study the cytotoxic behavior of Ag/AgCl nanoparticles and, as a counterpart, the nanoparticles were also tested on mononuclear cells. Ag/AgCl nanoparticles with spherical and triangular morphology were obtained. The size of the nanoparticles (10-70 nm) and the size distribution depended on the reaction temperature. A dose close to 20 µg/mL of Ag/AgCl nanoparticles considerably decreased the cell viability of the MCF-7 line. The best cytotoxicity effects on cancer cells were obtained with nanoparticles at 60 and 80 °C where cell viability was reduced up to 80% at a concentration of 50 µg/mL. A significant preference was observed in the cytotoxic effect of Ag/AgCl nanoparticles against cancer cells in comparison to monocytes.

A Highly Efficient Polystyrene-Based Cationic Resin to Reduce Bacterial Contaminations in Water

Nowadays, new water disinfection materials attract a lot of attention for their cost-saving and ease of application. Nevertheless, the poor durability of the matrices and the loss of physically incorporated or chemically attached antibacterial agents that can occur during water purification processes considerably limit their prolonged use. In this study, a polystyrene-based cationic resin (R4) with intrinsic broad-spectrum antibacterial effects was produced without needing to be enriched with additional antibacterial agents that could detach during use. Particularly, R4 was achieved by copolymerizing 4-ammonium-butyl-styrene (4-ABSTY) with N,N-dimethylacrylamide (DMAA) and using N-(2-acryloylamino-ethyl)-acrylamide (AAEA) as a cross-linker. The R4 obtained showed a spherical morphology, micro-dimensioned particles, high hydrophilicity, high-level porosity, and excellent swelling capabilities. Additionally, the swollen R4 to its maximum swelling capability, when dried with gentle heating for 3 h, released water following the Higuchi’s kinetics, thus returning to the original structure. In time–kill experiments on the clinical isolates of multidrug-resistant (MDR) pathogens of fecal origin, such as enterococci, Group B Salmonella species, and Escherichia coli, R4 showed rapid bactericidal effects on enterococci and Salmonella, and reduced E. coli viable cells by 99.8% after 4 h. When aqueous samples artificially infected by a mixture of the same bacteria of fecal origin were exposed for different times to R4 in a column, simulating a water purification system, 4 h of contact was sufficient for R4 to show the best bacterial killing efficiency of 99%. Overall, thanks to its physicochemical properties, killing efficiency, low costs of production, and scalability, R4 could become a cost-effective material for building systems to effectively reduce bacterial, even polymicrobial, water contamination.

Enhanced toxicity effects of iron particles together with PFOA in drinking water

Iron particles present in drinking water distribution systems (DWDSs) could cause discoloration, while organic pollutants in DWDSs, such as perfluorooctanoic acid (PFOA), could be enriched by iron particles. However, little is known about the enhanced effects of PFOA and iron particles in DWDSs. To fill in these knowledge gaps, herein, iron-PFOA (FEP) particles were generated using residual chlorine as an oxidant in drinking water conditions and then separated into different sizes (ranging from small to large: FEP-S, FEP-M ，and FEP-L). FEP-S harbored the greatest cytotoxicity among the sizes. Interestingly, our data revealed that the PFOA released from FEP particles transformed into PFOS (perfluorooctane sulfonate) upon digestion in the gastrointestinal environment (GI), and FEP-L bored the strongest transformation, showing a toxicity profile that was distinct from that of FEP-S. Furthermore, mechanistic studies revealed that FEP per se should be accountable for the conversion of PFOA to PFOS dependent on the generation of hydroxyl radicals (·OH) in GI, and that FEP-L revealed the greatest production of ·OH. Collectively, these results showed how iron particles and PFOA could result in enhanced toxicity effects in drinking water: (i) PFOA could increase the toxicity of iron particles by reducing particle size and inducing higher generation of ·OH; (ii) iron particles could induce the transformation of PFOA into more toxic PFOS through digestion.

Bioactive inorganic particles-based biomaterials for skin tissue engineering

The challenge for treatment of severe cutaneous wound poses an urgent clinical need for the development of biomaterials to promote skin regeneration. In the past few decades, introduction of inorganic components into material system has become a promising strategy for improving performances of biomaterials in the process of tissue repair. In this review, we provide a current overview of the development of bioactive inorganic particles-based biomaterials used for skin tissue engineering. We highlight the three stages in the evolution of the bioactive inorganic biomaterials applied to wound management, including single inorganic materials, inorganic/organic composite materials, and inorganic particles-based cell-encapsulated living systems. At every stage, the primary types of bioactive inorganic biomaterials are described, followed by citation of the related representative studies completed in recent years. Then we offer a brief exposition of typical approaches to construct the composite material systems with incorporation of inorganic components for wound healing. Finally, the conclusions and future directions are suggested for the development of novel bioactive inorganic particles-based biomaterials in the field of skin regeneration.

The Stability and Anti-Angiogenic Properties of Titanium Dioxide Nanoparticles (TiO2NPs) Using Caco-2 Cells

Titanium dioxide nanoparticles (TiO₂NPs) are found in a wide range of products such as sunscreen, paints, toothpaste and cosmetics due to their white pigment and high refractive index. These wide-ranging applications could result in direct or indirect exposure of these NPs to humans and the environment. Accordingly, conflicting levels of toxicity has been associated with these NPs. Therefore, the risk associated with these reports and for TiO₂NPs produced using varying methodologies should be measured. This study aimed to investigate the effects of various media on TiO₂NP properties (hydrodynamic size and zeta potential) and the effects of TiO₂NP exposure on human colorectal adenocarcinoma (Caco-2) epithelial cell viability, inflammatory and cell stress biomarkers and angiogenesis proteome profiles. The NPs increased in size over time in the various media, while zeta potentials were stable. TiO₂NPs also induced cell stress biomarkers, which could be attributed to the NPs not being cytotoxic. Consequently, TiO₂NP exposure had no effects on the level of inflammatory biomarkers produced by Caco-2. TiO₂NPs expressed some anti-angiogenic properties when exposed to the no-observed-adverse-effect level and requires further in-depth investigation.

NF-κB mediates silica-induced pulmonary inflammation by promoting the release of IL-1β in macrophages

Long-term exposure to respirable silica particles causes pulmonary inflammation and fibrosis primarily promoted by cytokines released from alveolar macrophages, yet the underlying mechanism is still unclear. From the perspective of nuclear factor kappa B (NF-κB), we studied the mechanism of IL-1β biosynthesis and release. Utilizing BAY 11-7082, an NF-κB specific inhibitor, we showed the alteration of macrophage viability and examined the expression of both IL-1β and NF-κB in vitro. We found that silica nanoparticles (SiNPs) were internalized by macrophages and caused damage to cell integrity. The immunofluorescence assay showed that SiNPs exposure enhanced the expression of IL-1β and NF-κB, which could be effectively suppressed by BAY 11-7082. Besides, we built silica exposure mouse model by intratracheally instilling 5 mg of SiNPs and checked the effect of silica exposure on pulmonary pathological changes. Consistently, we found an upregulation of IL-1β and NF-κB after SiNPs exposure, along with the aggravated inflammatory cell infiltration, thickened alveolar wall, and enhanced expression of collagens. In conclusion, SiNPs exposure causes pulmonary inflammation and fibrosis that is regulated by NK-κB through upregulating IL-1β in alveolar macrophages.

Obtaining Ultrafine Dispersions of Silver Particles in Poly(vinyl Alcohol) Matrix Using Mechanical Alloying

Mechanical alloying was performed to obtain a composite material with a homogeneous dispersion of silver particles in a poly(vinyl alcohol) (PVA) matrix. Silver is a bactericidal material, and PVA is a widely used biocompatible polymer. Therefore, this mix can lead to a potentially functional biomaterial. This study focuses on the combination of both materials, processed by mechanical alloying, which has a promising application potential. The silver (Ag) used was ultrafine, measuring between 200 and 400 nanometers, produced from silver nitrate (AgNO3) redox. The Attritor high-energy, water-cooled ball mill was used to mill PVA for 4 h, at 600 rpm speed rotation and 38:1 power milling. Mechanical alloying was demonstrated to cause particle refinement in PVA with a timespan of 1 h. A slight additional particle decrease occurred for long-time milling. A milling time of 4 h was used to disperse the silver particles in the polymer matrix homogeneously. Hot pressing films were produced from the obtained dispersion powders. The microstructural features were studied using several material characterization techniques. Antimicrobial Susceptibility Tests (AST), conducted in an in-vitro assay, showed a hydrophilic character of the films and a protection against bacterial growth, making the process a promising path for the production of surface protective polymeric films.

Impact of ultra-small silver nanoparticles of 2 nm (AgNP2) on neutrophil biology: AgNP2 alter the actin cytoskeleton and induce karyorrhexis by a mitogen-activated protein kinase-dependent mechanism in vitro and transitorily attract neutrophils in vivo

Silver (Ag) is known as an antibacterial agent and there is a growing interest to use silver nanoparticles (AgNPs) in a variety of medical applications and other sectors. Some studies reported that one of the undesired effects of AgNPs is inflammation and that these NPs can alter the biology of neutrophils. Since it is commonly accepted that the more NPs are small, the more toxic they are the aim of this study was to determine the impact of ultra-small silver nanoparticles of 2 nm (AgNP₂) on the biology of neutrophils, key player cells in inflammation. We report that AgNP₂ are potent neutrophil activators as they rapidly induce actin polymerization and dismantling the actin network. Although AgNP₂ are not necrotic for neutrophils and do not induce ROS production, kinetic studies reveal that AgNP₂ are rapid inducer of apoptosis. Pyknosis (mainly 1-2 large nuclear dots) was observed after only 1h of treatment followed by karyorrhexis (several small dots) and by a complete nuclear dissolution leading to anuclear neutrophils after 6h. These observations are not associated with the release of silver ions since treatment of neutrophils with 1-50 μg/ml AgNO₃ (as a source of Ag⁺) did not induce any apparent changes. AgNP₂ induce p38 and Erk-1/2 mitogen-activated protein kinase (MAPK) and although karyorrhexis was markedly reversed by MAPK inhibitors, the cell nuclei remain with a pyknotic-like phenotype but do not return to the characteristic polylobed nucleus. Using the murine air pouch model of inflammation AgNP₂ were found to induce a neutrophil influx. Our data indicate that AgNP₂ are potent neutrophil activators targeting the actin cytoskeleton and the mechanism involved for inducing apoptosis is rapid, complex, and partially includes MAPK pathways. Therefore, the ultra-small AgNP₂ are more potent than larger ones for inducing apoptosis and they can transitorily attract neutrophils in vivo.

Developmental neurotoxicity of silver nanoparticles: the current state of knowledge and future directions

The increasing production and use of silver nanoparticles (AgNPs) as an antimicrobial agent in an array of medical and commercial products, including those designed for infants and children, poses a substantial risk of exposure during the developmental period. This review summarizes current knowledge on developmental neurotoxicity of AgNPs in both pre- and post-natal stages with a focus on the biological specificity of immature organisms that predisposes them to neurotoxic insults as well as the molecular mechanisms underlying AgNP-induced neurotoxicity. The current review revealed that AgNPs increase the permeability of the blood-brain barrier (BBB) and selectively damage neurons in the brain of immature rats exposed pre and postnatally. Among the AgNP-induced molecular mechanisms underlying toxic insult is cellular stress, which can consequently lead to cell death. Glutamatergic neurons and NMDAR-mediated neurotransmission also appear to be a target for AgNPs during the postnatal period of exposure. Collected data indicate also that our current knowledge of the impact of AgNPs on the developing nervous system remains insufficient and further studies are required during different stages of development with investigation of environmentally-relevant doses of exposure.

Nanoparticle Effects on Stress Response Pathways and Nanoparticle-Protein Interactions

Nanoparticles (NPs) are increasingly used in a wide variety of applications and products; however, NPs may affect stress response pathways and interact with proteins in biological systems. This review article will provide an overview of the beneficial and detrimental effects of NPs on stress response pathways with a focus on NP-protein interactions. Depending upon the particular NP, experimental model system, and dose and exposure conditions, the introduction of NPs may have either positive or negative effects. Cellular processes such as the development of oxidative stress, the initiation of the inflammatory response, mitochondrial function, detoxification, and alterations to signaling pathways are all affected by the introduction of NPs. In terms of tissue-specific effects, the local microenvironment can have a profound effect on whether an NP is beneficial or harmful to cells. Interactions of NPs with metal-binding proteins (zinc, copper, iron and calcium) affect both their structure and function. This review will provide insights into the current knowledge of protein-based nanotoxicology and closely examines the targets of specific NPs.

Antioxidant, Cytotoxic, and Antimicrobial Potential of Silver Nanoparticles Synthesized using Tradescantia pallida Extract

Silver nanoparticles have received much attention, due to their wide range of biological applications as an alternative therapy for disease conditions utilizing the nanobiotechnology domain for synthesis. The current study was performed to examine the antioxidant, anticancer, antibacterial, and antifungal potential of biosynthesized silver nanoparticles (TpAgNPs) using plant extract. The TpAgNPs were produced by reacting the Tradescantia pallida extract and AgNO₃ solution in nine various concentration ratios subjected to bioactivities profiling. According to the current findings, plant extract comprising phenolics, flavonoids, and especially anthocyanins played a critical role in the production of TpAgNPs. UV–visible spectroscopy also validated the TpAgNP formation in the peak range of 401–441 nm. Further, the silver ion stabilization by phytochemicals, face-centered cubic structure, crystal size, and spherical morphology of TpAgNPs were analyzed by FTIR, XRD, and SEM. Among all TpAgNPs, the biosynthesized TpAgNP6 with a medium concentration ratio (5:10) and the plant extract had effective antioxidant potentials of 77.2 ± 1.0% and 45.1 ± 0.5% free radical scavenging activity, respectively. The cytotoxic activity of TpAgNP6 in comparison to plant extract for the rhabdomyosarcoma cell line was significantly the lowest with IC₅₀ values of 81.5 ± 1.9 and 90.59 ± 1.6 μg/ml and cell viability % of 24.3 ± 1.62 and 27.4 ± 1.05, respectively. The antibacterial and antifungal results of TpAgNPs revealed significant improvement in comparison to plant extract, i.e., minimum inhibition concentration (MIC) 64 μg/ml against Gram-negative Pseudomonas aeruginosa while, in the case of antifungal assay, TpAgNP6 was active against Candida parapsilosis. These TpAgNPs play a crucial role in determining the therapeutic potential of T. pallida due to their biological efficacy.

The importance of mineralogical composition for the cytotoxic and pro-inflammatory effects of mineral dust

Background

Respirable mineral particles represent a potential health hazard in occupational settings and ambient air. Previous studies show that mineral particles may induce cytotoxicity and inflammatory reactions in vitro and in vivo and that the potency varies between samples of different composition. However, the reason for these differences is largely unknown and the impact of mineralogical composition on the biological effects of mineral dust remains to be determined.

Methods

We have assessed the cytotoxic and pro-inflammatory effects of ten mineral particle samples of different composition in human bronchial epithelial cells (HBEC3-KT) and THP-1-derived macrophages, as well as their membranolytic properties in erythrocytes. Moreover, the results were compiled with the results of recently published experiments on the effects of stone particle exposure and analysed using linear regression models to elucidate which mineral components contribute most to the toxicity of mineral dust.

Results

While all mineral particle samples were more cytotoxic to HBEC3-KT cells than THP-1 macrophages, biotite and quartz were among the most cytotoxic in both cell models. In HBEC3-KT cells, biotite and quartz also appeared to be the most potent inducers of pro-inflammatory cytokines, while the quartz, Ca-feldspar, Na-feldspar and biotite samples were the most potent in THP-1 macrophages. All particle samples except quartz induced low levels of membranolysis. The regression analyses revealed associations between particle bioactivity and the content of quartz, muscovite, plagioclase, biotite, anorthite, albite, microcline, calcite, chlorite, orthopyroxene, actinolite and epidote, depending on the cell model and endpoint. However, muscovite was the only mineral consistently associated with increased cytotoxicity and cytokine release in both cell models.

Conclusions

The present study provides further evidence that mineral particles may induce cytotoxicity and inflammation in cells of the human airways and that particle samples of different mineralogical composition differ in potency. The results show that quartz, while being among the most potent samples, does not fully predict the toxicity of mineral dust, highlighting the importance of other particle constituents. Moreover, the results indicate that the phyllosilicates muscovite and biotite may be more potent than other minerals assessed in the study, suggesting that this group of sheet-like minerals may warrant further attention.

A Novel Artificial Hemoglobin Carrier Based on Heulandite-Calcium Mesoporous Aluminosilicate Particles

Tetraethyl-orthosilicate (TEOS)-based nanoparticles are most extensively used as a silica-based hemoglobin carrier system. However, TEOS-based nanoparticles induce adverse effects on the hemoglobin structure. Therefore, a heulandite-calcium-based carrier was investigated as a novel silica-based hemoglobin carrier system. The heulandite-calcium mesoporous aluminosilicate particles (MSPs) were fabricated by a patented tribo-mechanical activation process, according to the manufacturer, and its structure was assessed by X-ray diffraction analysis. Upon hemoglobin encapsulation, alternation in the secondary and tertiary structure was observed. The hemoglobin-particle interactions do not cause heme degradation or decreased activity. Once encapsulated inside the particle pores, the hemoglobin shows increased thermal stability, and higher loading capacity per gram of particles (by a factor of >1.4) when compared to TEOS-based nanoparticles. Futhermore, we introduced a PEGlyted lipid bilayer which significantly decreases the premature hemoglobin release and increases the colloidal stability. The newly developed hemoglobin carrier shows no cytotoxicity to human umbilical vein endothelial cells (HUVEC).

Enhanced antibacterial activity of Rosehip extract-functionalized Mg(OH)2 nanoparticles: An in vitro and in vivo study

The development of nanoparticles as antimicrobial agents against pathogenic bacteria has emerged as one of the leading global healthcare challenges. In this study, Mg(OH)₂ NPs with controlled morphology and nanometric size, using two distinct counterions, chloride or nitrate, have been synthesized using Rosehip (RH) extract that has privileges beyond conventional chemical and physical methods. Various physicochemical techniques were used to characterize the RH-functionalized Mg-based NPs. They exhibited a spherical shape with a diameter of ~10 nm, low crystallinity compared to non-functionalized NPs, high polyphenol content, and negative zeta potential in three different media (H₂O, TSB, and cell medium). The resulting RH-functionalized Mg-based NPs also exhibited an increased antibacterial activity against Gram-positive (S. Epidermis and S. aureus) and Gram-negative (E. Coli) bacteria compared to those prepared in pure water (0 % RH), an effect that was well evident with low NPs contents (250 μg/mL). A preliminary attempt to elucidate their mechanism of action revealed that RH-functionalized Mg-based NPs could disrupt cellular structures (bacterial cell wall and cytoplasmic membrane) and damage the bacterial cell, as confirmed by TEM imaging. Noteworthy is that Mg-based NPs exhibited higher toxicity to bacteria than to eukaryotic cells. More significantly, was their enhanced in vivo efficacy in a Galleria mellonella invertebrate animal model, when infected with S. aureus bacteria. Overall, our findings indicate that well-engineered Rosehip magnesium-based nanoparticles can be used as a green non-cytotoxic polyphenolic source in different antibacterial applications for the biomedical industry.

A biomechanical evaluation on Cubic, Octet, and TPMS gyroid Ti6Al4V lattice structures fabricated by selective laser melting and the effects of their debris on human osteoblast-like cells

Lattice structures are widely used in orthopedic implants due to their unique features, such as high strength-to-weight ratios and adjustable biomechanical properties. Based on the type of unit cell geometry, lattice structures may be classified into two types: strut-based structures and sheet-based structures. In this study, strut-based structures (Cubic & Octet) and sheet-based structure (triply periodic minimal surface (TPMS) gyroid) were investigated. The biomechanical properties of the three different Ti6Al4V lattice structures fabricated by selective laser melting (SLM) were investigated using room temperature compression testing. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were used to check the 3D printing quality with regards to defects and quantitative compositional information of 3D printed parts. Experimental results indicated that TPMS gyroid has superior biomechanical properties when compared to Cubic and Octet. Also, TPMS gyroid was found to be less affected by the variations in relative density. The biocompatibility of Ti6Al4V lattice structures was validated through the cytotoxicity test with human osteoblast-like SAOS2 cells. The debris generated during the degradation process in the form of particles and ions is among the primary causes of implant failure over time. In this study, Ti6Al4V particles with spherical and irregular shapes having average particle sizes of 36.5 μm and 28.8 μm, respectively, were used to mimic the actual Ti6Al4V particles to understand their harmful effects better. Also, the effects and amount of Ti6Al4V ions released after immersion within the cell culture media were investigated using the indirect cytotoxicity test and ion release test.

Effects of Particle Size and Surface Charge on Mutagenicity and Chicken Embryonic Toxicity of New Silver Nanoclusters

Though there are many toxicological studies on metal nanoparticles (NPs), it remains difficult to explain discrepancies observed between studies, largely due to the lack of positive controls and disconnection between physicochemical properties of nanomaterials with their toxicities at feasible exposures in a specified test system. In this study, we investigated effects of particle size and surface charge on in vitro mutagenic response and in vivo embryonic toxicity for newly synthesized silver nanoclusters (AgNCs) at human or environmental relevant exposure and compared the new findings with one of the most common nanoscale particles, titanium dioxide NPs (TiO₂ NPs as a positive control). We hypothesized that the interaction of the test system and physicochemical properties of nanomaterials are critical in determining their toxicities at concentrations relevant with human or environmental exposures. We assessed the mutagenicity of the AgNCs (around 2 nm) and two sizes of TiO₂ NPs (i.e., small: 5-15 nm, big: 30-50 nm) using a Salmonella reverse mutation assay (Ames test). The smallest size of AgNCs showed the highest mutagenic activity with the Salmonella strain TA100 in the absence and presence of the S9 mixture, because the AgNCs maintained the nano-size scale in the Ames test, compared with two other NPs. For TiO₂ NPs, the size effect was interfered by the agglomeration of TiO₂ NPs in media and the generation of oxidative stress from the NPs. The embryonic toxicity and the liver oxidative stress were evaluated using a chicken embryo model at three doses (0.03, 0.33, and 3.3 μg/g egg), with adverse effects on chicken embryonic development in both sizes of TiO₂ NPs. The non-monotonic response was determined for developmental toxicity for the tested NPs. Our data on AgNCs was different from previous findings on AgNPs. The chicken embryo results showed some size dependency of nanomaterials, but they were more well correlated with lipid peroxidation (malondialdehyde) in chicken fetal livers. A different level of agglomeration of TiO₂ NPs and AgNCs was observed in the assay media of Ames and chicken embryo tests. These results suggest that the test nanotoxicities are greatly impacted by the experimental conditions and the nanoparticle's size and surface charge.

Bilayer silk fibroin/sodium alginate scaffold promotes vascularization and advances inflammation stage in full-thickness wound

An ideal wound dressing for full-thickness wound regeneration should offer desirable biocompatibility, adequate mechanical properties, barrier function, and cellular regulation. Here, a bilayer scaffold resembling the hierarchical structure of human skin was developed using silk fibroin and sodium alginate. The upper membrane was prepared through casting and functioned as the epidermis, whereas the lower porous scaffold was prepared by freeze-drying and mimicked extracellular matrix structures. The membrane had nonporous structure, desirable mechanical properties, moderate hydrophilic surface, and suitable water vapor transmission rate, whereas the porous scaffold revealed 157.61 ± 41.67 µm pore size, 86.10 ± 3.60% porosity, and capability of stimulating fibroblast proliferation. The combination of the two structures reinforced the tensile strength by 5-fold and provided protection from wound dehydration. A suitable degradation rate reduced potential administration frequency. Furthermore, an in vivo rabbit full-thickness wound healing test demonstrated that the bilayer scaffold facilitated wound closure, granulation tissue formation, re-epithelialization and skin component transition towards normal skin by providing a moist wound environment, advancing the inflammation stage, and stimulating angiogenesis. Collectively, as an off-the-shelf and cell-free wound dressing with single topical administration, the bilayer scaffold is a promising wound dressing for full-thickness wound regeneration.

Five nanometer size highly positive silver nanoparticles are bactericidal targeting cell wall and adherent fimbriae expression

To tackle growing antibiotic resistance (AR) and hospital-acquired infections (HAIs), novel antimicrobials are warranted that are effective against HAIs and safer for human use. We hypothesize that small 5 nm size positively charged nanoparticles could specifically target bacterial cell wall and adherent fimbriae expression, serving as the next generation antibacterial agent. Herein we show highly positively charged, 5 nm amino-functionalized silver nanoparticles (NH₂–AgNPs) were bactericidal; highly negatively charged, 45 nm citrate-functionalized AgNPs (Citrate–AgNPs) were nontoxic; and Ag⁺ ions were bacteriostatic forming honeycomb-like potentially resistant phenotype, at 10 µg Ag/mL in E. coli. Further, adherent fimbriae were expressed with Citrate–AgNPs (0.5–10 µg/mL), whereas NH₂–AgNPs (0.5–10 µg/mL) or Ag⁺ ions (only at 10 µg/mL) inhibited fimbriae expression. Our results also showed no lipid peroxidation in human lung epithelial and dermal fibroblast cells upon NH₂–AgNPs treatments, suggesting NH₂–AgNPs as a biocompatible antibacterial candidate. Potent bactericidal effects demonstrated by biocompatible NH₂–AgNPs and the lack of toxicity of Citrate–AgNPs lend credence to the hypothesis that small size, positively charged AgNPs may serve as a next-generation antibacterial agent, potentially addressing the rising HAIs and patient health and safety.

Mechanistic study of silica nanoparticles on the size-dependent retinal toxicity in vitro and in vivo

Background

Silica nanoparticles (SiO₂ NPs) are extensively applied in the biomedical field. The increasing medical application of SiO₂ NPs has raised concerns about their safety. However, studies on SiO₂ NP-induced retinal toxicity are lacking.

Methods

We investigated the retinal toxicity of SiO₂ NPs with different sizes (15 and 50 nm) in vitro and in vivo along with the underlying mechanisms. The cytotoxicity of SiO₂ NPs with different sizes was assessed in R28 human retinal precursor cells by determining the ATP content and LDH release. The cell morphologies and nanoparticle distributions in the cells were analyzed by phase-contrast microscopy and transmission electron microscopy, respectively. The mitochondrial membrane potential was examined by confocal laser scanning microscopy. The retinal toxicity induced by SiO₂ NPs in vivo was examined by immunohistochemical analysis. To further investigate the mechanism of retinal toxicity induced by SiO₂ NPs, reactive oxygen species (ROS) generation, glial cell activation and inflammation were monitored.

Results

The 15-nm SiO₂ NPs were found to have higher cytotoxicity than the larger NPs. Notably, the 15-nm SiO₂ NPs induced retinal toxicity in vivo, as demonstrated by increased cell death in the retina, TUNEL-stained retinal cells, retinal ganglion cell degeneration, glial cell activation, and inflammation. In addition, The SiO₂ NPs caused oxidative stress, as demonstrated by the increase in the ROS indicator H₂DCF-DA. Furthermore, the pretreatment of R28 cells with N-acetylcysteine, an ROS scavenger, attenuated the ROS production and cytotoxicity induced by SiO₂ NPs.

Conclusions

These results provide evidence that SiO₂ NPs induce size-dependent retinal toxicity and suggest that glial cell activation and ROS generation contribute to this toxicity.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01326-8.

Nanoarchitectonics for enhanced antibacterial activity with Lactobacillus buchneri S-layer proteins-coated silver nanoparticles

Various multi-drug-resistant microorganisms have appeared while a single antibacterial agent is increasingly no longer adequate for dealing with these resistant microorganisms. Herein, commercially purchased 50 nm-average-diameter silver nanoparticles (AgNPs) and Lactobacillus buchneri-isolated surface-layer proteins (SLPs) as a capping agent were used to fabricate a hybrid antibacterial agent (SLP-AgNPs) with enhanced antibacterial activity, and the possible synergistic antibacterial mechanism was explored. Characterization results revealed that SLP-AgNPs were uniformly surrounded by protein corona provided from SLP, and the formulations were mainly mediated by the electrostatic interactions and hydrogen bonding, which was evidenced by the results of Fourier transform infrared spectroscopy. According to the antibacterial tests, the minimum inhibitory concentration of SLP-AgNPs against Salmonella enterica (0.010 mg/mL) and Staphylococcus aureus (0.005 mg/mL) was 5-10 times lower than that of bare AgNPs, and while SLP-AgNPs showed a higher antibiofilm activity. Furthermore, bacterial cells exposed to SLP-AgNPs exhibited higher cell membrane permeability and stronger inhibition of respiratory-chain dehydrogenase activity, resulting in more severe cell death compared with bare AgNPs. The synergistic effect of SLP on AgNPs was probably carried out by enhanced function of adhesion to bacteria and antibacterial ability of SLP and SLP's supramolecular lattice structure on the sustained release of silver ion.

Metallic Nanoparticles: A New Frontier in the Fight Against Leishmaniasis

Abstract:

Leishmaniasis is a cutaneous, mucocutaneous, or visceral parasitic disease caused by protozoa of the Leishmania genus. According to the World Health Organization, Leishmaniasis causes approximately 20–40 thousand deaths annually, and Brazil, India, and some countries in Africa are the most affected by this neglected disease. In addition to parasite’s ability to evade the host’s immune system, the incidence of vectors, the genetics of different hosts, and the large number of deaths are mainly due to failures in conventional treatments that have high toxicity, low effectiveness, and prolonged therapeutic regimens. Thus, the development of new alternative therapeutics with more effective and safer actions has become one of the main challenges for researchers studying leishmaniasis. Among the many research and tested options, metallic nanoparticles, such as gold, silver, zinc oxide, and titanium dioxide, have been shown to be one of the most promising therapeutic tool because they are easily prepared and chemically modified, have a broad spectrum of action, low toxicity, and can generate reactive oxygen species and other immune responses that favor their use against different species of Leishmania. This review explores the progress of the use of metallic nanoparticles as a new tool in the treatment of leishmaniasis, as well as discusses the gaps in knowledge that need to be addressed to consolidate a safe, effective, and definitive therapeutic intervention against these infections.

Green approaches for the synthesis of metal and metal oxide nanoparticles using microbial and plant extracts

Green synthesis approaches are gaining significance as promising routes for the sustainable preparation of nanoparticles, offering reduced toxicity towards living organisms and the environment. Nanomaterials produced by green synthesis approaches can offer additional benefits, including reduced energy inputs and lower production costs than traditional synthesis, which bodes well for commercial-scale production. The biomolecules and phytochemicals extracted from microbes and plants, respectively, are active compounds that function as reducing and stabilizing agents for the green synthesis of nanoparticles. Microorganisms, such as bacteria, yeasts, fungi, and algae, have been used in nanomaterials' biological synthesis for some time. Furthermore, the use of plants or plant extracts for metal and metal-based hybrid nanoparticle synthesis represents a novel green synthesis approach that has attracted significant research interest. This review discusses various biosynthesis approaches via microbes and plants for the green preparation of metal and metal oxide nanoparticles and provides insights into the molecular aspects of the synthesis mechanisms and biomedical applications. The use of agriculture waste as a potential bioresource for nanoparticle synthesis and biomedical applications of biosynthesized nanoparticles is also discussed.

Efficient Route for the Preparation of Composite Resin Incorporating Silver Nanoparticles with Enhanced Antibacterial Properties

An efficient and facile route for the immobilization of silver (Ag) nanoparticles (NPs) in anion exchange resin beads with different silver loading is proposed. In this method, BH₄⁻ ions were first introduced into chloride-form resin through an ion exchange process with Cl⁻ ions, followed by in-situ chemical reduction of Ag⁺ ions at the surface of the resin to form metallic Ag nanoparticles. Morphology and structure of the resulting Ag-resin nanocomposites were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), Fourier transform infra-red (FTIR), inductively coupled plasma-optical emission spectrometry (ICP-OES), and thermogravimetry analysis (TGA). The results confirmed the presence of smaller diameter Ag NPs incorporated into the resin beads having an average diameter on the order of 10 nm with a few Ag NP clusters of 20–100 nm. The nanoparticles were homogeneously distributed throughout the resin. There were no dramatic increases in average particle sizes even at very high Ag loadings. The resin retained its structure and stability, allowing higher stability of immobilized AgNPs than the colloidal ones. The Ag-loaded resins made with 50 mM AgNO₃ were tested for antibacterial activity in vitro against Escherichia coli (E. coli) as a model microbial contaminant in water. Results showed greater than 99% bacterial inhibition within 3 h of exposure. The resin form offers greater ease of handling, long-term storage at room temperature, reusability in repeated reactions, and reduces the risk of environmental contamination.

Development of Red-Emissive Carbon Dots for Bioimaging through a Building Block Approach: Fundamental and Applied Studies

In recent years, many researchers have struggled to obtain carbon dots (CDs) that possess strong photoluminescence in the red region of light. Success in this area has been limited, although the past few years have brought several promising reports on this topic. The most successful efforts in this area still seem to struggle from a lack of dispersibility/reduced emission in water. This work endeavors to understand the formation process of CDs that do not possess strong performance in an aqueous environment and to improve their capabilities in bioimaging. o-Phenylenediamine (o-PDA) is used along with various precursors in several different solvents (varying acidic and oxidative strengths) to understand the formation process behind the structure leading to red emission that is sensitive to water. These results showed that the combination of acid properties and oxidation is essential for this process, and the important reactions are oligomerization of o-PDA and the crosslinking of these oligomers to form aromatic structural segments of CDs. These CDs are shown to be capable of quantitatively detecting water in organic solvents. Additionally, we have shown that conjugation with transferrin remarkably enhances the biocompatibility of these CDs. Transferrin-conjugated CDs with better biocompatibility were applied to bioimaging studies of neuroblastoma cell lines with N-myc and non-N-myc gene amplification, for the first time. Furthermore, CDs showed versatile bioimaging capability toward a highly aggressive neuroblastoma subgroup of tumors. The importance of creating red-emissive CDs has been well established, and this work is an important step toward understanding their formation and realizing their use in biological systems.

Green approaches for the synthesis of metal and metal oxide nanoparticles using microbial and plant extracts

Green synthesis approaches are gaining significance as promising routes for the sustainable preparation of nanoparticles, offering reduced toxicity towards living organisms and the environment.

Silver nanoparticle-coated self-expandable metallic stent suppresses tissue hyperplasia in a rat esophageal model

BACKGROUND

To evaluate the efficacy of a silver nanoparticle (AgNP)-coated self-expandable metallic stent (SEMS) for suppressing tissue hyperplasia in a rat esophageal model.

METHODS

Twenty-four male Sprague-Dawley rats were randomly assigned to four groups. Animals in group A underwent uncoated SEMS placement, whereas animals in groups B, C, and D underwent 6, 12, and 24 mg/mL AgNP-coated SEMS placement, respectively. All animals were euthanized 4 weeks after SEMS placement, and a gross examination and histological analyses were performed.

RESULTS

All rats achieved technical success and survived until the end of the study. The gross examination showed moderate to severe tissue hyperplasia in 5 rats in group A and 2 rats in group B. In contrast, no animals in groups C and D had moderate or severe tissue hyperplasia. The gross examination revealed no complications. The percentage of granulation tissue area, number of epithelial layers, thickness of submucosal fibrosis, percentage of connective tissue area, inflammatory cell infiltration grade, degree of collagen deposition, and degrees of Ki67, TUNEL, and α-SMA-positive deposition were significantly lower in groups C and D than in group A (all p < 0.05). However, only the percentage of granulation tissue area, number of epithelial layers, thickness of submucosal fibrosis, and percentage of connective tissue area were significantly lower in group B than in group A (all p < 0.05). No histological parameters were significantly different between group D and group C (all p > 0.05).

CONCLUSION

AgNP-coated SEMSs suppressed tissue hyperplasia in a rat esophageal model.

Is titanium alloy Ti-6Al-4 V cytotoxic to gingival fibroblasts-A systematic review

OBJECTIVES

Grade V titanium alloy (Ti-6Al-4 V) is a well-recognized metallic biomaterial for medical implants. There has been some controversy regarding the use of this alloy in medical devices in relation to the toxicity of vanadium. In Dentistry, Ti-6Al-4 V remains prevalent. This systematic review aims to evaluate the effects of Ti-6Al-4 V on cells relevant to oral environments such as gingival fibroblasts.

MATERIALS AND METHODS

A literature search was undertaken for relevant English language publications in the following databases: Dental and Oral Science, Medline and Web of Science. The electronic search was supplemented with a search of references.

RESULTS

After application of inclusion and exclusion criteria. A total of eight papers are included in this review. These papers were all in vitro studies and were categorized into whole implant, discs, or implant particles based on the type of test materials used in the studies.

CONCLUSION

Based on the analyses of the eight included studies in this review, if Ti-6Al-4 V as a material is unchallenged, i.e., as a whole implant in pH neutral environments, there appears to be little effect on fibroblasts. If Ti-6Al-4 V is challenged through corrosion or wear (particle release), the subsequent release of vanadium and aluminium particles has an increased cytotoxic effect in vitro in comparison to commercially pure titanium, hence concerns should be raised in the clinical setting.