Silver-nanoparticle-embedded antimicrobial paints based on vegetable oil

Advances in the Methods for the Synthesis of Carbon Dots and Their Emerging Applications

Cutting-edge technologies are making inroads into new areas and this remarkable progress has been successfully influenced by the tiny level engineering of carbon dots technology, their synthesis advancement and impressive applications in the field of allied sciences. The advances of science and its conjugation with interdisciplinary fields emerged in carbon dots making, their controlled characterization and applications into faster, cheaper as well as more reliable products in various scientific domains. Thus, a new era in nanotechnology has developed into carbon dots technology. The understanding of the generation process, control on making processes and selected applications of carbon dots such as energy storage, environmental monitoring, catalysis, contaminates detections and complex environmental forensics, drug delivery, drug targeting and other biomedical applications, etc., are among the most promising applications of carbon dots and thus it is a prominent area of research today. In this regard, various types of carbon dot nanomaterials such as oxides, their composites and conjugations, etc., have been garnering significant attention due to their remarkable potential in this prominent area of energy, the environment and technology. Thus, the present paper highlights the role and importance of carbon dots, recent advancements in their synthesis methods, properties and emerging applications.

Advanced nanomedicine approaches applied for treatment of skin carcinoma

Skin-cancer is the commonest malignancy affecting huge proportion of the population, reaching heights in terms of morbidity. The treatment strategies are presently focusing on surgery, radiation and chemotherapy, which eventually cause destruction to unaffected cells. To overcome this limitation, wide range of nanoscaled materials have been recognized as potential carriers for delivering selective response to cancerous cells and neoplasms. Nanotechnological approach has been tremendously exploited in several areas, owing to their functional nanometric dimensions. The alarming incidence of skin cancer engenders burdensome effects worldwide, which is further awakening innovational medicinal approaches, accompanying target specific drug delivery tools for coveted benefits to provide reduced toxicity and tackle proliferative episodes of skin cancer. The developed nanosystems for anti-cancer agents include liposomes, ethosomes, nanofibers, solid lipid nanoparticles and metallic nanoparticles, which exhibit pronounced outcomes for skin carcinoma. In this review, skin cancer with its sub-types is explained in nutshell, followed by compendium of specific nanotechnological tools presented, in addition to therapeutic applications of drug-loaded nano systems for skin cancer.

Synthetic preparations and atomic scale engineering of silver nanoparticles for biomedical applications

Owing to their peculiar oxidative effect, silver cations (Ag⁺) are well known for their antimicrobial properties and explored as therapeutic agents for biomedical applications. Size control with improved dispersion and stability are the key factors of Ag NPs (silver nanoparticles) to be used in biomedical applications. Silver based nano-materials are highly efficient due to their biological, chemical and physical properties in comparison with bulk silver. Atomic scale fabrication is achieved by rearranging the internal components of a material, in turn, influencing the mechanical, electrical, magnetic, thermal and chemical properties. For instance, size and shape have a strong impact on the optical, thermal and catalytic properties of Ag NPs. Such properties can be tuned by controlling the surface/volume ratio of Ag nanostructures with a small size (ideally <100 nm), in turn showing peculiar biological activity different from that of bulk silver. Silver nanomaterials such as nanoparticles, thin films and nanorods can be synthesized by various physical, chemical and biological methods whose most recent implementations will be described in this review. By controlling the structure-functionality relationship, silver based nano-materials have high potential for commercialization in biomedical applications. Antimicrobial, antifungal, antiviral, and anti-inflammatory Ag NPs can be applied in several fields such as pharmaceutics, sensors, coatings, cosmetics, wound healing, bio-labelling agents, antiviral drugs, and packaging.

Antibacterial effect of TiAg alloy motivated by Ag-containing phases

The precipitates in Ti-Ag alloy made an important contribution to antibacterial activity. In order to study this specific effects, Ti-Ag samples with different forms of precipitates were produced by powder metallurgy and ingot metallurgy followed by heat treatment: Ti-Ag(T4) with no precipitate, Ti-Ag(as-cast) and Ti-Ag(T6) with Ti₂Ag and Ti-Ag(PM) with Ti₂Ag and Ag-rich phase. Microstructure was analyzed by scanning electronic microscope (SEM), and the antibacterial effects, expression of reactive oxygen species (ROS), protein leakage and biocompatibility were investigated by plate count method, staining technology and cell test. The antibacterial ability was in the following order from low to high: Ti-Ag(T4) < Ti-Ag(as-cast) < Ti-Ag(T6) < Ti-Ag(PM). It was elucidated that Ag-containing phase was the major controlling factor of Ti-Ag antibacterial property and Ti-Ag(PM) with micro-size Ti₂Ag and Ag-rich phase exhibited high antibacterial activity. It was proposed that the existence of Ag-containing phases induced high expression of ROS in bacteria, which destroyed the homeostasis of the bacteria and eventually leads to the rupture of the bacterial membrane. Cell test indicated that Ti-Ag samples had no adverse effect on cells and had good biocompatibility.

Green Synthesis of Nanomaterials

Nanotechnology is considered one of the paramount forefronts in science over the last decade. Its versatile implementations and fast-growing demand have paved the way for innovative measures for the synthesis of higher quality nanomaterials. In the early stages, traditional synthesis methods were utilized, and they relied on both carcinogenic chemicals and high energy input for production of nano-sized material. The pollution produced as a result of traditional synthesis methods induces a need for environmentally safer synthesis methods. As the downfalls of climate change become more abundant, the scientific community is persistently seeking solutions to combat the devastation caused by toxic production methods. Green methods for nanomaterial synthesis apply natural biological systems to nanomaterial production. The present review highlights the history of nanoparticle synthesis, starting with traditional methods and progressing towards green methods. Green synthesis is a method just as effective, if not more so, than traditional synthesis; it provides a sustainable approach to nanomaterial manufacturing by using naturally sourced starting materials and relying on low energy processes. The recent use of active molecules in natural biological systems such as bacteria, yeast, algae and fungi report successful results in the synthesis of various nanoparticle systems. Thus, the integration of green synthesis in scientific research and mass production provides a potential solution to the limitations of traditional synthesis methods.

Tyrosine-Templated Dual-Component Silver Nanomaterials Exhibit Photoluminescence and Versatile Antimicrobial Properties through ROS Generation

The role of small molecules in the preparation of metal nanomaterials generates considerable interest in the fields from materials science to interdisciplinary sciences. In this study, a small amino acid, l-tyrosine (Tyr), has been used as a ligand precursor for the preparation of silver nanomaterials (AgNMs) comprising a dual system: smaller silver nanoclusters (responsible exclusively for the photophysical properties) and larger silver nanoparticles (responsible exclusively for the antimicrobial properties). The luminescent properties of this AgNM system substantiate the role played by Tyr as a capping and a reducing agent outside the protein environment. An interesting feature of this report is the promising antimicrobial properties of the AgNMs against Saccharomyces cerevisiae, Candida albicans, Escherichia coli, and Bacillus cereus cell lines. The importance of this work is that this investigation demonstrates the combating ability of our AgNM system against pathogenic strains (C. albicans and B. cereus) as well. Moreover, the mechanistic aspects of the antimicrobial activity of the AgNMs were elucidated using various methods, such as propidium iodide staining, monitoring reactive oxygen species generation, leakage of proteins, DNA cleavage, etc. We propose that AgNM-mediated cytotoxicity in S. cerevisiae stems from the generation of singlet oxygen (¹O₂) species that create oxidative stress, disrupting the cell membrane and thereby resulting in leakage of proteins from the cells. This study can pave the way toward elucidating the role of a small molecule, Tyr, in the formation of NMs and describes the use of new NMs in potential antimicrobial applications.

Advancements in release-active antimicrobial biomaterials: A journey from release to relief

Escalating medical expenses due to infectious diseases are causing huge socioeconomic pressure on mankind globally. The emergence of antibiotic resistance has further aggravated this problem. Drug-resistant pathogens are also capable of forming thick biofilms on biotic and abiotic surfaces to thrive in a harsh environment. To address these clinical problems, various strategies including antibacterial agent delivering matrices and bactericidal coatings strategies have been developed. In this review, we have discussed various types of polymeric vehicles such as hydrogels, sponges/cryogels, microgels, nanogels, and meshes, which are commonly used to deliver antibiotics, metal nanoparticles, and biocides. Compositions of these polymeric matrices have been elaborately depicted by elucidating their chemical interactions and potential activity have been discussed. On the other hand, various implant/device-surface coating strategies which exploit the release-active mechanism of bacterial killing are discussed in elaboration. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Cardiovascular Disease Implantable Materials and Surgical Technologies > Nanomaterials and Implants Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease.

Biocompatible silver nanoparticles: An investigation into their protein binding efficacies, anti-bacterial effects and cell cytotoxicity studies

Green synthesis of silver nanoparticles (AgNPs) has garnered tremendous interest as conventional methods include the use and production of toxic chemicals, products, by-products and reagents. In this regard, the synthesis of AgNPs using green tea (GT) extract and two of its components, (-)-epigallocatechin gallate (EGCG) and (+)-catechin (Ct) as capping/stabilizing agents, is reported. The synthesized AgNPs showed antibacterial activity against the bacterial strains Staphylococcus aureus and Escherichia coli, along with anticancer activity against HeLa cells. After administering nanoparticles to the body, they come in contact with proteins and results in the formation of a protein corona; hence we studied the interactions of these biocompatible AgNPs with hen egg white lysozyme (HEWL) as a carrier protein. Static quenching mechanism was accountable for the quenching of HEWL fluorescence by the AgNPs. The binding constant (K b) was found to be higher for EGCG-AgNPs ((2.309 ± 0.018) × 104 M-1) than for GT-AgNPs and Ct-AgNPs towards HEWL. EGCG-AgNPs increased the polarity near the binding site while Ct-AgNPs caused the opposite effect, but GT-AgNPs had no such observable effects. Circular dichroism studies indicated that the AgNPs had no such appreciable impact on the secondary structure of HEWL. The key findings of this research included the synthesis of AgNPs using GT extract and its constituent polyphenols, and showed significant antibacterial, anticancer and protein-binding properties. The -OH groups of the polyphenols drive the in situ capping/stabilization of the AgNPs during synthesis, which might offer new opportunities having implications for nanomedicine and nanodiagnostics.

Impact of Physico-Chemical Properties of Cellulose Nanocrystal/Silver Nanoparticle Hybrid Suspensions on Their Biocidal and Toxicological Effects

There is a demand for nanoparticles that are environmentally acceptable, but simultaneously efficient and low cost. We prepared silver nanoparticles (AgNPs) grafted on a native bio-based substrate (cellulose nanocrystals, CNCs) with high biocidal activity and no toxicological impact. AgNPs of 10 nm are nucleated on CNCs in aqueous suspension with content from 0.4 to 24.7 wt%. XANES experiments show that varying the NaBH4/AgNO3 molar ratio affects the AgNP oxidation state, while maintaining an fcc structure. AgNPs transition from 10 nm spherical NPs to 300 nm triangular-shaped AgNPrisms induced by H2O2 post-treatment. The 48 h biocidal activity of the hybrid tested on B. Subtilis is intensified with the increase of AgNP content irrespective of the Ag+/Ag0 ratio in AgNPs, while the AgNSphere-AgNPrism transition induces a significant reduction of biocidal activity. A very low minimum inhibitory concentration of 0.016 mg AgNP/mL is determined. A new long-term biocidal activity test (up to 168 h) proved efficiency favorable to the smaller AgNPs. Finally, it is shown that AgNPs have no impact on the phagocytic capacity of mammalian cells.

Biogenic Synthesis and Catalytic Efficacy of Silver Nanoparticles Based on Peel Extracts of Citrus macroptera Fruit

Biogenically synthesized silver nanoparticles (AgNP) increase the fascination over chemical ones due to their facile and green synthetic process. This study reports the development of an eco-friendly and cost-effective synthesis of AgNPs using an aqueous extract of Citrus macroptera fruit peel, an agricultural waste, as a sole agent with both reducing and capping abilities. The formation of AgNPs was verified by the surface plasmon resonance peak at 426 nm in the UV-vis spectrum, X-ray diffraction pattern, and transmission electron micrography images. The AgNPs obtained under the optimized conditions consist of face-centered cubic crystals and spherical morphology with an average size of 11 nm. The AgNPs are coated with phytochemicals in the C. macroptera fruit peel extract and are stably dispersible due to their negatively charged nature. The AgNPs effectively catalyzed the reduction of 4-nitrophenol to 4-aminophenol and the degradation of methyl orange and methylene blue in the presence of sodium borohydride. This method employing a fruit peel extract is facile, efficient, eco-friendly, and cost-effective and has potential for industrial green fabrication of AgNPs.

An overview of zinc oxide nanoparticles produced by plant extracts for anti-tuberculosis treatments

Tuberculosis (TB), induced by Mycobacterium tuberculosis (MTB), is a fatal infectious disease that kills millions of lives worldwide. The emergence of drug-resistant and multidrug-resistant cases is regarded as one of the most challenging threats to TB control due to the low cure rate. Therefore, TB and drug-resistant TB epidemics urge us to explore more effective therapies. The increasing knowledge of nanotechnology has extended to some nanomedicines for disease treatment in the clinic, which also provides novel possibilities for nano-based medicines for TB treatment. Zinc oxide nanoparticles (ZnO NPs) have gained increasing attention for anti-bacterial uses based on their strong ability to induce reactive oxidative species (ROS) and release bactericidal Zinc ions (Zn²⁺), which are expected to act as novel strategies for TB and drug-resistant TB treatment. Some active herbal medicines from plant extracts have been widely reported to show attractive anti-bacterial activity for infectious treatment, including TB. Here, we summarize the synthesis of ZnO NPs using plant extracts (green synthesized ZnO NPs) and further discuss their potentials for anti-TB treatments. This is the first review article discussing the anti-TB activity of ZnO NPs produced using plant extracts, which might contribute to the further applications of green synthesized ZnO NPs for anti-TB and drug-resistant TB treatment.

Single-Particle Hyperspectral Imaging Reveals Kinetics of Silver Ion Leaching from Alloy Nanoparticles

Gold-silver alloy nanoparticles are interesting for multiple applications, including heterogeneous catalysis, optical sensing, and antimicrobial properties. The inert element gold acts as a stabilizer for silver to prevent particle corrosion, or conversely, to control the release kinetics of antimicrobial silver ions for long-term efficiency at minimum cytotoxicity. However, little is known about the kinetics of silver ion leaching from bimetallic nanoparticles and how it is correlated with silver content, especially not on a single-particle level. To characterize the kinetics of silver ion release from gold-silver alloy nanoparticles, we employed a combination of electron microscopy and single-particle hyperspectral imaging with an acquisition speed fast enough to capture the irreversible silver ion leaching. Single-particle leaching profiles revealed a reduction in silver ion leaching rate due to the alloying with gold as well as two leaching stages, with a large heterogeneity in rate constants. We modeled the initial leaching stage as a shrinking-particle with a rate constant that exponentially depends on the silver content. The second, slower leaching stage is controlled by the electrochemical oxidation potential of the alloy being steadily increased by the change in relative gold content and diffusion of silver atoms through the lattice. Interestingly, individual nanoparticles with similar sizes and compositions exhibited completely different silver ion leaching yields. Most nanoparticles released silver completely, but 25% of them appeared to arrest leaching. Additionally, nanoparticles became slightly porous. Alloy nanoparticles, produced by scalable laser ablation in liquid, together with kinetic studies of silver ion leaching, provide an approach to design the durability or bioactivity of alloy nanoparticles.

Exploitation of Antimicrobial Nanoparticles and Their Applications in Biomedical Engineering

Antibiotic resistance is a major threat to public health, which contributes largely to increased mortality rates and costs in hospitals. The severity and widespread nature of antibiotic resistance result in limited treatments to effectively combat antibiotic-resistant pathogens. Nanoparticles have different or enhanced properties in contrast to their bulk material, including antimicrobial efficacy towards a broad range of microorganisms. Their beneficial properties can be utilised in various bioengineering technologies. Thus, antimicrobial nanoparticles may provide an alternative to challenge antibiotic resistance. Currently, nanoparticles have been incorporated into materials, such as fibres, glass and paints. However, more research is required to elucidate the mechanisms of action fully and to advance biomedical applications further. This paper reviews the antimicrobial efficacies and the intrinsic properties of different metallic nanoparticles, their potential mechanisms of action against certain types of harmful pathogens and how these properties may be utilised in biomedical and healthcare products with the aim to reduce cross contaminations, disease transmissions and usage of antibiotics.

Physico-Chemical Properties of Inorganic NPs Influence the Absorption Rate of Aquatic Mosses Reducing Cytotoxicity on Intestinal Epithelial Barrier Model

Noble metals nanoparticles (NPs) and metal oxide NPs are widely used in different fields of application and commercial products, exposing living organisms to their potential adverse effects. Recent evidences suggest their presence in the aquifers water and consequently in drinking water. In this work, we have carefully synthesized four types of NPs, namely, silver and gold NPs (Ag NPs and Au NPs) and silica and titanium dioxide NPs (SiO₂ NPs and TiO₂ NPs) having a similar size and negatively charged surfaces. The synthesis of Ag NPs and Au NPs was carried out by colloidal route using silver nitrate (AgNO₃) and tetrachloroauric (III) acid (HAuCl₄) while SiO₂ NPs and TiO₂ NPs were achieved by ternary microemulsion and sol-gel routes, respectively. Once the characterization of NPs was carried out in order to assess their physico-chemical properties, their impact on living cells was studied. We used the human colorectal adenocarcinoma cells (Caco-2), known as the best representative intestinal epithelial barrier model to understand the effects triggered by NPs through ingestion. Then, we moved to explore how water contamination caused by NPs can be lowered by the ability of three species of aquatic moss, namely, Leptodictyum riparium, Vesicularia ferriei, and Taxiphyllum barbieri, to absorb them. The experiments were conducted using two concentrations of NPs (100 μM and 500 Μm as metal content) and two time points (24 h and 48 h), showing a capture rate dependent on the moss species and NPs type. Then, the selected moss species, able to actively capture NPs, appear as a powerful tool capable to purify water from nanostructured materials, and then, to reduce the toxicity associated to the ingestion of contaminated drinking water.

In Situ Atomic-Scale Observation of Silver Oxidation Triggered by Electron Beam Irradiation

Understanding the mechanism of metal oxidation processes is critical for maintaining the desired properties of metals and catalysts, as well as for designing advanced materials. In this work, we investigate the electron beam induced oxidation of silver using in situ transmission electron microscopy. The additions of Ag-O columns on {111} and {110} planes were captured with atomic resolution. Interestingly, oscillatory growth on {110} planes was observed, which resulted from the double effect of electron beam irradiation. It was found that not only thermodynamic factors but also kinetic factors played significant roles in morphology evolutions. These results can facilitate the fundamental understanding of the oxidation process of Ag and provide a promising approach for the fabrication of desired nanostructures.

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

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

Fight against COVID-19: The case of antiviral surfaces

The COVID-19 pandemic is the largest global public health outbreak in the 21st century so far. Based on World Health Organization reports, the main source of SARS-CoV-2 infection is transmission of droplets released when an infected person coughs, sneezes, or exhales. Viral particles can remain in the air and on the surfaces for a long time. These droplets are too heavy to float in air and rapidly fall down onto the surfaces. To minimize the risk of the infection, entire surrounding environment should be disinfected or neutralized regularly. Development of the antiviral coating for the surface of objects that are frequently used by the public could be a practical route to prevent the spread of the viral particles and inactivation of the transmission of the viruses. In this short review, the design of the antiviral coating to combat the spread of different viruses has been discussed and the technological attempts for minimizing the coronavirus outbreak have been highlighted.

Development of a light activatable lignin nanosphere based spray coating for bioimaging and antimicrobial photodynamic therapy

Many coating materials are commercially available to combat microbial infections. However, these coatings are difficult to synthesize, and are mostly composed of toxic chemicals. Lignin is an under-explored natural biopolymer with multifaceted potential. Lignin, with adhesive, UV resistant, and antimicrobial properties, is a suitable candidate to develop coating materials. Here we report a smart method to fabricate a sustainable nanospray coating from lignin which does not require any toxic chemicals or additives during synthesis. Initially, we have developed stable lignin nanospheres in a single step in aqueous medium, which were later utilized as a lignin nanospray (LNSR). The LNSR was characterized by dynamic light scattering, scanning electron microscopy, FTIR and other analytical techniques. This LNSR showed remarkable UV blocking, antioxidant and light-activated antimicrobial properties. Interestingly, for the first time, the LNSR demonstrated photoluminescence, making it useful for bioimaging. Moreover, singlet oxygen generation potential was observed in the LNSR, which could render it useful in phototheranostic applications (i.e. light assisted imaging and photodynamic therapy). Further, the LNSR was directly utilized to fabricate a sustainable coating. The nanospray coating exhibited maximum light-induced cell killing when applied to common microbes as detected by live-dead cell imaging. Taken together, the lignin nanospray coating developed via a direct pathway holds great promise to disinfect microbes in the presence of light.

Silver-hydroxyapatite nanocomposites prepared by three sequential reaction steps in one pot and their bioactivities in vitro

Hydroxyapatite (HA) combined with antimicrobial agents for biomedical application can effectively avoid the bacteria infection, while HA have the good performance. In this study, we prepared silver-hydroxyapatite (Ag-HA) nanocomposites using a one-pot method consisting of three sequential steps of wet chemical precipitation, ion exchange, and a silver mirror reaction. The HA nanoparticles used as the precursor for Ag ion doping were first synthesised by wet chemical precipitation. Next, Ag⁺ absorbed on HA surface through ion exchange reaction. Glucose was then added to initiate the silver mirror reaction, which made the Ag⁺ ions reduce to Ag⁰ and Ag nanoparticles in situ formed on HA nanoparticles. Subsequently, Ag-HA nanocomposites with different Ag content were prepared. X-ray diffraction, SEM, EDX mapping and TEM imaging confirmed that spherical Ag nanoparticles ~20-40 nm in diameter were adhered to the surface of HA nano-rods (0.4-0.8 μm in length and 15-40 nm in diameter). The Ag content (1.9-15.2 wt%) in the Ag-HA nanocomposites was adjusted by varying the feeding Ag/Ca molar ratio (2.0-20%). The cell viability evaluation in vitro proved that Ag-HA nanocomposites had low cytotoxicity to L929 normal cells. Meanwhile, the antibacterial examinations in vitro demonstrated that Ag-HA nanocomposites had obvious antibacterial effects on Gram-positive bacteria, Gram-negative bacteria, and fungus. The antibacterial results were dose-dependent on the accumulation of silver content. The Ag-HA nanocomposites loaded PMMA resins also demonstrated a potential antibacterial activity against S. mutans. This paper presents a convenient and bio-friendly approach for preparing Ag-HA nanocomposites with adjustable Ag content, which are a promising material for biomedical applications.

Eco-Friendly Preparation of Epoxy-Rich Graphene Oxide for Wound Healing

Despite the ever-growing endangerment caused by the multidrug resistance (MDR) of bacteria, the development of effective antibacterial materials still remains a global challenge. Current antibiotic therapies cannot simultaneously inactivate bacteria and accelerate wound healing. This study aimed to originally separate the intercalation of MnO₃⁺ and the oxidation processes to synthesize epoxy-rich graphene oxide (erGO) nanofilms via an eco-friendly synthetic route, which possessed low density and large lamellar distribution and was rich in epoxide. Importantly, the MnO₃⁺ could be separated from the product and recycled for preparing the next generation of erGO nanofilms, which was quite economical and eco-friendly. The erGO nanofilm was capable of successfully inhibiting Gram-negative bacteria and even had excellent growth-inhibitory effects on Gram-positive bacteria including multidrug resistance (MDR) bacteria, as evidenced by antibacterial phenomena. Additionally, the erGO nanofilm with high ^•C density formed from epoxide exerted excellent antibacterial effects through tight membrane wrapping and induction of lipid peroxidation. The wound-healing property of the erGO nanofilm was evaluated via treatments of wounds infected by Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), which not only killed bacteria but also accelerated wound healing in mice with a skin infection. The novel erGO nanofilm with dual antimicrobial mechanisms might serve as a promising multifunctional antimicrobial agent for medical wound dressing with high biocompatibility.

A novel Ag/carrageenan-gelatin hybrid hydrogel nanocomposite and its biological applications: Preparation and characterization

A novel biohybrid hydrogel nanocomposite made of natural polymer carrageenan and gelatin protein were developed. The silver nanoparticles were prepared using the carrageenan polymer as reduction and capping agent. Here, the Ag/Carrageenan was combined with gelatin hydrogel using glutaraldehyde having a cross-link role in order to create the biohybrid hydrogel nanocomposite. The manufactured composite performances were anaylised by UV-visible spectroscopy, Fourier Transform infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), Energy dispersive X-ray (EDX) spectroscopy and Transmission Electron Microscopy (TEM) methods. The swelling behaviour of the Ag/Carrageenan-gelatin hybrid hydrogel nanocomposite was also analyzed. The antibacterial activity was tested against human pathogens viz. S.agalactiae 1661, S. pyogenes 1210 and E. coli. The bacterial cell wall damage of S.agalactiae 1661 was analyzed by scanning electron microscopy. The cytotoxic assay was performed against the A549 lung cancer cells.

Polyurethane/Nanosilver-Doped Halloysite Nanocomposites: Thermal, Mechanical Properties, and Antibacterial Properties

In this study, the researchers successfully embellished the surface of halloysite (Ag/HNTs) with silver using halloysite, silver nitrate (AgNO₃), and polyvinylpyrrolidone (PVP). The researchers then prepared polyurethane that contained pyridine ring by using 4,4′-diphenylmethane diisocyanate (MDI) and polytetramethylene glycol (PTMG) as the hard chain segment and the soft chain segment of polyurethane (PU), as well as 2,6-pyridinedimethanol (2,6-PDM) as the chain extension agent. This was followed by the preparation of Ag/HNTs/PUs nanocomposite thin films, achieved by mixing Ag/HNTs with different ratios into polyurethane that contains pyridine ring. First, the Ag/HNTs powders were analyzed using energy-dispersive X-ray spectroscopy, X-ray diffraction, and transmission electron microscopy. Subsequently, Fourier-transform infrared spectroscopy was used to examine the dispersibility of Ag/HNTs in PU, whereas the thermal stability and the viscoelasticity of Ag/HNTs/PU were examined using thermal gravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis. When the mechanical properties of Ag/HNTs/PU were tested using a universal strength tester, the results indicated a maximum increase of 109.5% in tensile strength. The researchers then examined the surface roughness and the hydrophobic ability of the Ag/HNTs/PU thin films by using atomic force microscopy and water contact angle. Lastly, antibacterial testing on Escherichia coli revealed that when the additive of Ag/HNTs reached 2.0 wt%, 99.3% of the E. coli were eliminated. These results indicated that the addition of Ag/HNTs into PU could enhance the thermal stability, mechanical properties, and antibacterial properties of PU, implying the potential of Ag/HNTs-02 as biomedicine material.

Polymer-Based Graphene Derivatives and Microwave-Assisted Silver Nanoparticles Decoration as a Potential Antibacterial Agent

Nanocomposites obtained by the decoration of graphene-based materials with silver nanoparticles (AgNPs) have received increasing attention owing to their antimicrobial activity. However, the complex synthetic methods for their preparation have limited practical applications. This study aims to synthesize novel NanoHybrid Systems based on graphene, polymer, and AgNPs (namely, NanoHy-GPS) through an easy microwave irradiation approach free of reductants and surfactants. The polymer plays a crucial role, as it assures the coating layer/substrate compatibility making the platform easily adaptable for a specific substrate. AgNPs' loading (from 5% to 87%) can be tuned by the amount of Silver salt used during the microwave-assisted reaction, obtaining spherical AgNPs with average sizes of 5-12 nm homogeneously distributed on a polymer-graphene nanosystem. Interestingly, microwave irradiation partially restored the graphene sp2 network without damage of ester bonds. The structure, morphology, and chemical composition of NanoHy-GPS and its subunits were characterized by means of UV-vis spectroscopy, thermal analysis, differential light scattering (DLS), Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive X-ray analysis (EDX), Atomic Force Microscopy (AFM), and High-Resolution Transmission Electron Microscopy (HRTEM) techniques. A preliminary qualitative empirical assay against the typical bacterial load on common hand-contacted surfaces has been performed to assess the antibacterial properties of NanoHy-GPS, evidencing a significative reduction of bacterial colonies spreading.

Glioma cells eradication by photoexcitation of bioengineered molybdenum trioxide nanoparticles synthesized by wet chemical and microwave route: Dose dependent photosensitizer bioactivity

Here, we surveyed the usage of MoO₃ nanostructure in role of a photosensitizer to eradicate glioma cells. This is the first endeavor upon survey of usage of nanostructured MoO₃ to treat glioma in vitro. Here, we offer a simple way for preparation of bioactive MoO₃ nanostructure via two different routes; wet chemical and microwave. The influence of diverse experimental factors like various alcoholic solvents and presence of capping agent was investigated on the final properties of synthesized products. Dimension and morphology of inorganic molybdenum trioxide nanostructures checked with TEM, HRTEM and also SEM images. Moreover, the cytotoxicity effect of optimized MoO₃ nanoparticles was investigated on T98 and A172 cell lines. Both T98 and A172 cell lines indicated dose-dependent manner in the presence of increasing concentration of MoO₃ nanostructures, but T98 cells were less sensitive to MoO₃ in comparison with A172. Anti-glioma role of MoO₃ nanostructures excited with the aid of UVC illumination studied in vitro as well. By studying the UV exposure lonely, it is evident that UV effects on cell viability about 50% in both cell lines after 24 h. Interestingly, by combining nanostructured MoO₃ with UVC illumination, decrement in the proliferation value could be remarkably occurred in comparison with controls. The outcomes denote that the photodynamic therapy with the help of nanostructured MoO₃ may be beneficial to treat glioma.

Biosynthesis of AgNPs onto the urea-based periodic mesoporous organosilica (AgxNPs/Ur-PMO) for antibacterial and cell viability assay

Nano-size silver particles were stabilized on the inner surfaces of urea based periodic mesoporous organosilica (Ur-PMO). Aqueous extract of Euphorbia leaves as a sustainable and green reducing agent was applied for Ag-nanoparticles growth into the Ur-PMO channels. Physical and chemical properties of organosilica materials synthesized using various techniques such as FT-IR, small-angle XRD, PXRD, FESEM, TEM, SEM-EDX and atomic absorption spectrometry (AAS) were examined. Finally, the AgNPs/Ur-PMO were investigated on cell viability assay. An in vitro cytotoxicity test using MMT assay displayed that the designed material has good biocompatibility and could be a promising candidate for biomedical applications. The results also showed that the AgNPs/Ur-PMO compounds (especially, PMO; 1.27% AgNPs) had relatively good antibacterial and antibiofilm effects. It seems that the use of these compounds in hospital environments can reduce nosocomial infections as well as reduce antibiotic-resistant bacteria.

Therapeutic Applications of Biostable Silver Nanoparticles Synthesized Using Peel Extract of Benincasa hispida: Antibacterial and Anticancer Activities

The purpose of this study was to fabricate biostable inorganic silver nanoparticles (AgNPs) using fresh peel (aqueous) extract of Benincasa hispida. A fast, robust, and eco-friendly approach was used for the synthesis of AgNPs, where bioactive components of peel extract of B. hispida acted as reducing and stabilizing agents. Synthesized AgNPs were characterized using a UV–Vis spectrophotometer, Fourier-transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), and electron microscopy. The synthesized nanoparticles exhibited maximum absorption at 418 nm under the typical AgNPs surface plasmon resonance band range. They depicted a mean size of 26 ± 2 nm with a spherical shape. Their therapeutic prospective was determined by evaluating their antimicrobial and anticancer potential. The bio-synthesized silver nanoparticles exhibited strong antimicrobial activity with minimum inhibitory concentration (MIC 50) values of 14.5, 8.6, 6.063, and 13.4 μg/mL against Staphylococcus aureus (ATCC 25923), Micrococcus luteus (ATCC 14593), Escherichia coli (ATCC 25922), and Klebsiella pneumonia (ATCC 13883), respectively. The biosynthesized AgNPs showed potent in vitro cytotoxicity against human cervical cancer cell line with a half maximal inhibitory concentration (IC₅₀) value of 0.066 μg/mL; however, no cytotoxic effect was observed on normal human primary osteoblasts cell line. This study explored B. hispida extract and confirmed its effectiveness as a promising source in producing AgNPs that could be employed for several therapeutic applications.

Direct Visualization and Quantification of Maternal Transfer of Silver Nanoparticles in Zooplankton

The immense application of silver nanoparticles (AgNPs) in biomedical fields is likely to increase the exposure of humans. However, little is known about whether these nanoparticles can be maternally transferred, especially regarding their biodistribution in the younger generation, maternal transfer efficiency, and toxic effects. In the present study, maternal transfer of AgNPs in model zooplankton (Daphnia magna) was for the first time visualized and quantified. We found that AgNPs were transferred from mother to offspring and mainly accumulated in the lipids due to the strong colocalization with lipid droplets, which were the major energy sources of Daphnia embryos. In contrast, Ag⁺ was irregularly distributed in different sites, probably due to the mobility and reactivity of Ag⁺. The maternal transfer efficiency quantified by the radiolabeling methodology was 2.37 ± 0.25 and 6.05 ± 0.89% for ^110mAgNPs and ^110mAg, respectively. Furthermore, AgNPs and Ag⁺ significantly inhibited the reproduction capability of F₀ and F₁ generations, but such maternal toxic effect inhibition was only found within the first two broods of F₀ and F₁ generations. Our bioimaging findings demonstrated that AgNPs could be maternally transferred to the next generation; thus, it is critical to produce AgNPs with lower toxic effects, higher delivery efficacy, and more precise targeting.

Electrophoretic Deposition of Nanoporous Oxide Coatings from Concentrated CuO Nanoparticle Dispersions

Electrophoretic deposition (EPD) of nanoporous oxide coatings is an interesting research avenue owing to the experimental simplicity and broad scope of applications and materials. In this study, the properties of concentrated (up to 5000 mg/L), nonaqueous CuO nanoparticle (NP) dispersions were tailored to produce micrometer-thick, nanoporous CuO films by EPD. In particular, we performed a systematic investigation of the electrophoretic mobilities and size distributions of dispersed CuO aggregates and developing agglomerates in different organic solvents for concentrations ranging from 50 to 5000 mg/L with and without surfactant addition. Time-resolved dynamic light scattering analyses showed that aggregate mobilities and agglomeration rates decrease with increasing hydrocarbon chain length of the organic solvent (from ethanol to hexanol) and thus with increasing viscosity. The highest electrophoretic mobility was obtained for CuO NP aggregates and agglomerates dispersed in ethanol as a solvent. However, the addition of ≥0.5 wt % acetylacetone as a surfactant is required to stabilize these dispersions for subsequent EPD and at the same time introduce a net attractive (electrostatic) interaction between neighboring agglomerates on the substrate to promote layer formation during the EPD step. The produced micrometer-thick nanoporous CuO coatings can serve as high surface area nanostructured materials or nanoporous scaffolds in catalysis, combustion, propellants, and nanojoining.

Eco Friendly Approach for Synthesis, Characterization and Biological Activities of Milk Protein Stabilized Silver Nanoparticles

Today, the overall occurrence of re-emerging and rising illnesses has been a serious load on economies as well as public health. Here, we describe a simple, nontoxic and eco-friendly method for the synthesis of milk protein (MP)-stabilized silver nanoparticles (MP-s-AgNPs) using ultrahigh-temperature full cream milk. Highly stable AgNPs were prepared with a fair control over their size, without using any reducing or stabilizing agent, and their formation was attributed to the presence of the MP casein. Ag⁺ ion reduction was possibly caused by the MPs. The synthesized MP-s-AgNPs were characterized in detail by ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and dynamic light scattering. MP-s-AgNPs showed inhibitory activity against both Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative microorganisms (Salmonella typhi and Escherichia coli). Moreover, MP-s-AgNPs were found to be more toxic to bacteria than to fungi (Aspergillus fumigatus, Aspergillus ochraceus and Penicillium chrysogenum).

New biodegradable nanoparticles-in-nanofibers based membranes for guided periodontal tissue and bone regeneration with enhanced antibacterial activity

Introduction

Guided tissue regeneration (GTR) and guided bone regeneration (GBR) are commonly used surgical procedures for the repair of damaged periodontal tissues. These procedures include the use of a membrane as barrier to prevent soft tissue ingrowth and to create space for slowly regenerating periodontium and bone. Recent approaches involve the use of membranes/scaffolds based on resorbable materials. These materials provide the advantage of dissolving by time without the need of surgical intervention to remove the scaffolds.

Objectives

This study aimed at preparing a new series of nanofibrous scaffolds for GTR/GBR applications with enhanced mechanical properties, cell adhesion, biocompatibility and antibacterial properties.

Methods

Electrospun nanofibrous scaffolds based on polylactic acid/cellulose acetate (PLA/CA) or poly(caprolactone) (PCL) polymers were prepared and characterized. Different concentrations of green-synthesized silver nanoparticles, AgNPs (1-2% w/v) and hydroxyapatite nanoparticles, HANPs (10-20% w/v) were incorporated into the scaffolds to enhance the antibacterial and bone regeneration activity.

Results

In-vitro studies showed that addition of HANPs improved the cell viability by around 50% for both types of nanofibrous scaffolds. The tensile properties were also improved through addition of 10% HANPs but deteriorated upon increasing the concentration to 20%. AgNPs significantly improved the antibacterial activity with 40 mm inhibition zone after 32 days. Additionally, the nanofibrous scaffolds showed a desirable degradation profile with losing around 40-70% of its mass in 8 weeks.

Conclusions

The obtained results show that the developed nanofibrous membranes are promising scaffolds for both GTR and GBR applications.

Antibacterial and cellular response of piezoelectric Na0.5K0.5NbO3modified 1393 bioactive glass

In the present study, the combined effect of addition of varying concentrations (10-30 vol%) of biocompatible piezoelectric Na_0.5K_0.5NbO₃ (NKN) as well as electrostatic and dynamic pulsed electrical treatment on antibacterial and cellular response of 1393 bioactive glass (1393 BG) has been examined. The phase analyses of the sintered (at 800 °C for 30 min) samples revealed the formation of 1393 BG - NKN composites without any appearance of secondary phases. The addition of 10-30 vol% NKN significantly improved the mechanical behaviour of 1393 BG like, hardness (1.7 to 2 times), fracture toughness (1.3 to 2.6 times), compressive (2.3 to 8 times) and flexural strengths (2 to 3.5 times) than monolithic 1393 BG. The piezoelectric NKN is observed to induce the antibacterial activity in 1393 BG - (10- 30 vol%) NKN composites, while Staphylococcus aureus (S. aureus, gram positive) and Escherichia coli (E. coli, gram negative) bacterial cells were exposed to unpolarized and polarized (20 kV, 500°C for 30 min) sample surfaces. The antibacterial response was examined using disc diffusion, nitro blue tetrazolium (NBT) and MTT assays. The statistical analyses revealed the significant reduction in the viability of bacterial cells on polarized 1393 BG - (10- 30 vol%) NKN composite samples. In addition, the combined effect of electrostatic and dynamic pulsed electrical stimulation (1 V/cm, 500 μs pulses) on the cellular response of 1393 BG and 1393 BG - 30 vol% NKN composites has been analysed with MG-63 osteoblast-like cells. The cell proliferation was observed to increase significantly for the dynamic pulsed electric field treated negatively charged surfaces.

Evaluate the Effect of Zinc Oxide and Silver Nanoparticles on Biofilm and icaA Gene Expression in Methicillin-Resistant Staphylococcus aureus Isolated From Burn Wound Infection

Methicillin-resistant Staphylococcus aureus is the cause of nosocomial and community-acquired infections. This study aimed to evaluate the effect of zinc oxide and silver nanoparticles (ZnO-Ag NPs) on biofilms formation and icaA gene expression in methicillin-resistant S. aureus (MRSA). In this study, three standard strains (ATCC 43300, 25923, and 29913) and a clinical isolate are included. The minimum inhibitory concentration (MIC) of nanoparticles was determined by microdilution broth method. The antibacterial effects of ZnO-Ag NPs either alone or in combination with each other were compared with vancomycin (as the control group). The effect of MIC and sub-MIC concentrations of ZnO-Ag NPs on biofilm formation was determined by the microtiter plate method. The expression level of the icaA gene was assessed by real-time PCR LightCycler® 96 software (Version 1.1.0.1320, Roche, Germany). technique. All experiments were repeated three times. Data were analyzed using SPSS software through ANOVA and t-test. The P-value of less than .05 was considered as statistically significant. The average MICs of ZnO, Ag, and ZnO-Ag NPs compounds were 393.2, 179.8, and 60.8 μg/ml, respectively. The compound of ZnO-Ag NPs had a synergistic effect against all isolates. ZnO-Ag NPs decreased the biofilm formation rate at MIC and sub-MIC concentrations (P < .001). Sub-MIC ZnO-Ag NPs concentration significantly reduced the icaA gene expression in S. aureus strains (P < .03). The sub-MIC concentration of ZnO-Ag NPs reduced biofilm formation rate and icaA gene expression in Staphylococcus aureus strains compared with vancomycin. It can be used to cover medical devices after examining more clinical isolates to prevent bacterial colonization.

The Impact of Engineered Silver Nanomaterials on the Immune System

Over the last decades there has been a tremendous volume of research efforts focused on engineering silver-based (nano)materials. The interest in silver has been mostly driven by the element capacity to kill pathogenic bacteria. In this context, the main area of application has been medical devices that are at significant risk of becoming colonized by bacteria and subsequently infected. However, silver nanomaterials have been incorporated in a number of other commercial products which may or may not benefit from antibacterial protection. The rapid expansion of such products raises important questions about a possible adverse influence on human health. This review focuses on examining currently available literature and summarizing the current state of knowledge of the impact of silver (nano)materials on the immune system. The review also looks at various surface modification strategies used to generate silver-based nanomaterials and the immunomodulatory potential of these materials. It also highlights the immune response triggered by various silver-coated implantable devices and provides guidance and perspective towards engineering silver nanomaterials for modulating immunological consequences.

Effective killing of bacteria under blue-light irradiation promoted by green synthesized silver nanoparticles loaded on reduced graphene oxide sheets

Graphene oxide (GO) materials loaded with silver nanoparticles (AgNPs) have drawn considerable attention due to their capacity to efficiently inactivate bacteria though a multifaceted mechanism of action, as well as for presenting a synergetic effect against bacteria when compared to the activity of AgNPs and GO alone. In this investigation, we present an inexpensive and environmentally-friendly method for synthesizing reduced GO sheets coated with silver nanoparticles (AgNPs/r-GO) using a coffee extract solution as a green reducing agent. The physical and chemical properties of the produced materials were extensively characterized by scanning electron microscopy (SEM), field-emission gun transmission electron microscopy (FEG-TEM), ultraviolet and visible absorption (UV-Vis), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), inductively coupled plasma-optical emission spectroscopy (ICP-OES) and ion release determination. The results demonstrated that AgNPs/r-GO composites were successfully produced, revealing the formation of micrometer-sized r-GO sheets decorated by AgNPs of approximately 70 nm diameter. Finally, bactericidal and photobactericidal effects of the AgNPs/r-GO composites were tested against Staphylococcus aureus, in which the results showed that the composites presented antimicrobial and photoantimicrobial activities. Moreover, our results demonstrated for the first time, to our knowledge, that an efficient process of bacterial inactivation can be achieved by using AgNPs/r-GO composites under blue light irradiation as a result of three different bacterial killing processes: (i) chemical effect promoted by Ag⁺ ion release from AgNPs; (ii) photocatalytic activity induced by AgNPs/r-GO composites, enhancing the bacterial photoinactivation due to the excited-Plasmons of the AgNPs when anchored on r-GO; and (iii) photodynamic effect produced by bacterial endogenous photosensitizers under blue-light irradiation. In summary, the present findings demonstrated that AgNPs/r-GO can be obtained by a non-toxic procedure with great potential for biomedical-related applications.

A hybrid lipid membrane coating "shape-locks" silver nanoparticles to prevent surface oxidation and silver ion dissolution

The controlled synthesis of stable silver nanoparticles (AgNPs), that do not undergo surface oxidation and Ag+ ion dissolution, continues to be a major challenge. Here the synthesis of robust hybrid lipid-coated AgNPs, comprised of l-α-phosphatidylcholine (PC) membranes anchored by a stoichiometric amount of long-chained hydrophobic thiols and sodium oleate (SOA) as hydrophobic binding partners, that do not undergo surface oxidation and Ag+ ion dissolution, is described. UV-Visible (UV-Vis) spectroscopy, transmission electron microscopy (TEM), and inductively coupled plasma mass spectrometry (ICP-MS) demonstrate that in the presence of strong oxidants, such as potassium cyanide (KCN), the hybrid lipid-coated AgNPs are stable and do not undergo surface oxidation even in the presence of membrane destabilizing surfactants. UV-Vis studies show that the stability of hybrid lipid-coated AgNPs of various sizes and shapes is dependent on the length of the thiol hydrocarbon chain and can be ranked in the order of increasing stability as follows: propanethiol (PT) < hexanethiol (HT) ≤ decanethiol (DT). UV-Vis and ICP-MS studies show that the hybrid lipid-coated AgNPs do not change in size or shape confirming that the AgNPs do not undergo surface oxidation and Ag+ ion dissolution when placed in the presence of strong oxidants, chlorides, thiols, and low pH. Long-term stability studies, over 21 days, show that the hybrid lipid-coated AgNPs do not release Ag+ ions and are more stable. Overall, these studies demonstrate hybrid membrane encapsulation of nanomaterials is a viable method for stabilizing AgNPs in a "shape-locked" form that is unable to undergo surface oxidation, Ag+ ion release, aging, or shape conversion. More importantly, this design strategy is a simple approach to the synthesis and stabilization of AgNPs for a variety of biomedical and commercial applications where Ag+ ion release and toxicity is a concern. With robust and shielded AgNPs, investigators can now evaluate and correlate how the physical features of AgNPs influence toxicity without the confounding factor of Ag+ ions present in samples. This design strategy also provides an opportunity where the membrane composition can be tuned to control the release rate of Ag+ ions for optimizing antimicrobial activity.

Electro-mechanical and Polarization-Induced Antibacterial Response of 45S5 Bioglass-Sodium Potassium Niobate Piezoelectric Ceramic Composites

Besides the excellent osteoconductivity and biocompatibility of 45S5 bioglass (BG), poor mechanical and electrical properties as well as susceptibility toward bacterial adhesion limit its widespread clinical applications. In this context, the present study investigates the effect of addition of piezoelectric sodium potassium niobate (Na_0.5K_0.5NbO₃; NKN) on mechanical, dielectric, and antibacterial response of BG. BG-xNKN (x = 0, 10, 20, and 30 vol%) composites were synthesized at 800 °C for 30 min. The phase analyses using spectral techniques revealed the formation of the composite without any reaction between BG and piezoelectric ceramic NKN. The dielectric and electrical measurements were performed over a wide range of temperature (30-500 °C) and frequency (1 Hz-1 MHz) which suggests that space charge and dipolar polarizations are the dominant polarization mechanisms. The complex impedance analyses suggest that the average activation energies for grain and grain boundary resistances for BG-xNKN (x = 10, 20, and 30 vol%) composites are 0.59, 0.87, 0.94 and 0.76, 0.93, 1.06 eV, respectively. The issue of bacterial infection has been addressed by electrical polarization of the developed composite samples, at 20 kV for 30 min. Statistical analyses reveal that the viability of Gram-positive (S. aureus) and Gram-negative (E. coli) bacterial cells has been reduced significantly on positively and negatively charged BG-NKN composite samples, respectively. The qualitative analyses using the Kirby-Bauer test supports the above findings. Nitro blue tetrazolium and lipid peroxide assays were performed to understand the mechanism of such antibacterial response, which suggested that the combined effect of NKN addition and polarization significantly enhances the superoxide production, which kills the bacterial cells. Overall, incorporation of NKN in BG enhances the mechanical, electrical, and dielectric properties as well as improves the antibacterial response of polarized BG-xNKN composites.

Nanomedicines for the Delivery of Antimicrobial Peptides (AMPs)

Microbial infections are still among the major public health concerns since several yeasts and fungi, and other pathogenic microorganisms, are responsible for continuous growth of infections and drug resistance against bacteria. Antimicrobial resistance rate is fostering the need to develop new strategies against drug-resistant superbugs. Antimicrobial peptides (AMPs) are small peptide-based molecules of 5–100 amino acids in length, with potent and broad-spectrum antimicrobial properties. They are part of the innate immune system, which can represent a minimal risk of resistance development. These characteristics contribute to the description of these molecules as promising new molecules in the development of new antimicrobial drugs. However, efforts in developing new medicines have not resulted in any decrease of drug resistance yet. Thus, a technological approach on improving existing drugs is gaining special interest. Nanomedicine provides easy access to innovative carriers, which ultimately enable the design and development of targeted delivery systems of the most efficient drugs with increased efficacy and reduced toxicity. Based on performance, successful experiments, and considerable market prospects, nanotechnology will undoubtedly lead a breakthrough in biomedical field also for infectious diseases, as there are several nanotechnological approaches that exhibit important roles in restoring antibiotic activity against resistant bacteria.

Application of FTIR-ATR spectroscopy to confirm the microwave assisted synthesis and curing of Cashew nut shell liquid derived nanostructured materials

The present work reports the development of nanostructured material from Cashew nut shell liquid (CNSL, an agro byproduct of cashew industry, 87% cardanol) to evaluate their potential in antibacterial applications as a substitute of petroleum feedstock via an energy-efficient method. The nanostructured material was synthesized by coordination polymerization reaction of cardanol and divalent Mn(II) salt with the aid of microwave irradiations. FTIR spectroscopy was used to confirm the proposed structure of the synthesized materials. FTIR-ATR spectroscopy was employed to verify the curing of material by comparing the spectra of the cured samples with the frequencies of uncured samples. Magnetic moment and UV-visible spectroscopy were used to confirm the proposed structure of the material further. Morphology of the synthesized material was investigated by XRD, optical microscopy, SEM and TEM and thermal behaviour by TGA/DTG/DSC technique. Agar diffusion method was utilized to investigate the antibacterial activity of the synthesized material against bacterial strains E. coli, K. pneumoniae, B. subtilis and S. aureus. N₂ adsorption-desorption was investigated to check BET specific surface area and BJH pore size distribution of the same. The results revealed that the synthesized materials were obtained as semicrystalline, porous, thermally stable and nanostructured film forming materials with moderate to good antibacterial activity against different nosocomial bacteria. They can be used as thermally stable antibacterial agents in the field of films/coatings for health care applications.

ISFET and Dex-AgNPs based portable sensor for reusable and real-time determinations of concanavalin A and glucose on smartphone

In this paper, a portable real-time sensing device was built for Concanavalin A (Con A) and glucose detection using a smartphone. The ion-sensitive field-effect transistor (ISFET) functioning at a low working point was selected as a small-size, low-power transducer, and dextran-capped silver nanoparticles (Dex-AgNPs) served as sensitive nanoprobes on the ISFET gate. Using the affinity between Con A and carbohydrates, Con A can be captured, and thus directly detected by the ISFET/Dex-AgNPs unit; then glucose can be determined indirectly by removing Con A from the ISFET/Dex-AgNPs/Con A unit via competition with dextran. The mechanism of this competition does less harm to the sensor, allows the reusability of the sensing device, and overcomes the Debye screening of the FET device in saline solutions. Powered by a button cell, the handheld device attains excellent Con A (0.16 ng mL^-1) and glucose (10 nM) detection limit, and can practically be used for at least 20 days.

Effective Inhibition of Candidiasis Using an Eco-Friendly Leaf Extract of Calotropis-gigantean-Mediated Silver Nanoparticles

The approaches used for the green biosynthesis of nanoparticles with clinical applications have been widely used in nanotechnology due to their potential to provide safe, eco-friendly, cost effective, high-stability, and high-loading-capacity nanoparticles. This study aimed to evaluate the anti-candidal activity of silver nanoparticles (AgNPs) biosynthesized using the aqueous leaf extract of Calotropis gigantea (CG) alone or in a combination with the plant extract of CG (AgNPs/CG). AgNPs were characterized using UV-Vis spectrophotometry, Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The results of the standard disk diffusion method revealed that AgNPs alone displayed anti-candidal activity (11.33-mm inhibition zone), while AgNPs/CG displayed a strong synergistic anti-candidal activity (17.76-mm inhibition zone). Similarly, AgNPs/CG completely inhibited the growth of C. albicans after 4 h of incubation, as measured using the time-kill assay. In addition, AgNPs/CG inhibited the dimorphic transition of C. albicans and suppressed both the adhesion and the biofilm formation of C. albicans by 41% and 38%, respectively. The treatment of Candida. albicans with AgNPs/CG showed a significant inhibition of the production of several antioxidant enzymes. Interestingly, AgNPs/CG did not show any cytotoxicity in animal cells, including the MCF-7 cell line and primary mouse bone marrow-derived mesenchymal stem cells (mBMSCs), at the concentration used to completely inhibit the dimorphic transition of C. albicans. In conclusion, we identified AgNPs/CG as a promising natural-product-based nanoparticle that can potentially be used as an anti-candidal drug.

Role of Trapped Air in the Attachment of Staphylococcus aureus on Superhydrophobic Silicone Elastomer Surfaces Textured by a Femtosecond Laser

Surface texturing is an easy way to control wettability as well as bacterial adhesion. Air trapped in the surface texture of an immersed sample was often proposed as the origin of the low adhesion of bacteria to surfaces showing superhydrophobic properties. In this work, we identified two sets of femtosecond laser processing parameters that led to extreme superhydrophobic textures on a silicone elastomer but showed opposite behavior against Staphylococcus aureus (S. aureus, ATCC 25923) over a short incubation times (6 h). The main difference from most of the previous studies was that the air trapping was not evaluated from the extrapolation of the results of the classical sessile drop technique but from the drop rebound and Wilhelmy plate method. Additionally, all wetting tests were performed with bacteria culture medium and at 37 °C in the case of the Wilhelmy plate method. Following this approach, we were able to study the formation of the liquid/silicone interface and the associated air trapping for immersed samples that is, by far, most representative of the cell culture conditions than those associated with the sessile drop technique. Finally, the conversion of these superhydrophobic coatings into superhydrophilic ones revealed that air trapping is not a necessary condition to avoid Staphylococcus aureus retention on one of these two textured surfaces at short incubation times.