Polyvinyl-Pyrrolidone-Coated Silver Nanoparticles-The Colloidal, Chemical, and Biological Consequences of Steric Stabilization under Biorelevant Conditions

Synthesis and Application of Silver Nanoparticles for Caries Management: A Review

Silver nanoparticles have unique physical, chemical, and biological properties that make them attractive for medical applications. They have gained attention in dentistry for their potential use in caries management. This study reviews the different synthesis methods of silver nanoparticles and the application of them for caries management. Silver nanoparticles are tiny silver and are typically less than 100 nanometres in size. They have a high surface area-to-volume ratio, making them highly reactive and allowing them to interact with bacteria and other materials at the molecular level. Silver nanoparticles have low toxicity and biocompatibility. Researchers have employed various methods to synthesise silver nanoparticles, including chemical, physical, and biological methods. By controlling the process, silver nanoparticles have defined sizes, shapes, and surface properties for wide use. Silver nanoparticles exhibit strong antibacterial properties, capable of inhibiting a broad range of bacteria, including antibiotic-resistant strains. They inhibit the growth of cariogenic bacteria, such as Streptococcus mutans. They can disrupt bacterial cell membranes, interfere with enzyme activity, and inhibit bacterial replication. Silver nanoparticles can inhibit biofilm formation, reducing the risk of caries development. Additionally, nano silver fluoride prevents dental caries by promoting tooth remineralisation. They can interact with the tooth structure and enhance the deposition of hydroxyapatite, aiding in repairing early-stage carious lesions. Silver nanoparticles can also be incorporated into dental restorative materials such as composite resins and glass ionomer cements. The incorporation can enhance the material's antibacterial properties, reducing the risk of secondary caries and improving the longevity of the restoration.

Implementation of green-assessed nanotechnology and quality by design approach for development of optical sensor for determination of tobramycin in ophthalmic formulations and spiked human plasma

A fast eco-friendly colorimetric method was developed for the determination of Tobramycin in drug substance, ophthalmic formulations, and spiked human plasma using silver nanoparticles optical sensor. Even though tobramycin is non-UV-visible absorbing, the developed method is based on measuring the absorbance quenching of silver nanoparticles resulting from the interaction with tobramycin. Different factors affecting the absorbance intensity were studied as; silver nanoparticle concentration, pH, buffer type, and reaction time using quality by design approach. Validation of the proposed method was performed according to ICH guidelines and was found to be accurate, precise, and sensitive. The linearity range of tobramycin was 0.35-4.0 μg/mL. The optical sensor was successfully applied for the determination of Tobramycin in ophthalmic formulations and spiked human plasma without pre-treatment. Additionally, the binding between Tobramycin and PVP- capped silver nanoparticles was studied using molecular docking software. The method was assessed and compared to colorimetric reported methods for the green character using Green Analytical Procedure Index (GAPI) and Analytical GREEnness calculator (AGREE) tools and found to be greener.

Synthesis, Structural Analysis, and Peroxidase-Mimicking Activity of AuPt Branched Nanoparticles

Bimetallic nanomaterials have generated significant interest across diverse scientific disciplines, due to their unique and tunable properties arising from the synergistic combination of two distinct metallic elements. This study presents a novel approach for synthesizing branched gold-platinum nanoparticles by utilizing poly(allylamine hydrochloride) (PAH)-stabilized branched gold nanoparticles, with a localized surface plasmon resonance (LSPR) response of around 1000 nm, as a template for platinum deposition. This approach allows precise control over nanoparticle size, the LSPR band, and the branching degree at an ambient temperature, without the need for high temperatures or organic solvents. The resulting AuPt branched nanoparticles not only demonstrate optical activity but also enhanced catalytic properties. To evaluate their catalytic potential, we compared the enzymatic capabilities of gold and gold-platinum nanoparticles by examining their peroxidase-like activity in the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB). Our findings revealed that the incorporation of platinum onto the gold surface substantially enhanced the catalytic efficiency, highlighting the potential of these bimetallic nanoparticles in catalytic applications.

"Therapeutic advancements in nanomedicine: The multifaceted roles of silver nanoparticles"

Nanotechnology has the advantages of enhanced bioactivity, reduced toxicity, target specificity, and sustained release and NPs can penetrate cell membranes. The small size of silver nanoparticles, AgNPs, large surface area, and unique physicochemical properties contribute to cell lysis and increased permeability of cell membranes used in the field of biomedicine. Functional precursors integrate with phytochemicals to create distinctive therapeutic properties and the stability of the nanoparticles can be enhanced by Surface coatings and encapsulation methods, The current study explores the various synthesis methods and characterization techniques of silver nanoparticles (AgNPs) and highlights their intrinsic activity in therapeutic applications, Anti-cancer activity noted at a concentration range of 5-50 μg/ml and angiogenesis is mitigated at a dosage range of 10-50 μg/ml, Diabetes is controlled within the same concentration. Wound healing is improved at concentrations of 10-50 μg/ml and with a typical range of 10-08 μg/ml for bacteria with antimicrobial capabilities. Advancement of silver nanoparticles with a focus on the future use of AgNPs-coated wound dressings and medical devices to decrease the risk of infection. Chemotherapeutic drugs can be administered by AgNPs, which reduces adverse effects and an improvement in treatment outcomes. AgNPs have been found to improve cell proliferation and differentiation, making them beneficial for tissue engineering and regenerative medicine. Our study highlights emerging patterns and developments in the field of medicine, inferring potential future paths.

Effects of Raman Labeling Compounds on the Stability and Surface-Enhanced Raman Spectroscopy Performance of Ag Nanoparticle-Embedded Silica Nanoparticles as Tagging Materials

Surface-enhanced Raman spectroscopy (SERS) tagging using silica(SiO2)@Ag nanoparticles (NPs) is easy to handle and is being studied in various fields, including SERS imaging and immunoassays. This is primarily due to its structural advantages, characterized by high SERS activity. However, the Ag NPs introduced onto the SiO2 surface may undergo structural transformation owing to the Ostwald ripening phenomenon under various conditions. As a result, the consistency of the SERS signal decreases, reducing their usability as SERS substrates. Until recently, research has been actively conducted to improve the stability of single Ag NPs. However, research on SiO2@Ag NPs used as a SERS-tagging material is still lacking. In this study, we utilized a Raman labeling compound (RLC) to prevent the structural deformation of SiO2@Ag NPs under various conditions and proposed excellent SiO2@Ag@RLC-Pre NPs as a SERS-tagging material. Using various RLCs, we confirmed that 4-mercaptobenzoic acid (4-MBA) is the RLC that maintains the highest stability for 2 months. These results were also observed for the SiO2@Ag NPs, which were unstable under various pH and temperature conditions. We believe that SERS tags using SiO2@Ag NPs and 4-MBA can be utilized in various applications on based SERS because of the high stability and consistency of the resulting SERS signal.

Infection-Free and Enhanced Wound Healing Potential of Alginate Gels Incorporating Silver and Tannylated Calcium Peroxide Nanoparticles

The treatment of chronic wounds involves precise requirements and complex challenges, as the healing process cannot go beyond the inflammatory phase, therefore increasing the healing time and implying a higher risk of opportunistic infection. Following a better understanding of the healing process, oxygen supply has been validated as a therapeutic approach to improve and speed up wound healing. Moreover, the local implications of antimicrobial agents (such as silver-based nano-compounds) significantly support the normal healing process, by combating bacterial contamination and colonization. In this study, silver (S) and tannylated calcium peroxide (CaO2@TA) nanoparticles were obtained by adapted microfluidic and precipitation synthesis methods, respectively. After complementary physicochemical evaluation, both types of nanoparticles were loaded in (Alg) alginate-based gels that were further evaluated as possible dressings for wound healing. The obtained composites showed a porous structure and uniform distribution of nanoparticles through the polymeric matrix (evidenced by spectrophotometric analysis and electron microscopy studies), together with a good swelling capacity. The as-proposed gel dressings exhibited a constant and suitable concentration of released oxygen, as shown for up to eight hours (UV-Vis investigation). The biofilm modulation data indicated a synergistic antimicrobial effect between silver and tannylated calcium peroxide nanoparticles, with a prominent inhibitory action against the Gram-positive bacterial biofilm after 48 h. Beneficial effects in the human keratinocytes cultured in contact with the obtained materials were demonstrated by the performed tests, such as MTT, LDH, and NO.

Systematic Investigation of Novel, Controlled Low-Temperature Sintering Processes for Inkjet Printed Silver Nanoparticle Ink

Functional inks enable manufacturing of flexible electronic devices by means of printing technology. Silver nanoparticle (Ag NP) ink is widely used for printing conductive components. A sintering process is required to obtain sufficient conductivity. Thermal sintering is the most commonly used method, but the heat must be carefully applied to avoid damaging low-temperature substrates such as polymer films. In this work, two alternative sintering methods, damp heat sintering and water sintering are systematically investigated for inkjet-printed Ag tracks on polymer substrates. Both methods allow sintering polyvinyl pyrrolidone (PVP) capped Ag NPs at 85°C. In this way, the resistance is significantly reduced to only 1.7 times that of the samples on polyimide sintered in an oven at 250°C. The microstructure of sintered Ag NPs is analyzed. Taking the states of the capping layer under different conditions into account, the explanation of the sintering mechanism of Ag NPs at low temperatures is presented. Overall, both damp heat sintering and water sintering are viable options for achieving high conductivity of printed Ag tracks. They can broaden the range of substrates available for flexible electronic device fabrication while mitigating substrate damage risks. The choice between them depends on the specific application and the substrate used.

LSPR sensing for in situ monitoring the Ag dissolution of Au@Ag core-shell nanoparticles in biological environments

Silver nanoparticles (AgNPs) are extensively used as an antibacterial agent, and monitoring the dissolution behavior of AgNPs in native biological environments is critical in both optimizing their performance and regulating their safety. However, current assessment methods rely on sophisticated analytical tools that are off-site and time-consuming with potential underestimations, due to complicated sample preparation. Although localized surface plasmon resonance (LSPR) sensing offers a facile method for the detection of AgNP dissolution, it is limited by low sensitivity and poor nanoparticle stability in native biological environments. Herein, we constructed a highly sensitive and stable LSPR sensor using gold-silver core-shell nanoparticles (Au@AgNPs), in combination with polymeric stabilizing agents, for the direct measurement of the Ag shell dissolution in native biological media. The high sensitivity was attributed to the acute and large LSPR shift generated by bimetallic nanoparticles. The sensor was used for the real-time monitoring of the Ag dissolution of Au@AgNPs during their co-culture with both bacteria and fibroblast cells. The media pH was found to dominate the Ag dissolution process, where Au@AgNPs exhibited bactericidal effects in the bacteria environment with relatively low pH, but they showed little toxicity towards fibroblast cells at pH 7.4. The minimum inhibition concentration of Au@AgNPs for bacterial growth was found similar to that of AgNO3 in terms of released Ag amount. Thus, stabilized Au@AgNPs not only allow the in-situ monitoring of Ag dissolution via LSPR sensing but also constitute an effective antibacterial agent with controlled toxicity, holding great potential for future biomedical and healthcare applications.

Biosynthesis, Spectrophotometric Follow-Up, Characterization, and Variable Antimicrobial Activities of Ag Nanoparticles Prepared by Edible Macrofungi

The biosynthesis of silver nanoparticles (Ag NPs) could play a significant role in the development of commercial antimicrobials. Herein, the biosynthesis of Ag NPs was studied using the edible mushroom Pleurotus floridanus, and following its formation, spectrophotometry was used to detect the best mushroom content, pH, temperature, and silver concentration. After that, the morphology was described via transmission electron microscopy (TEM), and nanoscale-size particles were found ranging from 11 to 13 nm. The best conditions of Ag content and pH were found at 1.0 mM and 11.0, respectively. In addition, the best mushroom extract concentration was found at 30 g/L. According to XRD analysis, the crystal structure of the formed amorphous Ag NPs is cubic with a space group of fm-3m and a space group number of 225. After that, the function groups at the surface of the prepared Ag NPs were studied via FTIR analysis, which indicated the presence of C=O, C-H, and O-H groups. These groups could indicate the presence of mushroom traces in the Ag NPs, which was confirmed via the amorphous characteristics of Ag NPs from the XRD analysis. The prepared Ag NPs have a high impact against different microorganisms, which could be attributed to the ability of Ag NPs to penetrate the cell bacterial wall.

Physicochemical Transformations of Silver Nanoparticles in the Oro-Gastrointestinal Tract Mildly Affect Their Toxicity to Intestinal Cells In Vitro: An AOP-Oriented Testing Approach

The widespread use of silver nanoparticles (Ag NPs) in food and consumer products suggests the relevance of human oral exposure to these nanomaterials (NMs) and raises the possibility of adverse effects in the gastrointestinal tract. The aim of this study was to investigate the toxicity of Ag NPs in a human intestinal cell line, either uncoated or coated with polyvinylpyrrolidone (Ag PVP) or hydroxyethylcellulose (Ag HEC) and digested in simulated gastrointestinal fluids. Physicochemical transformations of Ag NPs during the different stages of in vitro digestion were identified prior to toxicity assessment. The strategy for evaluating toxicity was constructed on the basis of adverse outcome pathways (AOPs) showing Ag NPs as stressors. It consisted of assessing Ag NP cytotoxicity, oxidative stress, genotoxicity, perturbation of the cell cycle and apoptosis. Ag NPs caused a concentration-dependent loss of cell viability and increased the intracellular level of reactive oxygen species as well as DNA damage and perturbation of the cell cycle. In vitro digestion of Ag NPs did not significantly modulate their toxicological impact, except for their genotoxicity. Taken together, these results indicate the potential toxicity of ingested Ag NPs, which varied depending on their coating but did not differ from that of non-digested NPs.

Characterization and Biological Studies of Synthesized Titanium Dioxide Nanoparticles from Leaf Extract of Juniperus phoenicea (L.) Growing in Taif Region, Saudi Arabia

Green synthesis of metal nanoparticles in nanosized form has acquired great interest in the area of nanomedicine as an environmentally friendly and cost-effective alternative compared to other chemical and physical methods. This study deals with the eco-friendly green synthesis of titanium dioxide nanoparticles (TiO2 NPs) utilizing Juniperus phoenicea leaf extract and their characterization. The biosynthesis of TiO2 NPs was completed in 3 h and confirmed by UV-Vis spectroscopy, a strong band at 205.4 nm distinctly revealed the formation of NPs. Transmissions electron microscopy (TEM) analysis showed the synthesized TiO2 NPs are spherical in shape, with a diameter in a range of 10–30 nm. The XRD major peak at 27.1° congruent with the (110) lattice plane of tetragonal rutile TiO2 phase. Dynamic light scattering (DLS) analysis revealed synthesized TiO2 NPs average particle size (hydrodynamic diameter) of (74.8 ± 0.649) nm. Fourier transmission infrared (FTIR) revealed the bioactive components present in the leaf extract, which act as reducing and capping agents. The antimicrobial efficacy of synthesized TiO2NPs against, Staphylococcus aureus, and Bacillus subtilis (Gram-positive), Escherichia coli and Klebsiella pneumoniae (Gram-negative), Yeast strain (Saccharomyces cerevisiae) and fungi (Aspergillus niger, and Penicillium digitatum) assayed by a disc diffusion method. TiO2NPs inhibited all tested strains by mean inhibition zone (MIZ), which ranged from the lowest 15.7 ± 0.45 mm against K. pneumoniae to the highest 30.3 ± 0.25 against Aspergillus niger. The lowest minimum inhibitory concentration (MIC) and bactericidal (MBC) values were 20 μL/mL and 40 μL/mL of TiO2NPs were observed against Asp. niger. Moreover, it showed significant inhibitory activity against human ovarian adenocarcinoma cells with IC50 = 50.13 ± 1.65 µg/mL. The findings concluded that biosynthesized TiO2 NPs using Juniperus phoenicea leaf extract can be used in medicine as curative agents according to their in vitro antibacterial, antifungal, and cytotoxic activities.

Green Synthesized Zinc Oxide Nanoparticles Based on Cestrum diurnum L. of Potential Antiviral Activity against Human Corona 229-E Virus

SARS-CoV-2 has caused more than 596 million infections and 6 million fatalities globally. Looking for urgent medication for prevention, treatment, and rehabilitation is obligatory. Plant extracts and green synthesized nanoparticles have numerous biological activities, including antiviral activity. HPLC analysis of C. dirnum L. leaf extract showed that catechin, ferulic acid, chlorogenic acid, and syringic acid were the most major compounds, with concentrations of 1425.16, 1004.68, 207.46, and 158.95 µg/g, respectively. Zinc nanoparticles were biosynthesized using zinc acetate and C. dirnum extract. TEM analysis revealed that the particle size of ZnO-NPs varied between 3.406 and 4.857 nm. An XRD study showed the existence of hexagonal crystals of ZnO-NPs with an average size of 12.11 nm. Both ZnO-NPs (IC₅₀ = 7.01 and CC₅₀ = 145.77) and C. dirnum L. extract (IC₅₀ = 61.15 and CC₅₀ = 145.87 µg/mL) showed antiviral activity against HCOV-229E, but their combination (IC₅₀ = 2.41 and CC₅₀ = 179.23) showed higher activity than both. Molecular docking was used to investigate the affinity of some metabolites against the HCOV-229E main protease. Chlorogenic acid, solanidine, and catchin showed high affinity (-7.13, -6.95, and -6.52), compared to the ligand MDP (-5.66 Kcal/mol). Cestrum dinurum extract and ZnO-NPs combination should be subjected to further studies to be used as an antiviral drug.

Development of 3D-Printed Collagen Scaffolds with In-Situ Synthesis of Silver Nanoparticles

UV-irradiation method has grown as an alternative approach to in situ synthetize silver nanoparticles (AgNPs) for avoiding the use of toxic reducing agents. In this work, an antimicrobial material by in situ synthesizing AgNPs within 3D-printed collagen-based scaffolds (Col-Ag) was developed. By modifying the concentration of AgNO₃ (0.05 and 0.1 M) and UV irradiation time (2 h, 4 h, and 6 h), the morphology and size of the in situ prepared AgNPs could be controlled. As a result, star-like silver particles of around 23 ± 4 μm and spherical AgNPs of 220 ± 42 nm were obtained for Ag 0.05 M, while for Ag 0.1 M cubic particles from 0.3 to 1.0 μm and round silver precipitates of 3.0 ± 0.4 μm were formed in the surface of the scaffolds at different UV irradiation times. However, inside the material AgNPs of 10-28 nm were obtained. The DSC thermal analysis showed that a higher concentration of Ag stabilizes the 3D-printed collagen-based scaffolds, while a longer UV irradiation interval produces a decrease in the denaturation temperature of collagen. The enzymatic degradation assay also revealed that the in situ formed AgNPs act as stabilizing and reinforcement agent which also improve the swelling capacity of collagen-based material. Finally, antimicrobial activity of Col-Ag was studied, showing high bactericidal efficiency against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. These results showed that the UV irradiation method was really attractive to modulate the size and shape of in situ synthesized AgNPs to develop antimicrobial 3D-printed collagen scaffolds with different thermal, swelling and degradation properties.

Amphiphilic Silver Nanoparticles for Inkjet-Printable Conductive Inks

The large-scale manufacturing of flexible electronics is nowadays based on inkjet printing technology using specially formulated conductive inks, but achieving adequate wetting of different surfaces remains a challenge. In this work, the development of a silver nanoparticle-based functional ink for printing on flexible paper and plastic substrates is demonstrated. Amphiphilic silver nanoparticles with narrow particle size distribution and good dispersibility were prepared via a two-step wet chemical synthesis procedure. First, silver nanoparticles capped with poly(acrylic acid) were prepared, followed by an amidation reaction with 3-morpholynopropylamine (MPA) to increase their lipophilicity. Density functional theory (DFT) calculations were performed to study the interactions between the particles and the dispersion medium in detail. The amphiphilic nanoparticles were dispersed in solvents of different polarity and their physicochemical and rheological properties were determined. A stable ink containing 10 wt% amphiphilic silver nanoparticles was formulated and inkjet-printed on different surfaces, followed by intense pulsed light (IPL) sintering. Low sheet resistances of 3.85 Ω sq^-1, 0.57 Ω sq^-1 and 19.7 Ω sq^-1 were obtained for the paper, coated poly(ethylene terephthalate) (PET) and uncoated polyimide (PI) flexible substrates, respectively. Application of the nanoparticle ink for printed electronics was demonstrated via a simple flexible LED circuit.

Toxicity of metal-based nanoparticles: Challenges in the nano era

With the rapid progress of nanotechnology, various nanoparticles (NPs) have been applicated in our daily life. In the field of nanotechnology, metal-based NPs are an important component of engineered NPs, including metal and metal oxide NPs, with a variety of biomedical applications. However, the unique physicochemical properties of metal-based NPs confer not only promising biological effects but also pose unexpected toxic threats to human body at the same time. For safer application of metal-based NPs in humans, we should have a comprehensive understanding of NP toxicity. In this review, we summarize our current knowledge about metal-based NPs, including the physicochemical properties affecting their toxicity, mechanisms of their toxicity, their toxicological assessment, the potential strategies to mitigate their toxicity and current status of regulatory movement on their toxicity. Hopefully, in the near future, through the convergence of related disciplines, the development of nanotoxicity research will be significantly promoted, thereby making the application of metal-based NPs in humans much safer.

Mutagenesis and Resistance Development of Bacteria Challenged by Silver Nanoparticles

Because of their extremely broad spectrum and strong biocidal power, nanoparticles of metals, especially silver (AgNPs), have been widely applied as effective antimicrobial agents against bacteria, fungi, and so on. However, the mutagenic effects of AgNPs and resistance mechanisms of target cells remain controversial. In this study, we discover that AgNPs do not speed up resistance mutation generation by accelerating genome-wide mutation rate of the target bacterium Escherichia coli. AgNPs-treated bacteria also show decreased expression in quorum sensing (QS), one of the major mechanisms leading to population-level drug resistance in microbes. Nonetheless, these nanomaterials are not immune to resistance development by bacteria. Gene expression analysis, experimental evolution in response to sublethal or bactericidal AgNPs treatments, and gene editing reveal that bacteria acquire resistance mainly through two-component regulatory systems, especially those involved in metal detoxification, osmoregulation, and energy metabolism. Although these findings imply low mutagenic risks of nanomaterial-based antimicrobial agents, they also highlight the capacity for bacteria to evolve resistance.

Designing Highly Efficient Temperature Controller for Nanoparticles Hyperthermia

This paper presents various control system design techniques for temperature control of Magnetic Fluid hyperthermia. The purpose of this research is to design a cost-effective, efficient, and practically implementable temperature controller for Magnetic Fluid hyperthermia, which is presently under research as a substitute to the radiation and chemotherapy treatment of cancer. The principle of this phenomenon centers on the greater sensitivity of tumor cells to changes in temperature in comparison to healthy cells. Once the nanoparticles reach the desired tissue, it can then be placed in a varying magnetic field to dissipate the heat locally by raising the temperature to 45 °C in order to kill cancerous cells. One of the challenging tasks is to maintain the temperature strictly at desired point i.e., 45 °C. Temperature controller for magnetic fluid hyperthermia provides the tight control of temperature in order to avoid folding of proteins and save the tissues around the cancerous tissue from getting destroyed. In contrast with most of the existing research on this topic, which are based on linear control strategies or their improved versions, the novelty of this research lies in applying nonlinear control technique like Sliding Mode Control (SMC) to accurately control the temperature at desired value. A comparison of the control techniques is presented in this paper, based on reliability, robustness, precision and the ability of the controller to handle the non-linearities that are faced during the treatment of cancer. SMC showed promising results in terms of settling time and rise time. Steady state error was also reduced to zero using this technique.

Platinum-based drug-induced depletion of amino acids in the kidneys and liver

Cisplatin (cis-diamminedichloroplatinum II; CDDP) is a widely used cytostatic agent; however, it tends to promote kidney and liver disease, which are a major signs of drug-induced toxicity. Platinum compounds are often presented as alternative therapeutics and subsequently easily dispersed in the environment as contaminants. Due to the major roles of the liver and kidneys in removing toxic materials from the human body, we performed a comparative study of the amino acid profiles in chicken liver and kidneys before and after the application of CDDP and platinum nanoparticles (PtNPs-10 and PtNPs-40). The treatment of the liver with the selected drugs affected different amino acids; however, Leu and Arg were decreased after all treatments. The treatment of the kidneys with CDDP mostly affected Val; PtNPs-10 decreased Val, Ile and Thr; and PtNPs-40 affected only Pro. In addition, we tested the same drugs on two healthy cell lines, HaCaT and HEK-293, and ultimately explored the amino acid profiles in relation to the tricarboxylic acid cycle (TCA) and methionine cycle, which revealed that in both cell lines, there was a general increase in amino acid concentrations associated with changes in the concentrations of the metabolites of these cycles.

Silver Nanoparticle-Based Combinations with Antimicrobial Agents against Antimicrobial-Resistant Clinical Isolates

The increasing prevalence of antimicrobial-resistant (AMR) bacteria along with the limited development of antimicrobials warrant investigating novel antimicrobial modalities. Emerging inorganic engineered nanomaterials (ENMs), most notably silver nanoparticles (AgNPs), have demonstrated superior antimicrobial properties. However, AgNPs, particularly those of small size, could exert overt toxicity to mammalian cells. This study investigated whether combining AgNPs and conventional antimicrobials would produce a synergistic response and determined the optimal and safe minimum inhibitory concentration (MIC) range against several wild-type Gram-positive and -negative strains and three different clinical isolates of AMR Klebsiella pneumoniae. Furthermore, the cytotoxicity of the synergistic combinations was assessed in a human hepatocyte model. The results showed that the AgNPs (15-25 nm) were effective against Gram-negative bacteria (MIC of 16-128 µg/mL) but not Gram-positive strains (MIC of 256 µg/mL). Both wild-type and AMR K. pneumoniae had similar MIC values following exposure to AgNPs. Importantly, co-exposure to combinations of AgNPs and antimicrobial agents, including kanamycin, colistin, rifampicin, and vancomycin, displayed synergy against both wild-type and AMR K. pneumoniae isolates (except for vancomycin against AMR strain I). Notably, the tested combinations demonstrated no to minimal toxicity against hepatocytes. Altogether, this study indicates the potential of combining AgNPs with conventional antimicrobials to overcome AMR bacteria.

Green Synthesis and Characterization of Iron Nanoparticles Synthesized from Aqueous Leaf Extract of Vitex leucoxylon and Its Biomedical Applications

The cold extraction method was used to obtain the aqueous extract of Vitex leucoxylon leaves in a ratio of 1:10. Iron nanoparticles (FeNPs) were synthesized using aqueous leaf extract of V. leucoxylon as a reducing agent. The phytoreducing approach was used to make FeNPs by mixing 1 mL of plant extract with 1 mM of ferric sulfate. Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), Ultraviolet–visible spectroscopy (UV-Vis), and energy-dispersive X-ray spectroscopy were used to examine the synthesized FeNPs. The reducing reaction was shown by a change in the color of the solution, and the formation of black color confirms that FeNPs have been formed. The greatest absorption peak (max) was found at 395 nm in UV-Vis spectral analysis. The FTIR spectra of V. leucoxylon aqueous leaf extract showed shifts in some peaks, namely 923.96 cm⁻¹ and 1709.89 cm⁻¹, with functional groups carboxylic acids, unsaturated aldehydes, and ketones, which were lacking in the FTIR spectra of FeNPs and are responsible for FeNPs formation. FeNPs with diameters between 45 and 100 nm were observed in SEM images. The creation of FeNPs was confirmed by EDX, which shows a strong signal in the metallic iron region at 6–8 Kev. XRD revealed a crystalline nature and an average diameter of 136.43 nm. Antioxidant, anti-inflammatory, cytotoxic, and wound healing in vitro tests reported significant activity of the FeNPs. The cumulative findings of the present study indicate that the green synthesis of FeNPs boosts its biological activity and may serve as a possible dermal wound-healing agent and cytotoxic agent against cancer. Future study is needed on the identification of mechanisms involved in the synthesis of FeNPs by V. leucoxylon and its biomedical applications.

Cancer Therapy by Silver Nanoparticles: Fiction or Reality?

As an emerging new class, metal nanoparticles and especially silver nanoparticles hold great potential in the field of cancer biology. Due to cancer-specific targeting, the consequently attenuated side-effects and the massive anti-cancer features render nanoparticle therapeutics desirable platforms for clinically relevant drug development. In this review, we highlight those characteristics of silver nanoparticle-based therapeutic concepts that are unique, exploitable, and achievable, as well as those that represent the critical hurdle in their advancement to clinical utilization. The collection of findings presented here will describe the features that distinguish silver nanoparticles from other anti-cancer agents and display the realistic opportunities and implications in oncotherapeutic innovations to find out whether cancer therapy by silver nanoparticles is fiction or reality.

Green Synthesis of Silver-Decorated Magnetic Particles for Efficient and Reusable Antimicrobial Activity

Metal and metal hybrid nanostructures have shown tremendous application in the biomedical and catalytic fields because of their plasmonic and catalytic properties. Here, a green and clean method was employed for the synthesis of silver nanoparticle (Ag NP)-SiO₂-Fe₂O₃ hybrid microstructures, and biomolecules from green tea extracts were used for constructing the hybrid structures. The SiO₂-Fe₂O₃ structures were synthesized using an ethanolic green tea leaf extract to form Bio-SiO₂-Fe₂O₃ (BSiO₂-Fe₂O₃) structures. Biochemical studies demonstrated the presence of green tea biomolecules in the BSiO₂ layer. Reduction of the silver ions was performed by a BSiO₂ layer to form Ag NPs of 5–10 nm in diameter in and on the BSiO₂-Fe₂O₃ microstructure. The reduction process was observed within 600 s, which is faster than that reported elsewhere. The antimicrobial activity of the Ag-BSiO₂-Fe₂O₃ hybrid structure was demonstrated against Staphylococcus aureus and Escherichia coli, and the nanostructures were further visualized using confocal laser scanning microscopy (CLSM). The magnetic properties of the Ag-BSiO₂-Fe₂O₃ hybrid structure were used for studying reusable antimicrobial activity. Thus, in this study, we provide a novel green route for the construction of a biomolecule-entrapped SiO₂-Fe₂O₃ structure and their use for the ultra-fast formation of Ag NPs to form antimicrobial active multifunctional hybrid structures.