Release Of Ag Research Articles

Simultaneous sterilization and biosensing of pathogenic bacteria via copper phthalocyanine-based COF embedded with Cu-N4 single atomic sites and silver nanoparticles

The efficient inactivation and sensitive detection of waste water and food stuffs polluted by pathogenic bacteria are vital for ensuring food safety and protecting people’s healthy. Herein, a 2D copper phthalocyanine-based covalent-organic framework (COF) embraced with Cu-N4 single atomic sites and silver nanoparticles (denoted as CuPc-Dha-COF@AgNPs) was employed as a bifunctional bioplatform for the efficient sterilization via the multi-modal antibacterial mechanism and the sensitive detection of pathogenic bacteria via the photocatalytic oxidization of glutathione (GSH) using a photoelectrochemical (PEC) technique. Given the superior photothermal conversion efficiency, the high production efficiency of reactive oxygen species, the enhanced H2O2 self-supplying capability, and the controlled release of Ag+ ions under near-infrared light irradiation (808 nm and 1.0 W cm−2), 100 % bacteria were eliminated by CuPc-Dha-COF@AgNPs (200 μg mL−1) at 24 h. Furthermore, the CuPc-Dha-COF@AgNPs-based PEC biosensing platform exhibited highly selective determination ability toward GSH because of its superior mimetic enzyme performance caused by Cu-N4 single atomic sites, narrow bandgap, wide photoabsorption performance, and high separation of photoinduced electrons and holes. It thus showed an ultralow detection limit of 99 fM toward GSH within wide range from 1.0 pM to 1.0 nM, as well as high selectivity, good stability and reproducibility, and promising practicality. This work provides a new strategy for the sterilization and sensitive detection of pathogenic bacteria, simultaneously implementing and monitoring measures for the water system and food safety.

Self-assembled LaCoO3/Ag3PO4 nanocomposite with enhanced anti-bacterial performance

Bacteria are mostly everywhere, some of them affect health safety of human beings, plants and animals all the time. Photocatalytic antibacterial technology has entered people's field of vision due to their high-efficiency and sustainability. In this study, LaCoO3 precursors were prepared by solvothermal synthesis, and then calcined to obtain self-assembled LaCoO3 microspheres. Subsequently, LaCoO3/Ag3PO4 microspheres were synthesized by in-situ precipitation method. Compared with pure LaCoO3 microspheres, the introduction of Ag3PO4 nanoparticles can effectively enhance the antibacterial performance of LaCoO3/Ag3PO4 nanocomposites. LaCoO3/Ag3PO4 nanocomposites' Minimum Inhibitory Concentrations (MICs) against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were tested to be 0.1 mg mL−1 and 0.15 mg mL−1, respectively. Under visible light irradiation for 20 min, the antibacterial rate of nanocomposites against E. coli and S. aureus was 99.9 % and 98.3 %, correspondingly. This can be attributed to the fact that LaCoO3/Ag3PO4 heterojunction significantly improves the responsiveness of visible light, carrier separation and migration efficiency of LaCoO3, which promotes the nanocomposite to produce a large number of ROS under visible light. In addition, LaCoO3/Ag3PO4 nanocomposites had a strong oxidation effect on glutathione (GSH), resulting in the failure of the antioxidant defense system of bacteria. Also, the release of Ag+ and plasma effect of Ag are also important reasons for the high antibacterial performance of LaCoO3/Ag3PO4 nanocomposites. The photoresponse of LaCoO3-based nanomaterials under visible light is effectively improved by constructing heterojunctions, the separation efficiency of photogenerated electron-hole pairs is increased, and the carrier transport is accelerated, thus achieving high efficiency and broad spectrum antibacterial effect. This research shows that LaCoO3 nanocomposites can be used as a prospective photocatalytic antibacterial material, enhances the value of practical applications.

Fabrication of an antibacterial system of arginine-modified chitosan with AgNPs-loaded montmorillonite for food preservation

Ag-based materials have potent antibacterial effects, but their potential toxicity problems should not be underestimated, so it is urgent to construct a safe and non-resistant dual antibacterial system. In this study, we utilized tea polyphenols (TPs) and montmorillonite (MMT) to control the growth of silver nanoparticles (AgNPs). Then, we combined the AgNPs with arginine to construct a synergistic antibacterial system of arginine-modified chitosan-assisted AgNPs-loaded MMT (ACS/G/AgNPs@MMT). The results showed that AgNPs with a uniform dispersion of 6.72 ± 4.66 nm and ACS with a grafting degree of 0.153 were successfully prepared, and the synergistic antibacterial effect between ACS and AgNPs@MMT was verified by the FIC index, and the antibacterial rate could still reach 99.9 % when the additions of ACS and AgNPs@MMT were reduced by 75 % and 79.1 %, respectively. The ACS/G/AgNPs@MMT-2 composite film exhibited excellent mechanical properties, water vapor/UV barrier properties, antioxidant activity, degradation properties, and biosafety. In addition, the synergistic effect enabled the ACS/G/AgNPs@MMT-2 film to achieve antibacterial rates of 99.24 ± 0.19 % against E. coli and 99.49 ± 0.40 % against S. aureus, and the film exhibited excellent long-lasting antibacterial performance due to the slow release of Ag+ (only about 11.27 % of Ag+ was released in 20 days). Finally, the ACS/G/AgNPs@MMT-2 film could significantly improve the food preservation ability. In conclusion, this study indicates that the film could be used as a novel antibacterial packaging material.

Nanoenzyme Hydrogel Film-Based Portable Point-of-Care Testing Platform for Double-Signal Visual Detection of PSA.

The development of the Point-of-Care Testing (POCT) platform that combines convenience and cost-effectiveness is crucial for enabling the visual detection of disease biomarkers. In this work, a POCT platform for the sensitive in situ detection of prostate specific antigen (PSA) with dual-signal output was constructed by functionalizing the Eppendorf (EP) tube. This was achieved through the modification of aptamer hairpin probes (AHPs) on the lid of the EP tube and the assembly of a nanoenzyme hydrogel film on its inner wall. The target could trigger the release of Ag+ by AHP and subsequently activate Ag+-dependent DNAzyme (Ag-DNAzyme). This would initiate the cleavage of the DNA-Au/Pt NP hydrogel network, leading to the release of Au/Pt NPs. The released Au/Pt NPs exhibit both peroxidase (POD)-like and catalase (CAT)-like activity to produce a colorimetric response and induce liquid flow under pressure. Therefore, the target can be measured visually and quantitatively through colorimetric analysis and the measurement of total dissolved solids (TDS) using a pressure-triggered liquid flow device integrated into the platform. The designed platform is distinguished by its simplicity, specificity, cost-effectiveness, and remarkable sensitivity. It allows for the visual detection of PSA within concentration ranges of 0.5-100 ng/L (colorimetric) and 3-100 ng/L (TDS reading), boasting detection limits as low as 0.15 ng/L (colorimetric) and 0.57 ng/L (TDS reading). The strategy of target-triggered nanoenzyme release significantly enhances sensitivity and provides a guiding approach for visual biomarker detection.

Multi-strategy combined bionic coating for long-term robust protection against marine biofouling

Polyurethane-fluorinated polysiloxane (PU-FPDMS) with high-strength, high-bonding and low surface energy is synthesized as the matrix, and the PU-FPDMS/MCs/Ag marine anti-fouling coating on the surface of imitation crab shells is constructed by assembling butenolide@1,1-stilbene-modified hydrolyzed polyglycidyl methacrylate/graphene oxide microcapsules (Bu@PGMAm/GO MCs) with compact multi-shell structure and Ag nanoparticles (AgNPs) step by step on the PU-FPDMS matrix. The PU-FPDMS/MCs/Ag bionic anti-fouling coatings achieve long-term and stable anti-fouling effect under the combination of robust low-surface-energy PU-FPDMS matrix, steady-state sustained release of butenolide encapsulated by the compact multi-shell, bionic surface formed by the microcapsules and AgNPs, and the release of Ag+. The shear strength, tensile strength, and elongation at break of the PU-FPDMS/MCs/Ag are 3.53 MPa, 6.7 MPa, and 192.83 %, respectively. Its static contact angle and sliding angle are 161.8° and 3.6°, respectively. The antibacterial rate of PU-FPDMS/MCs/Ag against Escherichia coli, Staphylococcus aureus, and Candida albicans can reach 100 %. Compared with glass blank, PU, PU-FPDMS, PU-FPDMS/Ag, and PU-FPDMS/MCs, both the adhesion number and coverage percentage of chlorella adhere to PU-FPDMS/MCs/Ag are the minimum values, which are 600 cell mm–2 and 1.53 %, respectively. After 6 months of marine field test, the primer blank, PU, PU-FPDMS all show different degrees of attachment by shellfish, spirorbis, algae and other biofouling, while the PU-FPDMS/MCs/Ag coating is still not covered with biofouling, while the PU-FPDMS/MCs/Ag coatings still exhibit little attachment of marine fouling. The PU-FPDMS/MCs/Ag bionic anti-fouling coatings are expected to be widely used in the fields of anti-fouling, anti-icing, anti-fogging, drag reduction, self-cleaning, and antibacterial.

The potential effect of silver nanoparticles to inhibit microbial activity in orthodontic adhesive appliances: A literature review

Silver nanoparticles have been the focus of research in various areas of dentistry, including orthodontics. Orthodontic treatment requires a long period of time, so the brackets are in the oral cavity for a long time. This can potentially trigger the formation of white spot lesions because plaque sticks more easily to the surrounding enamel. Using silver nanoparticles mixed with orthodontic adhesives has been reported to increase antibacterial and antimicrobial characteristics. This literature review aims to investigate the effect of adding silver nanoparticles to orthodontic adhesive devices in inhibiting antimicrobial activity. This study method was carried out by searching the online electronic databases PubMed, Science Direct, and Google Scholar with the keywords "silver nanoparticles AND antimicrobial", "silver nanoparticles AND orthodontic adhesive", "silver nanoparticles AND composite resin", which is an original article published the year 2019- 2023. The results of research from 10 articles that met the inclusion criteria showed that orthodontic adhesives with silver nanoparticles effectively inhibited microbial activity, such as Streptococcus mutans (S.mutans), Lactobacillus acidophilus (L.acidophilus), Streptococcus sanguinis (S.sanguinis) and Candida albicans through increased release of Ag+ ions. Silver has been known to have effects, including producing minimal bacterial resistance compared to antibiotics. Even though it results in a decrease in the shear bond strength (SBS), the decrease level is still within clinically tolerable limits. It can be concluded that research needs to continue to be developed to obtain the right concentration and composition of the addition of silver nanoparticles so that an orthodontic adhesive material is obtained that is not only superior in its antibacterial properties but also in its mechanical properties.

In-situ synthesis and binding of silver nanoparticles to dialdehyde and carboxylated cellulose nanofibrils, and active packaging therewith

The present work reveals the potential application of dialdehyde and carboxylated nanocellulose for the in-situ reduction of Ag+ and immobilization as silver nanoparticles (AgNPs) on cellulose surfaces. Tollens’ reagent (Ag(NH3)2OH) at concentrations ranging from 5·10–3 to 10–1 M was incorporated in both dialdehyde cellulose (DAC) and dialdehyde-modified TEMPO-oxidized cellulose nanofibers (DA-TOCNFs). The results showed that DA-TOCNFs facilitated faster reduction of Ag+ and effective immobilization of AgNPs on the nanocellulose surface. The resulting suspensions exhibited stability and demonstrated strong antimicrobial activity against Bacillus subtilis when coated on paper surfaces. Importantly, the coated papers did not show significant silver migration to food simulants B (3 vol% acetic acid) and D1 (ethanol/water mixture, 50 vol%), indicating the potential of these suspensions for active food packaging. The advantages of using DA-TOCNFs over DAC were attributed to their higher cationic demand and ζ-potential, resulting in a higher density of binding sites. Moreover, the charged and entangled network of DA-TOCNFs allowed for the individualization of AgNPs, unlike DAC, where some agglomerations were observed. Overall, this study presents an improved single-step process for the synthesis of AgNPs on nanocellulose surfaces, highlighting their potential for safe and high-performance applications in food packaging. Paper sheets coated with nanocellulose/AgNPs suspensions fully inhibited the growth of B. subtilis, at least for one month after coating, and caused damage to their cell membranes. This research provides a one-pot facile route to fabricating hybrid nanocellulose/AgNPs systems, stable in water, and may be used directly as a coating layer for board and paper active packaging with little or even undetectable release of Ag.

Impact of temperature variations on BISON predictions of Ag release in AGR-1 and AGR-2 experiments

Understanding and quantifying the release of fission products like silver (Ag) from TRistructural ISOtropic (TRISO) fuel particles is important to assess the safe operation of advanced high temperature reactors. Although the silicon carbide (SiC) layer of TRISO particles is effective as the main fission product barrier, Ag can be released from intact TRISO particles. A mechanistic model for the effective Ag diffusivity, Deff, was previously developed as a function of temperature and microstructure variables informed by atomistic modeling of Ag diffusivity. In this study, we use this model to explore how experimental temperature uncertainties impact the overall predicted Ag release. This analysis indicates that calculated temperature uncertainties have a significant impact on the overall Ag release predictions. Furthermore, we show that the time average volume average (TAVA) temperature is not an appropriate proxy for the detailed temperature histories to predict fission product release due to the Arrhenius dependence of Ag diffusivity with respect to temperature. The detailed temperature histories, therefore, provide the most accurate results and are of most importance for modeling efforts. Overall, this work shows the importance of considering the experimental uncertainty of the temperature on computational predictions of fission product transport and release and the need for more accurate temperature histories from future experiments.

Enzyme-free and label-free detection of HER2 in human serum based on Ag+-released hybridization chain reaction signal amplification

The overexpression of human epidermal growth factor receptor 2 (HER2) has been linked to aggressive breast cancer and worse clinical outcomes. However, accurately measuring HER2 remains challenging, due to its low serum content. Herein, we developed a novel method for HER2 detection in serum by the combination of aptamer with C-Ag+-C structure, Ag+-released hybridization chain reaction (Ag+-HCR) and coprecipitation of Ag+ and gold nanoparticles (AuNPs) in the solution including Eosin Y (EY) and AgI colloids. Following the aptamer bound to HER2, signal amplification occurred through the release of numerous Ag+ by Ag+-HCR. This process subsequently induced AuNPs aggregation on the surface of AgI colloids, resulting in reduced fluorescence intensity of EY in the supernatant. The reduced value of EY fluorescence intensity in the supernatant was proportional to the level of HER2. Under optimized reaction conditions, a wide detection range was obtained between 0.09 and 9000 pg/mL with a limit of detection of 11.7 fg/mL in diluted human serum, and 96 serum samples in a 96-well plate could be measured simultaneously by a microtiter plate reader within 2 h. Moreover, the quantitative results of HER2 were consistent with those obtained using the enzyme-linked immunosorbent assay kit (r = 0.9995). Therefore, leveraging the delicate design of Ag+-HCR signal amplification, this enzyme-free, label-free, and effective method has demonstrated to be capable of detecting HER2 in serum due to its high sensitivity. Remarkably, this method may be extended to detect other cancer-related proteins and genes by replacing the corresponding target sequences.

Simultaneous determination of picomolar level of dissolved silver with other key trace metals in seawater samples using solid phase extraction and isotope dilution methods

Simultaneous determination of dissolved silver (dAg) with other key GEOTRACES trace metals is difficult because dAg in seawater tends to form negatively charged chloride species that result in only 75% recovery efficiency with commonly used NOBIAS PA-1 chelating resins. In this study, we developed a method using solid phase extraction coupled with isotope dilution that enables full quantification (97.9 ± 2.1%) of dAg along with other major trace metals including cadmium (Cd), copper (Cu), manganese (Mn), nickel (Ni), and lead (Pb) (recovery efficiency = 100% to 102%) in seawater samples. Seawater samples were first spiked with Ag-109 and allowed to reach isotopic equilibrium before extraction using NOBIAS PA-1 chelating resin. Then, dAg isotope ratios (Ag-109/Ag-107) before and after solid phase extraction were determined and used to quantify dAg. Determination of dAg with dissolved Cd, Cu. Mn, Ni, and Pb in reference seawater material CASS-6 resulted in deviations of between 1.0% and 8.8% from the consensus values, which are well within the standard error of measurement. We then successfully determined the concentrations of dissolved Cd (0.05–0.2 nM), Cu (0.5–13 nM), Mn (10–140 nM), Ni (2–12 nM), Pb (5–110 nM), and Ag (10–40 pM) in Otsuchi Bay, Japan and its surrounding rivers. Evaluation of the behavior of dAg under a salinity gradient using estuarine samples collected from Samunsam River, Malaysia shows increasing dAg concentration with salinity (R2 = 0.68), which suggests release of sedimental Ag under high ambient chloride concentrations. Our new method enables rapid and simultaneous measurements of dAg with other key GEOTRACES trace metals in a single analysis, which is expected to expedite analysis and increase availability of oceanic dAg data globally.

Preparation of sodium alginate modified silver-metal organic framework and application in citric acid/PVA antimicrobial packaging

Silver-metal organic framework (Ag@MOF) has exhibited outstanding antimicrobial activity in antimicrobial applications, and reducing the biotoxicity associated with silver has become a research priority. In this study, Ag@MOF was initially modified with sodium alginate (SA) to form SA-Ag@MOF. The results showed that SA could control the release of Ag+, reducing the release by about 8% at 24 h, and the biotoxicity was significantly reduced. Finally, SA-Ag@MOF was applied as an antimicrobial agent in citric acid-modified PVA film to develop a novel composite antimicrobial film. When added at 2 MIC, the CA3-M2 film can effectively inhibit the growth of E. coli and S. aureus, and the inhibition rate has reached 98%. For white radish packaging applications, CA3-M2 film inhibited the growth of surface microorganisms, while ensuring moisture and tissue hardness to extend shelf-life up to 7 days. Overall, the strategy conceived here can be a theoretical basis for novel antimicrobial packaging.

Impacts of Differentially Shaped Silver Nanoparticles with Increasingly Complex Hydrophobic Thiol Surface Coatings in Small-Scale Laboratory Microcosms.

We investigated the impacts of spherical and triangular-plate-shaped lipid-coated silver nanoparticles (AgNPs) designed to prevent surface oxidation and silver ion (Ag+) dissolution in a small-scale microcosm to examine the role of shape and surface functionalization on biological interactions. Exposures were conducted in microcosms consisting of algae, bacteria, crustaceans, and fish embryos. Each microcosm was exposed to one of five surface chemistries within each shape profile (at 0, 0.1, or 0.5 mg Ag/L) to investigate the role of shape and surface composition on organismal uptake and toxicity. The hybrid lipid-coated AgNPs did not result in any significant release of Ag+ and had the most significant toxicity to D. magna, the most sensitive species, although the bacterial population growth rate was reduced in all exposures. Despite AgNPs resulting in increasing algal growth over the experiment, we found no correlation between algal growth and the survival of D. magna, suggesting that the impacts of the AgNPs on bacterial survival influenced algal growth rates. No significant impacts on zebrafish embryos were noted in any exposure. Our results demonstrate that the size, shape, and surface chemistry of AgNPs can be engineered to achieve specific goals while mitigating nanoparticle risks.

Nanoparticle/Engineered Bacteria Based Triple-Strategy Delivery System for Enhanced Hepatocellular Carcinoma Cancer Therapy.

New treatment modalities for hepatocellular carcinoma (HCC) are desperately critically needed, given the lack of specificity, severe side effects, and drug resistance with single chemotherapy. Engineered bacteria can target and accumulate in tumor tissues, induce an immune response, and act as drug delivery vehicles. However, conventional bacterial therapy has limitations, such as drug loading capacity and difficult cargo release, resulting in inadequate therapeutic outcomes. Synthetic biotechnology can enhance the precision and efficacy of bacteria-based delivery systems. This enables the selective release of therapeutic payloads in vivo. In this study, we constructed a non-pathogenic Escherichia coli (E. coli) with a synchronized lysis circuit as both a drug/gene delivery vehicle and an in-situ (hepatitis B surface antigen) Ag (ASEc) producer. Polyethylene glycol (CHO-PEG2000-CHO)-poly(ethyleneimine) (PEI25k)-citraconic anhydride (CA)-doxorubicin (DOX) nanoparticles loaded with plasmid encoded human sulfatase 1 (hsulf-1) enzyme (PNPs) were anchored on the surface of ASEc (ASEc@PNPs). The composites were synthesized and characterized. The in vitro and in vivo anti-tumor effect of ASEc@PNPs was tested in HepG2 cell lines and a mouse subcutaneous tumor model. The results demonstrated that upon intravenous injection into tumor-bearing mice, ASEc can actively target and colonise tumor sites. The lytic genes to achieve blast and concentrated release of Ag significantly increased cytokine secretion and the intratumoral infiltration of CD4/CD8+T cells, initiated a specific immune response. Simultaneously, the PNPs system releases hsulf-1 and DOX into the tumor cell resulting in rapid tumor regression and metastasis prevention. The novel drug delivery system significantly suppressed HCC in vivo with reduced side effects, indicating a potential strategy for clinical HCC therapy.

Synthesis and Reduction Processes of Silver Nanowires in a Silver(I) Sulfamate-Poly (Vinylpyrrolidone) Hydrothermal System.

Silver (Ag) nanowires, as an important one-dimensional (1D) nanomaterial, have garnered wide attention, owing to their applications in electronics, optoelectronics, sensors, and other fields. In this study, an alternative hydrothermal route was developed to synthesize Ag nanowires via modified reduction of Ag+. Silver sulfamate plays an important role in the formation of Ag nanowires via controlled release of free Ag+. Results of controlled experiments and characterizations such as UV-vis spectroscopy, FTIR, XPS, and 1H NMR revealed that sulfamic acid does not function as a reductant, supporting by the generation of free Ag+ instead of Ag nanostructures in hydrothermally treated silver sulfamate solution. The initial reduction of Ag+ was induced by the combination of poly (vinylpyrrolidone) (PVP) end group and degradation products. This phenomenon was supported by abundant free Ag+ in the mixed preheated silver sulfamatic and preheated PVP aqueous solutions, indicating a second and distinct Ag+ autocatalytic reduction. Thus, the roles of different reagents and Ag+ reduction must be studied for nanomaterial syntheses.

In Situ injectable photo-crosslinking hydrogel with heterojunction nanoparticles for dual-channel synergistic disinfection and cutaneous regeneration in diabetic chronic wound healing

Recurrent inflammation, intense bacterial infections, and inadequate blood vessel growth make diabetic wounds non-healing. Under pathological environment, cellular functions are also inhibited. In this paper, we developed a novel in situ injectable photo-crosslinking hydrogel embedded with heterojunction Ag@ZnO nanoparticles (NPs) which exhibit dual-channel synergistic ion release and reactive oxygen species (ROS) production for anti-bacteria and cutaneous regeneration. This novel hydrogel platform can be introduced onto any irregular wound and form gelation with 395 nm UV light irradiation in only 5 s. After being affixed to the wound, Ag+ and Zn2+ can be released as the first interaction for wound healing. Foremost, the heterojunction formed on interface of Ag and ZnO has the ability to capture oxygen and water to instigate the generation of a “ROS storm”, which can disrupt the structural integrity of bacteria, trigger the leakage of bacterial cytoplasmic content, enhance angiogenesis by activating VEGF and CD31 expression, and stimulate the steps of wound healing. The continuous release of Ag+, Zn2+ and “ROS storm” collaboratively drive bacterial deactivation, suppress inflammation, promote cellular proliferation, collagen deposition and angiogenesis. These effects significantly accelerate diabetic chronic wounds healing. Therefore, such dual-channel synergistic hydrogel platform might provide a promising new insight to diabetic chronic wound treatment.

Silver-infused lysine crosslinked hydrogel with oxidized regenerated cellulose for prospective advanced wound dressings

The study aimed to develop a multifunctional wound dressing with enhanced antibacterial properties and wound healing promotion. The synthesis process involved preparing oxidized regenerated cellulose (ORC) following a modified procedure, synthesizing chitosan/silver nanoparticles (CS/Ag NPs) via an in-situ reduction method, and subsequently preparing ORC/CS/Lys@Ag NPs hydrogels. Characterization techniques including FTIR, XRD, SEM, and EDS were employed to analyze functional groups, lattice structure, morphology, and elemental composition. Gelation time, swelling behavior, water retention, mechanical properties, viscosity, self-healing capacity, rheological behavior, oxygen permeability, in vitro degradation, release of Ag+, and antibacterial properties were evaluated using various experimental methods. Results indicated that the novel wound dressing has the capability to evenly distribute Ag NPs to effectively counteract bacteria. It can maintain moist conditions for 86 h, resist a sturdy mechanical pressure of 11.3 KPa, and degrade by 11.045 % ± 0.429 within 8 h. Combining its efficient gas exchange abilities, self-repairing function, and biocompatibility, almost full recovery was observed in injured mouse skin within 13 days, highlighting its promising clinical utility.

Is Silver Addition to Scaffolds Based on Polycaprolactone Blended with Calcium Phosphates Able to Inhibit Candida albicans and Candida auris Adhesion and Biofilm Formation?

Candida spp. periprosthetic joint infections are rare but difficult-to-treat events, with a slow onset, unspecific symptoms or signs, and a significant relapse risk. Treatment with antifungals meets with little success, whereas prosthesis removal improves the outcome. In fact, Candida spp. adhere to orthopedic devices and grow forming biofilms that contribute to the persistence of this infection and relapse, and there is insufficient evidence that the use of antifungals has additional benefits for anti-biofilm activity. To date, studies on the direct antifungal activity of silver against Candida spp. are still scanty. Additionally, polycaprolactone (PCL), either pure or blended with calcium phosphate, could be a good candidate for the design of 3D scaffolds as engineered bone graft substitutes. Thus, the present research aimed to assess the antifungal and anti-biofilm activity of PCL-based constructs by the addition of antimicrobials, for instance, silver, against C. albicans and C. auris. The appearance of an inhibition halo around silver-functionalized PCL scaffolds for both C. albicans and C. auris was revealed, and a significant decrease in both adherent and planktonic yeasts further demonstrated the release of Ag+ from the 3D constructs. Due to the combined antifungal, osteoproliferative, and biodegradable properties, PCL-based 3D scaffolds enriched with silver showed good potential for bone tissue engineering and offer a promising strategy as an ideal anti-adhesive and anti-biofilm tool for the reduction in prosthetic joints of infections caused by Candida spp. by using antimicrobial molecule-targeted delivery.

Thiourea‐Cation Chelation Based Hydrogel and its Application as Antibacterial Dressing for the Repair of Diabetic Wound

AbstractFor various chronic wounds, bacterial infection is one of the important reasons that hinder their healing. Ion‐crosslinked antibacterial hydrogel dressings based on Ag+, Cu2+ and Zn2+, have made progress in clinical application. However, the toxicity of released metal ions cannot be ignored. Therefore, how to ensure the antibacterial performance of hydrogel dressing while reducing the amount of metal ions is a major challenge for the fabrication of metal ion based antibacterial hydrogel. In this study, a general method is proposed to design cationic ion‐crosslinked hydrogel based on thiourea groups. Taking the hydrogel formed by mixing thiourea modified hyaluronic acid (H‐ANCSN) with Ag+ (HA‐NCSN/Ag+ hydrogel) as an example, the characteristics and application potential of this kind of hydrogel are thoroughly explored. Due to the strong cationic chelation characteristics of thiourea groups, HA‐NCSN/Ag+ hydrogel can gel at low Ag+ concentration and achieve long‐term slow release of Ag+ at stable concentration to balance the antibacterial and biocompatible properties. Moreover, this dynamic thiourea‐Ag+ crosslinking also endowed the hydrogel with the property of “gelation and encapsulation first, injection to cover wound when necessary”. Then, the mangiferin self‐assembled nanoparticles are loaded into HA‐NCSN/Ag+ hydrogel as the radical oxygen species scavenger.

Fabrication and evaluation of silver modified micro/nano structured titanium implant.

In order to enhance the antibacterial property of titanium implant without inducing obvious cytotoxicity, the combination of Ag nanolayer and micro/nano surface structure was conducted by magnetron sputtering and hot-alkali treatment in this study. A series of specimens (AH-Ti, AH-Ti/Ag0.25, AH-Ti/Ag1, AH-Ti/Ag2, and AH-Ti/Ag5) were prepared with different sputtering durations (0min, 0.25min, 1min, 2min, 5min), respectively, all realizing long-term release of Ag+. In vitro experiments indicated that AH-Ti/Ag1 group possessed good cytocompatibility, nice osteogenic ability, and excellent antibacterial efficiency as well. In addition, AH-Ti/Ag0.25 showed good biocompatibility, while the reduction of S.aureus (78.5%) was not enough compared with AH-Ti/Ag1. Although the AH-Ti/Ag2 and AH-Ti/Ag5 group showed superior antibacterial activity, their obvious cytotoxicity caused low ALP and mineralization level. Therefore, the design of suitable Ag nanolayer coating combined with micro/nano surface structure (AH-Ti/Ag1) might be a promising strategy to enhance osteogenic property and maintain excellent antibacterial ability at the same time.

Immunomodulatory poly(L-lactic acid) nanofibrous membranes promote diabetic wound healing by inhibiting inflammation, oxidation and bacterial infection.

Given the significant impact on human health, it is imperative to develop novel treatment approaches for diabetic wounds, which are prevalent and serious complications of diabetes. The diabetic wound microenvironment has a high level of reactive oxygen species (ROS) and an imbalance between proinflammatory and anti-inflammatory cells/factors, which hamper the healing of chronic wounds. This study aimed to develop poly(L-lactic acid) (PLLA) nanofibrous membranes incorporating curcumin and silver nanoparticles (AgNPs), defined as PLLA/C/Ag, for diabetic wound healing. PLLA/C/Ag were fabricated via an air-jet spinning approach. The membranes underwent preparation and characterization through various techniques including Fourier-transform infrared spectroscopy, measurement of water contact angle, X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, assessment of in vitro release of curcumin and Ag+, testing of mechanical strength, flexibility, water absorption and biodegradability. In addition, the antioxidant, antibacterial and anti-inflammatory properties of the membranes were evaluated in vitro, and the ability of the membranes to heal wounds was tested in vivo using diabetic mice. Loose hydrophilic nanofibrous membranes with uniform fibre sizes were prepared through air-jet spinning. The membranes enabled the efficient and sustained release of curcumin. More importantly, antibacterial AgNPs were successfully reduced in situ from AgNO3. The incorporation of AgNPs endowed the membrane with superior antibacterial activity, and the bioactivities of curcumin and the AgNPs gave the membrane efficient ROS scavenging and immunomodulatory effects, which protected cells from oxidative damage and reduced inflammation. Further results from animal studies indicated that the PLLA/C/Ag membranes had the most efficient wound healing properties, which were achieved by stimulating angiogenesis and collagen deposition and inhibiting inflammation. In this research, we successfully fabricated PLLA/C/Ag membranes that possess properties of antioxidants, antibacterial agents and anti-inflammatory agents, which can aid in the process of wound healing. Modulating wound inflammation, these new PLLA/C/Ag membranes serve as a novel dressing to enhance the healing of diabetic wounds.