Release Of Silver Ions Research Articles

A resource-efficient and portable nanotechnology-enabled disinfection system: Performance studies and a novel strategy to recycle spent material

The paper describes developing a point-of-use disinfection system consisting of a film-forming nanocomposite packed in a nylon sachet. The composite film consists of silver nanoparticles embedded in a matrix containing chitosan, reduced graphene oxide, and tannic acid. The long-term ability of the portable sachet bag to release silver ions and disinfect surface and groundwater is demonstrated. The sachet bag's disinfection potential is demonstrated by taking Escherichia coli MTCC 443 as the model microorganism. The system produced a complete and consistent 3 log10 reduction of E. coli over multiple cycles of use. The paper also describes a green recycling approach to utilise spent composite film and prevent AgNPs from entering the waste stream. The spent nanocomposite film is transformed into a concrete micro-crack sealant through a soft chemical route. The sealant's ability to plug micro-cracks in concrete is demonstrated, and the mechanism of sealant interaction with concrete is proposed. The sealant can fill cracks and solidify in an alkaline environment. The concrete cube specimens repaired with sealant showed enhanced compressive strength compared to the residual concrete cube specimens. The possible leaching of residual silver from the sealant in concrete is investigated via toxicity characteristic leaching procedure analysis. The study demonstrates that silver leaching is negligible (< 0.05 mg/L) and well below the permissible limit of 5 mg/L.

Flexible, robust and self-peeling PLA/AgNWs nanofiber membranes with photothermally antibacterial properties for wound dressing

Bacterial infection is the key factor challenging the success of wound healing. In view of the low and short-term antibacterial effects of traditional wound treatment, a photothermal activated antibacterial platform based on silver nanowires (AgNWs) embedded in polylactic acid (PLA) nanofiber membranes was fabricated by electrospinning in this study. SEM images showed that smooth and continuous PLA/AgNWs composite nanofibers with diameter distribution ranging from 200 to 700 nm were obtained. The composite membranes possess moderate hydrophobicity and self-peeling characters, which may contribute to prevent secondary injury during the removal of the dressing. Excellent water vapor permeability also could meet the requirement of wound dressing. Importantly, the presence of AgNWs endow the PLA/AgNWs membranes with not only enhanced plasticity, but also excellent antibacterial properties due to the near infrared (NIR) triggered silver ion release and local photothermal effect. Such NIR-controlled antibacterial action is also beneficial for achieving good biocompatibility. Therefore, the produced PLA/AgNWs composite nanofiber membrane is expected to be a promising candidate that can prevent bacterial infection and promote skin repair.

Antibacterial hydrogel therapy for eradication of wound associated polymicrobial biofilms

The recalcitrance of bacterial biofilms to current antimicrobials has presented a major cause of clinical recurrence of wound infections. These biofilm-associated infections are often present in polymicrobial nature associated with the presence of Pseudomonas aeruginosa and Staphylococcus aureus creating a large heterogeneity that shares a common resistance to current antimicrobials making pathogen eradication extremely challenging. In this study, we overcome the intrinsic biofilm barriers by delivering ultrasmall-sized silver nanoparticles (AgNP) using a smart hydrogel system that allows slow and sustained release of silver ions mediating successful accumulation and penetration of bacterial biofilms. The antibiofilm efficacy of the AgNP hydrogel was assessed using ex vivo porcine wound polymicrobial biofilms. Treatment with AgNP hydrogel resulted in significant dispersion of early to mature biofilms, 2–5-log reduction of bacteria compared to untreated controls. This approach overcomes the enhanced tolerance and resistance of polymicrobial biofilms by using the combined benefits of smart delivery system and the antibiofilm properties of ultrasmall AgNPs to ensure biofilm complete destruction and elimination.

A Review of Children’s Prosthetic Self-hygiene Using Antibacterial Silver Nanoparticles (AgNPs)

Sports prostheses represent a critical facet in enhancing the mobility and quality of life for children with limb loss. However, prolonged usage of these prosthetic devices introduces substantial challenges related to hygiene and the heightened risk of infection. This comprehensive review endeavors to delve into the untapped potential of utilizing antibacterial silver nanoparticles (AgNPs) to foster self-hygiene practices in pediatric sports prostheses. AgNPs have emerged as a compelling area of research, largely attributable to their formidable antibacterial properties, offering revolutionary prospects in the realm of antibacterial therapy. Central to this exploration is an in-depth analysis of their antibacterial activity, elucidating their intricate mechanisms of action against bacterial agents. The unique physicochemical attributes, characterized by their diminutive size and expansive surface area, synergize to elevate their antibacterial efficacy significantly. The antibacterial mechanisms involve the controlled release of silver ions, which disrupt bacterial cell membranes, impede vital cellular processes, and provoke oxidative stress within the pathogens. Moreover, they exhibit the propensity for synergistic interactions when employed in tandem with conventional antibiotics, thereby positioning themselves as promising candidates for combination therapy. This review further encompasses a comprehensive survey of diverse methodologies employed for the synthesis of AgNPs and their multifarious application in various domains, including the realm of prosthetics and medicine. Nevertheless, as with any emerging technology, the implementation of AgNPs does not come without its challenges. Issues pertinent to the stability of AgNPs, potential toxicity concerns, and the development of bacterial resistance necessitate critical consideration for their successful integration into pediatric sports prostheses. In summation, AgNPs epitomize a compelling arsenal of antibacterial agents, propelling the possibilities of innovative therapeutic strategies in the battle against bacterial infections. This review underscores their remarkable potential while underscoring the imperative need for further research and development to unlock their full efficacy in the context of pediatric sports prostheses and beyond.

Electric Spark Deposition of Antibacterial Silver Coating on Microstructured Titanium Surfaces with a Novel Flexible Brush Electrode.

Infection caused by orthopedic titanium implants, which results in tissue damage, is a key factor in endosseous implant failure. Given the seriousness of implant infections and the limitations of antibiotic therapy, surface microstructures and antimicrobial silver coatings have emerged as prominent research areas and have displayed certain antimicrobial effects. Researchers are now working to combine the two to produce more effective antimicrobial surfaces. However, building robust and homogeneous coatings on complex microstructured surfaces is a tough task due to the limits of surface modification techniques. In this study, a novel flexible electrode brush (silver brush) instead of a traditional hard electrode was designed with electrical discharge machining, which has the ability to adapt to complex groove interiors. The results showed that the use of flexible electrode brush allowed silver to be deposited uniformly in titanium alloy microgrooves. On the surface of Ag-TC4, a uniformly covered deposit was visible, and it slowly released silver ions into a liquid environment. In vitro bacterial assays showed that a Ag-TC4 microstructured surface reduced bacterial adhesion and bacterial biofilm formation, and the antibacterial activity of Ag-TC4 against Staphylococcus aureus and Escherichia coli was 99.68% ± 0.002 and 99.50% ± 0.007, respectively. This research could lay the groundwork for the study of antimicrobial metal bound to microstructured surfaces and pave the way for future implant surface design.

Emulgel-loaded mannosylated thiolated chitosan-coated silver nanoparticles for the treatment of cutaneous leishmaniasis

Topical treatment of cutaneous leishmaniasis holds great promise for decreasing drug associated side effects and improving efficacy. This study was aimed to develop mannosylated thiolated chitosan-coated silver nanoparticles (MTCAg) loaded emulgel for the treatment of cutaneous leishmaniasis. MTC-Ag were synthesized via a chemical reduction method and were loaded into the emulgel. The nanoparticles had a zeta potential of +19.8 mV, an average particle size of 115 nm and a narrow polydispersity index of 0.26. In-vitro release profiles showed controlled release of silver ions from both the MTC-Ag and the emulgel-loaded MTC-Ag nanoparticles after 24 h. An ex-vivo retention study indicated 5 times higher retention of silver by the emulgel-loaded MTC-Ag than by the MTC-Ag nanoparticles. The in-vitro anti-leishmanial assay revealed that MTC-Ag had an excellent inhibitory effect on intracellular amastigotes, leading to ~90 % inhibition at the highest concentration tested. A 4-fold reduction in the IC50 value was found for MTC-Ag compared to blank Ag nanoparticles. Cytotoxicity assay showed 83 % viability of macrophages for MTC-Ag and 30 % for Ag nanoparticles at a concentration of 80 μg/mL, demonstrating the improved biocompatibility of the polymeric nanoparticles. Drug release and retention studies corroborate the great potential of MTC-Ag-loaded emulgel for the treatment of cutaneous leishmaniasis.

Wheat gluten hydrolysates with embedded Ag-nanoparticles; a structure-function assessment for potential applications as wound sorbents with antimicrobial properties

Numerous approaches have been used to prevent bacterial infection from injured skin, such as bandages and topical creams. However, the higher level of reactive oxygen species, bacterial infections, and excess wound exudates remain the major challenges for wound healing. In this study, we have tailored the structure of wheat gluten hydrolysates (WGH) as a continuous matrix by compositing it with a minimal amount of PVA, PVP, and PEG as polymer crosslinkers (0.5 wt%) to provide film structure integrity. Silver nanoparticles (AgNPs) were impregnated into the WGH to develop a control release matrix of the AgNPs. Scanning electron microscopy, X-ray diffractogram, and functional group patterns of WG and AgNPs indicate a successful integration of AgNPs into the wheat gluten matrix. The swelling capacity of the films was tested at acidic, neutral, and basic pH and was found to be highest in WG/PEG/Ag at pH 9 with 389%. The gradual release of Ag+/AgNPs from the films significantly scavenged free radicals and increased the antibacterial activity with up to a 12 mm inhibition zone against Pseudomonas aeruginosa. According to these findings, WGH with AgNPs has been successfully cast in films with increased absorption capacity, free radicals scavenging, oxidant quenching, and antibacterial capabilities, along with the sustained release of silver ions. The results, therefore, show the potential of the developed films in biomedical applications such as wound dressing.

In-situ silver recovery for biofouling mitigation with catechol-assisted nanofiltration membrane

Silver (Ag) has been in widespread use in the field of medical/pharmaceutical and chemical industries. The discharge of produced Ag-containing wastewater not only threats the ecosystem but also causes resource exhaustion of non-renewable Ag. For a sustainable environment, a catechol-based membrane-assisted recovery-filtration concept is put forward, exemplified by integrating two processes of I) efficient silver ion (Ag+) retention and Ag resource recovery by a catechol-rich thin film composite membrane, and II) biofouling mitigation using the resultant antibacterial membrane in salt separation. Due to the strong affinity and reduction capacity of the catechol groups on membrane surface and pores to Ag+, the retained silver ions onto the membrane are spontaneously in-situ reduced into Ag nanoparticles. Consequently, the membrane achieves a remarkable Ag+ retention efficiency of 91.1 %. More importantly, the resultant membrane with recovered Ag holds a good separation efficiency towards common salt and excellent anti-microbial property over the ultra-long term, owing to the satisfactory Ag loading and well-regulated release of silver ions from the membrane surface. This membrane-based recovery-filtration pathway gives a new insight towards sustainable Ag resource recovery/reuse and nanofiltration technology for industrial wastewater with minimum facilities.

The antibacterial effect of silver anode treatment on raw milk

Silver has been used as an indirect antibacterial method by the food sector. In this study, the antibacterial effect of silver on raw milk was examined using the silver anode method. The samples were divided into two groups comprising silver-containing and non-silver-containing samples. Then, the two groups were stored at 5 °C, 10 °C, and 25 °C. The changes in the bacterial flora of the raw milk samples were observed at hours 0, 12, 24, and 36. The antibacterial effect of the silver anode treatment on both groups was observed after 12 h. The antibacterial effect increased with increasing storage time. The decreases in the Pseudomonas spp., coliform bacteria, and lactic acid bacteria counts of the silver-containing group were significantly different than those of the control group after 36 h (p < 0.05). The decreases in the Pseudomonas spp. and coliform bacteria counts were greater than the decrease in the lactic acid bacteria count. The Pseudomonas spp. count decreased during the storage period depending on temperature while the growth rates of coliform and lactic acid bacteria decreased with decreasing storage temperature in the silver anode-treated group. The strongest antibacterial effect was observed at 25 °C for Pseudomonas spp. and at 5 °C for coliform and lactic acid bacteria. The results of the study revealed that the silver anode method had a strong antibacterial effect on Pseudomonas spp. and coliform bacteria and a poor antibacterial effect on lactic acid bacteria. Silver ion release into the milk samples was consistently below the legal limits at all storage temperatures.

Surface properties-dependent antifungal activity of silver nanoparticles

Silver nanoparticles (AgNPs) exhibit unusual biocidal properties thanks to which they find a wide range of applications in diverse fields of science and industry. Numerous research studies have been devoted to the bactericidal properties of AgNPs while less attention has been focused on their fungicidal activity. Our studies were therefore oriented toward determining the impact of AgNPs characterized by different physicochemical properties on Fusarium avenaceum and Fusarium equiseti. The main hypothesis assumed that the fungicidal properties of AgNPs characterized by comparable morphology can be shaped by stabilizing agent molecules adsorbed on nanoparticle surfaces. Two types of AgNPs were prepared by the reduction of silver ions with sodium borohydride (SB) in the presence of trisodium citrate (TC) or cysteamine hydrochloride (CH). Both types of AgNPs exhibited a quasi-spherical shape. Citrate-stabilized AgNPs (TCSB-AgNPs) of an average size of 15 ± 4 nm were negatively charged. Smaller (12 ± 4 nm), cysteamine-capped AgNPs (CHSB-AgNPs) were characterized by a positive surface charge and higher silver ion release profile. The phytopathogens were exposed to the AgNPs in three doses equal to 2.5, 5 and 10 mg L−1 over 24 and 240 h. Additionally, the impact of silver ions delivered in the form of silver nitrate and the stabilizing agents of AgNPs on the fungi was also investigated. The response of phytopathogens to these treatments was evaluated by determining mycelial growth, sporulation and changes in the cell morphology. The results of our studies showed that CHSB-AgNPs, especially at a concentration of 10 mg L−1, strongly limited the vegetative mycelium growth of both species for short and long treatment times. The cell imaging revealed that CHSB-AgNPs damaged the conidia membranes and penetrated into the cells, while TCSB-AgNPs were deposited on their surface. The fungistatic (lethal) effect was demonstrated only for silver ions at the highest concentration for the F. equiseti species in the 240 h treatment. The number of spores of both Fusarium species was significantly reduced independently of the type of silver compounds used. Generally, it was found that the positively charged CHSB-AgNPs were more fungicidal than negatively charged TCSB-AgNPs. Thereby, it was established that the stabilizing agents of AgNPs and surface charge play a crucial role in the shaping of their fungicidal properties.

Biocompatible Polycationic Silver Nanocluster‐Impregnated PLGA Nanocomposites with Potent Antimicrobial Activity

AbstractUltrasmall cationic silver nanoparticles (AgNPs) have recently emerged as highly potent antimicrobial agents for the treatment of multidrug‐resistant bacteria and their biofilms. However, the clinical application of these cationic AgNPs is hampered by their poor stability and high reactivity in solution, leading to uncontrolled release of toxic silver ions. An ideal platform featuring broad‐spectrum antibacterial activity and high biocompatibility that prevents overexposure to silver ions, is therefore highly desirable. Herein, we explored a biocompatible and biodegradable polymer, poly(lactic‐co‐glycolic) acid (PLGA) as an effective carrier for the recently discovered polycationic silver nanoclusters (pAgNCs). These pAgNCs impregnated PLGA nanocomposites (pAgNCs@PLGA) were developed by water‐in‐oil‐in‐water (W1/O/W2) emulsion method and characterized by various analytical techniques. Our experimental results reveal that pAgNCs@PLGA had spherical morphology with an average diameter of ∼188 nm and consists of multiple ultrasmall (∼2 nm) pAgNCs at the polymeric core. The minimum inhibitory concentration of pAgNCs for Staphylococcus aureus and Pseudomonas aeruginosa were found to be 6.9 μg/mL. After impregnation within PLGA, the antimicrobial efficacy of our pAgNCs against Staphylococcus aureus and Pseudomonas aeruginosa remained consistent, while the nanocomposites were biocompatible at the minimum inhibitory concentration (MIC) against both bacteria. The pAgNCs@PLGA nanocomposite developed in this work may present a path forward to bring these highly potent pAgNCs into medical practice.

STUDY ON THE ANTIBACTERIAL ABILITY OF THE HYBRID MATERIAL BETWEEN PORPHYRIN AND NANO SILVER

Water-soluble porphyrins di(4-aminophenyl)-di(4-sulfophenyl)- diphenyl-porphyrin [(SO3)2-TPP-(NH2)2](TASP) and nano-silver materials (AgNPs) were successfully synthesized by chemical synthesis and green synthesis from guava leaf extracts, respectively. The silver nanoparticle size is well controlled in the range of 1.1 - 1.5 nm. Then, AgNPs\TASP hybrid materials were successfully synthesized by different mixing methods. The UV-Vis spectrum of the hybrid material depends on the AgNPs:TASP mixing ratio and still shows the Soret peaks and Q-bands characteristic of the porphyrin family and the broad absorption range from 300 - 600 nm of the silver nanoparticles initial. The results of an antibacterial test against both gram-negative and gram-positive strains on LB agar showed that all samples had different antibacterial activities. In which, the AgNPs\TASP hybrid material has better inactivation ability than silver nano for both tested bacterial strains. Besides, the presence of polypyrrole conducting polymer (PPy) has promoted the kinetics of silver ion release, which also gives outstanding antibacterial results, thereby opening the potential to fabricate hybrid materials for antibacterial applications.

In vitro release of silver ions and expression of osteogenic genes by MC3T3-E1 cell line cultured on nano-hydroxyapatite and silver/strontium-coated titanium plates.

Attempts are ongoing to improve the surface properties of dental implants by application of different coatings, aiming to enhance osseointegration, and decrease the adverse effects of titanium and its alloys used in dental implants. Coating of implant surface with hydroxyapatite (HA) is one suggested strategy for this purpose due to its high biocompatibility and similar structure to the adjacent bone. This study aimed to quantify the release of silver ions and expression of osteogenic genes by MC3T3-E1 cells cultured on nano-HA and silver/strontium (Ag/Sr)-coated titanium plates via the electrochemical deposition method. Plates measuring 10 × 10 × 0.9mm were fabricated from Ti-6Al-4V alloy, and polished with silicon carbide abrasive papers before electrochemical deposition to create a smooth, mirror-like surface. After applying homogenous nano-HA coatings with/without silver/strontium on the surface of the plates, the composition of coatings was confirmed by energy-dispersive X-ray spectroscopy (EDS), and their morphological properties were analyzed by scanning electron microscopy (SEM). The coated specimens were then immersed in simulated body fluid (SBF), and the concentration of released sliver ions was quantified by spectroscopy at 7-14days. The MC3T3-E1 osteoblastic cell line was cultured in osteogenic medium for 7-14days, and after RNA extraction and cDNA synthesis, the expression of runt-related transcription factor 2 (RUNX2), osteocalcin (OCN), and osteopontin (OPN); osteogenic genes was quantified by polymerase chain reaction (PCR) using SYBR Green Master Mix kit. The expression of genes and the released amount of silver ions were compared between the two groups using the Mann-Whitney U test. The two groups were not significantly different regarding silver ion release at 14days (P > 0.05). However, silver ion release was significantly higher from nano-HA coatings with silver/strontium at 7days (P = 0.03). The difference in expression of RUNX2 (P = 0.04), OPN (P = 0.04), and OCN (P = 0.03) genes was also significant between nano-HA coating groups with and without silver/strontium at 7days, and the expressions were higher in nano-HA with silver/strontium group, but this difference was not significant at 14days. Addition of silver and strontium to specimens coated with nano-HA increased the release of silver ions within the non-toxic range, and enhanced the expression of osteogenic genes particularly after 7days.

Silver as an Antibiotic-Independent Antimicrobial: Review of Current Formulations and Clinical Relevance.

Background: The increase of multi-drug-resistant organisms has revived the use of silver as an alternative antibiotic-independent antimicrobial. Although silver's multimodal mechanism of action provides low risk for bacterial resistance, high local and uncontrolled concentrations have shown toxicity. This has resulted in efforts to develop novel silver formulations that are safer and more predictable in their application. Optimization of silver as an antimicrobial is crucial given the growing resistance profile against antibiotics. This article reviews formulations of silver used as antimicrobials, focusing on the mechanisms of action, potential for toxicity, and clinical applications. Methods: A search of four electronic databases (PubMed, Embase, MEDLINE, and Cochrane Library) was conducted for relevant studies up to January 2022. Searches were conducted for the following types of silver: ionic, nanoparticles, colloidal, silver nitrate, silver sulfadiazine, silver oxide, silver carboxylate, and AQUACEL® (ConvaTec, Berkshire, UK). Sources were compiled based on title and abstract and screened for inclusion based on relevance and study design. Results: A review of the antimicrobial activity and uses of ionic silver, silver nanoparticles, colloidal silver, silver nitrate, silver sulfadiazine, silver oxide, Aquacel, and silver carboxylate was conducted. The mechanisms of action, clinical uses, and potential for toxicity were studied, and general trends between earlier and more advanced formulations noted. Conclusions: Early forms of silver have more limited utility because of their uncontrolled release of silver ions and potential for systemic toxicity. Multiple new formulations show promise; however, there is a need for more prospective in vivo studies to validate the clinical potential of these formulations.

Plasma polymerization for biomedical applications: A review

AbstractPlasma polymers have long been of interest as thin film coatings on biomedical devices and products, to generate desirable surface properties for favorable bio‐interfacial interactions. Plasma polymers have also been used as platforms for the covalent immobilization of bioactive molecules. More recently, additional aspects have been investigated, such as selective prevention of adhesion of microbial pathogens, either via plasma polymers per se or including antimicrobial drugs. Plasma polymers have also been investigated for the release of silver ions and small organic molecules. Complementing low‐pressure plasma approaches, processes at atmospheric pressure have attracted interest recently, including for nano/biocomposite coatings. This contribution reviews the use of plasma polymers for intended biomedical applications, with a focus on more recent topic areas.

Mesoporous silica-coated silver nanoparticles as ciprofloxacin/siRNA carriers for accelerated infected wound healing

The colonization of bacterial pathogens is a major concern in wound infection and becoming a public health issue. Herein, a core–shell structured Ag@MSN (silver core embedded with mesoporous silica, AM)-based nanoplatform was elaborately fabricated to co-load ciprofloxacin (CFL) and tumor necrosis factor-α (TNF-α) small interfering RNA (siTNF-α) (AMPC@siTNF-α) for treating the bacterial-infected wound. The growth of bacterial pathogens was mostly inhibited by released silver ions (Ag+) and CFL from AMPC@siTNF-α. Meanwhile, the loaded siTNF-α was internalized by macrophage cells, which silenced the expression of TNF-α (a pro-inflammatory cytokine) in macrophage cells and accelerated the wound healing process by reducing inflammation response. In the in vivo wound model, the Escherichia coli (E. coli)-infected wound in mice almost completely disappeared after treatment with AMPC@siTNF-α, and no suppuration symptom was observed during the course of the treatment. Importantly, this nanoplatform had negligible side effects both in vitro and in vivo. Taken together, this study strongly demonstrates the promising potential of AMPC@siTNF-α as a synergistic therapeutic agent for clinical wound infections.Graphical

Preparation of poly(ε-caprolactone) nanofibrous mats incorporating graphene oxide-silver nanoparticle hybrid composite by electrospinning method for potential antibacterial applications

In this study, poly(ε-caprolactone) based fibrous mats incorporating graphene oxide-silver hybrid nanocomposite as a nanofiller were successfully prepared by electrospinning method for potential biomedical applications. First, graphene oxide-silver nanoparticles (GO-AgNPs) were synthesized and the obtained GO-AgNPs nanohybrid was characterized by different analytical techniques. It was observed that the obtained AgNPs, with an average size of 5 ± 0.5 nm and spherical shape, were uniformly anchored on the surface of GO. Then, the synthesized GO-AgNPs were added into PCL to improve its tensile and bactericidal performances. The structural, morphological, mechanical and wettability properties of PCL-based fibrous mats as well as the release of silver ion release from PCL matrix were examined. Based on the results, we found that the addition of GO to the PCL-3.0%Ag nanofibers resulted in increased hydrophilicity, tensile strength and resistance to elastic deformation, and the PCL-GO-3.0%Ag sample also had a significantly higher release of silver ions. Besides, PCL-GO–3.0%Ag mats showed good antibacterial activity against Staphylococcus aureus and Escherichia coli compared to the PCL, PCL-GO and PCL-Ag nanofibrous mats. In summary, this study showed that PCL-GO–3.0%Ag nanofibrous mats could be a promising biomaterial for potential antibacterial applications.

Ecotoxicity Study of New Composite Materials Based on Epoxy Matrix DER-331 Filled with Biocides Used for Industrial Applications.

The impact of fillers in the epoxy oligomer on the test culture of the marine ecosystem was investigated. The content of additive—biocides—was selected based on the complex research using STAT-GRAPHICS® Centurion XVI. The ecotoxicity of composite surfaces was determined in model systems using methods which are standard in eco-microbiology. The microorganism was identified by studying morphological, cultural, biochemical, and antigenic properties. Studies of the structure and the microrelief of the surfaces of composite materials were conducted using scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy. Based on comprehensive research, it was established that the composition of oxytetracycline with content of q = 1.5 wt% and nanosilver with a content of q = 0.075 wt% per 100 wt% of the DER-331 oligomer and 10 parts by the mass of the TETA hardener ensures the formation of a porous nano-heterogeneous structure of the coating, which leads to the acceleration of the release of silver ions from the surface of the polymer. The rational content of the complex additives of biocides ensures adhesion to the cell wall of bacteria with subsequent penetration into it and subsequent change to the cell membrane, its death, and, therefore, the suppression of the fouling process of metal structures.

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

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

Multi-Biofunctional Silver-Containing Metallosupramolecular Nanogels for Efficient Antibacterial Treatment and Selective Anticancer Therapy

We develop a simple and efficient route for the fabrication of water-soluble metallosupramolecular polymers. We demonstrate that the introduction of environment-responsive metal-organic complexes within supramolecular polymers endows the resulting self-assembled nano-objects with outstanding antibacterial activity and may significantly improve the efficacy and safety of selective cancer therapy. Herein, we successfully developed a silver-containing supramolecular polymer (Ag-Cy-J) possessing a hydrophilic Jeffamine backbone and highly sensitive pH-responsive cytosine-silver-cytosine (Cy-Ag-Cy) linkages, which spontaneously self-assemble to produce sterically stabilized spherical nanogels in water. The resulting nanogels exhibit several attractive features such as unique fluorescence behavior in water, highly stable self-assembled structures in biological media, significant antihemolytic capability, highly sensitive pH-responsiveness and broad-spectrum antibacterial activity against various bacteria strains. Importantly, in vitro cellular assays clearly demonstrated Ag-Cy-J nanogels highly selectively target and induce cytotoxicity in cancer cells, without affecting normal cells. The selective cytotoxic activity in cancer cells is attributed to rapid dissociation of the Cy-Ag-Cy complexes within the nanogels in the cancer cell microenvironment, followed by the intracellular release of silver ions and induction of rapid, massive apoptosis. Overall, the pH-sensitive Cy-Ag-Cy complexes within this supramolecular nanogel system may provide a route to remarkably improve the efficacy of both antibacterial and cancer drug therapies. Statement of significanceWe present a significant breakthrough in the development of a water-soluble silver-containing metallosupramolecular polymer (Ag-Cy-J) that spontaneously self-assembles in water into a spherical nanogel with unique physical characteristics due to the existence of highly sensitive pH-responsive cytosine-silver-cytosine (Cy-Ag-Cy) linkages within the nanogels. Importantly, a series of in vitro antibacterial and anticancer assays demonstrated the Ag-Cy-J nanogels not only exert strong antibacterial activity against various bacterial strains, but also exhibit a high degree of selective uptake and rapidly induce massive apoptosis in cancer cells without harming normal cells. Thus, this newly discovered supramolecular system may potentially provide a multi-biofunctional soft nanomaterial for efficient and safe antibacterial and cancer therapies.