Silver Release Research Articles

Effects of composition and pH on the degradation of hyaluronate and carboxymethyl cellulose gels and release of nanocrystalline silver.

Adhesions are fibrous tissue connections which are a common complication of surgical procedures and may be prevented by protecting tissue surfaces and reducing inflammation. The combination of biodegradable polymers and nanocrystalline silver can be used to create an anti-inflammatory gel to be applied during surgery. In this study, sodium hyaluronate and sodium carboxymethyl cellulose were added in concentrations from 0.25% to 1% w/v to aqueous nanocrystalline silver solutions to create viscous gels. Gels were loaded into dialysis cassettes and placed in PBS for 3 days. pH was adjusted using potassium phosphate monobasic and sodium hydroxide. Release of silver into the PBS was measured at several time points. Polymer degradation was compared by measuring the viscosity of the gels before and after the experiment. Gels lost up to 84% of initial viscosity over 3 days and released between 24% and 41% of the added silver. Gels with higher initial viscosity did not have a greater degree of degradation, as measured by percent viscosity reduction, but still resulted in a higher final viscosity. Silver release was not significantly impacted by pH or composition, but still varied between experimental groups.

Photo reduced molybdenum oxide/polyacrylonitrile composite membrane for eco-friendly silver, copper ions reduction and release mechanisms

The development of hybrid composite antibacterial agents for wound dressing has garnered significant attention due to their remarkable antibacterial efficacy and their potential to mitigate microbial resistance. In this study, we present an approach to designing and fabricating wound dressing membranes utilizing MoO3/PAN hybrid composites through electrospinning. Subsequently, we enhanced the membrane's effectiveness by introducing silver (Ag-MoO3/PAN) and copper (Cu-MoO3/PAN) into the matrix via a rapid (within one minute) green synthesis method under UV irradiation. Initially, we discuss the morphological characteristics and structural attributes of the resulting membranes. Subsequent investigation explores the antibacterial mechanisms of MoO3, Ag+, and Cu+ revealing that the incorporation of silver and copper substantially enhanced antibacterial activity. Silver nanoparticles into the composite material significantly enhanced its antibacterial effectiveness, particularly against Escherichia coli, while copper nanoparticles exhibited an even more substantial inhibitory effect, approximately 28.12 % greater compared to silver nanoparticles, and 21.23 % greater than pristine molybdenum oxide nanofiber against Bacillus subtilis. Additionally, we elucidate the surface properties, noting that the introduction of silver increases the surface area of the composite membrane by 25.89 % while copper increases the surface area by 30.27 % compared to the pristine MoO3/PAN membrane. Furthermore, we observe a 15 %, and 33.75 % reduction in WCA for the Ag-MoO3/PAN membrane and Cu-MoO3/PAN membrane respectively, indicating improved hydrophilicity. Finally, we analyze the release behavior of the Ag+ and Cu+ from pristine nanofiber membranes. Our findings demonstrate an initial burst in silver release of about 70 % within the first 7 h, followed by a 33.52 % reduction and then a sustained release pattern over a period of 7 days, while for copper 41 % increased within the first 7 h, followed by gradually increased release pattern over a period of 7 days.

Influence of silver nanoparticles addition on antibacterial properties of PEO coatings formed on magnesium

Magnesium is a biodegradable material and thus could be a choice for bone fixation devices and implants with a specific purpose. This study aims to enhance the anti-corrosive, biocompatible, and antibacterial properties on magnesium-based materials through ceramic coatings formation. To achieve this the silicate-based electrolyte was used to create of Plasma Electrolytic Oxidation (PEO) coatings. During investigation the bioactive surfaces were presented by highly developed morphology with pore size from 0.008 ± 0.01 to 0.098 ± 0.14 μm2. The thickness of the coatings reached 7 μm, which provides better corrosive behaviour. The silver nanoparticles (AgNPs) added during plasma electrolytic oxidation (PEO) into a silicate electrolytic bath allowed for achieving enhanced bioactive properties of coating. It increased hydrophilicity from 118° to 62° and showed no cytotoxic effects, which made the coatings promising for further biomedical investigations. Moreover, incorporation of AgNPs into the PEO coating led to release of silver during immersion test, which enhanced antibacterial properties of the surfaces.

NEW HIGH-THROUGHPUT METHODS FOR ANTIBACTERIAL VALIDATION OF METALLIC THIN FILMS: DIFFERENT METALS FOR DIFFERENT MICROBIAL COMMUNITIES

Prosthetic joint infections represent complications connected to the implantation of biomedical devices, they have high incidence, interfere with osseointegration, and lead to a high societal burden. The microbial biofilm, which is a complex structure of microbial cells firmly attached to a surface, is one of the main issues causing infections. Biofilm- forming bacteria are acquiring more and more resistances to common clinical treatments due to the abuse of antibiotics administration. Therefore, there is increasing need to develop alternative methods exerting antibacterial activities against multidrug-resistant biofilm-forming bacteria. In this context, metal-based coatings with antimicrobial activities have been investigated and are currently used in the clinical practice. However, traditional coatings exhibit some drawbacks related to the insufficient adhesion to the substrate, scarce uniformity and scarce control over the toxic metal release reducing their efficacy. Here, we propose the use of antimicrobial silver-based nanostructured thin films to discourage bacterial infections. Coatings are obtained by Ionized Jet Deposition, a plasma-assisted technique that permits to manufacture films of submicrometric thickness having a nanostructured surface texture, allow tuning silver release, and avoid delamination. To mitigate interference with osseointegration, here silver composites with bone apatite and hydroxyapatite were explored. The antibacterial efficacy of silver films was tested in vitro against gram- positive and gram-negative species to determine the optimal coatings characteristics by assessing reduction of bacterial viability, adhesion to substrate, and biofilm formation. Efficacy was tested in an in vivo rabbit model, using a multidrug-resistant strain of Staphylococcus aureus showing significant reduction of the bacterial load on the silver prosthesis both when coated with the metal only (>99% reduction) and when in combination with bone apatite (>86% reduction). These studies indicate that IJD films are highly tunable and can be a promising route to overcome the main challenges in orthopedic prostheses.

A multifunctional collagen-base bilayer membrane integrated with a bimetallic/polydopamine network for enhanced guided bone regeneration.

The guided bone regeneration (GBR) technique is an effective treatment for small and medium-sized bone defects in the oral and maxillofacial region. However, currently available collagen membranes have limited functionality and are inadequate for clinical requirements. To address this challenge, this study pioneeringly developed a multifunctional bilayer membrane. Specifically, a bimetallic/polydopamine network (BPN), consisting of silver, magnesium, and dopamine, was successfully synthesized for the first time and integrated with collagen and hydroxyapatite. The resulting material was characterized, and its physicochemical properties, along with its barrier, osteogenic, angiogenic, antibacterial, hemostatic, and biosafety effects, were evaluated through both in vitro and in vivo studies. The results indicated that the BPN, composed of magnesium ions, silver nanoparticles (Ag NPs), and polydopamine (PDA), exhibited excellent thermal stability and slow release of silver and magnesium elements. The BPN/Col-HA membrane featured a bilayer structure with uniform distribution of silver and magnesium. It also demonstrated good hydrophilicity, suitable degradation and mechanical properties, as well as sustained release of silver and magnesium. In vitro experiments showed that the BPN/Col-HA membrane possessed desirable barrier, osteogenic, angiogenic, antibacterial, hemostatic, and biocompatible properties. In vivo results further confirmed its biosafety, hemostatic efficacy, and ability to effectively promote bone defect repair and angiogenesis. Thus, the BPN/Col-HA membrane emerges as a multifunctional GBR membrane with potential for clinical translation.

Effect of denture base acrylic resin containing silver nanoparticles on Candida Albicans adhesion and its release in artificial saliva

Background Candida albicans was considered a main reason of precipitate formations and decomposition of acrylic denture base; so many trials were objected to resist this microbial action and prolong the shelf life of the formulated fitting base. Aim of the work The present study aimed to adopt a new mixture of the silver nanoparticles with the PMMA denture base to get a prolonged antimicrobial protection for the formed base against Candida albicans. Statement of problem Accumulation of Candida Albicans on fitting surface of poly methyl meth-acrylate (PMMA) denture base. Purpose To evaluate the effect of denture base acrylic resin containing silver Nanoparticles (Ag NP) on Candida Albicans adhesion and its release in artificial saliva. Materials and methods Sixty round disks with dimensions of 15 mm diameter and 3 mm thickness specimens were prepared for this research. Control group A: 10 specimens were prepared from pure PMMA. Experimental group B: 50 specimens were prepared from PMMA containing 5% of Ag NP. Isolation and identification of Candida Albicans were taken from oral cavity of 10 patients by swabbing. The Specimens were immersed in artificial saliva for 3, 6, and 9 months. Microbiological test was done for specimens of each group to detect Candida Albicans accumulation at the same interval period by measuring the inhibition zone created around the disks. Specimens were taken from the artificial saliva to evaluate silver release in it by using UV-Vis Spectrophotometer Instrument ‘SHIMADZO UV-310 PC. For Spectrophotometer 1.0 cm and/or 0.2 cm matched silica cells. The amount of accumulated silver released was calculated to detect its cytotoxic effect1. Results For control group A there was no inhibition zone for Candida growth around the specimens. While for group B with Ag NP the greatest antimicrobial effect was found at zero time then was decreased gradually with increasing the time till reaching zero effect after 9 months resembling the control group. The amount of Nano silver in artificial saliva after 3 months was found to be little then it was increased gradually with increasing time. Conclusion Adding Ag NP to PMMA denture base has antimicrobial effect against Candida Albicans for only 9 months; then there was no effect as silver was released in saliva. The amount of released silver was found to be with no cytotoxic effect.

Bayesian uncertainty quantification of tristructural isotropic particle fuel silver release: Decomposing model inadequacy plus experimental noise and parametric uncertainties

Tristructural isotropic (TRISO) particle fuel is one of the most promising fuel concepts enabling high temperature and high burnup reactor operation. One dominant source of radioactivity released from the TRISO particles is silver (Ag), which is subject to a high release fraction and long decay life compared to other fission products. Previous modeling efforts using the fuel performance code BISON indicated nonnegligible uncertainties in modeling the diffusion process of fission products in TRISO compared to the Advanced Gas Reactor experiments. The overall uncertainties observed when modeling the fission product diffusion can result from uncertainties in model parameters, noisy experimental measurements, and deficiencies in the developed models. The three types of underlying uncertainties have not yet been properly quantified in open literature. This paper presents the Bayesian uncertainty quantification (UQ) using massively parallelizable Markov chain Monte Carlo samplers. The uncertainties due to model parameters, model inadequacy, and experimental measurement noise are quantified, with the σ term used to represent the sum of the model inadequacy and measurement noise uncertainties. It is worth noting that this is the first time the σ term is inferred for nuclear fuel experiments, as compared to using prescribed values for uncertainty quantification in previous work. The parallelizable Markov chain Monte Carlo samplers efficiently infer the model parameters and the σ term, giving insight into physical parameters like diffusion coefficients and the combined model discrepancy and measurement noise. A subsequent forward uncertainty quantification (UQ) is also performed based on the calibration results to generate more accurate predictions of the Ag release. The model inadequacy plus experimental noise is the most dominant source of uncertainty compared to the parametric uncertainty. All the UQ analyses presented in this work are based on the second series of the irradiation experiments in the Advanced Gas Reactor program.

Green synthesized silver nanoparticles using the plant-based reducing agent Matricaria chamomilla induce cell death in colorectal cancer cells.

There is a need to treat cancer cells with safe and natural nanoparticles to avoid the side effects of chemotherapeutic agents. Chamomile is considered a safe, natural plant with anticancer activity. We synthesize simple, inexpensive, and eco-friendly silver nanoparticles (SNs) using Chamomile (CHM) to tune their anticancer properties. SN-CHM was synthesized by reducing 1 mM silver nitrate aqueous solution in 100 mL with the aqueous ethanolic flower extract of CHM (18 mg/mL, w/v). The reaction proceeded overnight at 600 rpm and 28°C. SN-CHM was characterized for their % yield, average diameter, charge, morphology, and silver release. Moreover, SN-CHM was investigated for its antioxidant and anticancer activities at 200 µg/mL and 5 mg/ mL, respectively. A 59.12% yield and a uniform SN-CHM size of 115 ± 3.1 nm with a ζ-potential of -27.67 ± (-3.92) mv were observed. The UV-visible absorption showed shifts from 379.5 to 383.5 nm for CHM and SN-CHM, respectively. Moreover, Ag+ was ultimately released from SN-CHM after 5 h. Fourier Transform Infrared Spectroscopy (FT-IR) showed characteristic absorption peaks of CHM and produced SN-CHM. Furthermore, SN-CHM showed moderate antioxidant activity. SN-CHM inhibited the % viability of SW620 and HT-29 cell lines at 20 μM. SN-CHM may also greatly upregulate the apoptotic gene BAX while considerably downregulating the anti-apoptotic genes BCL2 and BCL-Xl. CHM can be a safe soft drink, especially when conjugated with Ag ions as anticancer NPs. SN-CHM is considered potent anticancer activity against SW620, and HT-29 cell lines.

Cytocompatibility, antibacterial, and corrosion properties of chitosan/polymethacrylates and chitosan/poly(4-vinylpyridine) smart coatings, electrophoretically deposited on nanosilver-decorated titania nanotubes.

The development of novel implants subjected to surface modification to achieve high osteointegration properties at simultaneous antimicrobial activity is a highly current problem. This study involved different surface treatments of titanium surface, mainly by electrochemical oxidation to produce a nanotubular oxide layer (TNTs), a subsequent electrochemical reduction of silver nitrate and decoration of a nanotubular surface with silver nanoparticles (AgNPs), and finally electrophoretic deposition (EPD) of a composite of chitosan (CS) and either polymethacrylate-based copolymer Eudragit E 100 (EE100) or poly(4-vinylpyridine) (P4VP) coating. The effects of each stage of this multi-step modification were examined in terms of morphology, roughness, wettability, corrosion resistance, coating-substrate adhesion, antibacterial properties, and osteoblast cell adhesion and proliferation. The results showed that the titanium surface formed nanotubes (inner diameter of 97 ± 12 nm, length of 342 ± 36 nm) subsequently covered with silver nanoparticles (with a diameter of 88 ± 8 nm). Further, the silver-decorated nanotubes were tightly coated with biopolymer films. Most of the applied modifications increased both the roughness and the surface contact angle of the samples. The deposition of biopolymer coatings resulted in reduced burst release of silver. The coated samples revealed potent antimicrobial activity against both Gram-positive and Gram-negative bacteria. Total elimination (99.9%) of E. coli was recorded for a sample with CS/P4VP coating. Cytotoxicity results using hFOB 1.19, a human osteoblast cell line, showed that after 3 days the tested modifications did not affect the cellular growth according to the titanium control. The proposed innovative multilayer antibacterial coatings can be successful for titanium implants as effective postoperative anti-inflammation protection.

On-Demand Release of Anti-Infective Silver from a Novel Implant Coating Using High-Energy Focused Shock Waves.

Implant-related infections are a significant concern in orthopedic surgery. A novel anti-infective implant coating made of bioresorbable polymer with silver nitrate was developed. A controlled release of silver ions into the vicinity of the prosthesis can be triggered on-demand by extracorporeal shock waves to effectively combat all clinically relevant microorganisms. Microscopy techniques were used to examine the effects of shock wave application on coated titanium discs. Cytotoxicity was measured using a fibroblast proliferation assay. The anti-infective effect was assessed by monitoring the growth curves of three bacterial strains and by conventional culture. Microscopic analysis confirmed surface disruption of the coatings, with a complete release of silver in the focus area after shock wave application. Spectrometry detected an increase in silver concentration in the surrounding of the discs that surpassed the minimum inhibitory concentration (MIC) for both S. epidermidis RP62A and E. coli ATCC 25922. The released silver demonstrated an anti-infective effect, significantly inhibiting bacterial growth, especially at 6% and 8% silver concentrations. Cytotoxicity testing showed decreasing fibroblast viability with increasing silver concentration in the coating, with 6% silver maintaining viability above 25%. Compared to a commonly used electroplated silver coating on the market, the new coating demonstrated superior antimicrobial efficacy and lower cytotoxicity.

Fabrication of controlled-release silver nanoparticle polylactic acid microneedles with long-lasting antibacterial activity using a micro-molding solvent-casting technique.

Most topical drug delivery techniques do not provide therapeutic concentrations for treatment of surgical site and other local infections and, therefore, require some kind of enhancement, such as physical methods like microneedles, the subject of the present investigation. Here, controlled-release long-lasting antibacterial polylactic acid (PLA) microneedles containing 1, 3, and 5% silver nanoparticles (AgNP) were prepared using micro-molding solvent-casting technique. Microneedles were characterized using optical microscopy, SEM, FTIR, XRD, and DSC. Also, mechanical strength, barrier disruption ability, insertion depth, in-vitro release kinetics, antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa, and silver permeation through rat skin were studied. Microneedles showed good mechanical strength with no signs of failure at an optimum PLA concentration of 25%(w/v). FTIR revealed no chemical interaction between ingredients, and XRD confirmed presence of AgNP in microneedles. Microneedles penetrated the skin model at depth of up to 1143μm resulting 5-7 times increase in transepidermal water loss (TEWL). Release studies showed 2.2, 6.8, and 8.1µg silver release from the whole body (obeying Higuchi's release model) and 0.33, 0.45, and 0.78µg from the needles alone (obeying Fickian-cylindrical type release) for 1, 3, and 5% AgNP microneedles, respectively. Also, prolonged antibacterial activity (for 34days) was observed. Skin studies over 72h indicated that besides needles, silver is also released from the baseplate which had a marginal share in total silver permeation through the skin. In conclusion, a straightforward solvent-casting technique can be used to successfully prepare strong AgNP-containing PLA microneedles capable of long-lasting antibacterial activity.

Release of silver and titanium from face masks traded for the general population

Previous assessments of a selection of face masks intended for the general population in Belgium found that silver (Ag)-based biocides were present in masks advertised for antimicrobial properties; whereas titanium dioxide (TiO2) particles were detected in all the face masks in at least one layer corroborating its widespread use in the textile industry. The presence of Ag-based biocides and TiO2 particles in face masks raised questions on the possibility of release under normal wearing conditions, which could potentially cause a health risk to the consumers. Direct measurement of release of Ag and TiO2 particles during normal wearing is problematic by the lack of methodology to test release and to quantify inhaled particles. Therefore in this study, we investigated leaching experiments using artificial acid sweat as a method to evaluate the release of Ag-based biocides and TiO2 particles present in face masks. Leaching experiments were proposed as an alternative method to evaluate the quality of face masks, and as a higher tier method to assess face masks that are not safe-by-design. Results from leaching experiments showed that Ag was released in amounts varying from 0.03 up to 36 % of total Ag content, in four out of the eight face masks that claimed antimicrobial properties and that contained Ag. The leaching data of titanium (Ti) showed that despite TiO2 being detected in all face masks, only in one mask Ti was measured in detectable concentrations in artificial sweat (0.35 % of total Ti content). Comparison of leachable Ag and Ti with respective acceptable exposure limit values derived from inhalation exposure limits indicate that three face masks would need further risk assessment and could not be considered as intrinsically safe.

Novel alginate-amino fatty acid amide composite hybrid gel beads as nanocarriers for in vitro release of silver nanoparticles

Nanosilver has been found to be a more effective alternative to conventional antibiotics due to its unique mechanisms of action. To facilitate prolonged topical drug delivery, a highly efficient 2,6-diaminopyridine-based silver nanocomposite gels, extended 22DAP/alginate hybrid gels and core-shell shaped hybrid gel beads are developed for prolonged topical drug delivery applications. The research revealed the benefits of in situ formation of nanosilver within the 22DAP gel and gel beads. A comparative study was conducted on silver uptake and release in a single component 22DAP gel, extended 22DAP/alginate hybrid gel, and gel beads. The study showed that the 22DAP/alginate hybrid gel beads had better efficiency of silver uptake (∼10 equivalents) due to their large surface area. These nanocomposites have also demonstrated excellent control and slow release of nanosilver, making them ideal for prolonged drug release and antimicrobial applications. The nanosilver composite 22DAP/alginate gel beads were tested against S. aureus and E. coli to evaluate their antibacterial activity, and the results were promising. The bead shape of these nanocomposites is anticipated to increase their usability for wound repair, biosensors, bone healing, and surgical interventions.

Dealloying and polydopamine/silver coating on NiTi alloy for improved antibacterial activity

Improved bone bonding ability and antibacterial activity are two critical requirements for implants. In this work, novel dual surface modifications of dealloying and polydopamine/silver coating on a NiTi alloy were conducted. Scanning electron microscopy (SEM) results show a porous layer with interconnected micro- and nano-pores on the dealloyed NiTi alloy. Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) results confirm the formation of a polydopamine/silver coating on the surface of the dealloyed NiTi alloy. The silver nanoparticles (58.9 nm, in the polydopamine/silver coating) on the dealloyed NiTi alloy surface are smaller when compared with pristine NiTi alloy (73.1 nm). Moreover, the dealloyed NiTi alloy with polydopamine/silver coating exhibits better antibacterial activity against Escherichia coli (99.7%) and Staphylococcus aureus (99.4%) than pristine NiTi alloy with the same coating (97.3% and 96.5%, respectively), due to the larger surface area, higher silver content, and smaller silver nanoparticles that trigger more silver ion release. The combined dealloying and coating method is an effective way of increasing antibacterial activity of NiTi alloys. The findings presented in this work may provide a new guidance for the surface modification of NiTi implant materials.

Comparative study of extraction methods of silver species from faeces of animals fed with silver-based nanomaterials

Extractions methods based on ultrapure water, tetramethylammonium hydroxide (TMAH), and tetrasodium pyrophosphate (TSPP) were applied to faeces collected from two in vivo experiments of pigs and chickens fed with a silver-based nanomaterial to study the fate and speciation of silver. For TMAH extraction, cysteine and CaCl2 were used to evaluate their stabilization effect on the silver forms. The analytical techniques single-particle inductively coupled plasma mass spectrometry (SP-ICP-MS), hydrodynamic chromatography hyphenated to ICP-MS (HDC-ICP-MS) and asymmetric flow field flow fractionation coupled to ICP-MS (AF4-ICP-MS) were applied to the simultaneous detection of particulate and dissolved silver. Results have shown that water extraction was a suitable option to assess the environmental release of silver, with percentages of 3 and 9% for faeces of pigs and chickens, respectively. The use of TMAH extraction combined with SP-ICP-MS analysis was useful to characterize Ag-containing particles (less than 1%). Both stabilizers, cysteine and CaCl2, have a similar effect on silver nanoparticle preservation for chicken faeces, whereas cysteine-Triton was better for pig samples. In any case, silver extraction efficiency with TMAH was low (39–42%) for both types of faeces due to a matrix effect. TSPP followed by ICP-MS enabled the fractionation of the silver in the faeces, with silver sulphide (41%) and ionic silver (62%) being the most abundant fractions.Graphical

Silver-manganese mixed oxide with crednerite structure as a catalyst for low-temperature catalytic CO oxidation

The paper describes the conditions for the preparation of AgMnO2 particles with the crednerite structure without impurity crystallized phases. It was shown that catalytic properties of AgMnO2 in CO oxidation might be different in dependence on the nature of the alkali-containing precursor used. The highest catalytic activity was achieved when using a combination of K- and Na-containing precursors. It has been found that the low-temperature catalytic activity of AgMnO2 increases noticeably with a decrease in the relative silver amount. An in situ X-ray diffraction study revealed a partial release of silver from crednerite structure with the formation of Ag0 particles when AgMnO2 was heated in a CO+O2 mixture to 150–200 °C, whereas heating to 250 °C followed by cooling to room temperature led to the incorporation of silver back into crednerite structure. The low-temperature catalytic activity of AgMnO2 correlates with the amount of weakly bounded oxygen species on the surface.

Silver release from dentine treated with combinations of silver diamine fluoride, potassium iodide and etching

For individuals with very high to extremely high caries activity and poor control of daily oral hygiene, a simple treatment for arresting their caries activity is necessary. Silver Diamine Fluoride (SDF) has become increasingly common for this purpose due to its efficacy and ease of application. To avoid or reduce tooth discoloration after SDF treatment potassium iodide (KI) may be applied. However, the release of silver from SDF-treated tooth surfaces may be of concern. Thus, the aim of the present study was to quantify the amount of silver leached in both a short- and long-term perspective. In this in vitro experiment we measured the cumulative release of silver from SDF-treated dentin surfaces with and without imminent application of KI, and with and without phosphoric acid etching as pre-treatment, after 24 h and weekly for four weeks. The release of silver was highest after 24 h for all treatment groups, with a significant drop after this point. When etching was not used, the use of KI did not affect the release of silver. However, when etching was used, there was a significantly lower silver release when KI was also used compared to when KI was not used. This effect was largest for the first two weeks, after which the difference was smaller as all groups released low amounts of silver.

Asymmetric synthesis of a novel “dual-matrix” mixed matrix membrane (MMM) and its food applications

The purpose of this study is to develop a ternary mixed matrix membrane (MMM) for food packaging using activation-graft-polymerization method. In this work, poly ether sulfone (PES) was activated by introducing -SO3H groups to establish a supported layer. Ag0 nanoparticles (AgNPs) were introduced on the activated surface of PES as functional fillers. Polyamide (PA) layer was formed as surface protective layer through interfacial polymerization of m-phenylenediamine and trimesoyl chloride. A series of physical and chemical assays were preformed to characterize the physical and chemical properties of the MMM. Results revealed that the antimicrobial rate of MMM for suspensions exceeded 86 %, while the silver release from the packaging was within the safety limit (below 100 µg/L). The prepared MMM was used as fresh-keeping packaging to preserve frozen salmon samples. It significantly slowed down the decline process of samples’ quality indexes, greatly extending the shelf life of preserved fish (26 % ∼ 47 %). The overall research results revealed the significant potential of the prepared MMM in food applications.

Optimization of crystal violet photodegradation and investigation of the antibacterial performance by silver-doped titanium dioxide/graphene aerogel nanocomposite

In this study, silver-doped titanium dioxide/graphene aerogel (Ag–TiO2/GA ‒ ATG) was synthesized using the simple hydrothermal method with different Ag contents. The obtained materials were characterized by various modern analytical methods, in which the ATG50 sample, prepared with 50 mg of AgNO3, demonstrated the highest photodegradation performance towards crystal violet (CV). The individual and simultaneous effects of crucial factors, namely pH, CV concentration, catalyst dose, adsorption time, and photodegradation time on the photocatalytic efficiency were evaluated via Plackett-Burman and Box-Behnken models, respectively, which revealed up to 99.95% of removal efficiency at pH 6.5, 25 mg/L of the dye, and 29 mg of catalyst. Besides, ATG50 also achieved notable photodegradation potentials against methylene blue and indigo carmine with 97.11 and 53.22% of elimination, respectively, whilst a sufficient silver release and great reusability were acquired even after the 5th recycling run. And the antibacterial activity of the as-chosen ATG50 was also affirmed against Staphylococcus aureus and Escherichia coli. Therefore, the acquired results elucidate the synthesized ATG material as a promising solution for the treatment of organic dyes in wastewater and antibacterial applications.

Facile One-Step Electrospinning Process to Prepare AgNPs-Loaded PLA and PLA/PEO Mats with Antibacterial Activity.

Nanofibers can play an important role in developing new kinds of medical applications. Poly(lactic acid) (PLA) and PLA/poly(ethylene oxide) (PEO) antibacterial mats containing silver nanoparticles (AgNPs) were prepared by a simple one-step electrospinning method that allows AgNPs to be synthesized simultaneously with the preparation of the electrospinning solution. The electrospun nanofibers were characterized by scanning electron microscopy, transmission electron microscopy and thermogravimetry, while silver release over time was monitored by inductively coupled plasma/optical emission spectroscopy. The antibacterial activity was tested against Staphylococcus epidermidis and Escherichia coli by colony forming unit (CFU) count on agar after 15, 24 and 48 h of incubation. AgNPs were found to be mainly concentrated in the PLA nanofiber core, and the mats showed steady but slow Ag release in the short term; in contrast, AgNPs were uniformly distributed in the PLA/PEO nanofibers, which released up to 20% of their initial silver content in 12 h. A significant (p < 0.05) antimicrobial effect towards both tested bacteria, highlighted by a reduction in the CFU/mL counts, was observed for the nanofibers of PLA and PLA/PEO embedded with AgNPs, with a stronger effect exerted by the latter, confirming the more efficient silver release from these samples. The prepared electrospun mats may have good potential for use in the biomedical field, particularly in wound dressing applications, where a targeted delivery of the antimicrobial agent is highly desirable to avoid infections.