Supported-adsorbents growing on the substrate in situ are equipped with the advantages of high adsorption capacity, excellent regeneration performance, and adaptability to complex wastewater. However, the effects of substrate on the adsorption properties of supported-adsorbent are rarely considered, which will hinder its development and scale-up applications. In this study, the influences of different substrates (Ti, Mo, W, CC) on the Ag+ adsorption behavior of supported-MoS2 adsorbents were investigated. The adsorption kinetics, adsorption mechanism, and the renewability of these supported-MoS2 were compared orderly. As a result, MoS2 grown on a tungsten substrate (MoS2-W) exhibits a remarkable adsorption capacity for Ag+ (1.98 mg cm-2 and 598.80 mg g-1), which is 6.38-33 times more than the other three supported-MoS2. Moreover, the MoS2-W also possesses an ultrahigh distribution coefficient (24.80 mL cm-2) for Ag+, and the selection coefficient can reach 1984. XRD and electrochemical characterization analysis indicated that Ag+ adsorption performance of supported-MoS2 is positively correlated with the degree of its amorphous structure. Substrate W with the terrific electrical properties which may facilitate the disordered growth of MoS2, resulting in more active sites exposed, and endow MoS2-W with outstanding Ag+ capture performance. Finally, the supported-MoS2 retains a high removal efficiency of Ag+ after 5 cycles of adsorption and desorption. This study provides a novel perspective for promoting the practical application of supported-sorbents to recycle heavy metals.

Background: A new silver-based dressing has been designed to reduce surgical sited infections. Patients and Methods: A prospective multicenter observational study was conducted from January 2020 to October 2021. Patients with and without silver-based dressing after surgical incision were observed and their data analyzed. The study aimed to assess the incidence of incisional surgical site infection and primary healing after general surgery procedures. Results: Overall, 218 patients with silver-based (n = 109) and conventional silver-free dressing (n = 109) were analyzed. Surgical site infection (SSI) and primary incision healing were reported in 10 (9.2%) versus 21 (19.3%) (p = 0.037) and in 95 (87.2%) versus 86 (78.9%) (p = 0.107) patients treated with and without silver-based dressing, respectively. Conclusions: Silver-based dressing demonstrated a lower incidence of incisional SSI and improved primary healing in comparison with patients in whom conventional non-silver-based dressing has been used.

Bacteriostatic action of a biocidal agent results from the cumulative impact of different kinetics, including those of bacterial growth, mass transfer of the agent and its antibacterial action against the targeted bacteria. Current studies on bacteriostatic effects always directly consider the combination of these kinetics at given times, without discrimination between each other. This work introduces a novel approach, consisting of first studying independently, by the experiment and the model, the different kinetics involved, and then in coupling these kinetics to obtain a model that will be confronted with experimental data. An agar diffusion test with silver ions against Escherichia coli bacteria was implemented herein to assess the relevance of this approach. This work achieved to characterize the different kinetics and to propose a dynamic model combining them, which fits the experimental data with a silver diffusivity in the biofilm fixed to 7.0 ± 0.1 × 10-12 m2 s-1. This study also proves that the diffusive phenomenon was limiting the bacteriostatic action of silver ions over the test duration.

Both commercial and experimental antibacterial urinary catheters were investigated for their efficacy in preventing planktonic growth and biofilm formation of Escherichia Coli bacteria in a synthetic urine solution. Experimental antibacterial catheters having thin (<500 µm) dispersions of Ag, Ag/Ag2O, or Zn/Ag2O in polydimethylsiloxane (PDMS) binder all exhibited significant antimicrobial activity, outperforming traditional commercial antibacterial catheters. All experimental catheters prevented planktonic growth of bacteria and did not exhibit biofilm formation during a six-day test period using a colony forming unit (CFU) measurement method. On the other hand, the best performing commercial catheters demonstrated efficacy for only 3 days in planktonic growth tests and formed multiple bacterial colonies in CFU measurements. The Zn/Ag2O/PDMS experimental catheter was the only catheter observed to produce hydrogen peroxide, a reactive oxygen species known to inhibit biofilm formation; lack of detectable hydrogen peroxide production by the Ag2O/PDMS and Ag/Ag2O/PDMS experimental catheters suggests that bactericidal action most likely arises from release of silver ions present in the PDMS coatings.

BACKGROUND: The wide application of silver nanoparticles (AgNPs) in medicals and daily utensils increases the risk of human exposure. The study on cell and protein changes induced by medical AgNPs (20 nm) and Ag+ gave insights into the toxicity mechanisms of them.
RESULTS: AgNPs and Ag+ affected the enzymatic and non-enzymatic antioxidant systems of red blood cells (RBCs). When RBCs were exposed to AgNPs or Ag+ (0-0.24 μg/mL), catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPX) were more sensitive to Ag+, whereas the RBCs had slightly higher glutathione (GSH) contents treated by AgNPs. Both AgNPs and Ag+ increased the malondialdehyde (MDA) content of RBCs, but the difference was not significant. The difference in the change of the enzyme activity indicated that AgNPs and Ag+ have different influencing mechanisms on CAT and GPX. And SOD has stronger resistance to both of AgNPs and Ag+. When AgNPs or Ag+ (0-10 μg/mL) was directly applied on enzymatic proteins, although AgNPs or Ag+ at a high concentration was toxic, at the concentration below 0.4 μg/mL could promote the activities of CAT/SOD/GPX. The spectroscopic results (fluorescence, synchronous fluorescence, resonance light scattering and ultraviolet absorption), including the changes in amino acid microenvironment, peptide chain conformation, and aggregation state, indicated that the interaction mechanism and conformational changes were also the important factors for the changes in the activities of SOD/CAT when SOD/CAT were directly exposed to AgNPs or Ag+.
CONCLUSIONS: Low concentration (< 0.4 μg/mL) of AgNPs is relatively safe and the direct effects of AgNPs and Ag+ on enzymes are important reasons for the change in antioxidant capacity of RBCs.

It is still unclear whether the toxicity of silver nanoparticles (AgNPs) can be attributed solely to the release of Ag+ or whether dissolved and nanoparticulate Ag act in parallel; this is due to the difficulty in distinguishing Ag+- from AgNP-effects. Also, AgNPs undergo changes during toxicity tests. This is the first study to investigate the influence of AgNP dissolution over time on viable counts at high time resolution and low cell density, avoiding the apparently reduced toxicity at higher cell densities identified in our study. Uncapped AgNPs were synthesized to avoid any interference from surface coatings. The transformations of AgNPs during storage were reduced. Lowering the concentration of AgNPs reduced their aggregation in Davis minimal medium (DMM). Also, AgNPs dissolved more slowly in DMM than in water. The minimum inhibitory concentrations (MICs) of Ag+ and AgNPs increased with cell density according to a power law, suggesting that binding to cells decreased effective concentrations. However, AgNPs acted as a reservoir of Ag, releasing new Ag+ to maintain the Ag stress. The toxicity of AgNPs was dominated by dissolved Ag. Combining controlled conditions, high time-resolution and low cell density, we could demonstrate different roles of ionic and nano Ag in bacterial death caused by AgNPs.

Laboratory studies have shown that small concentrations of silver are effective at inhibiting the growth micro-organisms through the disruption of important cell structures and processes. The additional ability to incorporate silver into surfaces has increased the usage of silver in the medical field and expanded its use into the consumer market. To understand the impact of increased silver-containing antimicrobial use, it is important to determine whether silver-based consumer goods are effective at reducing bacterial populations. Our study examined the antibacterial effectiveness of Agion silver zeolite technology applied to 25 silver- and control-coated door handles across a college campus. Door handles were sampled for 6 week periods in both the fall and spring semester, and bacteria were cultured and enumerated on tryptic soy agar (TSA), MacConkey agar (MAC) and mannitol salt agar (MSA). A significant difference was observed between the bacterial populations isolated from silver- and control-coated door handles after 3 years. However, bacteria were consistently isolated from silver-coated door handles suggesting that the silver zeolite was only effective against a portion of the bacterial populations, and further studies are necessary to determine the identities of the isolated bacteria and the prevalence of silver resistance.