Mechanisms underlying the potent antimicrobial effects of plasma-activated seawater (PASW) on fish spoilage bacterium Shewanella putrefaciens.

Plasma-activated seawater (PASW) presents a promising approach for marine fish preservation, yet its antimicrobial efficacy and mechanisms remain unclear. This study found that PASW exhibits superior bactericidal properties against the fish spoilage bacterium Shewanella putrefaciens compared to plasma-activated water (PAW), and increased effectiveness in preserving fish fillets. To clarify the mechanisms, a detailed investigation was conducted, including the generation of reactive oxygen/nitrogen species (ROS/RNS) and active halogen species in PASW, and their antimicrobial efficacy. Findings showed greater nitrite and hydrogen peroxide production in PASW relative to PAW, as well as the conversion of chloride/bromide ions into active species, which collectively enhanced PASW's antimicrobial activity. The synergistic action of ROS/RNS and active chlorine/bromine species in PASW promoted the generation of intracellular ROS, causing increased membrane damage, redox imbalance, and consequently higher bacterial mortality. This study enhances our understanding of PASW's antimicrobial effects and highlights its potential applications in the seafood industry.

Antibacterial activity of ibezapolstat against antimicrobial-resistant clinical strains of Clostridioides difficile.

Antimicrobial resistance is emerging in clinical strains of Clostridioides difficile. Ibezapolstat (IBZ) is a DNA polymerase IIIC inhibitor that has completed phase II clinical trials. IBZ has potent in vitro activity against wild-type, susceptible strains but its effect on C. difficile strains with reduced susceptibility to metronidazole (MTZ), vancomycin (VAN), or fidaxomicin (FDX) has not been tested. The primary objective of this study was to test the antibacterial properties of IBZ against multidrug-resistant C. difficile strains. The in vitro activity, bactericidal, and time-kill activity of IBZ versus comparators were evaluated against 100 clinical strains of which 59 had reduced susceptibility to other C. difficile antibiotics. Morphologic changes against a multidrug resistance strain were visualized by light and scanning electron microscopy. The overall IBZ MIC50/90 values (µg/mL) for evaluated C. difficile strains were 4/8, compared with 2/4 for VAN, 0.5/1 for FDX, and 0.25/4 for MTZ. IBZ MIC50/90 values did not differ based on non-susceptibility to antibiotic class or number of classes to which strains were non-susceptible. IBZ bactericidal activity was similar to the minimum inhibitory concentration (MIC) and maintained in wild-type and non-susceptible strains. Time-kill assays against two laboratory wild-type and two clinical non-susceptible strains demonstrated sustained IBZ activity despite reduced killing by comparator antibiotics for IBZ and VAN non-susceptible strains. Microscopy visualized increased cell lengthening and cellular damage in multidrug-resistant strains exposed to IBZ sub-MIC concentrations. This study demonstrated the potent antibacterial activity of IBZ against a large collection of C. difficile strains including multidrug-resistant strains. This study highlights the therapeutic potential of IBZ against multidrug-resistant strains of C. difficile.

Galacto-Oligosaccharides as an Anti-Infective and Anti-Microbial Agent for Macrolide-Resistant and -Sensitive Mycoplasma pneumoniae.

The worldwide increase in the incidence of antibiotic resistance of the atypical bacterium Mycoplasma pneumoniae (MP) challenges the treatment of MP infections, especially in children. Therefore, alternative strategies for the treatment of MP infections are warranted. Galacto- and fructo-oligosaccharides (GOS and FOS) are a specific group of complex carbohydrates that were recently shown to possess direct anti-pathogenic properties. In this study, we assessed whether GOS and FOS exert anti-microbial and anti-infective effects against MP and, especially, macrolide-resistant MP (MRMP) in vitro. The MIC values of GOS for MP and MRMP were 4%. In contrast, the MIC values of FOS for both MP and MRMP were 16%. A time-kill kinetic assay showed that FOS possess bacteriostatic properties, while for GOS, a bactericidal effect against MP and MRMP was observed after 24 h at a concentration of 4x MIC. In co-cultures with human alveolar A549 epithelial cells, GOS killed adherent MP and MRMP and also concentration-dependently inhibited their adherence to A549 cells. Further, GOS suppressed (MR)MP-induced IL-6 and IL-8 in A549 cells. None of the aforementioned parameters were affected when FOS were added to these co-cultures. In conclusion, the anti-infective and anti-microbial properties of GOS could provide an alternative treatment against MRMP and MP infections.

Cytotoxic and Bactericidal Effects of Inhalable Ciprofloxacin-Loaded Poly(2-ethyl-2-oxazoline) Nanoparticles with Traces of Zinc Oxide.

The bactericidal effects of inhalable ciprofloxacin (CIP) loaded-poly(2-ethyl-2-oxazoline) (PEtOx) nanoparticles (NPs) with traces of zinc oxide (ZnO) were investigated against clinical strains of the respiratory pathogens Staphylococcus aureus and Pseudomonas aeruginosa. CIP-loaded PEtOx NPs retained their bactericidal activity within the formulations compared to free CIP drugs against these two pathogens, and bactericidal effects were enhanced with the inclusion of ZnO. PEtOx polymer and ZnO NPs did not show bactericidal activity alone or in combination against these pathogens. The formulations were tested to determine the cytotoxic and proinflammatory effects on airway epithelial cells derived from healthy donors (NHBE), donors with chronic obstructive pulmonary disease (COPD, DHBE), and a cell line derived from adults with cystic fibrosis (CFBE41o-) and macrophages from healthy adult controls (HCs), and those with either COPD or CF. NHBE cells demonstrated maximum cell viability (66%) against CIP-loaded PEtOx NPs with the half maximal inhibitory concentration (IC50) value of 50.7 mg/mL. CIP-loaded PEtOx NPs were more toxic to epithelial cells from donors with respiratory diseases than NHBEs, with respective IC50 values of 0.103 mg/mL for DHBEs and 0.514 mg/mL for CFBE41o- cells. However, high concentrations of CIP-loaded PEtOx NPs were toxic to macrophages, with respective IC50 values of 0.002 mg/mL for HC macrophages and 0.021 mg/mL for CF-like macrophages. PEtOx NPs, ZnO NPs, and ZnO-PEtOx NPs with no drug were not cytotoxic to any cells investigated. The in vitro digestibility of PEtOx and its NPs was investigated in simulated lung fluid (SLF) (pH 7.4). The analysed samples were characterized using Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), and UV-Vis spectroscopy. Digestion of PEtOx NPs commenced one week following incubation and was completely digested after four weeks; however, the original PEtOx was not digested after six weeks of incubation. The outcome of this study revealed that PEtOx polymer could be considered an efficient drug delivery carrier in respiratory linings, and CIP-loaded PEtOx NPs with traces of ZnO could be a promising addition to inhalable treatments against resistant bacteria with reduced toxicity.

Carotenoids and Their Health Benefits as Derived via Their Interactions with Gut Microbiota.

Carotenoids have been related to a number of health benefits. Their dietary intake and circulating levels have been associated with a reduced incidence of obesity, diabetes, certain types of cancer, and even lower total mortality. Their potential interaction with the gut microbiota (GM) has been generally overlooked but may be of relevance, as carotenoids largely bypass absorption in the small intestine and are passed on to the colon, where they appear to be in part degraded into unknown metabolites. These may include apo-carotenoids that may have biological effects because of higher aqueous solubility and higher electrophilicity that could better target transcription factors, i.e., NF-κB, PPARγ, and RAR/RXRs. If absorbed in the colon, they could have both local and systemic effects. Certain microbes that may be supplemented were also reported to produce carotenoids in the colon. Although some bactericidal aspects of carotenoids have been shown in vitro, a few studies have also demonstrated a prebiotic-like effect, resulting in bacterial shifts with health-associated properties. Also, stimulation of IgA could play a role in this respect. Carotenoids may further contribute to mucosal and gut barrier health, such as stabilizing tight junctions. This review highlights potential gut-related health-beneficial effects of carotenoids and emphasizes the current research gaps regarding carotenoid-GM interactions.

Efficient inactivation of the contamination with pathogenic microorganisms by a combination of water spray and plasma-activated air.

The global pandemic caused by SARS-CoV-2 has lasted two and a half years and the infections caused by the viral contamination are still occurring. Developing efficient disinfection technology is crucial for the current epidemic or infectious diseases caused by other pathogenic microorganisms. Gas plasma can efficiently inactivate different microorganisms, therefore, in this study, a combination of water spray and plasma-activated air was established for the disinfection of pathogenic microorganisms. The combined treatment efficiently inactivated the Omicron-pseudovirus through caused the nitration modification of the spike proteins and also the pathogenic bacteria. The combined treatment was improved with a funnel-shaped nozzle to form a temporary relatively sealed environment for the treatment of the contaminated area. The improved device could efficiently inactivate the Omicron-pseudovirus and bacteria on the surface of different materials including quartz, metal, leather, plastic, and cardboard and the particle size of the water spray did not affect the inactivation effects. This study supplied a disinfection strategy based on plasma-activated air for the inactivation of contaminated pathogenic microorganisms.

Disrupting biofilm and eradicating bacteria by Ag-Fe3O4@MoS2 MNPs nanocomposite carrying enzyme and antibiotics.

In this study, novel multilayered magnetic nanoparticles (ML-MNPs) loaded with DNase and/or vancomycin (Vanc) were fabricated for eliminating multispecies biofilms. Iron-oxide MNPs (IO-core) (500-800 nm) were synthesized via co-precipitation; further, the IO-core was coated with heavy-metal-based layers (Ag and MoS2 NPs) using solvent evaporation. DNase and Vanc were loaded onto the outermost layer of the ML-MNP formed by nanoporous MoS2 NPs through physical deposition and adsorption. The biofilms of S. mutans or E. faecalis (or both) were formed in a brain-heart-infusion broth (BHI) for 3 days, followed by treatment with ML-MNPs for 24 h. The results revealed that coatings of Ag (200 nm) and ultrasmall MoS2 (20 nm) were assembled as outer layers of ML-MNPs successfully, and they formed Ag-Fe3O4@MoS2 MNPs (3-5 µm). The DNase-Vanc-loaded MNPs caused nanochannels digging and resulted in the enhanced penetration of MNPs towards the bottom layers of biofilm, which resulted in a decrease in the thickness of the 72-h biofilm from 48 to 58 µm to 0-4 µm. The sustained release of Vanc caused a synergistic bacterial killing up to 96%-100%. The heavy-metal-based layers of MNPs act as nanozymes to interfere with bacterial metabolism and proliferation, which adversely affects biofilm integrity. Further, loading DNase/Vanc onto the nanoporous-MoS2-layer of ML-MNPs promoted nanochannel creation through the biofilm. Therefore, DNase-and Vanc-loaded ML-MNPs exhibited potent effects on biofilm disruption and bacterial killing.

Evaluation of Bactericidal Effects of H2- and O3-filled Ultrafine Bubbles Water.

Ultrafine bubbles (UFBs) are gaining attention in diverse industries as a new type of material with specific physical properties. Bactericidal activity has been reported as one of the unique properties of UFB water; however, the bactericidal activities of UFBs related to the gas type remain unclear. In particular, the bactericidal effect of hydrogen (H2) -filled UFB water has not been verified. Therefore, this study aimed to evaluate the bactericidal effects of H2- or ozone (O3) -filled UFB water using a bacterial suspension test. The results of this study clearly showed that H2- or O3-filled UFB water had strong bactericidal activity. Exposure of Escherichia coli for 6 h and Staphylococcus aureus for 3 h reduced the survival rate of those bacteria by >90%. This finding suggests that both O3 gas- and H2-filled UFBs are novel environmentally friendly disinfectants that can be employed to avoid the use of chemicals.

Therapeutic stem cell-derived alveolar-like macrophages display bactericidal effects and resolve Pseudomonas aeruginosa-induced lung injury.

Bacterial lung infections lead to greater than 4 million deaths per year with antibiotic treatments driving an increase in antibiotic resistance and a need to establish new therapeutic approaches. Recently, we have generated mouse and rat stem cell-derived alveolar-like macrophages (ALMs), which like primary alveolar macrophages (1'AMs), phagocytose bacteria and promote airway repair. Our aim was to further characterize ALMs and determine their bactericidal capabilities. The characterization of ALMs showed that they share known 1'AM cell surface markers, but unlike 1'AMs are highly proliferative in vitro. ALMs effectively phagocytose and kill laboratory strains of P. aeruginosa (P.A.), E. coli (E.C.) and S. aureus, and clinical strains of P.A. In vivo, ALMs remain viable, adapt additional features of native 1'AMs, but proliferation is reduced. Mouse ALMs phagocytose P.A. and E.C. and rat ALMs phagocytose and kill P.A. within the lung 24 h post-instillation. In a pre-clinical model of P.A.-induced lung injury, rat ALM administration mitigated weight loss and resolved lung injury observed seven days post-instillation. Collectively, ALMs attenuate pulmonary bacterial infections and promote airway repair. ALMs could be utilized as an alternative or adjuvant therapy where current treatments are ineffective against antibiotic-resistant bacteria or to enhance routine antibiotic delivery.

Multicomponent Polyphenolic Extracts from Vaccinium corymbosum at Lab and Pilot Scale. Characterization and Effectivity against Nosocomial Pathogens.

An extraction method was designed and scaled up to produce multicomponent polyphenolic extracts from blueberries (Vaccinium corymbosum) of three different varieties. The process was specifically drawn up to comply with green chemistry principles. Extracts were obtained for the direct assessment of their antimicrobial and antiadhesive activities, and their direct use in the control of infections caused by concerning multidrug-resistant nosocomial pathogens. Analytical characterization was performed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Similar qualitative profiles were obtained in the three studied varieties with some significant quantitative differences. Up to 22 different polyphenols were identified with a clear predominance of anthocyani(di)ns followed by flavanols, non-flavonoids, and far behind by flavan-3-ols and procyanidins. The individual content of the main polyphenols was also discussed. A pilot scale extract has been also produced as a proof-of-concept, showing that scaling-up triples the content of bioactive phytochemicals. The effect of the polyphenolic extracts was analyzed against seven multidrug-resistance bacterial species by performing biofilm formation and growth and killing curves assays. All the studied varieties showed antibacterial and antiadhesive activities, being the extract containing the highest concentration of bioactive polyphenols, the most active with a high bactericidal effect.

relA Inactivation Converts Sulfonamides Into Bactericidal Compounds.

Folates are required for the de novo biosynthesis of purines, thymine, methionine, glycine, and pantothenic acid, key metabolites that bacterial cells cannot survive without. Sulfonamides, which inhibit bacterial folate biosynthesis and are generally considered as bacteriostats, have been extensively used as broad-spectrum antimicrobials for decades. Here we show that, deleting relA in Escherichia coli and other bacterial species converted sulfamethoxazole from a bacteriostat into a bactericide. Not as previously assumed, the bactericidal effect of SMX was not caused by thymine deficiency. When E. coli ∆relA was treated with SMX, reactive oxygen species and ferrous ion accumulated inside the bacterial cells, which caused extensive DNA double-strand breaks without the involvement of incomplete base excision repair. In addition, sulfamethoxazole showed bactericidal effect against E. coli O157 ∆relA in mice, suggesting the possibility of designing new potentiators for sulfonamides targeting RelA. Thus, our study uncovered the previously unknown bactericidal effects of sulfonamides, which advances our understanding of their mechanisms of action, and will facilitate the designing of new potentiators for them.

Traditional Chinese Medicine is an Alternative Therapeutic Option for Treatment of Pseudomonas aeruginosa Infections.

Pseudomonas aeruginosa is an opportunistic pathogen causing life-threatening infections in cystic fibrosis patients and immunocompromised individuals, and it is a leading cause of nosocomial infections associated with significant morbidity and mortality. Treatment of P. aeruginosa infections is challenging due to the antibiotic resistance to most of the conventional antibiotics. Development of alternative therapeutic options is urgently demanded for the patients who have antibiotic-resistant infections. Traditional Chinese medicine (TCM) has a clinical history of thousands of years for prevention and treatment of infectious diseases in China, taking advantages of improving clinical outcomes, producing less side effects, inhibiting pathogen, and modulating host immunity. Recent research has revealed a variety of natural products derived from TCM showing significant antimicrobial effects on antibiotic-resistant strains of P. aeruginosa alone or combined with antibiotics in vitro or in animal models, suggesting that TCM is a promising complementary and alternative therapeutic approach for treatment of chronic P. aeruginosa infections. This review summarizes the recent findings attempting to dissect the mechanisms of TCM combating P. aeruginosa infections and highlights the molecular targets of TCM on P. aeruginosa and host.

Solar-excited graphene quantum dots for bacterial inactivation via generation of reactive oxygen species.

Nanoscale photocatalysts have attracted abundant research attention in the solar-activated disinfection. In this work, we find that solar irradiation significantly improves the antimicrobial activity of graphene quantum dots (GQDs), accompanied by severe oxidative stress and membrane damage. By using electron spin resonance (ESR) technique, we confirm that different reactive oxygen species (ROS), including singlet oxygen (1O2), hydroxyl radical (•OH), and superoxide anion (O2•-) were generated by GQDs upon irradiation with simulated sunlight. Additionally, these generated ROS will further facilitate lipid peroxidation of cell membrane and suppress bacterial antioxidant systems, enhancing the phototoxicity of GQDs. These findings will bring major advancements of GQDs in applications of solar-driven bacterial disinfection.

Effectiveness of zinc oxide-assisted photocatalysis for concerned constituents in reclaimed wastewater: 1,4-Dioxane, trihalomethanes, antibiotics, antibiotic resistant bacteria (ARB), and antibiotic resistance genes (ARGs).

Microbial and emerging chemical contaminants are unwanted constituents in reclaimed wastewater, due to the health concerns of using the water for agricultural irrigation, aquifer recharges, and potable water. Removal of these contaminants is required but it is currently challenging, given that there is no simple treatment technology to effectively remove the mixture of these contaminants. This study examined the effectiveness of ZnO-assisted photocatalytic degradation of several constituents, including 1,4-dioxane, trihalomethanes (THMs), triclosan (TCS), triclocarban (TCC), antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARGs), under low intensity of UV exposure. E. coli with an ARGs-carrying circular plasmid (pUC19) was used as a model antibiotic resistant bacterium. Our results show that commercial zinc oxide (C-ZnO) assisted photodegradation of 1,4-dioxane, and dehalogenation of THMs, TCS, and TCC, while tetrapodal zinc oxide (T-ZnO) enhanced the dehalogenation of TCS and TCC. Additionally, T-ZnO assisted the photocatalytic inactivation of the E. coli within 6 h and caused structural changes in the plasmid DNA (pUC19) with additional UV exposure, resulting in non-functional AGR-containing plasmids. These results also suggest that higher UV dose is required not only to inactivate ARB but also to damage ARGs in the ARB in order to decrease risks in promoting ARB population in the environment. Overall, our results implicated that, under low UV intensity, ZnO-assisted photocatalysis is a promising alternative to simultaneously remove biological and emerging chemical contaminants in treated wastewater for safe reuse.

Nanostructured Ag+-substituted fluorhydroxyapatite-TiO2 coatings for enhanced bactericidal effects and osteoinductivity of Ti for biomedical applications.

BACKGROUND: Poor mechanical properties, undesirable fast dissolution rate, and lack of antibacterial activity limit the application of hydroxyapatite (HA) as an implant coating material. To overcome these limitations, a hybrid coating of Ag+-substituted fluorhydroxyapatite and titania nanotube (TNT) was prepared. METHODS: The incorporation of silver into the HA-TiO2 hybrid coating improves its antimicrobial properties. The addition of F as a second binary element increases the structural stability of the coating. The TNT/F-and-Ag-substituted HA (FAgHA) bilayer coating on the Ti substrate was confirmed by X-ray diffraction, scanning electron microscope, energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). RESULTS: The results indicate that the FAgHA/TNT nanocomposite coating has a dense and uniform morphology with a nano-rod-like structure. The solubility measurement result shows that the substitution of F- ions into the AgHA structure has a positive effect on the dissolution resistance of HA. The adhesion strength of FAgHA/TNT has significantly increased because of the interlocking of the roughened surface with nano-rod-like particles that entered into the voids of the TiO2 nanotubes. Compared with that of the bare Ti, the corrosion current density of FAgHA/TNT-coated Ti substrate decreased from 3.71 to 0.18 µA, and its corrosion resistance increased by almost two orders of magnitude. Moreover, despite pure HA, the FAgHA killed all viable Staphylococcus aureus after 24 hours of incubation. Although the fabricated FAgHA/TNT coating is hydrophobic, it induced deposition of the typical spherical apatite when immersed in a simulated body fluid (SBF); the osteoblasts spread very well on the surface of the coating. In addition, in vitro cell culture tests demonstrated cell viability and alkaline phosphatase (ALP) similar to pure HA, which indicated good cytocompatibility. Interestingly, compared with bare Ti, FAgHA/TNT-coated Ti surface was innocent for cell vitality and even more beneficial for cell osteogenesis in vitro. CONCLUSION: Enhancing the osseointegration and preventing infection in implants, the FAgHA/TNT-coated Ti makes implants more successful.

Effects of Extended Storage of Chlorhexidine Gluconate and Benzalkonium Chloride Solutions on the Viability of Burkholderia cenocepacia.

Chlorhexidine gluconate (CHX) and benzalkonium chloride (BZK) formulations are frequently used as antiseptics in healthcare and consumer products. Burkholderia cepacia complex (BCC) contamination of pharmaceutical products could be due to the use of contaminated water in the manufacturing process, over-diluted antiseptic solutions in the product, and the use of outdated products, which in turn reduces the antimicrobial activity of CHX and BZK. To establish a "safe use" period following opening containers of CHX and BZK, we measured the antimicrobial effects of CHX (2-10 µg/ml) and BZK (10-50 µg/ml) at sublethal concentrations on six strains of Burkholderia cenocepacia using chemical and microbiological assays. CHX (2, 4, and 10 µg/ml) and BZK (10, 20, and 50 µg/ml) stored for 42 days at 23°C showed almost the same concentration and toxicity compared with freshly prepared CHX and BZK on B. cenocepacia strains. When 5 µg/ml CHX and 20 µg/ml BZK were spiked to six B. cenocepacia strains with different inoculum sizes (10° -105 CFU/ml), their toxic effects were not changed for 28 days. B. cenocepacia strains in diluted CHX and BZK were detectable at concentrations up to 10² CFU/ml after incubation for 28 days at 23°C. Although abiotic and biotic changes in the toxicity of both antiseptics were not observed, our results indicate that B. cenocepacia strains could remain viable in CHX and BZK for 28 days, which in turn, indicates the importance of control measures to monitor BCC contamination in pharmaceutical products.

Bactericidal and antimicrobial effects of pure titanium and titanium alloy treated with short-term, low-energy UV irradiation.

OBJECTIVES: The surface of pure titanium (Ti) shows decreased histocompatibility over time; this phenomenon is known as biological ageing. UV irradiation enables the reversal of biological ageing through photofunctionalisation, a physicochemical alteration of the titanium surface. Ti implants are sterilised by UV irradiation in dental surgery. However, orthopaedic biomaterials are usually composed of the alloy Ti6Al4V, for which the antibacterial effects of UV irradiation are unconfirmed. Here we evaluated the bactericidal and antimicrobial effects of treating Ti and Ti6Al4V with UV irradiation of a lower and briefer dose than previously reported, for applications in implant surgery. MATERIALS AND METHODS: Ti and Ti6Al4V disks were prepared. To evaluate the bactericidal effect of UV irradiation, Staphylococcus aureus 834 suspension was seeded onto the disks, which were then exposed to UV light for 15 minutes at a dose of 9 J/cm2. To evaluate the antimicrobial activity of UV irradiation, bacterial suspensions were seeded onto the disks 0, 0.5, one, six, 24 and 48 hours, and three and seven days after UV irradiation as described above. In both experiments, the bacteria were then harvested, cultured, and the number of colonies were counted. RESULTS: No colonies were observed when UV irradiation was performed after the bacteria were added to the disks. When the bacteria were seeded after UV irradiation, the amount of surviving bacteria on the Ti and Ti6Al4V disks decreased at 0 hours and then gradually increased. However, the antimicrobial activity was maintained for seven days after UV irradiation. CONCLUSION: Antimicrobial activity was induced for seven days after UV irradiation on both types of disk. Irradiated Ti6Al4V and Ti had similar antimicrobial properties.Cite this article: T. Itabashi, K. Narita, A. Ono, K. Wada, T. Tanaka, G. Kumagai, R. Yamauchi, A. Nakane, Y. Ishibashi. Bactericidal and antimicrobial effects of pure titanium and titanium alloy treated with short-term, low-energy UV irradiation. Bone Joint Res 2017;6:108-112. DOI: 10.1302/2046-3758.62.2000619.

Silver nanoparticles: Synthesis methods, bio-applications and properties.

Silver nanoparticles size makes wide range of new applications in various fields of industry. Synthesis of noble metal nanoparticles for applications such as catalysis, electronics, optics, environmental and biotechnology is an area of constant interest. Two main methods for Silver nanoparticles are the physical and chemical methods. The problem with these methods is absorption of toxic substances onto them. Green synthesis approaches overcome this limitation. Silver nanoparticles size makes wide range of new applications in various fields of industry. This article summarizes exclusively scalable techniques and focuses on strengths, respectively, limitations with respect to the biomedical applicability and regulatory requirements concerning silver nanoparticles.

Progress in Research on Antibacterial Mechanisms and Safety of Silver Nanoparticles / 医药导报

Infection diseases induced by bacteria continue to be one of the greatest health problems worldwide. In this framework, nanotechnology-based solutions, and in particular silver nanoparticles ( AgNPs) , have recently emerged as promising candidates in the market as new antibacterial agents because of the enhanced broad-range antibacterial/antiviral properties and low cost.Here we analyze the experimental conclusions on the bactericidal effects of AgNPs, and discuss the safety issues.

Bacterial and osteoblast behavior on titanium, cobalt-chromium alloy and stainless steel treated with alkali and heat: a comparative study for potential orthopedic applications.

HYPOTHESIS: Anatase-modified titanium (Ti) substrates have been found to possess antibacterial properties in the absence of ultraviolet irradiation, but the mechanism is not known. We hypothesize that this is due to the bactericidal effects of reactive oxygen species (ROS) generated by the surface anatase. EXPERIMENTS: Alkali and heat treatment was used to form anatase on Ti surface. The generation of ROS, and the behavior of bacteria and osteoblasts on the anatase-modified Ti were investigated. Cobalt-chrome (Co-Cr) alloys and stainless steel (SS) were similarly treated with alkali and heat, and their surface properties and effects on bacteria and osteoblasts were compared with the results obtained with Ti. FINDINGS: The anatase-functionalized Ti substrates demonstrated significant bactericidal effects and promoted apoptosis in osteoblasts, likely a result of ROS generated by the anatase. The alkali and heat-treated Co-Cr and SS substrates also reduced bacterial adhesion but were not bactericidal. This effect is likely due to an increase in hydrophilicity of the surfaces, and no significant ROS were generated by the alkali and heat-treated Co-Cr and SS substrates. The treated Co-Cr and SS substrates did not induce significant apoptosis in osteoblasts, and thus with these properties, they may be promising for orthopedic applications.