Bacterial Reduction Research Articles

Development of Antibacterial Cotton Fabric by Application of Fruit and Vegetable Peel Extracts - A Sustainable Approach

The objective of this study is to assess the effect of Solanum incanum fruit (SIFE) and red onion peel (ROPE) extracts treatments on cotton fabric properties. The two factor factorial design was used, the first factor is concentration of the methanolic extract with two levels (3 g/l and 5 g/l) and the second is combination of extracts (25:75 SIFE: ROPE; 50:50 SIFE: ROPE; 75:25 SIFE: ROPE, 100% SIFE, 100% ROPE). Each extract was applied separately and in combination of different proportions on cotton fabric by the pad-dry-cure method using citric acid as a cross-linking agent. After treatment, the physical properties antimicrobial, wash durability and structual properties were determined. Air permeability, water absorbency and tensile strength were decreased for the treated fiber compared with control. Among all treatments, the cotton fabric treated with 50:50 combination was found best in bacterial reduction. This study concluded that, the natural source can sucessfully replace with synthetic chemicals.

A record of overpressure and Sevier tectonics within beef calcite of the Heath Formation, Central Montana Trough

The Central Montana Trough is an important sedimentary basin for petroleum resources and as a record of North American tectonism. The thermal, overpressure, and tectonic histories of the trough are investigated through a study of beef calcite veins taken from the Heath Formation, the primary hydrocarbon source rock of the basin. Results from beef calcite analysis include petrographic characterization, U-Pb geochronology via LA-ICP-MS, clumped isotope thermometry, and conventional carbon and oxygen stable isotopes. U-Pb ages and clumped isotope temperatures are 121.8 ± 19.2 Ma at 43.1 ± 2.3 °C; 96.2 ± 25.9 Ma at 52.1 ± 3.7 °C; and 101.6 ± 24.2 Ma at 50.2 ± 2.4 °C. Large errors on U-Pb ages result from very low U contents (<0.03 ppm). Ages and temperatures indicate staged vein precipitation at burial depths between 600 m to 1.3 km during the major burial event of the basin and a normal geothermal gradient of 25 °C/km. Beef calcite emplacement and basin burial are the direct result of regional tectonism of the Sevier Orogeny. Calculated fluid δ18O using clumped isotope temperatures revealed δ18O values of 3–7 ‰ (SMOW), indicating beef calcite precipitation from connate formation brine. Analysis of median-symmetrical beef carbonate δ18O and δ13C values indicates precipitating fluids were diagenetically modified by bacterial sulfate reduction and methanogenesis of organic matter. A thin (0.1 mm) second generation of growth is found on the outermost vein margin by a sharp chemical boundary and a trail of inclusions. This second growth stage could not be dated separately, but significantly lower δ18O and δ13C values of −2 ‰ and −5.5 ‰, respectively, indicate precipitating fluids were hotter and further diagenetically altered by thermal organic matter breakdown.Supplemental data: https://osf.io/39znd/.

Novel microbial synthesis of rGO nanosheets for effective photocatalytic remediation of Acid Blue 113 dye, improved seed germination, antimicrobial and antioxidant applications

We report for the first time reduction of graphene oxide (GO) nanosheets (NS) by an isolated bacterium from Lonar lake Bacillus cabrialesii RIRD-SK (MCC 4670). Facile, rapid, ecofriendly, and cost-effective biological approach makes it advantageous over physical and chemical methods. Isolated bacterial strain is deposited in Gene Bank accession number MMZ151886. The physiochemical characterization of rGO NS revealed formation of dark black precipitate within 8 h. UV–Visible spectra of rGO shows absorption peak mainly at 269 nm. Fourier-transform infrared spectroscopy (FTIR) revealed presence of functional biomolecules involved in capping and stabilization of NS. X- ray diffraction (XRD) pattern of rGO confirms pure crystal structure. Scanning electron microscopy (SEM) of rGO showed ultrathin graphene NS morphology having thickness less than 3.5 nm. The elemental composition of graphene oxide (GO) and rGO was studied by energy dispersive spectroscopy (EDS) confirms bacterial reduction GO. Specific surface area rGO about 139.53 m2/g was measured by Brunauer-Emmett-Teller (BET) technique. Raman spectroscopy indicates decrease oxygen containing functional group after bacterial reduction with unique fingerprint of material. The rGO NS showed 90.10 % degradation of Acid Blue 113 diazo dye within 45 min. Bioremediation was confirmed with the help of UV–Visible spectroscopy, thin layer chromatography (TLC), FTIR, High-performance liquid chromatography (HPLC) and Liquid chromatography mass spectroscopy (LCMS). Reduced toxicity of the degraded products was observed by the phytotoxicity experiment. A mechanistic degradation pathway has been proposed. rGO NS also exhibit good antimicrobial and antioxidant properties emphasizing its role in biomedical field.

Influence of MHz-order acoustic waves on bacterial suspensions

The development of alternative techniques to efficiently inactivate bacterial suspensions is crucial to prevent transmission of waterborne illness, particularly when commonly used techniques such as heating, filtration, chlorination, or ultraviolet treatment are not practical or feasible. We examine the effect of MHz-order acoustic wave irradiation in the form of surface acoustic waves (SAWs) on Gram-positive (Escherichia coli) and Gram-negative (Brevibacillus borstelensis and Staphylococcus aureus) bacteria suspended in water droplets. A significant increase in the relative bacterial load reduction of colony-forming units (up to 74%) can be achieved by either increasing (1) the excitation power, or, (2) the acoustic treatment duration, which we attributed to the effect of the acoustic radiation force exerted on the bacteria. Consequently, by increasing the maximum pressure amplitude via a hybrid modulation scheme involving a combination of amplitude and pulse-width modulation, we observe that the bacterial inactivation efficiency can be further increased by approximately 14%. By combining this scalable acoustic-based bacterial inactivation platform with plasma-activated water, a 100% reduction in E. coli is observed in less than 10 mins, therefore demonstrating the potential of the synergistic effects of MHz-order acoustic irradiation and plasma-activated water as an efficient strategy for water decontamination.

Reduced bacterial load in stallion semen by modified single layer centrifugation or sperm washing

The presence of bacteria poses a significant challenge to the quality of stallion semen used in artificial insemination. The bacterial content of insemination doses arises from various sources, such as the healthy stallion, environment, and collection equipment, and is implicated in fertility problems as well as reduced sperm quality during storage. The conventional approach of adding antibiotics to semen extenders raises concerns about antimicrobial resistance and potential negative effects on sperm characteristics, and may not be effective in inhibiting all bacteria. The objective of this study was to determine whether an innovative alternative to antibiotic usage – centrifugation through a single layer of a low density colloid (SLC) – could reduce the bacterial load in stallion semen, and to compare sperm characteristics in samples arising from this procedure, or simple extension of the ejaculate in semen extender, or from sperm washing, i.e. adding extender and then centrifuging the sample to allow the removal of most of the seminal plasma and extender. Eighteen semen samples were collected from six stallions. The semen samples were split and extended prior to washing or SLC, or received no further treatment other than extension. After preparation aliquots from each type of sample were sent for bacteriological examination; the remaining samples were stored for up to 72 h, with daily checks on sperm quality. The low density colloid SLC outperformed sperm washing or extension for bacterial reduction, effectively removing several bacterial species. The bacterial load in the samples was as follows: extended semen, 16 ± 6.7 × 105; washed, 5.8 ± 2.0 × 105; SLC, 2.3 ± 0.88 × 105, p < 0.0001. In addition, SLC completely removed some bacterial species, such as Staphylococcus xylosus. Although there is no selection for robust spermatozoa with the low density colloid, sperm motility, membrane integrity, and DNA fragmentation were not different to washed sperm samples. These findings suggest that SLC with a low density colloid offers a promising method for reducing bacterial contamination in stallion semen without resorting to antibiotics.

Metal sources and fluid pathways of karst-hosted Mississippi Valley-type Zn–Pb deposits in the fold-thrust belt: A case study of the Changdong deposit in the southeastern Himalayan-Tibetan orogen

The metal sources and fluid pathways for Mississippi Valley-type (MVT) Zn–Pb deposits in fold-thrust belts remain open topics of debate. To develop a more comprehensive understanding of these issues, this study presents the sulfide morphology, S and Pb isotopes, and trace element data of the paleokarst-hosted Changdong MVT Zn–Pb deposit in the “Sanjiang” fold-thrust belt. Bulk Pb isotopic ratios for galena were homogenous and indicated potential metal sources. These sources include Triassic to Early Jurassic volcanic rocks at the western margin of the Simao Basin, Cenozoic intrusive rocks at the eastern margin, and Jurassic clastic rocks. The spatial distribution of the in situ Pb isotopic ratios, combined with the spatial relationship between the faults and ore bodies, suggest that the tensile faults acted as vertical pathways for the fluid. The galena grains displayed oscillatory zones of As and Sb elements, indicating that alternating ore-forming fluids with varying chemical compositions entered the local reservoir. The δ34SV-CDT values of sulfides in substage I range from −19.3 to 29.6 ‰, and in substage II, they range from −21.2 to 52.6 ‰. The high fractionation degree (approximately 38.9 ‰) and the presence of microspherulitic morphology suggest that the reduced sulfur originated from a bacterial sulfate reduction. A GGIMFis geothermometer revealed that the precipitation temperatures of substage I sphalerite ranged from 56.68 to 211.58 °C and were higher than substage II. This indicated that the mixing of Zn–Pb-bearing fluid with reduced sulfur was the main controlling factor for sphalerite precipitation, and the temperature decrease represented another important factor. In the fold-thrust system, the complete process of Zn–Pb mineralization was established as follows: the fluid extracted metals from regional rocks and then migrated laterally over long distances. During the regional transition from compression to extension, metal-bearing fluid was injected into the deposit along the normal faults through seismic pumping. The fluid was then mixed with reduced sulfur to precipitate Zn–Pb sulfides. This study provides new insights into the metal sources and fluid pathways of MVT Zn–Pb deposits developed in a fold-thrust belt.

(Invited) A Flexible Anti-Biofilm Hygiene Coating for Water Devices

Biofilm is a microbiome complex comprising different bacterial colonies that typically adhere to device surfaces in water, which causes serious medical issues such as indwelling infections and outbreaks. Here we introduce a non-nanoparticle, flexible anti-biofilm hygiene coating consisting of lithocholic acid (LCA), zinc pyrithione (Zn) and cinnamaldehyde (Cn) (named as LCA-Zn-Cn) that largely prevents the bacteria adhesion to various water device surfaces such as stainless steel and glass through a synergistic mechanism (ACS Applied Bio Materials, 5 (2022) 3991). The existing chelated groups on LCA and Cn attract plenty of bacteria via hydrophobic interaction. Both bactericidal reaction by grafting biocidal groups from both LCA and Cn and bacteriostatic reaction by inhibiting cell division via zinc ions (Zn) lead to a largely improved bacteria/biofilm prevention. The antibacterial performance was assessed by using JIS Z 2801/ISO 22196 method. The designed LCA-Zn-Cn coating displayed log10 reduction of 4.23 (99.9% reduction) of E. coli and log10reduction of 3.51 (99.8% reduction) of E. faecalis on stainless steel, which are much higher than the control samples, demonstrating a promising colonization inhibition. Due to the strong crosslinked configuration, the coating still showed >90.9% bacterial reduction after 3000 abrasion cycles and over 99.9% bacteria reduction after a high flow velocity of 1.99 m/s test, which confirmed the enhanced mechanical durability. By applying either spray or dip-coating, the designed polymer composite can be coated on a variety of irregular water devices with mass production using auto-controlled robot arm. The desired hybrid coating provides an effective solution to prevent bacterium and biofilm formation on flexible water devices. Keywords: Anti-biofilm; Anti-bacteria; Coating; Water devices; Flexibility

Evaluation of White Rot Fungus to Control Growth of Escherichia coli in Cattle Manure

Biological soil amendments of animal origin, such as aqueous dairy manure, may be contaminated with microbial pathogens that can subsequently result in contaminated soil, water runoff, and crops. Multiple mitigation strategies are being evaluated to reduce these risks. Inclusion of filamentous fungus in a biofiltration system to inactivate pathogenic bacteria in aqueous dairy manure prior to land application is explored in this study as a preharvest preventative method. Of the microbes used to remediate biologically contaminated sites, ligninolytic white-rot fungi have been previously studied for their ability to degrade a wide variety of toxic or persistent environmental contaminants. Reduction of two E. coli strains (E. coli TVS355 and E. coli O157:H7 4407) was evaluated in aqueous dairy manure and PBS and in the presence of white-rot fungi Pleurotus ostreatus on three different nutrient sources (woodchips (WC), spent mushroom compost (SMC), and reticulated polyurethane foam (RPF)). Overall, E. coli TVS355 was more persistent in aqueous dairy manure and PBS, surviving for 50 days in the presence of P. ostreatus, with a final concentration of 4 log CFU/g in aqueous manure and 7 log CFU/g in PBS. However, greater (p < 0.0001) reduction of E. coli O157:H7 was observed, surviving for 50 days at an average of 4 log CFU/g in aqueous dairy manure and an average of 3 log CFU/g in PBS. Therefore, P. ostreatus has the potential to result in bacterial decay, with potential reduction observed in E. coli O157:H7. The RPF matrix showed positive results as a potential model for a nutrient limiting resource for P. ostreatus and could be the key to increased bacterial reductions if resulting in ligninolytic activity in order to seek other nutrient sources.

Reducing Multidrug-Resistant (MDR) Klebsiella pneumoniae via the Efficient Use of Bacteriophages ZI3 and HI3

Klebsiella pneumoniae is a common cause of multidrug-resistant (MDR) pneumonia, bacteremia, urinary tract infections (UTIs), and other systemic infections. K. pneumoniae is the third most common pathogen in blood cultures from sepsis patients. It can cause severe epidemic and endemic nosocomial infections. Antibiotic treatment of K. pneumoniae infections is getting increasingly challenging due to the development of antimicrobial resistance among pathogens. Hence, a new alternative strategy is required to treat such infections. Bacteriophages are the most prevalent biological entity on the planet with an estimated 1031 particles. As obligatory intracellular parasites, they infect bacterial cells. They have a high host specificity and can replicate and lyse bacterial cells. In this research, two novel indigenous bacteriophages against K. pneumoniae strain kp8890 were isolated, characterized, and labeled as ZI3 and HI3. Both these phages were found to have a specific host range for K. pneumoniae. HI3 was able to lyse 7 out of 10 different K. pneumoniae clinical isolates, while ZI3 was able to lyse 5 out of 10 isolates, although it could not infect bacteria from other species. The isolated phages showed viability up to 50°C and pH ranging from 3 to 9. HI3 inhibited bacterial growth for 18 hours. Whereas, ZI3 showed an excellent bacterial reduction ability by inhibiting and decreasing the number of initial bacterial inoculum for 24 hours of observation. Keeping in view the excellent bacterial growth reduction, phage titer, pH and thermal stability, and host range, it is suggested that both bacteriophages, that is, ZI3 and HI3 can be potential phage therapy candidates after necessary animal modeling and clinical trials in the future.

Cationic cellulose filter papers modified with ZnO/Ag/GO nanocomposite as point of use gravity-driven filters for bacterial removal from water

The surface modification of filters with large pore sizes for the development of low-cost gravity-driven point-of-use (POU) technologies for water disinfection can be an effective strategy to empower people to access safe water instantly, especially in low- and middle-income countries. In this study, the surface of commercial cellulose filter papers, as cheap and bio-based filters, was modified with polydopamine (PDA), polyethyleneimine (PEI) and ZnO/Ag/GO nanocomposite (ZnO/Ag/GO@PDA/PEI papers) for bacterial removal from water. PDA/PEI incorporation introduced a cationic functional layer, which can entrap negative bacteria and make a stable chemical bond with the nanocomposite. ZnO/Ag/GO exhibited promising synergistic antibacterial activities (30 times stronger than ZnO). As a result, 3 sheets of ZnO/Ag/GO@PDA/PEI papers showed a 99.98% bacterial reduction (E. coli), which met the WHO standards. Moreover, the leached zinc and silver in the filtrate were far below the WHO’s limits (380 and 10 ppb, respectively). The results showed that the modified papers could be reused multiple times. After six times of reuse, the flow rate dropped slightly (below 20%) and the bacterial removal efficiency was more than 99.9%. This study is valuable for developing filters for treating bacterial-contaminated water on-site with no need for energy, which is a demand in many countries.

Comparative Evaluation of Bacterial Reduction by Laser-Activated Irrigation Technique (LAI) With Conventional Needle Irrigation (CNI) in Single-Rooted Teeth With Pulpal Necrosis: A Single-Blinded Randomized Controlled Trial.

Aim To compare the bacterial reduction in single-rooted teeth with pulpal necrosis after laser-activated irrigation technique(LAI) and conventional needle irrigation (CNI). Methodology In this clinical trial (CTRI/2021/09/047767), 32 patients with pulpal necrosis were enrolled. Under complete aseptic conditions, access cavity preparation was done and the baseline sample S1 was collectedfrom the root canal using paper points. After chemo-mechanical preparation they were allocated into two groups, following block randomization; Group A - CNI with 27 gauge side-vented needle, Group B - LAI with pulsed Er,Cr:YSGG (erbium, chromium:yttrium-scandium-gallium-garnet) (2780 nm) laser. After irrigant activation, canals were dried and a second sample S2 was taken using paper points. Microbial analysis using quantitative polymerase chain reaction (qPCR) was done to quantify the bacterial reduction among the two groups. Inter-group and intra-group analysis was done using the independent student t-test and Bonferroni test, respectively. The data was represented in terms of quantification cycle (Cq) values, which are inversely proportional to the microbial count. Results There was no significant difference in S1 between the two groups (mean difference=0.0205; p=0.912). There was a significant difference in S2 between the two groups for the organisms (mean difference=0.8042; p=0.000). The mean percentage of bacterial reduction in CNI was 10.82% and in LAI it was 25.92%. There was a significant difference in S1 through S2 within the two groups for the organisms (p=0.000). The mean difference of Cq value is high for LAI compared to CNI (1.3494). The fold change was calculated by taking the ΔCq value and ΔΔCq value after the logarithmic transformation of the Cq value. LAI showed lower levels of DNA at S2 similar to CNI. There is no significant difference in mean fold change between CNI and LAI (p=0.564). Conclusion This clinical trial concluded that both LAI and CNI were effective in bacterial reduction. There was greater bacterial reduction with LAI (25.92%) than with the CNI (10.82%) in single-rooted teeth with pulpal necrosis using qPCR analysis.

Influence of photodynamic action on pure and mixed cultures of gram-negative bacteria: related to growth mechanisms

Gram-negative bacteria present a significant challenge to conventional treatments due to their structurally complex cell walls, setting them apart from their gram-positive counterparts. These structural distinctions, coupled with various antimicrobial resistance mechanisms, make them highly resilient. Photodynamic inactivation (PDI) has emerged as a promising technique to address this challenge, capitalizing on oxidative stress induced by the synergy of light and a photosensitizer (PS). In this study, we delved into the application of PDI and its repercussions on both Klebsiella pneumoniae and Escherichia coli bacteria, in both pure cultures and mixed populations. Our investigation encompassed an analysis of changes in growth curves when influenced by photodynamic and the response to the susceptibility to gentamicin. Methods: Various concentrations (50 μM, 100 μM, and 150 μM) of synthetic curcumin solutions served as PS in treatment groups. Additionally, solvents such as dimethyl sulfoxide and 0.1% sodium dodecyl sulfate (SDS) were evaluated to enhance PS mobility and absorption. Growth curves for pure and mixed cultures were established, both pre- and post-PDI, and in the presence of 0.1% SDS. Blue light irradiation at 30 J cm−2 and 450 nm was employed. The minimum inhibitory concentration (MIC) of the antibiotic was determined with and without PDI + SDS. Results: While PDI did not achieve optimal bacterial reduction for these strains, it did introduce oxidative damage that has the potential to affect other critical aspects of the temporal progression of cultures and their responses to antibiotics. Conclusion: This study shows that even with the minimal impact of PDI in the presence of 0.1% SDS, observable alterations in bacterial growth profiles and MIC values occur and can be used in favor of treatment involving such infections.

Bacterial and fungal bioburden reduction on material surfaces using various sterilization techniques suitable for spacecraft decontamination.

Planetary protection is a guiding principle aiming to prevent microbial contamination of the solar system by spacecraft (forward contamination) and extraterrestrial contamination of the Earth (backward contamination). Bioburden reduction on spacecraft, including cruise and landing systems, is required to prevent microbial contamination from Earth during space exploration missions. Several sterilization methods are available; however, selecting appropriate methods is essential to eliminate a broad spectrum of microorganisms without damaging spacecraft components during manufacturing and assembly. Here, we compared the effects of different bioburden reduction techniques, including dry heat, UV light, isopropyl alcohol (IPA), hydrogen peroxide (H2O2), vaporized hydrogen peroxide (VHP), and oxygen and argon plasma on microorganisms with different resistance capacities. These microorganisms included Bacillus atrophaeus spores and Aspergillus niger spores, Deinococcus radiodurans, and Brevundimonas diminuta, all important microorganisms for considering planetary protection. Bacillus atrophaeus spores showed the highest resistance to dry heat but could be reliably sterilized (i.e., under detection limit) through extended time or increased temperature. Aspergillus niger spores and D. radiodurans were highly resistant to UV light. Seventy percent of IPA and 7.5% of H2O2 treatments effectively sterilized D. radiodurans and B. diminuta but showed no immediate bactericidal effect against B. atrophaeus spores. IPA immediately sterilized A. niger spores, but H2O2 did not. During VHP treatment under reduced pressure, viable B. atrophaeus spores and A. niger spores were quickly reduced by approximately two log orders. Oxygen plasma sterilized D. radiodurans but did not eliminate B. atrophaeus spores. In contrast, argon plasma sterilized B. atrophaeus but not D. radiodurans. Therefore, dry heat could be used for heat-resistant component bioburden reduction, and VHP or plasma for non-heat-resistant components in bulk bioburden reduction. Furthermore, IPA, H2O2, or UV could be used for additional surface bioburden reduction during assembly and testing. The systemic comparison of sterilization efficiencies under identical experimental conditions in this study provides basic criteria for determining which sterilization techniques should be selected during bioburden reduction for forward planetary protection.

Antimicrobial effects and metabolomics analysis of cell-free supernatant produced by Pediococcus acidilactici LWX 401 isolated from Yunnan traditional pickles

Foodborne pathogens pose a significant risk to human health via the food chain. Here, we evaluated the antibacterial effects of cell-free supernatant (CFS) of Pediococcus acidilactici (P. acidilactici) LWX 401 isolated from food-grade Chinese traditional pickles and found that it exhibited broad antibacterial activity against multidrug-resistant gram-negative Escherichia coli (E. coli) O157:H7 and yogurt-derived gram-positive Staphylococcus aureus (S. aureus), with inhibition zone sizes of 23.10 ± 0.80 and 20.53 ± 0.07 mm, respectively (all P < 0.001 compared with the controls). Moreover, the CFS exhibited strong thermostability and pH tolerance and was capable of inhibiting the formation of biofilms of these foodborne pathogens. Notably, the LWX 401 CFS inhibited both E. coli O157:H7 and S. aureus contamination in milk samples under different storage temperatures (4 °C, 25 °C, and 35 °C), with considerable bacterial reduction by 1–7 log CFU/mL compared with untreated controls. Additionally, the potential antibacterial metabolites (VIP >1, adjusted P < 0.05, and fold-change >2; n = 56) were identified in the LWX 401 CFS by UHPLC-QE-MS metabolomic analysis, and these metabolites were mostly lipids (25.73%) and organic acids (23.30%). Our results provide insights for the development of bio-preservatives against foodborne pathogens in the milk industry.

Ginger extract loaded Fe2O3/MgO-doped hydroxyapatite: Evaluation of biological properties for bone-tissue engineering.

Since antiquity, the medicinal properties of naturally sourced biomolecules such as ginger (Zingiber officinale) extract are documented in the traditional Indian and Chinese medical systems. However, limited work is performed to assess the potential of ginger extracts for bone-tissue engineering. Our work demonstrates the direct incorporation of ginger extract on iron oxide-magnesium oxide (Fe2O3 and MgO) co-doped hydroxyapatite (HA) for enhancement in the biological properties. The addition of Fe2O3 and MgO co-doping system and ginger extract with HA increases the osteoblast viability up to ~ 1.4 times at day 11. The presence of ginger extract leads to up to ~ 9 times MG-63 cell viability reduction. The co-doping does not adversely affect the release of ginger extract from the graft surface in the biological medium at pH 7.4 for up to 28 days. Assessment of antibacterial efficacy according to the modified ISO 22196: 2011 standard method indicates that the combined effects of Fe2O3, MgO, and ginger extract lead to ~ 82 % more bacterial cell reduction, compared to the control HA against S. aureus. These ginger extract-loaded artificial bone grafts with enhanced biological properties may be utilized as a localized site-specific delivery vehicle for various bone tissue engineering applications.

Bioactive and Multifunctional Wool Textiles Finishing with Diospyros mollis Griff. Extract

Due to the sudden pandemic outbreak, there is a substantial demand for antimicrobial textiles for health and hygiene. Natural dyeing with plant sources has been proven to be an excellent eco-friendly method for producing healthcare textiles. In this study, Diospyros mollis Griff. extract was applied to the simultaneous dyeing and multi-functionalization (antibacterial activity and UV-protection) of wool fabrics. Response surface methodology was applied to optimize the treatment procedure and assess parameter interactions. The optimal result was achieved when dyeing at pH 4, dye concentration 25 g/L, temperature 88°C, and time 95 min. The dyed fabrics had good antibacterial activity against both E.coli and S.aureus (bacterial colony reduction &gt; 90%), with E.coli being more pronounced. The UV protection factor (UPF) also reached the maximum (40+) level, demonstrating their superior UV protection. The finished wools are black, with high color strength (K/S &gt; 9), good light and washing fastness, and fair to good crocking fastness. Thus, Diospyros mollis Griff. fruit extract can be used as a new bioactive agent for multifunctional textiles, as well as simultaneous black coloring.

Functionalization of graphene oxide with amphiphilic block copolymer to enhance antibacterial activity

Functionalization of GO with an amphiphilic block copolymer is designed with an aim to enhance its biocompatibility, however, long copolymer chains can screen the blade effect of GO to sacrifice its antimicrobial activities. To solve this problem, low molecular weight of poly(ethylene glycol) (PEG), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and their block copolymer were respectively introduced onto GO via an isophorone diisocyanate modified GO as a intermediate, followed by a solvent evaporation of an oil-in-water emulsion treatment (SE treatment) to induce block copolymer into polymer micelle via phase separation to refresh the sharp edges of GO. Block copolymer modified GO possessed similar dispersibility and stability to PEG modified GO, and even higher loading capacity of the hydrophobic drug than PHBV modified GO, illustrating its superior properties to homopolymer. PEG, PHBV and their block copolymer modified GO were nontoxic towards ATDC5 cells while cultured for 3 days and compatible with erythrocytes within 8 h. SE treatment enhanced greatly the loading capacity of the hydrophobic drug and the accumulative release reached 91.3% within 24 h. The inhibition zone of the block copolymer modified GO was 14.1 mm and 14.8 mm against E. coli and S. aureus, comparable to that of PEG modified GO. The bacterial reduction rate of the copolymer micelle modified GO was 87.1% and 82.7% towards E. coli and S. aureus, much greater than that of PEG, PHBV and their block copolymer modified GO at a concentration of 1 mg/mL. The antibiofilm capacity of the copolymer micelle modified GO were equal to that of PEG modified, demonstrating its great promise in tissue engineering application for repair of infected tissue defects.

One-step silver coating of polypropylene surgical mask with antibacterial and antiviral properties

Face masks can filter droplets containing viruses and bacteria minimizing the transmission and spread of respiratory pathogens but are also an indirect source of microbes transmission.A novel antibacterial and antiviral Ag-coated polypropylene surgical mask obtained through the in situ and one-step deposition of metallic silver nanoparticles, synthesized by silver mirror reaction combined with sonication or agitation methods, is proposed in this study.SEM analysis shows Ag nanoparticles fused together in a continuous and dense layer for the coating obtained by sonication, whereas individual Ag nanoparticles around 150 nm were obtained combining the silver mirror reaction with agitation. EDX, XRD and XPS confirm the presence of metallic Ag in both coatings and also oxidized Ag in samples by agitation. A higher amount of Ag nanoparticles is deposited on samples by sonication, as calculated by TGA. Further, both coatings are biocompatible and show antibacterial properties: coating by sonication caused 24 % and 40 % of bacterial reduction while coating by agitation 48 % and 96 % against S. aureus and E. coli, respectively. At 1 min of contact with SARS-CoV-2, the coating by agitation has an antiviral capacity of 75 % against 24 % of the one by sonication. At 1 h, both coatings achieve 100 % of viral inhibition. Nonetheless, larger samples could be produced only through the silver mirror reaction combined with agitation, preserving the integrity of the mask.In conclusion, the silver-coated mask produced by silver mirror reaction combined with agitation is scalable, has excellent physico-chemical characteristics as well as significant biological properties, with higher antimicrobial activities, providing additional protection and preventing the indirect transmission of pathogens.

Genesis of Neogene Formation Waters in the Central Qaidam Basin: Clues from Hydrochemistry and Stable D‐O‐S‐Sr Isotopes

AbstractGeological explorations have revealed plentiful Neogene formation waters in anticlines in the central Qaidam Basin (QB). However, the hydrochemistry and origin of these waters are obscure. In this study, the hydrochemistry and D‐O‐S‐Sr isotopes of these formation waters were determined to study their origin and evolution. The formation waters are enriched in Na‐Ca‐Cl, and depleted in Mg‐K‐SO4‐HCO3 ions with elevated Li‐B‐Br‐Sr elements. The D‐O isotopes prove that the formation waters originated from weak‐evaporated meteoric waters, and experienced water‐rock interactions. Ion comparisons and Caexcess–Nadeficit diagrams suggest that solute sources of these waters include evaporite dissolution, water‐rock interaction, and minor residual lake brines. Bacterial sulfate reduction and water‐rock interactions are supported by the high S‐Sr isotopes. The enriched Li‐B‐Br‐Sr concentrations of these waters are in accord with the high geochemical background values of the QB. Regarding the genesis of the formation waters, it can be concluded that meteoric waters from the southern Kunlun Mountains were discharged into the basin, weakly evaporated, and then infiltrated into the Neogene strata through faults leaching the soluble ions and mixing with residual lake brines, and all experienced water–rock interactions and a sulphate reduction process.

The efficiency of protection of structural steel by cationic inhibitor under conditions of corrosion with bacterial sulfate reduction

The effectiveness of protecting a structural steel by cationic inhibitor against biocorrosion caused by Desulfovibrio sp. М-4.1, Desulfomicrobium sp. TC 4, and sulfidogenic microbial communities was investigated by using gravimetric and electrochemical methods. The research showed that at a concentration of 1 g/l, the inhibitor offers greater protection to steel St3ps against Desulfomicrobium sp. TC 4 (up to 81.0%) than to Desulfovibrio sp. М-4.1 (up to 72.2%). The structure of the molecules of the inhibitor's compounds determines their ability to form a protective layer on the surface of the metal and exhibit antimicrobial action to sulfate-reducing bacteria and their satellites (iron-reducing bacteria). The inhibitor provides a high degree of protection (&gt;92.9%) in microbial corrosion under the influence of sulfidogenic microbial communities. The cationic inhibitor was shown to have a greater effect on the electrochemical performance of the corrosion process for the biofilm form of sulfate-reducing bacteria than for the planktonic form.