Antibacterial Efficiency Research Articles

Vat Photopolymerization 3D Printing of Hydrogels Embedding Metal-Organic Frameworks for Photodynamic Antimicrobial Therapy.

Given the variability in wounds based on the underlying causes, personalized medicine and tailored care for patients with wounds are required to ensure optimal therapeutic outcomes. With the emergence of high-precision and high-efficiency photocuring 3D printing technology, there is the potential for its use in customizing precise shapes that can match complex wound sites, thereby providing better treatment for patients with wound infections. In this work, porphyrinic metal-organic framework (MOF) crystals, serving as the functional filler, were incorporated into gelatin methacrylate (GelMA) as a photocurable composite resin to investigate the capabilities of producing customizable wound dressings through vat photopolymerization 3D printing. The embedded MOF crystals allow for better control of the photopolymerization process due to photon competition with the photoinitiator, enabling the precise printing of complex structures. In addition, these crystals impart photothermal and photodynamic capabilities to the printed object. The antibacterial assay confirms the potent photothermal and photodynamic bactericidal properties of the printed GelMA/MOF hydrogels. The hydrogel with the highest MOF content exhibited over 99.99% antibacterial efficiency against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli after 30 min of light exposure (∼30 mW/cm2, λ ≥ 420 nm). Simultaneously, hemolysis and cytotoxicity evaluations validated their excellent biocompatibility. The findings presented here introduce a strategy for integrating photosensitive MOF and 3D printing to fabricate size-adjustable photothermal/photodynamic monoliths and patches, opening perspectives toward personalized treatment for wound management.

Eco-Friendly Facile Conversion of Waste Eggshells into CaO Nanoparticles for Environmental Applications.

Amongst the many types of food waste, eggshells contain various minerals and bioactive materials, and they can become hazardous if not properly disposed of. However, they can be made useful for the environment and people by being converted to environmentally friendly catalytic materials or environmental purification agents. Simple calcination can enhance their properties and thereby render them suitable for catalytic and environmental applications. This work aimed to prepare CaO from waste eggshells and examine its effectiveness in photocatalytic pollution remediation, electrocatalytic activity, optical sensing, and antibacterial activities. As opposed to other techniques, this calcination process does not require any chemical reagents due to the high purity of CaCO3 in eggshells. Calcium oxide nanoparticles were prepared by subjecting waste eggshells (ES) to high-temperature calcination, and the synthesized CaO nanoparticles were characterized for their structural, morphological, chemical, optical, and other properties. Furthermore, their photocatalytic degradation of methylene blue dye and antibacterial efficiency against Escherichia coli and Staphylococcus aureus were investigated. It was found that the green-converted CaO can be efficiently used in environmental applications, showing good catalytic properties.

SAW-driven directional clearance of bacteria on submerged surfaces

The process of bacterial film formation on submerged surfaces commences with the attachment of bacteria to the substrate. Appropriate combinations of topology and surface chemistry have been explored to prevent biofilm anchoring at the solid–liquid interface. However, the failure to actively remove bacteria from solid surfaces within a fluid in a directional manner results in bacterial backflow onto those surfaces, thus leading to secondary contaminations. Herein, inspired by the biology broom of the ciliary beating system, we propose an active surface sweeper mechanism assisted by charged particles and surface acoustic waves (SAW) to facilitate the directional clearance of bacteria. Through the synergistic effect of charge trapping and acoustic propelling, the sweeper system demonstrates an effective inhibition of bacterial adhesion in the initial stage of biofilm formation. Utilizing SAW for twenty seconds yields a remarkable 94.8% efficiency in bacterial clearance, with antibacterial adhesion efficiency up to 92.4% and 98.8% for Escherichia coli and Staphylococcus aureus, respectively. Moreover, the accompanying theoretical force modeling offers a comprehensive mechanistic insight into the relationship between acoustic streaming and bacteria repelling. The motion analysis of bacteria-loaded particles suggests that the acoustic radiation force, rather than the Strokes force, determines the clearance direction of bacteria.

Bacterial cellulose nanofiber reinforced self-healing hydrogel to construct a theranostic platform of antibacterial and enhanced wound healing

In order to promote wound healing, self-healing hydrogels with moisturizing property are employed as wound dressing. In this study, bacterial cellulose nanofibers (BCN) with high mechanical strength are used as reinforcement to improve the mechanical properties of self-healing hydrogels. A multifunctional self-healing hydrogel has been constructed by incorporating natural biomass, including Ag hybrid bacterial cellulose nanofiber (Ag-BCN), resveratrol (Res), and carbon nanodots (CNDs). The results of in vitro experiments demonstrate that the mechanical strength of the hybrid hydrogel was increased by 6 times with the addition of Ag-BCN, which also offers excellent antibacterial efficiency (S. aureus 99.99 % and E. coli 99.68 %). The hydrogel with CNDs can observe the healing process of the crack in real time and realize the controlled release of Res through photothermal effect. Moreover, the results of animal model experiments indicate that the prepared hydrogel could reduce the infection of the wound, effectively shorten the progress of wound healing (from 21d to 14 d). All the results imply that the prepared hydrogel has great promise in the application of skin wound healing.

Novel benzothiophene‒tethered 1,3,4‒oxadiazoles as potent antimicrobial targets: Design, synthesis, biological evaluation, DFT exploration and in silico docking study

Based on previous developments of oxadiazole research programs in trying to find novel compounds with multiple biological targets, such as antibacterial and antitubercular medications. In the context, a new series of 1,3,4-oxadiazole derivatives based on benzo[b]thiophene moiety 6a‒d, 7a‒d, and 8a‒d was synthesized from 5-(3-methylbenzo[b]thiophen-2-yl)-1,3,4-oxadiazole-2-thiol. The structures of 1,3,4‒oxadiazole derivatives were elucidated via NMR (1H and 13C), IR, and HRMS spectrum data as well as physical data. Subsequently, the derivatives were evaluated for their inhibitory activity against different bacterial microorganisms, and the MICs were determined in vitro tubercular activity against the sensitive M. tuberculosis H37Rv strain. Remarkably, hybrids 6c and 7a exhibited excellent antibacterial activity against S. aureus with ZI values of 31 ± 0.99, and 30 ± 0.32 mm, and it has been noticed that 8b demonstrated the most prominent antibacterial efficiency with MICs = 3.1, 3.6, 5.6, and 5.1 μg/mL against S. pneumoniae, S. pyrogenes, E. coli, and K. pneumoniae. Among them, compound 8b, featuring a benzo[b]thiophene moiety linked to oxadiazole, exhibited a significant tubercular inhibitory effect with an MIC value of 2.2.5 μM. Additionally, the docked compound 7a showed the strongest key active key amino acids Arg44(A), Arg45(A), Ala126(A), Gly18(A), Ser49(A), Asp48(A) in the antitubercular active site of 1DG5 protein. The study of computer aided ADMET was also carried out, using SwissADME and ADMETlab2.0 to investigate the pharmacokinetic properties of the tested triazole compounds. To support the experimental data, molecular docking and density functional theory (DFT) studies help in understanding the interactions better.

Green synthesis of nano silver-modified date syrup 3D graphene for adsorptive removal of heavy metals from wastewater and its antibacterial efficiency

Abstract Many researchers are focusing on the eco-friendly and cost-effective green synthesis of materials for removing heavy metals from wastewater using materials made from natural sources. In this research, date syrup was used as a rich carbon source while potassium chloride particles were used as a substrate. Green synthesized silver nanoparticles modified the graphene foam to enhance its heavy metal removal and antibacterial efficiency. The morphology and structure of the graphene foam were examined using scanning electron microscopy and Raman spectroscopy. The Brunauer-Emmett-Teller method examines textural features such as surface area, pore volume and diameter. The study focused on evaluating the efficiency of removing heavy metals including cadmium, lead, zinc, and chromium from water. The results indicated that the date syrup graphene foam has high heavy metal removal efficiency despite the short contact time, especially for Cd2+ and Pb2+, with removal efficiencies of 68% and 39%, respectively. It shows a relatively lower efficacy for Zn2+ and Cr2+, with removal efficiencies of 10% and 27%, respectively. The addition of silver nanoparticles greatly improved the removal efficiency of Cd2+ (75%), Zn+2 (22%), and Cr2+ (33%). Moreover, the antibacterial efficacy test showed significant improvement after the nanosilver modification to reach a 100% bacterial-killing rate.

Physico-mechanical properties, hydroxyapatite conversion, biodegradability and antibacterial activity studies of melt-derived BGs based on SiO2-CaO-Na2O-P2O5 quaternary system

The slow biodegradation and low hydroxyapatite (HA) conversion of silicate-based bioactive glasses (BGs) have severely limited their compatibility with biological tissues. To address these challenges, four samples in the form of (52-x)SiO2-24Na2O-24CaO-xP2O5, where x is 2, 4, 6, and 8 mol%, were prepared by a unified melt-quenching method, and the feasibility of P2O5 content fine-tuning in improving glass structure, biodegradability, bioactivity, and antibacterial efficiency was evaluated. The results indicated that as the degree of P2O5 substitution increased, the network structure of the glass became looser, which provided favourable conditions for its degradation. The variation in activation energy for Si4+ ion release from 0.39 eV to 0.25 eV also supported this observation. After 7 days of immersion in simulated body fluid (SBF), analyses by energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) confirmed that the Ca-P compounds deposited on the glass surfaces were essentially hydroxycarbonated apatite (HCA), and scanning electron microscopy (SEM) images revealed that the generation rate of the HCA were positively correlated with the P2O5 content in the glass system. Meanwhile, antibacterial studies showed that after 24 h of incubation, the antibacterial activity of the four glass samples against Escherichia coli (E. coli) successively increased, with the highest percentage reaching 87.13 ± 2.51 %. In conclusion, this study demonstrates that controllable degradation and high-level bioactivity can be achieved by modulating the P2O5 content in silicate-based BGs, which proves to be an effective and practicable strategy.

Enhanced Antibacterial and Anti‐Biofilm Functions of Black Bean Skin Anthocyanins Against V. parahaemolyticus

ABSTRACTBlack bean skin anthocyanins (BBSAs), as by‐products of black beans, have not been fully exploited. BBSAs are rich in anthocyanins and have a wide range of health benefits. In this study, the antibacterial and antibiofilm action mode of BBSAs against Vibrio parahaemolyticus (V. parahaemolyticus) was evaluated. The antibacterial and antibiofilm efficiency was evaluated under different conditions, shedding light on their mode of action against V. parahaemolyticus. The results showed that the inactivation efficacy of BBSAs on V. parahaemolyticus was positively correlated with its concentration and incubating time. The MIC value for BBSAs was determined to be 10 μg/mL. The formation of V. parahaemolyticus biofilm was hindered by the presence of the BBSAs, especially at higher concentrations of BBSAs and during the early intervention stage. After exposure to 1 MIC of BBSA, the inhibition rate of biofilm reached 91.94%. The release of cellular components and alterations in membrane morphology indicated that BBSAs can damage the integrity of V. parahaemolyticus cell membrane. Furthermore, BBSAs may interact with membrane proteins, causing a notable conformational change in membrane proteins. HPLC and UPLC‐MS analysis confirmed that the major antibacterial compound in BBSAs was Cyanidin‐3‐O‐glucoside (C3G), which can form a stable complex with LolB protein in the outer membrane via hydrogen bonding. This study can provide strong technical support for the accurate control of V. parahaemolyticus and pave the way for the application of natural antibacterial agents in the realm of food‐borne bacterial control.

A novel ZnO-TiO2-Bi2WO6/Carboxymethyl chitosan composite with high antimicrobial activity and visible-light catalytic degradation of ethylene towards banana preservation in hot and humid environments

In order to solve the problem of significantly shortened storage time of bananas in hot and humid environment (e.g., 30 °C and 90 % relative humidity), this paper reports the preparation of ZnO-TiO2-Bi2WO6 (ZTB) ternary heterojunction antimicrobial photocatalysts composite carboxymethyl chitosan film (ZTB/CMCS). ZTB were prepared by hydrothermal method and composited with CMCS by surface deposition method to construct ZTB/CMCS edible nano-preservation film. It is noteworthy that the ZTB/CMCS composite film exhibited excellent antibacterial efficiency (>99.99 %) against E. coli and S. aureus suspensions (106 CFU/mL) after 24 h of incubation at 37 °C. Time-resolved photoluminescence (TRPL) spectroscopy showed that the incorporation of Zinc oxide nanoparticles (ZnO NPs) into the ZTB structure led to a decrease in fluorescence lifetime. Moreover, the interfacial interaction between ZnO and TiO2/Bi2WO6 inhibited the recombination of photogenerated electron-hole pairs, promoting carrier separation and improving photocatalytic activity. The combination of high antibacterial activity, photocatalytic degradation of ethylene and inhibition of gas exchange provided multiple protections for fruit preservation. Therefore, this work provides a novel, effective and safe method for prolonging the preservation of bananas in hot and humid environments.

Engineering dual-reinforced antibacterial and anti-fouling ultrafiltration membrane by in-situ synthesising super-dispersion and high-activity silver nanoparticles (AgNPs)

Membrane fouling, especially biofouling, would result in frequent cleaning and shorten membrane lifespan. Fabricating Ag nanoparticle (AgNP)-modified ultrafiltration (UF) membranes provided an innovative solution for in-situ membrane biofouling control. Inspired by the tongue’s taste generation mechanism, this study adopted sodium citrate and AgNO3 to in-situ synthesize AgNP-modified UF (i-Ag-UF) membrane with the characteristics of ‘super-dispersion and high-activity’ AgNPs, enhancing the antimicrobial and anti-fouling properties. Compared to the control, a perpendicular and rich macroporous finger-type structure was engineered in the i-Ag-UF membrane, which contributed to a 59 % permeability improvement (421.7 L m-2h−1 bar−1), thereby improving filtration efficiency and reducing operational costs. This enhancement was attributed to the in-situ synthesis of small-sized, super-dispersed AgNPs, improving compatibility and stability with membrane matrix, and enhancing resistance to interlayer shear stress during phase inversion. Furthermore, the i-Ag-UF membrane surface exhibited the highest hydrophilicity and surface polarity, which formed a hydration layer and increased pollutant repulsion, thereby greatly enhancing its anti-fouling performance and achieving a higher flux recovery rate of 98.64 %. Such enhancement could significantly improve the economic benefits and sustainability of the UF process. The i-Ag-UF membrane demonstrated exceptionally high antibacterial efficiency (>99.99 %), attributed to the widely dispersed, high-activity AgNPs with numerous exposure points. In addition, the i-Ag-UF membrane, with only 2.5 wt% Ag release after 50 days owing to the entanglement between AgNPs and polymer chains. These findings provide new insights into the fabrication of highly antibacterial and anti-fouling dual-enhanced UF membranes.

A broad-spectrum biological activities of Heracleum humile extracts: A first report of the antiviral, anti-cancer and chemical properties

The current work focused on researching the bioactive potential of ethyl acetate (EA), methanol (MeOH), and water extract of H. humile plant, specifically ethyl acetate, methanol extracts were acquired with maceration method, and water extract was obtained by the infusion method. The highest total phenolic ingredient was determined in the water extract, while the highest total flavonoid ingredient was found in the MeOH extract. The water extract displayed the most potent antioxidant activity in the assays used. The ethyl acetate extract showed the highest enzyme inhibition activity in Butyrylcholinesterase inhibition (BChE) and amylase assay. Antibacterial efficiency was analyzed using microdilution analysis. The minimum inhibitory concentration (MIC) amounts ranged from 125 to 500 μg/mL except for water extract. The antiviral potential of the extracts was assessed against Bovine herpes virus 1 (BoHV-1) (Cooper strain). Methanol extract showed more potent antiviral effect. Selectivity indices were calculated for ethyl acetate and methanol extract as 3.32 and 13.39, respectively. All extracts displayed Deoxyribonucleic Acid (DNA) protection activity at approximately 25%–35%. For cell viability evaluation, 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) test was performed against triple-negative human breast adenocarcinoma cells (MDA-MB-231) and Michigan Cancer Foundation-7 (MCF-7) cells. The most effective results were found in ethyl acetate extract at 48h. The 50% inhibitor concentrations (IC50) were determined for MDA-MB-231 and MCF-7 as 116.7 μg/mL and 247.9 μg/mL, respectively. Based on the bioactive compound content results, extracts of H. humile include valuable compounds that possess significant biological properties. In conclusion, these extracts could offer promising novel plant-derived therapeutics.

Off-site production of plasma-activated water for efficient disinfection: The crucial role of high valence NOx and new chemical pathways

Efficient disinfection of pathogens is a critical concern for environmental disinfection and clinical anti-infective treatment. Plasma-activated water (PAW) is a promising alternative to chemical disinfectants and antibiotics for its strong disinfection ability and not inducing any acute toxicity. Previous plasma sources are commonly placed near or fully in contact with water as possible for more efficient activation, but the risk of electrode corrosion and metal particle contamination of water threatens the safety and stability of PAW. In this work, plasma-activated gas (PAG) rich in high-valence NOx is generated by a hybrid plasma configuration and introduced into water for off-site PAW production. It is found that plasma-generated O3 dominates the gas-phase reactions for the formation of high-valence NOx. With the time-evolution of O3 concentration, the gaseous NO3 radicals are produced behind N2O5 formation, but will be decomposed before N2O5 quenching. By decoupling the roles of gaseous NO3, N2O5, and O3 in the water activation, results show that short-lived aqueous species induced by gaseous NO3 radicals play the most crucial role in PAW disinfection, and the acidic environment induced by N2O5 is also beneficial for microbial inactivation. Moreover, SEM photographs and biomacromolecule leakage assays demonstrate that PAW disrupts the cell membranes of bacteria and thus achieves inactivation. In real-life applications, an integrated device for off-site PAW production with a yield of 2 L/h and a bactericidal efficiency of >99.9 % is developed. The PAW of 50 mL produced in 3 min using this device is more effective in disinfection than 0.5 % NaClO and 3 % H2O2 with the same bacterial contact time. Overall, this work provides new avenues for efficient PAW production and deepens insights into the fundamental chemical processes that govern the reactive chemistry in PAW for environmental and biomedical applications.

Unprecedented one-pot synthesis of 3,4-dihydropyrimidine-2-(1h)-ones catalyzed by hydrazine sulfate through Biginelli reaction, ADMET property, molecular docking studies and their antibacterial activity on Bacillus brevis and E. coli

The syntheses of 3,4-dihydropyrimidin-2(1H)-ones by one-pot, three-component condensation of aldehydes, β-ketoesters and urea or thiourea have been made more simple and efficient by using 20 mol% hydrazine sulfate as catalyst. Aldehydes, β-ketoesters and urea are cyclocondensed in the presence of hydrazine sulfate to produce dihydropyrimidines in ethanol under reflux conditions. The advantages of using hydrazine sulfate as a catalyst over the traditional Biginelli reaction conditions include outstanding yields (80–91%) and a shorter (10–15 hours) reaction time. In order to evaluate the antibacterial efficiencies of the synthesized compounds, we have studied the inhibitions of microbial proliferation of both Gram-positive (Bacillus brevis) and Gram-negative (E. coli) bacterial strains in comparison to a control group. The microbial inhibitions occur in the range of 40–98% by different derivatives of dihydropyrimidinones. Molecular docking studies of the synthesized compounds have also been done using software tools such as SwissADME.

Photocatalytic inactivation of bio-aerosol using surface-active iron-titanium thin film immobilized on sustainable cementitious composite

The current research introduces a novel in-situ and visibly-active heterojunction formation concept to fabricate a sustainable antimicrobial cementitious material. To achieve this, cement mortar incorporating iron-rich industrial waste products (FWPs) was outer-coated with photocatalyst Titanium dioxide (TiO2). The proposed technique forms a novel surface-active Fe2TiO5 heterojunction oxide layer, which considerably improves the photocatalytic and antimicrobial properties of TiO2 under the visible spectrum of light. Primarily, the study evaluated the structural suitability of the developed iron-rich cementitious material in terms of its durability and strength properties. The findings indicate that the iron-rich cementitious material performed better than conventional cementitious material. After this, the effectiveness and novelty of the proposed research were examined, such that the Fe2TiO5 photocomposite was subjected to detailed microscopic investigations such as XRD, HRTEM, UV-DRS, XPS, FESEM, etc. The results verified the production of the inherent Fe2TiO5 heterojunction through the presence of Fe in the photocatalyst TiO2 lattice via the formation of ITO complex bonds. It also revealed that the Fe2TiO5 photocomposite functions effectively under visible light with an energy band gap of 2.57 eV. The antimicrobial activity of the Fe2TiO5 photocomposite was also assessed by neutralizing E.coli bioaerosols. The disinfection results indicated that the Fe2TiO5 photocomposite exhibits excellent antimicrobial properties. It achieved 69.33 % and 95–98 % antibacterial efficiency under dark and visible light, respectively. Thus, the study establishes a Fe2TiO5 photocomposite material that combines photocatalytic and antimicrobial properties, making it suitable for use as a sustainable building material. Also, it contributes to environmental sustainability by promoting a circular economy and green building practices.

Novel approaches of mycosynthesized zinc oxide nanoparticles (ZnONPs) using Pleurotus sajor-caju extract and their biological and environmental applications.

In this study, mycosynthesized zinc oxide nanoparticles (ZnONPs) are fabricated via Pleurotus sajor-caju mushroom extract, and their potential medical and environmental applications are demonstrated. The biosynthesized ZnONPs were assessed for their antibacterial, anticancer, and biodecolorization potential efficiency. They were also characterized and morphologically analyzed by UV-visible spectroscopy, XRD, FT-IR, FE-SEM, EDX, HR-TEM, Zeta potential, and GC-MS analysis. The UV visible spectrum analysis of synthesized ZnONPs analyzed outcome 354nm was the SPR peak that the nanoparticles displayed. The characteristic Zn-O bond was indicated by a strong peak in the FT-IR study at 432.05cm-1. Based on XRD analysis, P. sajor-caju mediated ZnONPs were crystalline nature, with an average nano particle size of 14.21nm and a polydispersity directory of 0.29. The nanoparticles exhibit modest constancy, as shown by their zeta potential value of - 33.2mV. The presence of oxygen and zinc was verified by EDX analysis. The ZnONPs were found to be spherical in shape and crystalline nature structure, with smooth surface morphology and a mean particle size of 10nm using HR-TEM and SAED analysis. The significant antibacterial activity against S. aureus (6.2 ± 0.1), S. mutans (5.4 ± 0.4), and B. subtilis (5.2 ± 0.1mm) was demonstrated by the synthesized ZnONPs made using mushroom extract. It was discovered that when the concentration of mushroom extract was increased together with synthesized ZnONPs, the bactericidal activity increased considerably. A higher concentration of ZnONPs demonstrated superior antibacterial activity across the ZnONPs ratio tests. The in vitro cytotoxicity assay showed that ZnONPs, even at low doses, had a substantial number of cytotoxic effects on liver cancer cells (LC50 values 47.42µg/mL). The effectiveness test revealed that acid blue 129 was degraded. The best decolorization of acid blue 129 at 72.57% after 3h of soaking serves as evidence for the theory that myco-synthesized ZnONPs by P. sajor-caju mushroom can function as catalysts in reducing the dye. The mycosynthesized ZnONPs from P. sajor-caju extract, and its potential for antibacterial, anticancer, and decolorization are in this investigation. The mycosynthesized ZnONPs suggest a novel use for nanoparticles in the creation of environmental and medicinal products.

Enhancement in the antibacterial activity of Rifaximin by delivery through gelatin nanoparticles

Objectives Bacterial infections are a noteworthy global health concern that necessitates the development of new strategies to enhance the potency and efficacy of antibiotics. Rifaximin (RFX), a broad-spectrum antibiotic, exhibits promising antibacterial activity against several bacterial strains. However, its insolubility and impermeability impede the exploitation of its full potential. The objective of the current study is to overcome the inherent caveats of RFX to exploit its maximum potential. Significance The exploitation of the full potential of antibiotics is necessary for reduction in their dosage and to minimize antibiotic pollution. This is a preliminary study aiming for maximum utilization of RFX at the target site and reduction in its release in unmetabolized form. Methods Gelatin is a biopolymer that has gained significant attention for biomedical applications owing to its inherent biocompatibility and biodegradability. In this study, bovine gelatin nanoparticles (BGNPs) were fabricated by the self-assembly method for their application as a carrier of RFX to enhance its antibacterial activity. The study employs a comprehensive range of experimental techniques to characterize the fabricated BGNPs such as DLS, Zeta Potential, FT-IR, AFM, SEM-EDX, and UV-Vis spectrophotometry. Results The average size of the fabricated BGNPs was 100 nm with a zeta potential value of −15.3 mV. The loading of RFX on BGNPs rendered an increase in its size to 136 nm with a zeta potential value of −16 mV. In-vitro assays and microscopic analyses were conducted to compare the antibacterial efficacy of RFX and RFX@BGNPs. An excellent loading capacity followed by sustained release of RFX from RFX@BGNPs rendered a significant enhancement in its pharmaceutical efficacy. The release of RFX from RFX@BGNPs followed the Higuchi and Korsmeyer-Peppas models. The antibacterial efficacy of RFX against Staphylococcus aureus has doubled by delivery through RFX@BGNPs, assessed by inhibitory and biofilm inhibitory assays. The enhancement in the antibacterial efficiency was further endorsed by SEM and microscopic imaging of the control and treated bacterial colonies. Conclusion The study demonstrates an enhancement in the antimicrobial efficacy of RFX by its delivery in the form of RFX@BGNPs to exploit its full potential for practical applications.

Simultaneous improvement in mechanical properties, corrosion resistance and antibacterial properties of Ti-Ag sintered alloy with gradient nanostructure

Bioinert titanium (Ti) with antibacterial properties is crucial for bone implantations. Alloying Ag can endow Ti with antibacterial properties, while the mechanical, corrosion and antibacterial properties of Ti-Ag alloys are not satisfactorily balanced. In this work, Ti-x wt%Ag alloys (x=0.5, 1 and 3) were sintered by spark plasma sintering and then subjected to a surface mechanical rolling treatment (SMRT). The Ti-Ag alloys are composed of Ti, Ti-Ag and Ti2Ag phases. After SMRT, a gradient nanostructured (GNS) layer formed on the Ti-Ag surface, the mean grain size is ∼ 6 nm at the top surface and increases gradually with depth. The GNS layer endows Ti-Ag alloys with better wettability, higher nano-roughness and compressive residual stress. Incorporating limited Ag (≤1 wt%) in Ti can effectively enhance its mechanical (surface hardness, wear resistance and compressive strength) and anti-corrosion properties, and they can be further improved by forming a GNS layer. The antibacterial efficiency of Ti-Ag is positively proportional to Ag content, and they are significantly enhanced after surface nanocrystallization. The bacteriostatic mechanism is the synergistic interaction between leach Ag+ and nano Ag-containing phases of GNS Ti-Ag alloy. Both Ti-Ag and GNS Ti-Ag alloys possess good cytocompatibility, the GNS layer has the potential to encourage early differentiation of osteoblasts. The GNS Ti-Ag alloy with 1 wt% Ag has excellent comprehensive properties, which shows larger potential in orthopedic applications.

Amphiphilic diblock copolymers of polyisobutylene-b-poly(2-ethyl-2-oxazoline) via cationic polymerization

A series of amphiphilic polyisobutylene-b-poly (2-ethyl-2-oxazoline) (PIB-b-PEOX) diblock copolymer/Ag nanoparticle composites were successfully in-situ synthesized via cationic ring-opening polymerization of 2-ethyl-2-oxazoline (EOX) with high initiation efficiency by using allyl bromide end functionalized polyisobutylene (PIB-allylBr) as a macroinitiator and AgClO4 as a coinitiator. The microphase separation formed in the resulting PIB-b-PEOX diblock copolymers due to the thermodynamic imcompability of hydrophilic PEOX segments and hydrophobic PIB segments. The micromorphology of phase separation is dependent on the copolymer composition, in which sea-island micromorphology formed for PIB118-b-PEOX80 and bicontinuous phase micromorphology formed for PIB118-b-PEOX97. The micelles with nano-scale size in the range of 15–80 nm and having high drug loading rate of ca. 48.9 % can be formed by self-assembly of the amphiphilic diblock copolymers in n-hexane. The drug cumulative release rate can be increased with an increase in the proportion of PEOX segments, due to the strong interaction between ibuprofen and the PEOX segments. The hydrophilicity of the PIB-b-PEOX diblock copolymer surfaces can be improved after ethanol vapor induction. The PIB-b-PEOX diblock copolymers behave biocompatibility and good anti-protein adsorption property. The amphiphilic PIB-b-PEOX diblock copolymer/Ag nanoparticle composites exhibit high antibacterial efficiency for Gram-negative bacterium (E. coli) and Gram-positive bacterium (S. aureus). To the best of our knowledge, this is the first example of PIB-b-PEOX diblock copolymer/Ag nanoparticle (6.4 ± 2.6 nm) composites synthesized in-situ with good biocompatibility, anti-protein adsorption, and antibacterial properties, which would have potential applications for drug delivery and anti-protein coating in biomedical areas.

CeO2 nanoparticle-modified BiOI nanoflowers as visible-light-driven heterojunction photocatalyst for tetracycline degradation and antibacterial

BiOI, a typical narrow-band gap visible-light-driven photocatalyst, possesses a high recombination rate of photogenerated electrons and holes, which hinders its practical application in environmental remediation. To improve its photocatalytic efficiency, BiOI/CeO2 heterojunction was designed and prepared via a facile chemical bath method. Compared to pure BiOI, the BiOI/CeO2 heterojunction not only enhanced the absorption of visible-light but also improved the separation and transfer efficiency of photogenerated carriers. Impressively, the BiOI/CeO2 heterojunction with a BiOI:CeO2 molar ratio of 2:1 (named CBOI-2) exhibited the best photocatalytic performance. The CBOI-2 heterojunction can degrade 80 % of tetracycline within 60 min, and the degradation activity was almost intact after three cycles. The reaction rate constant of CBOI-2 heterojunction was 22.1 times that of BiOI and 5.8 times that of CeO2. Moreover, CBOI-2 heterojunction behaves much better in antibacterial effect whose antibacterial efficiency reaches ∼99.6 %. A double charge-transfer mechanism was proposed in this work and it indicated that the improved photocatalytic efficiency mainly resulted from an enhanced separation and transfer of photogenerated carriers. During the photocatalytic reaction process, superoxide radicals, hydroxyl radicals and holes were generated, which play important roles in the degradation of tetracycline and antibacterial. This work provides important insights into the design of visible-light-driven photocatalysts with high photocatalytic activity for antibiotic degradation and bacteria killing.

Evaluation of antibacterial activity on nanoline-array surfaces with different spacing

Extensive research has been conducted on anti-biofouling or antibacterial surfaces, with nanostructured surfaces that mimic cicada and dragonfly wings emerging as promising candidates for mechano-bactericidal applications. These biomimetic nanostructured surfaces are capable of exerting a bactericidal effect by directly damaging the membranes of bacteria attached to nanostructures. Although research on bactericidal effect using various nanostructures have been conducted, no specific studies have yet reported on the antibacterial efficiency of the surface having nanoline array, especially regarding the spacing between nanolines. This study details the fabrication of nanoline array via ultraviolet (UV) molding with polyurethane acrylate (PUA), noted for its UV sensitivity and rapid curing, enabling the fabrication of precise and scalable nanoscale structures. Investigation into the nanoline array’s antibacterial effects against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) reveals that nanoline spacing critically influences bacterial adherence and viability, with specific spacings enhancing antibacterial properties. Scanning electron microscopy (SEM) and confocal microscopy analyses show that surface topography significantly affects bacterial behavior, with specific spacings leading to varied bacterial responses, including membrane damage and altered attachment patterns. The study highlights the potential of nanoline array in fabricating surfaces with tailored antibacterial properties, emphasizing the importance of nanoscale design in influencing bacterial interaction and viability. We also confirm the relative mechanical rigidity of the nanoline array, which exhibits antibacterial effects, through both experimental observations and numerical analysis. This indicates our proposed nanoline-array surface could have potential future applications in mechanical anti-bacterial functions that require such structural robustness.