Sustained Antibacterial Activity Research Articles

Sustained Antibacterial Effect of Levofloxacin Drug in a Polymer Matrix by Hybridization With A Layered Double Hydroxide

AbstractThe immobilization of antimicrobial drugs can be used to expand the application of antibacterial properties to consumer products. The purpose of this study was to stabilize an antimicrobial agent, levofloxacin (LVX), for sustained antibacterial activity by immobilizing the drug molecules in a layered double hydroxide (LDH) and embedded in a polyurethane substrate. As-prepared MgAl-LDH was calcined at 400°C and reconstructed with LVX for intercalation. The X-ray diffraction patterns and cross-sectional transmission electron microscopy images showed lattice expansion along the crystallographic c axis upon LVX intercalation, suggesting successful loading of the drug. Fourier-transform infrared spectra revealed that the structure of LVX was well preserved between LDH layers. Elemental analysis indicated that the loading capacity of LVX in the hybrid was 41.7%. Bacterial-colony forming inhibitory assay on Bacillus subtilis exhibited ~100% antibacterial activity of both LVX alone and LVX-LDH hybrid (LL). To determine sustainability of antibacterial activity by the hybrid, either LVX alone or LL hybrid was loaded in the polyurethane (PU) substrate for which antibacterial activity was evaluated before and after immersion in a phosphate-buffered saline for 3 days. The LVX-composited PU showed a dramatic decrease in antibacterial activity, down to 0% after buffer treatment; LL-composited PU still contained antibacterial activity (~34% of colony suppression) after phosphate-buffered saline immersion.

Maltoheptaose-Presenting Nanoscale Glycoliposomes for the Delivery of Rifampicin to E. coli.

Liposomes, a nanoscale drug delivery system, are well known for their ability to improve pharmacokinetics and reduce drug toxicity. In this work, maltoheptaose (G7)-presenting glycoliposomes were synthesized and evaluated in the delivery of the antibiotic rifampicin. Two types of liposomes were prepared: nonfluid liposomes from l-α-phosphatidylcholine (PC) and cholesterol, and fluid liposomes from 1,2-dipalmitoyl-sn-glycero-3-phosphocholine and 1,2-dimyristoyl-sn-glycero-3-phospho-(1'-rac-glycerol). G7-derivatized glycolipid, G7-DPPE (DPPE: 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine), was incorporated into the liposomes at 21 and 14 μmol/mg to form nanoparticles of 75 ± 12 and 146 ± 14 nm for the nonfluid and fluid G7-glycoliposomes, respectively. The multivalent G7-glycoliposomes were characterized by lectin binding with concanavalin A (Con A). The dissociation constant K d between Con A and the nonfluid or fluid G7-glycoliposomes was 0.93 or 0.51 μM, which represented ~900- or 1600-fold stronger affinity than the binding between Con A and G7. The G7-glycoliposomes were loaded with rifampicin at 6.6 and 16 wt % encapsulation for the nonfluid and fluid G7-glycoliposomes, respectively. Introducing a carbohydrate in the liposomes slowed down the release of rifampicin, with the G7-glycoliposomes having the slowest release rate and the lowest permeability coefficient among the liposome formulations. The fluid G7-glycoliposomes lowered the minimal inhibitory concentration (MIC) of rifampicin against E. coli ORN208 by about 3 times, whereas liposomes without G7 or Man (d-mannose)-glycoliposomes showed no improvement in MIC. The rifampicin-loaded fluid G7-glycoliposomes demonstrated the best sustained antibacterial activity against E. coli, with up to 2 log reduction in the colony forming units at 4 × MIC after 24 h. Fluorescence resonance energy transfer and confocal fluorescence microscopy revealed stronger interactions of the bacterium with the fluid G7-glycoliposomes than other liposome formulations.

Novel procyanidins-loaded chitosan-graft-polyvinyl alcohol film with sustained antibacterial activity for food packaging

Active food packaging materials containing procyanidins (PC) exhibits outstanding antimicrobial activity, but PC is easy to be hydrolyzed by acid. A novel water-soluble chitosan (CS)-based copolymer was prepared to be used as a carrier to provide a pH-stable environment for loading PC. CS was copolymerized with polyvinyl alcohol (PVA) via a coupling reagent-mediated approach. The CS-graft-PVA film exhibited a desirable PC encapsulation efficiency of over 95% and excellent long-term release sustainability, which was better than the conventional CS and CS-blend-PVA films. Moreover, CS-graft-PVA film had satisfactory mechanical properties and barrier properties, as well possessed a desirable antibacterial activity and biofilm inhibition against foodborne pathogenic microbes and spoilage bacteria. The film was also applied in the salmon muscle perseveration and showed a potential ability to prevent microorganism contamination and texture deterioration in 10 days. These results suggested that the CS-graft-PVA film has an excellent promise for future food packaging applications.

Evaluation of the anti-biofilm effect of poloxamer-based thermoreversible gel of silver nanoparticles as a potential medication for root canal therapy

The purpose of this study was to design silver nanoparticles (AgNPs) poloxamer thermoreversible gel (AgNPs-PL) and investigate whether this gel could provide sustained antibacterial activity against Enterococcus faecalis (E. faecalis) in the root canal. The gels fabricated were characterized in terms of gelatin temperature, particle size, in-vitro Ag+ release, and elemental content. Cytotoxicity of AgNPs-PL on primary human periodontal ligament fibroblasts (HPDLFs) was examined by CCK-8 assay. Characterization of AgNPs-PL gel revealed that it contained particles existing as large clumps/fused aggregates of different shapes, with a mean diameter of 21.624 ± 14.689 nm, exhibited sustained release of Ag+ for 9 days, and non-toxic to HPDLFs at a low dose (4–32 μg/mL) through 24, 48, and 72 h exposures. The antibacterial effect of 16 and 32 μg/mL concentrations of AgNPs-PL was compared with blank poloxamer gel (PL) and calcium hydroxide (CH) using three methods: (I) agar counting plate, (II) scanning electron microscope (SEM) observations, and (III) confocal laser scanning microscope (CLSM) analysis. AgNPs-PL at the two doses above was more effective than PL and CH in removing E. faecalis biofilm at 1, 3, 9 days. Thus, AgNPs-PL exhibits strong activity against E. faecalis and is easy to produce, with a continuous release profile of Ag+. AgNPs-PL gel may be a candidate for a new root canal disinfection.

Visible light responsive, self-activated bionanocomposite films with sustained antimicrobial activity for food packaging

The research on a new type of low-cost, less-loss and adjustable sustained antibacterial activity food packaging films with self-activation ability and great industrialization potentiality is of great scientific and technological interest. Herein, a novel chitosan/negatively charged graphitic carbon nitride self-activation bionanocomposite films was prepared by one-step electrostatic self-assembly. First, the antibacterial efficiency of this film could reach to 99.8 ± 0.26% against E. coli and 99.9 ± 0.04% against S. aureus through self-activated under visible light. Second, this film can effectively extend the shelf life of tangerines to 24 days. Hemolysis and cell experiment test proved that this film was safe and nontoxic. Finally, negatively charged graphitic carbon nitride with low-cost can improve the mechanical, thermal and hydrophobic properties of neat chitosan films. This work can provide a new pathway for the preparation of low-cost packaging films with excellent visible light responsive property and sustainable antibacterial activity.

In vitro evaluation of antibacterial efficacy of vancomycin-loaded suture tapes and cerclage wires

Usage of implants containing antibiotic agents has been a common strategy to prevent implant related infections in orthopedic surgery. Unfortunately, most implants with microbial repellent properties are characterized by accessibility limitations during daily clinical practice. Aim of this in vitro study was to investigate whether suture tapes and cerclage wires, which were treated with vancomycin, show a sustainable antibacterial activity. For this purpose, we used 24 stainless steel wire cerclages and 24 ultra-high molecular weight polyethylene and polyester suture tape test bodies. The test bodies were incubated for 30 min. in 100 mg/ml vancomycin solution or equivalent volumes of 0.9% NaCl. After measuring the initial solution uptake of the test bodies, antibacterial efficacy via agar diffusion test with Staphylococcus aureus and vancomycin elution tests were performed 1, 2, 3, and 6 days after incubation. Vancomycin-loaded tapes as well as vancomycin-loaded cerclage wires demonstrated increased bacterial growth inhibition when compared to NaCl-treated controls. Vancomycin-loaded tapes showed an additional twofold and eightfold increase of bacterial growth inhibition compared to vancomycin-loaded wires at day 1 and 2, respectively. Elution tests at day 1 revealed high levels of vancomycin concentration in vancomycin loaded tapes and wires. Additionally, the concentration in vancomycin loaded tapes was 14-fold higher when compared to vancomycin loaded wires. Incubating suture tapes and cerclage wires in vancomycin solution showed a good short-term antibacterial activity compared to controls. Considering the ease of vancomycin application on suture tapes or wires, our method could represent an attractive therapeutic strategy in biofilm prevention in orthopedic surgery.

Comparative Evaluation of Antibacterial Effects of Nanoparticle-Incorporated Orthodontic Primer: An In Vitro Study

Aim and Objectives: To compare and evaluate the antibacterial efficacy of various nanoparticles incorporated in orthodontic primer with that of conventional antimicrobial agents at different concentrations on Streptococcus mutans ( S. mutans) strain. Materials and Methods: Transbond XT Primer was mixed with 2.5% and 5% benzalkonium chloride (BAC), 0.2% and 2.5% chlorhexidine, 1% and 3% titanium dioxide (TiO2) nanoparticles, 0.2% and 0.5% nanohydroxyapatite, and 0.2% and 0.5% silica-doped nanohydroxyapatite powders. Antibacterial activity against S. mutans for all the materials was evaluated by the disk diffusion method for periods of 48 (T1) and 72 (T2) hours. Results: There was a significant increase in the antimicrobial activity of the orthodontic primer modified by the addition of antibacterial agents. The highest zone of inhibition against S. mutans was observed for silica-doped nanohydroxyapatite of 0.5% (11.03 mm) among all the nanoparticles, which was similar to the conventional antibacterial agents used in our study. Conclusions: • Among all the groups, BAC at 5% concentration showed the highest antimicrobial activity, and the least activity was exhibited by 1% TiO2 nanoparticles. • Silica-doped nanohydroxyapatite at 0.5% expressed the greatest antibacterial activity among all the nanoparticles. • All the materials showed sustained antibacterial activity even after 72 hours.

Osteogenic and antibacterial surfaces on additively manufactured porous Ti-6Al-4V implants: Combining silver nanoparticles with hydrothermally synthesized HA nanocrystals

The recently developed additively manufacturing techniques have enabled the fabrication of porous biomaterials that mimic the characteristics of the native bone, thereby avoiding stress shielding and facilitating bony ingrowth. However, aseptic loosening and bacterial infection, as the leading causes of implant failure, need to be further addressed through surface biofunctionalization. Here, we used a combination of (1) plasma electrolytic oxidation (PEO) using Ca-, P-, and silver nanoparticle-rich electrolytes and (2) post-PEO hydrothermal treatments (HT) to furnish additively manufactured Ti-6Al-4V porous implants with a multi-functional surface. The applied HT led to the formation of hydroxyapatite (HA) nanocrystals throughout the oxide layer. This process was controlled by the supersaturation of Ca2+ and PO43− during the hydrothermal process. Initially, the high local supersaturation resulted in homogenous nucleation of spindle-like nanocrystals throughout the surface. As the process continued, the depletion of reactant ions in the outermost surface layer led to a remarkable decrease in the supersaturation degrees. High aspect-ratio nanorods and hexagonal nanopillars were, therefore, created. The unique hierarchical structure of the microporous PEO layer (pore size < 3 μm) and spindle-like HA nanocrystals (<150 nm) on the surface of macro-porous additively manufactured Ti-6Al-4V implants provided a favorable substrate for the anchorage of cytoplasmic extensions assisting cell attachment and migration on the surface. The results of our in vitro assays clearly showed the important benefits of the HT and the spindle-like HA nanocrystals including a significantly stronger and much more sustained antibacterial activity, significantly higher levels of pre-osteoblasts metabolic activity, and significantly higher levels of alkaline phosphatase activity as compared to similar PEO-treated implants lacking the HT.

Scalable synthesis of robust and stretchable composite wound dressings by dispersing silver nanowires in continuous bacterial cellulose

While silver nanoparticles are widely used to endow materials with antibacterial activity, silver nanowires (AgNWs) have not attracted much attention. Herein, the composites of bacterial cellulose (BC) and AgNWs were prepared through a novel step-by-step in situ biosynthesis which retains the three-dimensional network of BC. The results of water vapor permeability, water uptake rate, and water retention rate showed that the BC/AgNW wound dressings could absorb wound skin exudates and maintain moisture environments. Furthermore, the BC/AgNW dressings were robust and stretchable. More importantly, the BC/AgNW dressings exhibited sustained release of Ag+. The results from animal tests indicated that the BC/AgNW dressing with 38.4 wt% AgNWs exhibited higher expression levels of cytokeratin-10 and integrin-β4, greater proliferation of keratinocytes and formation of epithelial tissues and greatly improved skin regeneration over the bare BC. We propose that the integrated nanofibrous structure and the excellent and sustained antibacterial activity of AgNWs are responsible for the excellent in vivo wound healing ability and biocompatibility. These results suggest that the BC/AgNW composites have promising application as wound dressings.

Evaluation of Sustained Antibacterial Effect of Alcohol-Based Disinfectant Containing Monovalent Copper Compound Against Antibiotic-Resistant Bacteria

Background Monovalent copper compounds have high antiviral and antibacterial activity. Unlike divalent copper compounds, monovalent copper compounds can generate hydroxyl radical which causes oxidative damage to microorganisms. However, the antibacterial activity of monovalent copper compounds against antibiotic-resistant bacteria is not clear. The objective of this study is to evaluate the sustained antibacterial activity of alcohol disinfectant containing monovalent copper compound against antibiotic-resistant bacteria and to compare its antibacterial activity with those of conventional disinfectants. Methods Monovalent copper compound dispersed in 70% ethanol (Ethanol/monovalent copper) was applied on stainless plate by swabbing with cotton fabric. Ethanol (70%), sodium hypochlorite (5000 ppm), and benzalkonium chloride (0.2%) were also applied for comparison. After each disinfectant was dried, each bacterial suspension of antibiotic-resistant bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant Acinetobacter baumannii (MDRA), was dropped onto the stainless plate sample. Viable bacteria were evaluated at 1 and 3 hours after each bacterial suspension was applied. Results As compared to the untreated stainless plate, the stainless plates treated with Ethanol/monovalent copper, ethanol, sodium hypochlorite, and benzarconium chloride showed log reductions in the average number of CFUs, 1.08, -0.10, -0.56, and 0.83 log10 at 1 hour contact, >4.01, 0.08, -0.86, and 1.63 log10 at 3 hour contact for MRSA, and >4.86, -0.16, -0.08, and 3.61 log10 at 1 hour contact, >5.14, -0.04, -0.07, and 4.28 log10 at 3 hour contact for MDRA, respectively. Conclusions This study demonstrated that ethanol/monovalent copper have sustained antibacterial activity against MRSA and MDRA even after drying. The antibacterial activity is also higher than a quaternary ammonium salt, benzalkonium chloride which is widely used in healthcare settings. These study findings suggest that monovalent copper compounds serve as a continuously active disinfectant against antibiotic-resistant bacteria in the healthcare environment. Monovalent copper compounds have high antiviral and antibacterial activity. Unlike divalent copper compounds, monovalent copper compounds can generate hydroxyl radical which causes oxidative damage to microorganisms. However, the antibacterial activity of monovalent copper compounds against antibiotic-resistant bacteria is not clear. The objective of this study is to evaluate the sustained antibacterial activity of alcohol disinfectant containing monovalent copper compound against antibiotic-resistant bacteria and to compare its antibacterial activity with those of conventional disinfectants. Monovalent copper compound dispersed in 70% ethanol (Ethanol/monovalent copper) was applied on stainless plate by swabbing with cotton fabric. Ethanol (70%), sodium hypochlorite (5000 ppm), and benzalkonium chloride (0.2%) were also applied for comparison. After each disinfectant was dried, each bacterial suspension of antibiotic-resistant bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant Acinetobacter baumannii (MDRA), was dropped onto the stainless plate sample. Viable bacteria were evaluated at 1 and 3 hours after each bacterial suspension was applied. As compared to the untreated stainless plate, the stainless plates treated with Ethanol/monovalent copper, ethanol, sodium hypochlorite, and benzarconium chloride showed log reductions in the average number of CFUs, 1.08, -0.10, -0.56, and 0.83 log10 at 1 hour contact, >4.01, 0.08, -0.86, and 1.63 log10 at 3 hour contact for MRSA, and >4.86, -0.16, -0.08, and 3.61 log10 at 1 hour contact, >5.14, -0.04, -0.07, and 4.28 log10 at 3 hour contact for MDRA, respectively. This study demonstrated that ethanol/monovalent copper have sustained antibacterial activity against MRSA and MDRA even after drying. The antibacterial activity is also higher than a quaternary ammonium salt, benzalkonium chloride which is widely used in healthcare settings. These study findings suggest that monovalent copper compounds serve as a continuously active disinfectant against antibiotic-resistant bacteria in the healthcare environment.

Electrospun vancomycin-loaded nanofibers for management of methicillin-resistant Staphylococcus aureus-induced skin infections.

Skin damage exposes the underlying layers to bacterial invasion, leading to skin and soft tissue infections. Several pathogens have developed resistance against conventional topical antimicrobial treatments and rendered them less effective. Recently, several nanomedical strategies have emerged as a potential approach to improve therapeutic outcomes of treating bacterial skin infections. In the current study, nanofibers were utilized for topical delivery of the antimicrobial drug vancomycin and evaluated as a promising tool for treatment of topical skin infections. Vancomycin-loaded nanofibers were prepared via electrospinning technique, and vancomycin-loaded nanofibers of the optimal composition exhibited nanosized uniform smooth fibers (ca. 200nm diameter), high drug entrapment efficiency and sustained drug release patterns over 48h. In vitro cytotoxicity assays, using several cell lines, revealed the biocompatibility of the drug-loaded nanofibers. In vitro antibacterial studies showed sustained antibacterial activity of the vancomycin-loaded nanofibers against methicillin-resistant Staphylococcus aureus (MRSA), in comparison to the free drug. The nanofibers were then tested in animal model of superficial MRSA skin infection and demonstrated a superior antibacterial efficiency, as compared to animals treated with the free vancomycin solution. Hence, nanofibers might provide an efficient nanodevice to overcome MRSA-induced skin infections and a promising topical delivery vehicle for antimicrobial drugs.

Sponges containing tetracycline loaded-PLGA-zein microparticles as a periodontal controlled release device

This paper aimed to design collagen sponges containing tetracycline-loaded PLGA-zein microparticles with controlled release characteristics as an alternative for periodontal treatment. Tetracycline microparticles were prepared by spray-drying technique, while the sponges were prepared by their dispersion in collagen suspension and subsequent freeze-drying. Release studies of two microparticles compositions loaded and unloaded-collagen sponges were carried over a 10 days period. Antibiogram tests were used to ensure the sustained antibacterial activity against Staphylococcus aureus. SEM imagens demonstrated spherical and non-aggregated microparticles (2–5 μm) and their effective dispersion within the sponges, what together with the pronounced water sorption promoted by the collagen fibers enhanced the drug release from the unitary particles. The dissolution profiles showed a sustained-release pattern for both sponges and microparticles formulations, reaching in some cases almost the complete drug recovery. The sponge formulations increased the release of tetracycline up to 45 and 60% in the first 12 h, while their microparticles pairs released less than 30 and 10%, respectively, as a result of their aggregation. Antibiograms showed that the sponges sustained released tetracycline over 10 days and could represent an alternative for periodontal insertion as well as for those applications where the prevention and control of bacterial infections is needed. The incorporation of tetracycline microparticles to collagen sponges improved the release rates of this antimicrobial agent and therefore represents an alternative for controlled antimicrobial activity.

PVA/anionic collagen membranes as drug carriers of ciprofloxacin hydrochloride with sustained antibacterial activity and potential use in the treatment of ulcerative keratitis.

Devices such as contact lenses and collagen shields have been used to improve the antibiotic bioavailability of eye drops formulations in the treatment of ulcerative keratitis. Nevertheless, these devices are not sustained drug delivery systems, and a combination with eye drops is necessary. In animal patients, it requires constant supervision by trained personnel to avoid device loss, which increases the cost of treatment. In this study, PVA/anionic collagen membranes containing ciprofloxacin or tobramycin were prepared using two different methodologies, and the release, physical and antimicrobial properties were evaluated. The membrane containing ciprofloxacin was selected as a sustained drug delivery system with antibacterial activity against Staphylococcus aureus and Escherichia coli during 48 h. Despite to be opaque, due to its heterogeneous morphology, this membrane had the adequate mechanical strength, water content, hydrophilicity, water vapor permeability, and surface pH to interact with cornea without causing discomfort. In the surface of this membrane it was observed dispersed collagen fibrils which could serve as a substrate for corneal proteinases, contributing to the reduction in stromal damage and enhancing the epithelium regeneration. These results encourage the idea these membranes are new cost-effective and safe alternatives to treat corneal ulcers in animal patients.

Ciprofloxacin Loaded Nanostructured Lipid Carriers Incorporated into In-Situ Gels to Improve Management of Bacterial Endophthalmitis.

Bacterial endophthalmitis (BE) is a potentially sight-threatening inflammatory reaction of the intraocular fluids or tissues caused by bacteria. Ciprofloxacin (CIP) eye drops are prescribed as first-line therapy in BE. However, frequent administration is necessary due to precorneal loss and poor ocular bioavailability. The objective of the current research was to prepare CIP containing nanostructured lipid carriers (CIP-NLCs) loaded an in situ gel system (CIP-NLC-IG) for topical ocular administration for enhanced and sustained antibacterial activity in BE treatment. CIP-NLCs were prepared by the hot homogenization method and optimized based on physicochemical characteristics and physical stability. The optimized CIP-NLC formulation was converted into CIP-NLC-IG with the addition of gellan gum as a gelling agent. Furthermore, optimized CIP-NLC and CIP-NLC-IG were evaluated for in vitro release and ex vivo transcorneal permeation studies, using commercial CIP ophthalmic solution (CIP-C) as the control. The optimized CIP-NLC formulation showed particle size, polydispersity index, zeta potential, assay and entrapment efficiency of 193.1 ± 5.1 nm, 0.43 ± 0.01, −32.5 ± 1.5 mV, 99.5 ± 5.5 and 96.3 ± 2.5%, respectively. CIP-NLC-IG with 0.2% w/v gellan gum showed optimal viscoelastic characteristics. The in vitro release studies demonstrated sustained release of CIP from CIP-NLC and CIP-NLC-IG formulations over a 24 h period. Transcorneal flux and permeability increased 4 and 3.5-fold, and 2.2 and 1.9-fold from CIP-NLC and CIP-NLC-IG formulations, respectively, when compared to CIP-C. The results demonstrate that CIP-NLC-IG could be considered as an alternate delivery system to prolong the residence time on the ocular surface after topical administration. Thus, the current CIP ophthalmic formulations may exhibit improved ocular bioavailability and prolonged antibacterial activity, which may improve therapeutic outcomes in the treatment of BE.

Intelligent magnetic imprinted nanoparticles for efficient lysozyme separation from egg whites and sustained antibacterial activity

Intelligent magnetic materials are capable of responding to environmental stimuli in an on/off manner. The photo- and thermal-responsive nanogel layer was surface-grafted onto several magnetic nanoparticles to prepare the magnetic imprinted nanoparticles (Fe3O4 MIPs). The Fe3O4 MIPs show dramatic temperature and light, dual-dependent rebinding and release characteristics for lysozyme. Above the volume phase transition temperature of the PNIPAAm, the imprinted protein (lysozyme) can be selectively separated from egg whites and the activity remained unchanged. By combining low temperature and UV irradiation, a more finely tuned release of the binding protein can be achieved. Time-dependent antibacterial activity was observed, and it was found that Fe3O4 MIPs-loaded lysozyme almost completely suppressed the growth of E. coli with the continuous lysozyme release. More importantly, the Fe3O4 MIPs could easily be separated by an external magnetic field and can be recycled. The photo- and thermal-responsive Fe3O4 MIPs pave a new way for the development of an advanced, sustainable material for use in bioseparation, drug delivery, and antibacterial materials.

Biocides: Durable Antibacterial Cotton Fabrics Based on Natural Borneol‐Derived Anti‐MRSA Agents (Adv. Healthcare Mater. 11/2020)

In article number 202000186 by Liangzhi Hong, Jianyu Su and coworkers, a water-soluble antibacterial agent is developed by integrating membrane-active natural borneol with a hydrophilic PDMAEMA chain. Cotton fabrics with sustained antibacterial activity can be fabricated by grafting the borneol-based antibacterial agents on the surface.

Durable Antibacterial Cotton Fabrics Based on Natural Borneol-Derived Anti-MRSA Agents.

Borneol, a natural extract with unique bicyclic monoterpene structure, has attracted increasing attention due to its broad-spectrum antibacterial properties via membrane disruption mechanism. However, the negligible water solubility of borneol limits its antibacterial efficiency. Herein, borneol-based water-soluble antibacterial agents are designed and synthesized to combat multi-drug resistant bacteria. The integration of borneol with hydrophilic poly(N,N-dimethylethyl methacrylate) (PDMAEMA) polymer chains boosts the antibacterial capability of borneol against Gram-negative, Gram-positive, and even multi-drug resistant bacteria. Methicillin-resistant Staphylococcus aureus (MRSA) are completely killed upon treatment with 50µg mL-1 of borneol-based polymers and Escherichia coli are annihilated at 39µg mL-1 . It is further demonstrated that the borneol-based antibacterial agents can be grafted onto cotton fabrics as a nonleaching antibacterial agent, which have higher sustained antibacterial activity than cotton fabrics coated with the commercial quaternary ammonium finishing agents (AEM 5700). The functionalized fabrics with excellent bactericidal activity, especially against MRSA, may have great potential applications in managing hospital-acquired infections.

Preparation of Polyvinyl Alcohol/Bacterial-Cellulose-Coated Biochar–Nanosilver Antibacterial Composite Membranes

Pathogenic bacteria and microorganisms in drinking water can cause various diseases, and new types of antibacterial material for water treatment and filtration are urgently needed. In this work, polyvinyl alcohol/bacterial cellulose/biochar–nanosilver (PVA/BC/C-Ag) antibacterial composite membrane materials were prepared by uniformly dispersing C-Ag particles in a PVA/BC mixed gel. Fourier-transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD), scanning electron microscopy (SEM), and thermogravimetric differential scanning calorimetry (TG-DSC) were used to characterize the composite membranes. Results indicated that the BC was uniformly mixed into the PVA gel and that the C-Ag particles were uniformly immobilized in the PVA/BC hybrid membrane. The PVA/BC/C-Ag composite membranes exhibited excellent antibacterial activity against Escherichia coli when assayed using a plate-counting technique. When used to treat actual contaminated water, the composite membranes demonstrated sustained antibacterial activity and good reusability. PVA/BC/C-Ag composite membranes have great potential for the development of drinking water treatment applications.

Two-Stage Electrochemical Synthesis of Copper Nanoparticles on Hydroxyapatite Coatings for Antibacterial Implants

A two-stage electrochemical synthesis method was developed to deposit copper nanoparticles onto hydroxyapatite-coated titanium. During the first-stage of electrochemical reaction, a submicron thick hydroxyapatite coating was deposited on the titanium cathode followed by electrochemical reduction of copper ions to form copper nanoparticles on the surface of the hydroxyapatite coating. Reaction parameters, including reaction time, deposition current density, copper ion precursor, and concentration were optimized to uniformly deposit nanosized copper particles. The size of the nanoparticles and overall copper content were controlled by adjusting reaction parameters in the second synthesis stage. This method, therefore, offers a route to adjust copper content in electrolytically deposited hydroxyapatite coatings independently from the hydroxyapatite coating reaction. The morphology and composition of the coatings were examined using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), respectively. The crystalline structure and the surface composition of the material were studied using X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. The topography and surface roughness of the coatings were measured using atomic force microscopy (AFM). The quantity of copper ions released in the bacterial growth medium was measured using inductively coupled plasma mass spectrometry (ICP-MS) and was associated with the antimicrobial activity of copper-hydroxyapatite coating. Antibacterial properties of these materials were investigated by culturing Escherichia coli (Gram-negative bacteria) and Staphylococcus aureus (Gram-positive bacteria) in the presence of the coatings. The antibacterial effect of the copper-hydroxyapatite coatings was enhanced by increasing the copper content. The data further suggested that the antibacterial activity was a result of the elution of copper ions from the coatings. The copper nanoparticles acted as a reservoir for copper ions, providing sustained antibacterial activity. The incorporation of nanosized copper into bioactive hydroxyapatite coatings will offer protection against post-surgical infection of orthopedic and dental implants, to reduce or eliminate the use of prophylactic antibiotics that are known to cause antibiotic-resistant bacteria strains to develop.

Engineering antimicrobial and biocompatible electrospun PLGA fibrous membranes by irradiation grafting polyvinylpyrrolidone and periodate

Postoperative adhesion may form as the result of a complicated fibrosis and inflammatory response, thus leads to a series of complications or increases the risk of surgery failure. Herein, we prepared poly (lactic-co-glycolic acid)-graft-polyvinylpyrrolidone/polyiodide (PLGA-g-PVP/I) electrospun fibrous membranes to prevent postoperative adhesion and infection formation. Firstly, hydrophilic PVP molecules were grafted on the surface of PLGA powders by gamma ray, and then iodine ions were coordinated with the grafted PVP. Subsequently, PLGA-g-PVP/I fibrous membranes were prepared by electrospinning. The PLGA-g-PVP/I membranes were analyzed via UV–vis, FTIR, Raman, and XPS. The formed polyiodide endowed the membranes with sustained antibacterial activity. The antimicrobial property of PLGA-g-PVP/I membranes was ascribed to the synergistic effect of intracellular ROS production and glutathione oxidation. Furthermore, the prevention efficacy of postoperative abdominal adhesion from the PLGA-g-PVP/I composite membranes was characterized in a rat model of sidewall defect-cecum abrasion. The results demonstrated that the PLGA-g-PVP/I fibrous membranes could prevent the postoperative abdominal adhesion effectively. Therefore, to endow the PLGA-g-PVP/I electrospun fibrous membranes with durable antibacterial property may be a promising strategy towards an anti-bacterial and anti-adhesion system for commercial and clinical uses.