In vitro anti-biofilm and anti-bacterial activity of Junceella juncea for its biomedical application

Objective:To investigate the anti-biofilm and anti-bacterial activity of Junceella juncea(J.juncea)against biofilm forming pathogenic strains.Methods:Gorgonians were extraeted with methanol and analysed with fourier transform infrared spectroscopy.Biofilm forming pathogens were identified by Congo red agar supplemented with sucrose.A quantitative spectrophotometric method was used to monitor in vitro biofilm reduction by microtitre plate assay.Anti-bacterial activity of methanolic gorgonian extract(MGE)was carried out by disc diffusion method followed by calculating the percentage of increase with crude methanol(CM).Results:The presence of active functional group was exemplified by FT-IR spectroscopy.Dry,black,crystalline colonies confirm the production of extracellular polymeric substances responsible for biofilm formation in Congo red agar.MGE exhibited potential anti-biofilm activity against all tested bacterial strains.The anti-bacterial activity of methanolic extract was comparably higher in Salmonella typhii followed by Escherichia colt,Vibrio cholerae and Shigella flexneri.The overall percentage of increase was higher by 50.2%to CM.Conclusions:To conclude,anti-biofilm and anti-bacterial efficacy of J.juncea is impressive over biofilm producing pathogens and are good source for novel anti-bacterial compounds.

Determination of the Anti-Adhesive and Anti-Biofilm Capacity of a Wheat Extract on <i>Staphylococcus aureus</i>in Farms

The formation of biofilm by pathogenic microorganisms has become a problem in the livestock industry since it is considered a potential source of infection for farm animals while increasing microbial resistance to physical and chemical agents. Some plant extracts, such as soluble wheat extract, have been shown to be effective in inhibiting or destroying the biofilm of certain micro-organisms under specific conditions. The objective of this study is to evaluate the capacity of the pathogen to form biofilm on different surfaces used in livestock, as well as to evaluate the anti-biofilm capacity of the soluble wheat extract against S. aureus on these surfaces. The inhibition potential of inhibition or destruction of biofilm was tested in vitro. Wheat extract at a concentration of 0.29 mg/100mL showed anti-biofilm activity on S. aureus, inhibiting its formation, as well as destroying it greatly after a contact time of 24 hours, on those surfaces where the microorganism presents more adhesion capacity.

Cationic and Anionic Antimicrobial Agents Co‑Templated Mesostructured Silica Nanocomposites with a Spiky Nanotopology and Enhanced Biofilm Inhibition Performance

Silica-based materials are usually used as delivery systems for antibacterial applications.In rare cases,bactericidal cationic surfactant templated silica composites have been reported as antimicrobial agents.However,their antibacterial efficacy is limited due to limited control in content and structure.Herein,we report a“dual active templating”strategy in the design of nanostructured silica composites with intrinsic antibacterial performance.This strategy uses cationic and anionic structural directing agents as dual templates,both with active antibacterial property.The cationic-anionic dual active templating strategy further contributes to antibacterial nanocomposites with a spiky surface.With controllable release of dual active antibacterial agents,the spiky nanocomposite displays enhanced anti-microbial and anti-biofilm properties toward Staphylococcus epidermidis.These findings pave a new avenue toward the designed synthesis of novel antibacterial nanocomposites with improved performance for diverse antibacterial applications.

Mechanical Properties, Biocompatibility and Anti-Bacterial Adhesion Property Evaluation of Silicone-Containing Resin Composite with Different Formulae

Novel branched silicone methacrylate was developed.The mechanical and biological properties of the resin system were investigated to select the formula proportion with the best overall performance.The novel silicone-containing monomers were combined with an incremental sequence of glass filler concentrations in commonly used Bis-GMA/TEGDMA(50/50,wt./wt.)dental resin systems.Physicochemical properties,surface properties,antibacterial adhesion effect,anti-biofilm effect,protein adsorption,and cytotoxicity were evaluated.The results showed that BSMs did not affect the double bond conversion of dental resin,but could reduce volumetric shrinkage(p<0.05).The BSM containing resins can resist protein and bacteria adhesion(S.mutans)because it has increased hydrophobicity and a lower free energy surface(p<0.05).However,there were no statistically significant differences in cytotoxicity,surface roughness,and double bond conversion rate.Overall,the results indicate that changes in a material’s properties are not strictly proportional to its composition.Synthetic silicone resin methacrylate can reduce the polymerization shrinkage,have low surface energy and anti-adhesion properties.Silicone composite resin containing 70%matrix has the best comprehensive properties.The silicone methacrylate composite represents an innovative method to improve the properties and reducing secondary caries.

Harnessing antimicrobial peptide-coupled photosensitizer to combat drug-resistant biofilm infections through enhanced photodynamic therapy

Bacterial biofilm-associated infection was one of the most serious threats to human health. However, effective drugs for drug-resistance bacteria or biofilms remain rarely reported. Here, we propose an innovative strategy to develop a multifunctional antimicrobial agent with broad-spectrum antibacterial activity by coupling photosensitizers (PSs) with antimicrobial peptides (AMPs). This strategy capitalizes on the ability of PSs to generate reactive oxygen species (ROS) and the membrane-targeting property of AMPs (KRWWKWIRW, a peptide screened by an artificial neural network), synergistically enhancing the antimicrobial activity. In addition, unlike conventional aggregation-caused quenching (ACQ) photosensitizers, aggregation-induced emission (AIE) PSs show stronger fluorescence emission in the aggregated state to help visualize the antibacterial mechanism. In vitro antibacterial experiments demonstrated the excellent killing effects of the developed agent against both Gram-positive (G^(+)) and Gram-negative (G^(–)) bacteria. The bacterial-aggregations induced ability enhanced the photoactivatable antibacterial activity against G^(–) bacteria. Notably, it exhibited a significant effect on destroying MRSA biofilms. Moreover, it also showed remarkable efficacy in treating wound infections in mice in vivo. This multifunctional antimicrobial agent holds significant potential in addressing the challenges posed by bacterial biofilm-associated infections and drug-resistant bacteria.

Evaluation of the anti-biofilm activities of bacterial cellulose-tannic acid-magnesium chloride composites using an in vitro multispecies biofilm model

Chronic wounds are a serious worldwide problem,which are often accompanied by wound infections.In this study,bacterial cellulose(BC)-based composites introduced with tannic acid(TA)and magnesium chloride(BC-TA-Mg)were fabricated for anti-biofilm activities.The prepared composites’surface properties,mechanical capacity,thermal stability,water absorption and retention property,releasing behavior,anti-biofilm activities and potential cytotoxicity were tested.Results showed that TA and MgCl_(2) particles closely adhered to the nanofibers of BC membranes,thus increasing surface roughness and hydrophobicity of the membranes.While the introduction of TA and MgCl_(2) did not influence the transparency of the membranes,making it beneficial for wound inspection.BC-TA and BC-TA-Mg composites displayed increased tensile strength and elongation at break compared to pure BC.Moreover,BC-TA-Mg exhibited higher water absorption and retention capacity than BC and BC-TA,suitable for the absorption of wound exudates.BC-TA-Mg demonstrated controlled release of TA and good inhibitory effect on both singly cultured Staphylococcus aureus and Pseudomonas aeruginosa biofilm and co-cultured biofilm of S.aureus and P.aeruginosa.Furthermore,the cytotoxicity grade of BC-TA-6Mg membrane was eligible based on standard toxicity classifications.These indicated that BC-TA-Mg is potential to be used as wound dressings combating biofilms in chronic wounds.

Antibacterial surface design of biomedical titanium materials for orthopedic applications

Titanium(Ti)and titanium alloys have become widely used as biomedical materials in orthopedics because of their good machinability,corrosion resistance,low elastic modulus and excellent biocompatibility.However,when Ti-based implants are used for bone repair and replacement,they are easy to cause bacteria adhesion and aggregation,which leads to postoperative infection.In addition,Ti and its alloys,as bio-inert materials,cannot induce desirable tissue responses such as osseointegration after implantation,which will eventually lead to implant loosening.Postoperative bacterial infection and lack of osseointegration directly lead to the failure of implantation surgery and are not conductive to the long-term service of titanium-based implants.Recently,researchers have made many attempts to focus on the surface modification of multifunctional Ti-based implants to endow them with both antibacterial activity and simultaneous osteoinductive property.In this review,we primarily highlighted the recent progresses in the surface design of Ti implants with both antimicrobial and osteoinductive properties for orthopedic applications.First,the challenges for treating implant-associated infections were briefly introduced such as the emergence of antibiotic resistance,the formation of biofilms,and the construction of cell-selective surfaces.Some of the essential fundamentals were concisely introduced to address these emerging challenges.Next,we intended to elaborate the potential strategies of multifunctional surface design to endow good osseointegration for antibacterial Ti implants and highlighted the recent advances of the implants.We hope that this review will provide theoretical basis and technical support for the development of new Ti implant with antibacterial and osteogenic functions.

Inhibition of bacterial adhesion and biofilm formation by a textured fluorinated alkoxyphosphazene surface

The utilization of biomaterials in implanted blood-contacting medical devices often induces a persistent problem of microbial infection,which results from bacterial adhesion and biofilm formation on the surface of biomaterials.In this research,we developed new fluorinated alkoxyphosphazene materials,specifically poly[bis(octafluoropentoxy)phosphazene](OFP)and crosslinkable OFP(X–OFP),with improved mechanical properties,and further modified the surface topography with ordered pillars to improve the antibacterial properties.Three X–OFP materials,X–OFP3.3,X–OFP8.1,X–OFP13.6,with different crosslinking densities were synthesized,and textured films with patterns of 500/500/600 nm(diameter/spacing/height)were fabricated via a two stage soft lithography molding process.Experiments with 3 bacterial strains:Staphylococcal epidermidis,Staphylococcal aureus,and Pseudomonas aeruginosa showed that bacterial adhesion coefficients were significantly lower on OFP and X–OFP smooth surfaces than on the polyurethane biomaterial,and surface texturing further reduced bacterial adhesion due to the reduction in accessible surface contact area.Furthermore the anti-bacterial adhesion effect shows a positive relationship with the crosslinking degree.Biofilm formation on the substrates was examined using a CDC biofilm reactor for 7 days and no biofilm formation was observed on textured X–OFP biomaterials.The results suggested that the combination of fluorocarbon chemistry and submicron topography modification in textured X–OFP materials may provide a practical approach to improve the biocompatibility of current biomaterials with significant reduction in risk of pathogenic infection.

Effect of loureirin A against Candida albicans biofilms

Loureirin A is a major active component of Draconis sanguis, a traditional Chinese medicine. This work aimed to investigate the activity of loureirin A against Candida albicans biofilms. 2, 3-Bis-(2-methoxy-4-nitro-5-sulfophenyl)-2 H-tetrazolium-5-carboxanilide(XTT) reduction assay and scanning electron microscopy were used to investigate the anti-biofilm effect.Minimal inhibitory concentration testing and time-kill curve assay were used to evaluate fungicidal activity. Cell surface hydrophobicity(CSH) assay and hyphal formation experiment were respectively carried out to investigate adhesion and morphological transition,two virulence traits of C. albicans. Real-time RT-PCR was used to investigate gene expression. Galleria mellonella-C. albicans and Caenorhabditis elegans-C. albicans infection models were used to evaluate the in-vivo antifungal effect. Human umbilical vein endothelial cells and C. elegans nematodes were used to evaluate the toxicity of loureirin A. Our data indicated that loureirin A had a significant effect on inhibiting C. albicans biofilms, decreasing CSH, and suppressing hyphal formation. Consistently, loureirin A down-regulated the expression of some adhesion-related genes and hypha/biofilm-related genes. Moreover, loureirin A prolonged the survival of Galleria mellonella and Caenorhabditis elegans in C. albicans infection models and exhibited low toxicity. Collectively,loureirin A inhibits fungal biofilms, and this effect may be associated with the suppression of pathogenic traits, adhesion and hyphal formation.

Nanomaterial-based strategies in antimicrobial applications:Progress and perspectives

The dramatic increase of microbial resistances against conventional available antibiotics is a huge challenge to the effective treatment of infectious disease and thus becoming a daunting global threat of major concern,which necessitates the development of innovative therapeutics.Nanomaterial-based antimicrobial strategies have emerged as novel and promising tools to combat lethal bacteria and recalcitrant biofilm,featuring the abilities to evade existing drug resistance-related mechanisms.In this review,recent advances in“state-of-the-art”nanosystems which acting either as inherent therapeutics or nanocarriers for the precise delivery of antibiotics,are comprehensively summarized.Those nanosystems can effectively accumulate at the infectious sites,achieve multifunctional synergistic antibacterial efficacy,and provide controlled release of antibiotics in response to endogenous or exogenous stimulus(e.g.,low pH,enzymes,or illumination).Especially,the nanoplatform that integrated with photothermal/photodynamic therapy(PTT/PDT)can enhance the bacterial destruction and biofilm penetration or ablation.In addition,nanoparticle-based approaches with enzymatically promoting bacterial killing,anti-virulence,and other mechanisms were also involved.Overall,this review provides crucial insights into the recent progress and remaining limitations of various antimicrobial nanotherapeutic strategies,and enlightens the further developments in this field simultaneously,which eventually benefiting public health.

Synergistic antibacterial activity of physical-chemical multi-mechanism by TiO2 nanorod arrays for safe biofilm eradication on implant

Treatment of implant-associated infection is becoming more challenging,especially when bacterial biofilms form on the surface of the implants.Developing multi-mechanism antibacterial methods to combat bacterial biofilm infections by the synergistic effects are superior to those based on single modality due to avoiding the adverse effects arising from the latter.In this work,TiO2 nanorod arrays in combination with irradiation with 808 nearinfrared(NIR)light are proven to eradicate single specie biofilms by combining photothermal therapy,photodynamic therapy,and physical killing of bacteria.The TiO2 nanorod arrays possess efficient photothermal conversion ability and produce a small amount of reactive oxygen species(ROS).Physiologically,the combined actions of hyperthermia,ROS,and puncturing by nanorods give rise to excellent antibacterial properties on titanium requiring irradiation for only 15 min as demonstrated by our experiments conducted in vitro and in vivo.More importantly,bone biofilm infection is successfully treated efficiently by the synergistic antibacterial effects and at the same time,the TiO2 nanorod arrays improve the new bone formation around implants.In this protocol,besides the biocompatible TiO2 nanorod arrays,an extra photosensitizer is not needed and no other ions would be released.Our findings reveal a rapid bacteria-killing method based on the multiple synergetic antibacterial modalities with high biosafety that can be implemented in vivo and obviate the need for a second operation.The concept and antibacterial system described here have large clinical potential in orthopedic and dental applications.

A facile and general method for synthesis of antibiotic-free protein-based hydrogel:Wound dressing for the eradication of drug-resistant bacteria and biofilms

Antibacterial protein hydrogels are receiving increasing attention in the aspect of bacteria-infected-wound healing. However, bacterial drug resistance and biofilm infections lead to hard healing of wounds, thus the construction of biological agents that can overcome these issues is essential. Here, a simple and universal method to construct antibiotic-free protein hydrogel with excellent biocompatibility and superior antibacterial activity against drug-resistant bacteria and biofilms was developed. The green industrial microbicide tetrakis (hydroxymethyl) phosphonium sulfate (THPS) as cross-linking agent can be quickly cross-linked with model protein bovine serum albumin (BSA) to form antibacterial hydrogel through simple mixing without any other initiators, subsequently promoting drug-resistance bacteria-infected wound healing. This simple gelatinization strategy allows at least ten different proteins to form hydrogels (e.g. BSA, human serum albumin (HSA), egg albumin, chymotrypsin, trypsin, lysozyme, transferrin, myohemoglobin, hemoglobin, and phycocyanin) under the same conditions, showing prominent universality. Furthermore, drug-resistance bacteria and biofilm could be efficiently destroyed by the representative BSA hydrogel (B-Hydrogel) with antibacterial activity, overcoming biofilm-induced bacterial resistance. The in vivo study demonstrated that the B-Hydrogel as wound dressing can promote reepithelization to accelerate the healing of methicillin-resistant staphylococcus aureus (MRSA)-infected skin wounds without inducing significant side-effect. This readily accessible antibiotic-free protein-based hydrogel not only opens an avenue to provide a facile, feasible and general gelation strategy, but also exhibits promising application in hospital and community MRSA disinfection and treatment.

Mitigating microbiologically influenced corrosion of an oilfield biofilm consortium on carbon steel in enriched hydrotest fluid using 2,2-dibromo-3-nitrilopropionamide(DBNPA) enhanced by a 14-mer peptide

In the oil and gas industry,microbiologically influenced corrosion(MIC) is a major threat to hydrotest,a procedure which is required to certify whether a pipeline can be commissioned.Seawater is frequently used as a hydrotest fluid.In this bio film prevention lab study,an oilfield biofilm consortium was grown in an enriched artificial seawater anaerobically at 37℃ for 60 days.The combination of 100 ppm(w/w) 2,2-dibromo-3-nitrilopropionamide(DBNPA)+100 nM(180 ppb) Peptide A(a biofilm dispersal agent) led to extra SRB(sulfate reducing bacteria),APB(acid producing bacteria) and GHB(general heterotrophic bacteria) sessile cell count reductions of 0.9-log,0.8-log and 0.6-log,respectively,compared with the outcome obtained by using 100 ppm DBNPA only.The Peptide Aenhancement also led to extra reductions of 44 % in weight loss,43 % in maximum pit depth,and 54 % in corrosion current density.

Comparative in vitro Study of the biological activity and chemical composition extracts of Helicteres isora L. obtained by water and subcritical water extraction

Objectives:Subcritical water extraction technique is considered as an environmentally extraction technique.The aim of this study was to compare the different characteristics of water extract and subcritical water extract of Helicteres isora L.Materials and Methods:Water extraction was performed under the following conditions:25℃,24 h,and solid-to-water ratio 1:30.Subcritical water extract was carried out under specific conditions(pressure=10 bar,temperature=160℃,solid-to-water ratio=1:30,time=30 min).Chemical composition analysis was performed using GC-Mass chromatography.Anti-biofilm activity in the terms of anti-attach and removal of biofilm were assessed using the ELISA reader method and reading absorbance at 570 nm.Anti-microbial activity against Bacillus cereus,Staphylococcus aureus,Staphylococcus saprophyticus,and Bacillus subtilis was investigated by measurement of inhibitory zone diameter.Anti-enzymatic and antioxidant properties were also assessed.Results:The results of GC-Mass analysis showed some components extracted in subcritical method which were absent in water extract such as octadecanoic acid,hexadecanoic acid,and berberin.Antioxidant activity of the two tested extracts revealed that subcritical water extract had more antioxidant capacity than water extract(P≤0.05).The two tested extracts exhibited anti-enzymatic activity against polyphenol oxidase enzyme with better performance of subcritical water extract.Anti-biofilm activity of the two extracts implies that,in the case of preventing biofilm formation,both extracts had similar efficiency but in the removal of biofilm,subcritical water extract showed better performance.Both extracts had anti-microbial activity against B.cereus,S.aureus,S.saprophyticus,and B.subtilis with better performance of subcritical water extract.Anti-enzymatic assay also showed similar results.Conclusions:Subcritical water extract of H.isora showed more antioxidant activity as well as anti-biofilm,anti-bacterial,and anti-enzymatic activity rather than ordinary water extract.