Inhibition Of Bacterial Adhesion Research Articles

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.

Preventing bacterial adhesion on scaffolds for bone tissue engineering

Bone implant infection constitutes a major sanitary concern which is associated to high morbidity and health costs. This manuscript focused on overviewing the main research efforts committed up to date to develop innovative alternatives to conventional treatments, such as those with antibiotics. These strategies mainly rely on chemical modifications of the surface of biomaterials, such as providing it of zwitterionic nature, and tailoring the nanostructure surface of metal implants. These surface modifications have successfully allowed inhibition of bacterial adhesion, which is the first step to implant infection, and preventing long-term biofilm formation compared to pristine materials. These strategies could be easily applied to provide three-dimensional (3D) scaffolds based on bioceramics and metals, of which its manufacture using rapid prototyping techniques was reviewed. This opens the gates for the design and development of advanced 3D scaffolds for bone tissue engineering to prevent bone implant infections.

Antibacterial evaluation of 2-(6-Chloro-2-p-tolylquinazolin-4-ylthio) acetonitrile against pathogenic bacterial isolates with special reference to biofilm formation inhibition and anti-adherence properties

BackgroundEvaluating the effectiveness of a specific quinazoline molecule with antibacterial activity on microorganisms as a potential antibiotic substitution. MethodsA variety of microorganisms were tested with the designated quinazoline molecule. Differences within two groups were analyzed using the two-tailed Student’s t-test,. ResultsSusceptibility tests revealed that the chemical has stronger antibacterial action against S. saprophyticus than other isolates, with just a slight effect on E. coli and M. smegmatis. The bacterial cells were subjected to varying concentrations of a certain molecule, and the results showed that the inhibition of bacterial adhesion was not consistent. This suggests that the effect of the molecule on bacterial adhesion is dependent on its concentration. After 24 h of treatment with varying chemical doses, all of the periodontal bacterial strains examined showed considerable inhibition of biofilm formation. ConclusionsAccording to the findings, the chemical molecule quinazoline could be utilized as an alternative therapeutic approach for microorganism-caused infections.

The influence of low nitrogen doping on bacterial adhesion of sputtered a-C:H coatings

Heavily dependent on both surface and bacteria characteristics, multiple and complex parameters control bacterial adhesion to any biomaterial surface. That's why there are so many contradictory results regarding the antibacterial and adhesion inhibition properties of Diamond-Like Carbon (DLC) protective coatings, despite the well-established biocompatibility of this very broad group of materials. Aiming at Orthodontics, this study reports the modification of hydrogenated amorphous carbon coatings (a-C:H), by nitrogen incorporation upon reactive magnetron sputtering. The effect of low N content up to 10 at.% on the microstructure and bacterial adhesion was studied. Despite the progressive graphitization upon doping, the surface roughness was not significantly influenced and the water contact angles remained above 70°. The adhesion of three bacterial strains of Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa was evaluated. The median colony forming units was lower on the a-C:H and a-C:H:N coatings in comparison to the bare AISI 316L medical grade stainless steel surface, regardless the bacterial strain. The best bacterial adhesion inhibition capacity was achieved for N doping of 6 at.%, without using any antibacterial agents.

Cinnamaldehyde: An effective component of Cinnamomum cassia inhibiting Helicobacter pylori

Ethnopharmacological relevanceCinnamomum cassia Presl (Cinnamomum cassia) is a common traditional Chinese medicine, which can promote the secretion and digestion of gastric juice, improve the function of gastrointestinal tract. Cinnamaldehyde (CA) is a synthetic food flavoring in the Chinese Pharmacopoeia. Aim of the studyThis study aimed to search for the active ingredient (CA) of inhibiting H. pylori from Cinnamomum cassia, and elucidate mechanism of action, so as to provide the experimental basis for the treatment of H. pylori infection with Cinnamomum cassia. Materials and methodsIt's in vitro and in vivo pharmacological properties were evaluated based on minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and an acute gastric inflammation model in mice infected with H. pylori. Drug safety was evaluated using the CCK8 method and high-dose administration in mice. The advantageous characteristics of CA in inhibiting H. pylori were confirmed using acidic conditions and in combination with the antibiotics. The mechanism underlying the action of CA on H. pylori was explored using scanning electron microscopy (SEM), adhesion experiments, biofilm inhibition tests, ATP and ROS release experiments, and drug affinity responsive target stability (DARTS) screening of target proteins. The protein function and target genes were verified by molecular docking and Real-Time quantitative reverse transcription PCR (qRT-PCR). ResultsThe results demonstrated that CA was found to be the main active ingredient against H. pylori in Cinnamomum cassia in-vitro tests, with a MIC of 8–16 μg/mL. Moreover, CA effectively inhibited both sensitive and resistant H. pylori strains. The dual therapy of PPI + CA exhibited remarkable in vivo efficacy in the acute gastritis mouse model, superior to the standard triple therapy. DARTS, molecular docking, and qRT-PCR results suggested that the target sites of action were closely associated with GyrA, GyrB, AtpA, and TopA, which made DNA replication and transcription impossible, then leading to inhibition of bacterial adhesion and colonization, suppression of biofilm formation, and inhibition ATP and enhancing ROS. ConclusionsThis study demonstrated the suitability of CA as a promising lead drug against H. pylori, The main mechanisms can target GyrA ect, leading to reduce ATP and produce ROS, which induces the apoptosis of bacterial.

Sweet Janus Particles: Multifunctional Inhibitors of Carbohydrate-Based Bacterial Adhesion.

Escherichia coli and other bacteria use adhesion receptors, such as FimH, to attach to carbohydrates on the cell surface as the first step of colonization and infection. Efficient inhibitors that block these interactions for infection treatment are multivalent carbohydrate-functionalized scaffolds. However, these multivalent systems often lead to the formation of large clusters of bacteria, which may pose problems for clearing bacteria from the infected site. Here, we present Man-containing Janus particles (JPs) decorated on one side with glycomacromolecules to target Man-specific adhesion receptors of E. coli. On the other side, poly(N-isopropylacrylamide) is attached to the particle hemisphere, providing temperature-dependent sterical shielding against binding and cluster formation. While homogeneously functionalized particles cluster with multiple bacteria to form large aggregates, glycofunctionalized JPs are able to form aggregates only with individual bacteria. The formation of large aggregates from the JP-decorated single bacteria can still be induced in a second step by increasing the temperature and making use of the collapse of the PNIPAM hemisphere. This is the first time that carbohydrate-functionalized JPs have been derived and used as inhibitors of bacterial adhesion. Furthermore, the developed JPs offer well-controlled single bacterial inhibition in combination with cluster formation upon an external stimulus, which is not achievable with conventional carbohydrate-functionalized particles.

Bacterial adhesion inhibition by microalgal EPSs from Cylindrotheca closterium and Tetraselmis suecica biofilms.

In the food industry, successful bacterial pathogen colonization and persistence begin with their adhesion to a surface, followed by the spatial development of mature biofilm of public health concerns. Compromising bacterial settlement with natural inhibitors is a promising alternative to conventional anti-fouling treatments typically based on chemical biocides that contribute to the growing burden of antimicrobial resistance. In this study, three extracellular polymeric substance (EPS) fractions extracted from microalgae biofilms of Cylindrotheca closterium (fraction C) and Tetraselmis suecica (fraction Ta rich in insoluble scale structure and fraction Tb rich in soluble EPS) were screened for their anti-adhesive properties, against eight human food-borne pathogens belonging to Escherichia coli, Staphylococcus aureus, Salmonella enterica subsp. enterica, and Listeria monocytogenes species. The results showed that the fraction Ta was the most effective inducing statistically significant reduction for three strains of E. coli, S. aureus, and L. monocytogenes. Overall, EPSs coating on polystyrene surfaces of the different fractions increased the hydrophilic character of the support. Differences in bacterial adhesion on the different coated surfaces could be explained by several dissimilarities in the structural and physicochemical EPS compositions, according to HPLC and ATR-FTIR analysis. Interestingly, while fractions Ta and Tb were extracted from the same microalgal culture, distinct adhesion patterns were observed, highlighting the importance of the extraction process. Overall, the findings showed that EPS extracted from microalgal photosynthetic biofilms can exhibit anti-adhesive effects against food-borne pathogens and could help develop sustainable and non-toxic anti-adhesive surfaces for the food industry. KEY POINTS: •EPSs from a biofilm-based culture of C. closterium/T. suecica were characterized. •Microalgal EPS extracted from T. suecica biofilms showed bacterial anti-adhesive effects. •The anti-adhesive effect is strain-specific and affects both Gram - and Gram + bacteria.

Exploring In Vitro the Combination of Cistus × incanus L. and Castanea sativa Mill. Extracts as Food Supplement Ingredients against H. pylori Infection.

Cistus spp. have been traditionally used for inflammatory and infectious disorders, including gastrointestinal ailments, in the Mediterranean area. Among them, Cistus × incanus L. is one of the most frequently cited species in the literature for a variety of biological activities which include inflammatory diseases. Cistus spp. aerial parts are rich in polyphenols such as condensed and hydrolysable tannins, procyanidins, and flavonoids, which show gastroprotective activities. The purpose of the present study is to investigate the biological activities of a hydroalcoholic extract from Cistus × incanus L. aerial parts in gastric epithelial cells (GES-1) infected with H. pylori. The extracts inhibited IL-8 and NF-κB induced by H. pylori and showed antibacterial activity after simulated digestion. Since our previous paper reported interesting results on the ability of Castanea sativa Mill. leaf extract to decrease inflammatory conditions in H. pylori-infected gastric cells, the combination of Castanea sativa and Cistus × incanus extracts was also investigated, showing strong anti-inflammatory activity and inhibition of bacterial adhesion. This association of botanicals is proposed herein as a novel food supplement capable of counteracting gastric inflammatory conditions.

Tissue Stabilization, Bacterial Adhesion, and Stem Cell Viability in Trans-cinnamaldehyde-conditioned Dentin

IntroductionThis laboratory study aimed to evaluate the effect of trans-cinnamaldehyde (TC) conditioning on dentin tissue stabilization, bacterial adhesion, and stem cell toxicity. MethodsDentin beams (n = 204) from extracted human molars were demineralized in phosphoric acid and treated with TC (2.5, 5, and 7.5%), 50% ethanol-water mixture (vehicle control) or 2.5% glutaraldehyde (GA) (positive control) for 30 minutes. Demineralized but untreated specimens served as the negative control. After treatment, collagen crosslinking was characterized by measuring the elastic modulus (Er) and hardness (n = 5). Biodegradation resistance was examined by determining the loss of dry mass (n = 8), hydroxyproline release (n = 4) and scanning electron microscopy (n = 2), after exposure to bacterial collagenase. Inhibition of bacterial adhesion was investigated by colony counting assay (n = 12) and scanning electron microscopy (n = 2). Viability of stem cells of the apical papilla on TC-conditioned dentin was determined using the Cell Counting Kit-8 assay (n = 8). Data were statistically analyzed using one-way analysis of variance (ANOVA) test followed by Dunnett's multiple comparisons at a significance level of 5%. ResultsTC-conditioned dentin showed a concentration-dependent increase in Er and hardness. The Er and hardness of 5% and 7.5% TC-conditioned dentin were significantly greater than that of the negative control and vehicle control groups (P < .05). There was no significant difference in the biodegradation resistance between GA and 5% TC-conditioned dentin (P > .05). TC-conditioned dentin showed a well-preserved collagen fibril network with clear cross-banding, comparable to GA-conditioned dentin. All concentrations of TC inhibited bacterial adhesion on dentin, significantly greater than the negative control (P < .05). There was no reduction in viability of stem cells of the apical papilla viability on TC-conditioned dentin compared to the negative control (P > .05). ConclusionsTC conditioning stabilized the dentin and protected it from enzymatic degradation. TC prevented bacterial adhesion on the dentin but maintained stem cell viability.

Plasmonic inhibition of bacterial adhesion on gold-decorated mesoporous zirconium oxide thin films

Preventing bacterial development on surfaces is essential to avoid problems caused by biofouling. Surfaces decorated with gold nanoparticles have been shown to thermally kill bacteria under high-intensity NIR illumination. In this study, we evaluated the colonization by E. coli of nanostructured surfaces composed of mesoporous zirconia thin films, both with and without gold nanoparticles embedded into the pores. We studied the effect of the nanostructure and of low intensity visible light excitation of the gold nanoparticles on the colonization process. We found that neither the zirconia, nor the presence of pores, or even gold nanoparticles affect bacterial adhesion compared to the bare glass substrate. Therefore, mesoporous zirconia thin films are biologically inert scaffolds that enable the construction of robust surfaces containing functional nanoparticles that can affect bacterial growth. When the gold containing surfaces are irradiated with light, bacterial adhesion shows a remarkable 96 ± 4% reduction. Our studies revealed that these surfaces affect early colonization steps, prior to biofilm formation, preventing bacterial adhesion without affecting its viability. In contrast to related systems where plasmonic excitation induces membrane damage due to strong local heating, the membrane integrity is preserved, showing that these surfaces have a different working principle.

Thymol-loaded polylactic acid electrospun fibrous membranes with synergistic biocidal and anti-bacterial adhesion properties via morphology control

Antibiotic resistance is a growing challenge in modern medicine, highlighting the urgent need for alternative antimicrobial strategies. The combination of synergistic sterilization and inhibition of bacterial adhesion presents a promising approach for achieving a long-lasting antibacterial effect. Herein, we report the fabrication of thymol-loaded polylactic acid (Thy-PLA) porous fibrous membranes that exhibit both bacteria-killing and bacteria-repellent functions, accomplished through control of microstructure and morphology during the electrospinning process. Notably, we employed the breath figure method, a humidity-induced morphology control technique, which significantly increased the surface roughness of the Thy-PLA fibers and resulted in a nano-porous structure for bacterial repulsion. Additionally, this method facilitated the enhanced release of thymol, thereby enabling efficient sterilization. By simply modifying the morphology, we achieved bacterial reduction rates of up to 99.92 % and 99.87 % for Escherichia coli and Staphylococcus aureus, respectively, and robust mechanical properties (ultimate tensile stress of 20 MPa and elongation at break of 822.7 %). Furthermore, the fibrous membranes exhibited an impressive oil/water absorption capacity (∼36.7 g/g in 90 s) thanks to the interior and surface porosity. The porous fibrous membranes with synergistic antimicrobial efficiency and tunable mechanical properties demonstrate great potential for diverse applications, particularly in wound dressing and oil/water filtration.

Application of mixture design for the optimum antibacterial action of chemically-analyzed essential oils and investigation of the antiadhesion ability of their optimal mixtures on 3D printing material

Contamination of food and medical devices has become a serious public health concern. Therefore, this work intended to assess the single and combined antibacterial effect of essential oils (EOs) obtained from Clinopodium nepeta, Ruta montana, and Dittrichia viscosa, through mixture design approach. In addition, the anti-adhesive action of the obtained optimal mixtures of EOs was investigated against bacterial adhesion on 3D printed surface, widely used in food and medical industries. Indeed, Chromatography Gas/Mass spectrometry (CG/MS) analysis showed that pulegone (30.2%), piperitenone oxide (15.71%), and limonene (10.32%), mainly characterized the Clinopodium nepeta essential oil (CNEO), whereas Ruta montana essential oil (RMEO) was dominated by 2-undecanone (46.13%), and 2-nonanone (20.53%). By contrast, the Dittrichia viscosa essential oil (DVEO) principally contained (E)-nerolidol (32.21%), τ-muurolol (18.17%), and α-eudesmol (10.36%). The obtained optimum mixtures revealed that the binary combination consisting of 36% of RMEO, 64% of CNEO certified the maximal inhibition against Staphylococcus aureus (S. aureus), while a formulation of 25%, 50%, and 25% of RMEO, CNEO, and DVEO respectively, was associated to the ideal restriction of Pseudomonas aeruginosa (P. aeruginosa). The time-kill analysis showed that all studied EOs are able to eradicate the total growth (bactericidal action) of S. aureus and P. aeruginosa at twice-minimal inhibitory concentration (2xMIC) after 12 h. Interestingly, the contact angle method and environmental scanning electron microscopy (ESEM) analysis reported that the optimal EOs mixtures are effective in preventing biofilm formation by modification of physico-chemical parameters of the 3D printing resin surface and complete inhibition of bacterial adhesion on the material surface. Thereby, the interaction between EOs might be applied as natural preservatives in the food and medical industries.

Surface proteins of Shiga toxin-producing Escherichia coli mediate association with milk fat globules in raw milk.

By adhering to host cells and colonizing tissues, bacterial pathogens can successfully establish infection. Adhesion is considered the first step of the infection process and bacterial adhesion to anti-adhesive compounds is now seen as a promising strategy to prevent infectious diseases. Among the natural sources of anti-adhesive molecules, the membrane of milk fat globules (MFGs) is of interest because of its compositional diversity of proteins and glycoconjugates. However, few studies have focused on the bacterial molecules involved in MFG- mediated inhibition of bacterial adhesion to enterocytes. We used three pathogenic Shiga toxin-producing Escherichia coli (STEC) strains (O26:H11 str. 21765, O157:H7 str. EDL933, and O103:H3 str. PMK5) as models to evaluate whether STEC surface proteins are involved in the affinity of STEC for MFG membrane proteins (MFGMPs). The affinity of STEC for MFGMPs was assessed both indirectly by a natural raw milk creaming test and directly by an adhesion test. Mass spectrometry was used to identify enriched STEC proteins within the protein fraction of MFGMs. Bacterial mutants were constructed and their affinity to MFGs were measured to confirm the role of the identified proteins. We found that free STEC surface proteins inhibit the concentration of the pathogen in the MFG-enriched cream in a strain-dependent manner. Moreover, the OmpA and FliC proteins were identified within the protein fraction of MFGMs. Our results suggest that FliC protein participates in STEC adhesion to MFGMPs but other STEC molecules may also participate. For the first time, this study highlighted, the involvement of STEC surface proteins in the affinity for MFGs. The mechanism of STEC-MFG association is still not fully understood but our results confirm the existence of receptor/ligand type interactions between the bacteria and MFGs. Further studies are needed to identify and specify the molecules involved in this interaction. These studies should consider the likely involvement of several factors, including adhesion molecules, and the diversity of each STEC strain.

Inhibition of bacterial adhesion and anti-biofilm effects of Bacillus cereus and Serratia nematodiphila biosurfactants against Staphylococcus aureus and Pseudomonas aeruginosa.

Biosurfactants are amphiphilic surface-active agents that mainly produced by various microorganisms. In this study, the anti-biofilm and inhibition of bacterial adhesion activities of two bacterial biosurfactants were investigated. After extraction and evaluation of Bacillus cereus and Serratia nematodiphila biosurfctants, inhibition of bacterial adhesion and anti-biofilm effects of them on Staphylococcus aureus and Pseudomonas aeruginosa were determined. On average, the synergistic effect of two bacterial biosurfactants, caused about 60% decrease in adhesion and about 80% decrease in biofilm formation of S. aureus and P. aeruginosa. The results of this study showed that combination of B. cereus and S. nematodiphila biosurfactants would increase the potential of attachment inhibition and biofilm eradication with very low toxicity.

Biocidal activity of multifunctional cuprite-doped anion exchanger – Influence of bacteria type and medium composition

The study presents unconventional, bifunctional, heterogeneous antimicrobial agents – Cu2O-loaded anion exchangers. The synergetic effect of a cuprous oxide deposit and polymeric support with trimethyl ammonium groups was studied against the reference strains of Enterococcus faecalis ATCC 29212 and Pseudomonas aeruginosa ATCC 27853. Biological testing (minimum bactericidal concentration, MBC), time- and dose-dependent bactericidal effect (under different conditions – medium composition and static/dynamic culture) demonstrated promising antimicrobial activity and confirmed its multimode character. The standard values of MBC, for all studied hybrid polymers and bacteria, were similar (64–128 mg/mL). However, depending on the medium conditions, due to the copper release into the bulk solution, bacteria were actively killed even at much lower doses of the hybrid polymer (25 mg/mL) and low Cu(II) concentrations in solution (0.01 mg/L). Simultaneously, confocal microscopic studies confirmed the effective inhibition of bacterial adhesion and biofilm formation on their surface. The studies conducted under different conditions showed also the influence of the structure and physical properties of studied materials on the biocidal efficacy and an antimicrobial action mechanism was proposed that could be significantly affected by electrostatic interactions and copper release to the solution. Although the antibacterial activity was also dependent on various strategies of bacterial cell resistance to heavy metals present in the aqueous medium, the studied hybrid polymers are versatile and efficient biocidal agents against bacteria of both types, Gram-positive and Gram-negative. Therefore, they can be a convenient alternative for point-of-use water disinfection systems providing water quality in medical devices such as dental units, spa equipment, and aesthetic devices used in the cosmetic sector.

Anti-adhesive activity of some secondary metabolites against Staphylococcus aureus on 3D printing medical materials

Recent improvements in 3D printing technology have increased the usage of 3D printed materials in several areas. An exciting and emerging area of applying these next-generation manufacturing strategies is the development of devices for biomedical applications. The main aim of this work was to investigate the effect of tannic acid, gallic acid, and epicatechin gallate on the physicochemical characteristics of acrylonitrile butadiene–styrene (ABS) and Nylon 3D printing materials using the contact angle method. The adhesion of Staphylococcus aureus on untreated and treated materials was evaluated by scanning electron microscopy (SEM) analysis and the images were treated by MATLAB software. The results of the contact angle measurements showed a significant change in the physicochemical properties of both surfaces, indicated an increase in the electron donor character of 3D printing materials following treatment. Thus, the ABS surfaces treated with tannic acid, gallic acid, and epicatechin gallate have become more electron donating. Furthermore, our results proved the ability of S. aureus to adhere on all materials with a percentage of 77.86% for ABS and 91.62% for nylon. The SEM has shown that all actives molecules were sufficient to obtain better inhibition of bacterial adhesion, which tannic acid has shown a total inhibition of S. aureus on ABS. From these results, our treatment presents a high potential for utilization as an active coating to prevent bacterial attachment and the eventual biofilm development in medical field.

PROBIOTICS FOR INFANTILE COLIC : A SYSTEMATIC REVIEW

Colic in infants is a self-limiting ailment; nonetheless, it can be unpleasant for parents and tough for doctors to treat. Approximately 20% of infants suffer from infantile colic, which typically reaches its peak between 5 and 6 weeks of age. The challenge for the medical staff is in making an accurate diagnosis and coming up with a treatment plan for the ailment. In order to give doctors with a full grasp of the problem, current advancements, and future possibilities, the purpose of this review article is to outline the pathophysiology of infantile colic, as well as the treatment choices and prognosis for the condition. There are a few potential treatments for infantile colic, the most prominent of which is the use of probiotics, specifically lactobacillus. The most compelling evidence in support of probiotics comes from the prevention or treatment of these five conditions: necrotizing enterocolitis, acute infectious diarrhea, acute respiratory tract infections, antibiotic-associated diarrhea, and newborn colic. Inhibition of bacterial adhesion, improvement of mucosal barrier function, manipulation of both the innate and adaptive immune systems, release of bioactive metabolites, and control of the enteric and central nervous systems are some of the mechanisms of action that probiotics exhibit.

Antioxidant, Antibacterial and Antibiofilm Activity of Nanoemulsion-Based Natural Compound Delivery Systems Compared with Non-Nanoemulsified Versions.

This study aimed to develop nanoemulsions with a focus on improving the bioactivity of oregano essential oil (OEO), carvacrol and thymol for possible food applications. Nanoemulsions were prepared with acoustic cavitation using ultrasound. The nanodroplets had average diameters of 54.47, 81.66 and 84.07 nm for OEO, thymol and carvacrol, respectively. The main compound in OEO was carvacrol (74%), and the concentration in the nanoemulsions was 9.46 mg/mL for OEO and the isolated compounds. The effects of droplet size reduction on antioxidant, antibacterial and antibiofilm activity were evaluated. Regarding antioxidant activity, the nanoemulsions performed better at the same concentration, with inhibitions >45% of the DPPH radical and significant differences compared with their non-nanoemulsified versions (p < 0.05). The nanoemulsions' minimum inhibitory concentration (MIC) and non-nanoemulsified compounds were evaluated against foodborne pathogens with inhibition ranges between 0.147 and 2.36 mg/mL. All evaluated pathogens were more sensitive to nanoemulsions, with reductions of up to four times in MIC compared with non-nanoemulsified versions. E. coli and S. Enteritidis were the most sensitive bacteria to the carvacrol nanoemulsion with MICs of 0.147 mg/mL. Concerning antibiofilm activity, nanoemulsions at concentrations up to four times lower than non-nanoemulsified versions showed inhibition of bacterial adhesion >67.2% and removal of adhered cells >57.7%. Overall, the observed effects indicate that droplet size reduction improved the bioactivity of OEO, carvacrol and thymol, suggesting that nanoemulsion-based delivery systems for natural compounds may be alternatives for food applications compared with free natural compounds.

Improving mechanical properties and antibacterial response of α/β ternary Ti–Ta alloy foams for biomedical uses

This study investigates the potential of Ti–Ta–Sn alloys for biomedical applications due to their excellent mechanical properties and biocompatibility, with a particular focus on their use in trabecular bone replacement. This work aims to analyze the influence that of Sn has on the mechanical properties and antibacterial response of α−β ternary Ti–13Ta–xSn (x:3, 6, 9, and 12 at.%) alloy foams. The Ti-based alloys were designed considering three aspects; (i) final microstructure, (ii) alloying element types, and (iii) thermodynamics while using MAAT and ThermoCalc software. The alloys were obtained by mechanical alloying, with used milling times being 30 h for Ti–13Ta–3Sn, 10 h for Ti–13Ta–6Sn, 10 h for Ti–13Ta–9Sn, and 15 h for Ti–13Ta–12Sn. The foams were obtained using NaCl as the space holder (50 v/v% porosity) and consolidated by a hot pressing method at 780 °C for 30 min, applying a load of 40 MPa. Both the Staphylococcus aureus ATCC 6538 strain and Escherichia coli ATCC 8739 strain were used to evaluate the antibacterial responses of Ti-based alloy foams. The Ti-based alloy foams were composed mostly by a mix of α and β-phases. The metallic foams exhibited relative homogeneous pore distribution with a size between 100 and 450 μm and having an average porosity slightly higher than 50%. The samples showed elastic modulus values between 1 and 2 GPa, compressive yield strengths over 150 MPa, and microhardness over 450 HV. All Ti-based alloy foams showed no antibacterial activity nor bacterial adhesion, indicating that there is bacterial adhesion inhibition.

Comparison Effect of Leaves and Bark Extract of Eucalyptus (Melaleuca leucadendra), Sappan (Caesalpinia sappan), and Cinnamon (Cinnamomum zeylanicum) to Reduce Streptococcus mutans Biofilm Formation

To evaluate the effect of eucalyptus, sappan, and cinnamon leaf and bark extract on the percentage of S. mutans biofilm formation. The test group was divided into a negative control (1% Dimethyl sulfoxide), a treatment group (eucalyptus, sappan, and cinnamon leaves and bark at concentrations of 50%, 25%, and 12.5%, respectively), and a positive control (0.2% chlorhexidine). Each concentration of eucalyptus, sappan, and cinnamon leaves and barks extract, Brain Heart Infusion Broth (BHI-B), bacteria according to the McFarland 0.5 standard, a positive control, and a negative control were added to a 96-well microplate. They were incubated at 37 °C for twenty-four hours before being rinsed with phosphate buffer saline (PBS) and stained with 0.1% crystal violet. The optical density was then measured using a microplate reader with a 540 nm wavelength. The absorbance value is then factored into the percentage of bacterial adhesion inhibition formula. A statistical test revealed a significant difference (p &lt; 0.05) in the percentage of inhibition between the three extracts of leaves and bark and the negative control group (1% DMSO). There is a significant difference between all leaves and barks concentration and the positive control group except the 50% concentration of sappan leaf group and 50% concentration of cinnamon leaf group. The sappan leaf and cinnamon leaf at 50% concentration exhibit no significant difference (p &gt; 0.05) with the positive control. Eucalyptus, sappan, cinnamon leaves and barks at a concentration of 50% demonstrated effectiveness of the extractant in inhibiting the formation of biofilm masses by S. mutans in comparison with the other group.