Inhibition Of Bacterial Growth Research Articles

Antibacterial Screening of Lippia origanoides Essential Oil on Gram-negative Bacteria

Essential oils (EO) are extracted from different plant species and can be present in different plant organs. Rosemary-pepper EO is composed of around 50% to 70% thymol, a phenolic compound proven to be active against fungi and bacteria. The active components present in these compounds can affect the vital functionality of bacterial cells, leading to protein denaturation and cell lysis. Therefore, the present study aims to evaluate in vitro the antibacterial potential of Lippia origanoides EO against gram-negative bacteria. This is an exploratory study, with a technical-experimental procedure, with a quantitative approach, carried out at the Federal University of Campina Grande. The strains used were Pseudomonas aeruginosa ATCC 27853, Proteus mirabilis ATCC 25933, and Escherichia coli ATCC 25922, using concentrations of 1024, 512, 256, and 128 μg/ml using the disc diffusion method in triplicate. After the incubation period, the formation of halos of bacterial growth inhibition was not observed. There are possible causes for the lack of antibacterial activity of the EO concerning the strains of gram-negative bacteria used in the study, including the possibility of not containing components with antibacterial properties in concentrations sufficient for the expected activity at the concentrations tested. Based on the results obtained, the Rosemary-Pepper EO (Lippia organoids) did not demonstrate antimicrobial activity against the gram-negative bacteria used in the study. Therefore, the development of new research with Lippia origanoides essential oil with gram-positive bacteria is suggested.

Synthesis and characterization of MOF polymer nanocomposites for Chromium adsorption and their antimicrobial properties

This study describes the preparation of MOF and its polymer composites, namely Co@BTC(MOF1), Co@BTC(PAA)(MOF2), and Co@BTC(PAA)(CTAB)(MOF3), by assimilating cobalt nitrate hexahydrate [(CoNO3)2·6H2O] with trimesic acid, polyacrylic acid (PAA), and cetyltrimethylammonium bromide (CTAB) using a solvothermal procedure at 100℃ for 12 h. All MOF composites exhibited remarkable adsorption properties and thermal and chemical stability properties. These polymer composite MOFs are explored for the adsorption of anionic dyes such as Methyl Orange (MO) and Congo Red (CR), cationic dye Methylene Blue (MB), and Chromium (VI) from wastewater. A 90–95 % adsorption rate for MO and CR dyes was observed within 60 min using 100 mg of MOF composites. Within 60 min, the MOF composites achieved an adsorption rate of 90–95 % for MO and CR dyes when 100 mg of the composites were used. Furthermore, MOF2 and MOF3 have exhibited a remarkable 92 % efficiency in adsorbing Cr(VI) during one hour, following a pseudo-second-order kinetic model. The composites were examined for their anti-bacterial efficacy against Bacillus (Gram-positive), E. Coli (Gram-negative), and Saccharomyces cerevisiae. The results were compared to ciprofloxacin, a conventional antibiotic, using the agar diffusion method. MOF2 and MOF3 have demonstrated long-lasting and potent antimicrobial activity, successfully inhibiting the growth of bacteria for a period of at least 90 days. Furthermore, the polymer composites of MOFs exhibit notable capability in scavenging radicals, particularly against ascorbic acid, as determined by the DPPH method. The inhibition rates for the composites are 68.7 % and 65.9 %, respectively. This indicates that these polymer MOF composites possess potent anti-microbial activity, making them an ideal candidate for addressing the inhibition of bacterial growth.

In-silico and in-vitro targeting of organic dye pollutants from synthetic and real wastewater by the hierarchically self-assembled laccase@bismuth phosphate hybrid nanorods

The increasing presence of dyes in wastewater and even surface or groundwater has progressively become an emerging global concern. This study evaluated the potential use of facile, straightforward, and hierarchical laccase@BiPO4•hybrid nanostructures (HNSs) in the elimination of anthraquinone, monoazo, diazo, and triarylmethane dyes from municipal wastewater through in-silico and in-vitro analyses. The prepared HNSs possessed rod-like morphological features with more than 8 cycles of reusability and about 10 U mg–1 catalytic activity. The nitrogen sorption analysis revealed that the prepared HNRs presented a Brunauer-Emmett-Teller (BET) surface area of 15.3 ± 1.6 m2 g−1 and an average pore size of 9.7 ± 0.5 nm. The total pore volume of HNRs was also measured at 4.0 ± 0.1 (× 10−2 cm3 g−1). Molecular docking predicted the preferred orientation of dye molecules with the enzyme's active site, facilitating the formation of stable complexes. The constructed hybrid nanorods (HNRs) showed proper in-vitro oxidation activity on the pollutant dyes with a more than 95% bioremoval for Direct Blue-15, Direct Blue-71, Crystal Violet, and Acid Blue-92. The maximum adsorption capacity of the prepared HNRs was 401 ± 11 mg per g of the carrier after 240 min of contact time with initial dyes' concentrations. Freundlich isotherm well fitted on the removal data compared with the Langmuir model due to the formation of a uniform monolayer of the dyes onto the prepared HNRs. For Direct Blue-15, Direct Blue-71, Crystal Violet, Acid Blue-92, and Acid Red-18, R2 values of pseudo-second-order kinetic were closer to 1 than that of first-order. The thermodynamic evaluations indicated that the removal of the dyes by the immobilized enzyme proceeded spontaneously and favorably (0 > ΔG°), albeit with endothermic characteristics (0 < ΔH°). Bioremoval efficiencies of 32%, 51%, 64%, and 72% were recorded when actual wastewater samples underwent treatment with 0.3 U mL−1, 0.6 U mL−1, 0.9 U mL−1and 1.2 ≤ U mL−1 of HNPs, respectively. Furthermore, the enzymatic removal process led to less toxic metabolites as confirmed using the bacterial growth inhibition test. Therefore, laccase@BiPO4•HNRs can be a worthy approach in dye removal from wastewater due to their distinct physicochemical and catalytic properties.

Bacteriophage Cocktail Comprising Fifi044 and Fifi318 for Biocontrol of Erwinia amylovora.

Erwinia amylovora is a plant pathogen that causes fire blight on apples and pears. Bacteriophages, which are viruses that selectively infect specific species of bacteria and are harmless to animal cells, have been considered as biological control agents for the prevention of bacterial pathogens. In this study, we aimed to use bacteriophages that infect E. amylovora as biocontrol agents against fire blight. We isolated bacteriophages Fifi044 and Fifi318 infecting E. amylovora, and characterized their morphology, plaque form, and genetic diversity to use as cocktails for disease control. The stabilities of the two phages were investigated at various temperatures and pH values and under sunlight, and long-term storage experiment was conducted for a year. To evaluate whether the two phages were suitable for use in cocktail form, growth curves of E. amylovora were prepared after treating the bacterial cells with single phages and a phage cocktail. In addition, a disease control test was conducted using immature apples and in vitro cultured apple plantlets to determine the biocontrol effects of the phage cocktail. The two phages were morphologically and genetically different, and highly stable up to 50°C and pH value from 4 to 10. The phages showed synergistic effect when used as a cocktail in the inhibition of host bacterial growth and the disease control. This study demonstrated that the potential of the phage cocktail as a biocontrol agent for commercial use.

Modifying cellulose fibres with carbon dots: a promising approach for the development of antimicrobial fibres.

This study focuses on the development of antimicrobial fibres for use in medical and healthcare textile industries. Carbon dots (CDs) were designed with boronic acid groups for the attachment to cellulose fibres found in cotton textiles and to enhance their attachment to glycogens on bacterial surfaces. Boronic acid-based and curcumin-based CDs were prepared and characterized using various techniques, showing a nanoscale size and zeta potential values. The CDs inhibited the growth of both Staphylococcus epidermidis and Escherichia coli bacteria, with UV-activated CDs demonstrating improved antibacterial activity. The antimicrobial activity of the CDs was then tested, revealing strong adherence to cellulose paper fibres with no CD diffusion and potent inhibition of bacterial growth. Cytotoxicity assays on human cell lines showed no toxicity towards cells at concentrations of up to 100 µg ml-1 but exhibited increased toxicity at concentrations exceeding 1000 µg ml-1. However, CD-modified cellulose paper fibres showed no toxicity against human cell lines, highlighting the antimicrobial properties of the CD-modified cellulose fibres are safe for human use. These findings show promising potential for applications in both industrial and clinical settings.

Fabrication of Titanium – Copper Alloy and Study the Antibacterial Activity

The composition of the phases and the microscopic structure of Ti-X% Cu (0, 0.5, 2.5, 5)% prepared alloys was investigated by scanning electron microscope (SEM), and the antibacterial activity was assessed to investigate the effect of the Cu content on the antibacterial activity with or without coating with sliver nanoparticles and graphene nanosheets. The alloys were coated using pulse laser deposition. The alloys of Ti-X%Cu were prepared by the metallurgy process. Finally, the thermal conductivity was studied to determine the effect of increasing the copper content and the coating with nanoparticles. Electron microscopy (SEM) of the alloys before coating showed that the pure titanium is homogeneously distributed and the (Ti-0.5%Cu, Ti-2.5%Cu, and Ti-5%Cu) there are precipitates of (200–800) nm while in scanning electron microscopy (SEM) images of the coated alloys the silver nanoparticles were distributed (20- 26) nm, and graphene oxide was found to be less than (100) nm. The rate of inhibition of bacterial growth increases with increasing concentration copper and with the presence of coatings, and the best inhibition ratio for the sample was (Ti-5%Cu with AgNPs/rGONPs). On the other hand, thermal conductivity of the alloys after coating is less than it was in the uncoated alloys.

Antibacterial effect and biocompatibility of silver nanoparticle-coated bone allograft substitutes.

Osteoinduction, and/or osteoconduction, and antibacterial characteristics are prerequisites for achieving successful bone grafting. This study aimed to coat bone allografts with silver nanoparticles and assess their antibacterial activity and biocompatibility compared to uncoated bone allografts. In this study, the bone allografts were coated with varying concentrations of silver nanoparticles (5 mg/l, 10 mg/l, and 50 mg/l) through a simple adsorption technique. Subsequently, the coated samples underwent characterization using SEM, FTIR, EDS, and XRD. The Minimal Inhibitory Concentration (MIC) of the silver nanoparticles was determined against Staphylococcus aureus and Streptococcus mutans. Bacterial growth inhibition was evaluated by measuring turbidity and performing a disk diffusion test. Moreover, qualitative investigation of biofilm formation on the coated bone allograft was conducted using SEM. Following this, MG-63 cell lines, resembling osteoblasts, were cultured on the bone allografts coated with 5 mg/l of silver nanoparticles, as well as on uncoated bone allografts, to assess biocompatibility. The MIC results demonstrated that silver nanoparticles exhibited antimicrobial effects on both microorganisms, inhibiting the growth of isolates at concentrations of 0.78 mg/L for Staphylococcus aureus and 0.39 mg/L for Streptococcus mutans. The bone allografts coated with varying concentrations of silver nanoparticles exhibited significant antibacterial activity against the tested bacteria, completely eradicating bacterial growth and preventing biofilm formation. The osteoblast-like MG-63 cells thrived on the bone allografts coated with 5 mg/l of silver nanoparticles, displaying no significant differences compared to both the uncoated bone allografts and the control group. Within the limit of this study, it can be concluded that silver nanoparticles have a positive role in controlling graft infection. In addition, simple adsorption technique showed an effective method of coating without overwhelming the healing of the graft.

Antibacterial effects of children's and adults' toothpastes containing different amounts of fluoride: An in vitro study.

In recent years, fluoride concentrations in toothpaste for children and adults have increased. However, the effects of different concentrations on bacterial activity have rarely been compared. We aimed to investigate and compare the antibacterial activity of children's and adults' toothpaste containing 500, 1000‒1100, and 1450‒1500 ppm fluoride. Three strains of bacteria (Streptococcus mutans, Streptococcus salivarius, and Lactobacillus casei) were cultured in brain heart infusion agar. Thirty commercially available toothpaste products for children and adults containing 500, 1000‒1100, and 1450‒1500 ppm fluoride were selected and tested. Toothpaste's ability to inhibit bacterial growth was evaluated by agar diffusion assay, in which plates were incubated for 24 hours, and then the diameter of the microbial inhibition zone was measured. Comparisons between children's and adults' fluoride toothpastes were made using the Mann-Whitney U test. The association between bacterial growth inhibition and sodium lauryl sulfate (SLS) was analyzed by the chi-square test. A P value of <0.05 was considered statistically significant. No difference in the inhibition zone was observed for different fluoride concentrations. However, there were significant differences between toothpastes for children and adults, with higher inhibition zones for adults' toothpastes. Most toothpastes for adults contained SLS, which was associated with antibacterial activity. Fluoride concentrations ranging from 500 to 1500 ppm did not affect bacterial growth. The antibacterial activity of toothpastes for adults was significantly higher than that of toothpastes for children, which was mainly attributed to the SLS usually added to adult formulations.

Enhanced antibacterial activity of porous chitosan-based hydrogels crosslinked with gelatin and metal ions

Addressing the increasing drug resistance in pathogenic microbes, a significant threat to public health, calls for the development of innovative antibacterial agents with versatile capabilities. To enhance the antimicrobial activity of non-toxic biomaterials in this regard, this study focuses on novel, cost-effective chitosan (CS)-based hydrogels, crosslinked using gelatin (GEL), formaldehyde, and metallic salts (Ag+, Cu2+, and Zn2+). These hydrogels are formed by mixing CS and GEL with formaldehyde, creating iminium ion crosslinks with metallic salts without hazardous crosslinkers. Characterization techniques like FTIR, XRD, FESEM, EDX, and rheological tests were employed. FTIR analysis showed metal ions binding to amino and hydroxyl groups on CS, enhancing hydrogelation. FESEM revealed that freeze-dried hydrogels possess a crosslinked, porous structure influenced by various metal ions. Antibacterial testing against gram-negative and gram-positive bacteria demonstrated significant bacterial growth inhibition. CS-based hydrogels containing metal ions showed reduced MIC and MBC values against Staphylococcus aureus (0.5, 8, 16 µg/mL) and Escherichia coli (1, 16, 8 µg/mL) for CS-g-GEL-Ag+, CS-g-GEL-Cu2+, and CS-g-GEL-Zn2+. MTT assay results confirmed high biocompatibility (84.27%, 85.24%, 84.96% viability at 10 µg/mL) for CS-based hydrogels towards HFF-1 cells over 48 h. Therefore, due to their non-toxic nature, these CS hydrogels are promising for antibacterial applications.

Biological Control of Pseudomonas syringae in Tomato Using Filtrates and Extracts Produced by Alternaria leptinellae

Endophytic fungi offer promising alternatives for sustainable plant disease management strategies, often through the production of bioactive secondary metabolites. This study investigated the biocontrol potential of filtrates and extracts, produced under controlled conditions, from Alternaria leptinellae E138 against Pseudomonas syringae in tomato plants under greenhouse conditions. To understand the main mechanisms involved in biocontrol, the direct inhibition of bacterial growth and disruption of quorum sensing activity caused by metabolites were studied in vitro, as well as indirect mechanisms, such as their capacity to produce phytohormone-like substances, nutrient mobilization, and antioxidant activity, which can enhance plant growth and fitness. Moreover, a mass spectrometry analysis was used to tentatively identify the secondary metabolites present in the extract with antimicrobial properties, which could explain the biocontrol effects observed. Mycopriming assays, involving the direct treatment of tomato seeds with the fungal A. leptinellae E138 extracts, produced increased germination rates and seedling vigor in tomato seeds. As another treatment, postemergence application of the extracts in greenhouse conditions significantly improved plant health and resulted in a 41% decrease in disease severity. Overall, this study underscores the potential of A. leptinellae E138 extract as a plant growth promoter with biocontrol capabilities, offering promising avenues for sustainable plant disease management.

Simultaneous effect of medicinal plants as natural photosensitizers and low-level laser on photodynamic inactivation.

Photodynamic inactivation (PDI) technology is a promising alternative to antibiotics. This technology is defined as the inhibition of bacterial growth with photosensitizers while irradiated with low-level laser light in the wavelength of 532 ± 2.08nm. A challenging area in this field is selecting photosensitizers with antibacterial potential. In this paper, to enhance the antibacterial efficiency, the photosensitizers (the selected plant extracts) with a high absorption peak at the selected laser frequency, 532nm, were prepared. Low-concentration ethanolic plant extracts of Hibiscus sabdariffa and Opuntia ficus-indica were found to exhibit significant antibacterial activity against, Acinetobacter baumannii ATCC 19606 and, Staphylococcus aureus ATCC 33591 as two important human pathogenic bacteria. The effectiveness of these natural photosensitizers was measured by determining their Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) values and by performing a time-killing assay in the absence and the presence of laser irradiation. Our results showed that the combination of low-level laser irradiation and the selected photosensitizers had excellent potential for treating in vitro bacterial infections. Therefore, PDI technology has great potential as a viable alternative to traditional antibiotics for combating bacterial infections. This study presents a promising avenue for further exploration of PDI and the use of laser technology in medical science.

Comparison of Organic Liquid Soap Made from Papaya-Turmeric and Aloe Vera-Piper Betel

&lt;p&gt;In the wake of the COVID-19 pandemic, the imperative to mitigate pathogen transmission has catalyzed the innovation of soaps imbued with antimicrobial and antibacterial properties. Diverging from conventional reliance on synthetic chemicals, often associated with adverse dermatological reactions, this study explores the formulation of organic liquid soaps. These soaps leverage naturally occurring antibacterial and antimicrobial compounds from readily accessible plants, presenting a viable alternative to commercially available inorganic body washes predominantly manufactured by small to medium-sized enterprises. Specifically, this research harnesses papaya and aloe vera extracts for their antimicrobial attributes, augmented with turmeric and piper betel for enhanced antibacterial efficacy. Despite the recognized potency of turmeric and piper betel, variability in their effectiveness necessitates rigorous validation against the Indonesian National Standards (SNI) to ensure product quality and safety. This includes comprehensive evaluations of pH levels, density, Total Plate Count (TPC), and Mold and Yeast Count (MYC) to certify the soap's inhibitory capacity against bacterial and fungal proliferation. Employing maceration and hot processing techniques, the formulated papaya-based soap adhered to SNI 4085:2017 criteria for pH and MYC, although initially failing the TPC test. Subsequent incorporation of turmeric extract facilitated compliance with all SNI benchmarks. Conversely, aloe vera formulations only satisfied pH requirements under the SNI, even after adding piper betel. However, substituting piper betel with turmeric extract enabled the aloe vera soap to fulfill the requisite SNI parameters. These findings underscore turmeric extract's superior antibacterial properties, positioning it as a pivotal component in papaya and aloe vera soap formulations. Contrary to prevalent assumptions regarding piper betel's antimicrobial and antibacterial effectiveness, our investigation substantiates turmeric's superior role in bacterial growth inhibition within organic soap matrices.&lt;/p&gt;

Daptomycin Liposomes Exhibit Enhanced Activity against Staphylococci Biofilms Compared to Free Drug.

The purpose of the present study was to investigate the anti-staphylococcal activity of liposomal daptomycin against four biofilm-producing S. aureus and S. epidermidis clinical strains, three of which are methicillin-resistant. Neutral and negatively charged daptomycin-loaded liposomes were prepared using three methods, namely, thin-film hydration (TFH), a dehydration-rehydration vesicle (DRV) method, and microfluidic mixing (MM); moreover, they were characterized for drug encapsulation (EE%), size distribution, zeta-potential, vesicle stability, drug release, and drug integrity. Interestingly, whilst drug loading in THF and DRV nanosized (by extrusion) vesicles was around 30-35, very low loading (~4%) was possible in MM vesicles, requiring further explanatory investigations. Liposomal encapsulation protected daptomycin from degradation and preserved its bioactivity. Biofilm mass (crystal violet, CV), biofilm viability (MTT), and growth curve (GC) assays evaluated the antimicrobial activity of neutral and negatively charged daptomycin-liposomes towards planktonic bacteria and biofilms. Neutral liposomes exhibited dramatically enhanced inhibition of bacterial growth (compared to the free drug) for all species studied, while negatively charged liposomes were totally inactive. Biofilm prevention and treatment studies revealed high antibiofilm activity of liposomal daptomycin. Neutral liposomes were more active for prevention and negative charge ones for treating established biofilms. Planktonic bacteria as well as the matured biofilms of low daptomycin-susceptible, methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus epidermidis (MRSE) strains were almost completely eradicated by liposomal-daptomycin, indicating the need for their further exploration as antimicrobial therapeutics.

Study of disinfectant activity against bee pathogenic enterobacteria in vitro

Dysbiosis is a pathological condition caused by violating the normal coexistence of bacterial organisms in one or more body systems. This disease arises due to the action of many ethological factors, the mechanisms of which arise from each other. Klebsiellosis of bee colonies is a relatively new disease of Apis mellifera, caused by pathogenic enterobacteria, which leads to the mass death of bees with signs of acute dyspepsia, particularly in the spring and autumn periods. To prevent klebsiellosis in bees, it is necessary to carry out veterinary and sanitary measures in apiaries every year, including disinfection. Modern beekeeping encourages the search for new antibacterial drugs to ensure the production technology of safe and high-quality beekeeping products suitable for sale. Preliminary laboratory assessment (in vitro) of the effectiveness of disinfectants against specific pathogens of specific diseases of bees will ensure an increase in the effectiveness of such agents in apiaries, which is economically effective for practical beekeeping. The purpose of the research was to determine the activity of different concentrations of the disinfectant (0.25 %, 0.5 %, 1.25 %, 2.5 %) with an active substance of an organic nature with covalent weakly polar bonds against pure cultures of pathogenic enterobacteria of bees of the species Klebsiella pneumoniae and Klebsiella (Enterobacter) aerogenes in vitro. The modified Kirby-Baur method on Mueller-Hinton agar was used for research. A bactericidal effect against a pure culture of Klebsiella pneumoniae species was registered after 24 hours with lysis zone diameters at 8.6 ± 0.27 mm (0.25 % concentration) – 15.0 ± 0.35 mm (2.5 % concentration). On the 3rd day of research, a bacteriostatic effect was registered with the largest diameter of the zone of growth retardation (24.4 ± 0.27 mm) at 2.5 % disinfectant concentration. Bactericidal and bacteriostatic effects were recorded on the culture of enterobacteria of bees of the species Klebsiella (Enterobacter) aerogenes for 24 hours of cultivation with zones of lysis – 6.8 ± 0.42 mm (0.25 %) – 11.8 ± 0.22 mm (2.5 %) and inhibition of bacterial growth at the level of – 21.8 ± 0.42 mm (0.25 %) – 25.8 ± 0.42 mm (2.5 %). At the same time, there was no significant difference between the zones of Klebsiella (Enterobacter) aerogenes growth retardation in concentrations of 0.5 % – 2.5 % on the 3rd day of research. The studied disinfectant has bactericidal and bacteriostatic effects on pure cultures of bee enterobacteria of the species Klebsiella pneumoniae and Klebsiella (Enterobacter) aerogenes in laboratory conditions, which is promising for further study of the drug.

3D-printing of alginate/gelatin scaffold loading tannic acid@ZIF-8 for wound healing: In vitro and in vivo studies

In the present study, ZIF-8 metal-organic framework (MOF) modified with Tannic acid (TA@ZIF-8) was synthesized and impregnated in alginate-gelatin (Alg-Gel) hydrogel. The Alg-Gel scaffolds containing 0, 5, and 10 % of TA@ZIF-8 were fabricated through the 3D printing method specifically denoted as Alg-Gel 0 %, Alg-Gel 5 %, and Alg-Gel 10 %. XRD, FTIR, FESEM, and EDX physically and chemically characterized the synthesized ZIF-8 and TA@ZIF-8 MOFs. Besides, Alg-Gel containing TA@ZIF-8 prepared scaffolds and their biological activity were also evaluated. SEM images verified the nano-size formation of MOFs. Improved swelling and decreased degradation rates after adding TA@ZIF-8 were also reported. Increased compression strength from 0.628 to 1.63 MPa in Alg-Gel 0 % and Alg-Gel 10 %, respectively, and a 2.19 increase in elastic modulus in Alg-Gel 10 % scaffolds were exhibited. Biological activity of scaffolds, including Live-dead and Cell adhesion, antibacterial, in-vivo, and immunohistochemistry assays, demonstrated desirable fibroblast cell proliferation and adhesion, increased bacterial growth inhibition zone, accelerated wound closure and improved expression of anti-inflammatory cytokines in Alg-Gel 10 % scaffolds. The findings of this study confirm that Alg-Gel 10 % scaffolds promote full-thickness wound healing and could be considered a potential candidate for full-thickness wound treatment purposes.

Abstract 1090 Investigation of Protein Binding in a Bacterial Growth Inhibition System

Abstract 1090 Investigation of Protein Binding in a Bacterial Growth Inhibition System

Cationized gelatin-sodium alginate polyelectrolyte nanoparticles encapsulating moxifloxacin as an eye drop to treat bacterial keratitis

A mucoadhesive polyelectrolyte complex (PEC) nanoparticles were developed for ocular moxifloxacin (Mox) delivery in Bacterial Keratitis (BK). Moxifloxacin-loaded G/CG-Alg NPs were prepared by an amalgamation of cationic polymers (gelatin (G)/cationized gelatin (CG)), and anionic polymer (sodium alginate (Alg)) along with Mox respectively. Mox@CG-Alg NPs were characterized for physicochemical parameters such as particle size (DLS technique), morphology (SEM analysis), DSC, XRD, encapsulation efficiency, drug loading, mucoadhesive study (by texture analyzer), mucin turbidity, and viscosity assessment. The NPs uptake and toxicity of the formulation were analyzed in the Human Corneal Epithelial (HCE) cell line and an ocular irritation study was performed on the HET-CAM. The results indicated that the CG-Alg NPs, with optimal size (217.2 ± 4 nm) and polydispersity (0.22 ± 0.05), have shown high cellular uptake in monolayer and spheroids of HCE. The drug-loaded formulation displayed mucoadhesiveness, trans-corneal permeation, and sustained the release of the Mox. The anti-bacterial efficacy studied on planktonic bacteria/biofilms of P. aeruginosa and S. aureus (in vitro) indicated that the Mox@CG-Alg NPs displayed low MIC, higher zone of bacterial growth inhibition, and cell death compared to free Mox. A significant reduction of bacterial load was observed in the BK-induced mouse model.

Silver Nanoparticles-Chitosan Nanocomposites: A Comparative Study Regarding Different Chemical Syntheses Procedures and Their Antibacterial Effect.

Nanocomposites based on silver nanoparticles and chitosan present important advantages for medical applications, showing over time their role in antibacterial evaluation. This work presents the comparative study of two chemical synthesis procedures of nanocomposites, based on trisodium citrate dihydrate and sodium hydroxide, using various chitosan concentrations for a complex investigation. The nanocomposites were characterized by AFM and DLS regarding their dimensions, while FT-IR and UV-VIS spectrometry were used for the optical properties and to reveal the binding of silver nanoparticles with chitosan. Their antibacterial effect was determined using a disk diffusion method on two bacteria strains, E. coli and S. aureus. The results indicate that, when using both methods, the nanocomposites obtained were below 100 nm, yet the antibacterial effect proved to be stronger for the nanocomposites obtained using sodium hydroxide. Furthermore, the antibacterial effect can be related to the nanocomposites' sizes, since the smallest dimension nanocomposites exhibited the best bacterial growth inhibition on both bacteria strains we tested and for both types of silver nanocomposites.

Assessment of the Antibacterial Activity of Spilanthes acmella Against Bacteria Associated with Dental Caries and Periodontal Disease: An In-vitro Microbiological Study

Dental caries and periodontal disease are two of the most common oral diseases caused by bacterial infections. Traditional medicine in India has a long history of using plant extracts for dental care. Spilanthes acmella (S. acmella), also known as the “Toothache Plant,” is a medicinal plant that has been traditionally used for its medicinal properties but has not been extensively studied for its applicability and use in dentistry. This study aims to investigate the antimicrobial action of S. acmella ethanol extract on Streptococcus mutans (S. mutans), and Lactobacillus fermentum (L. fermentum), which causes dental caries, and Porphyromonas gingivalis (P. gingivalis), Capnocytophaga gingivalis (C. gingivalis), which causes periodontal infection. The ethanol extract of S. acmella in various dilutions of 10mg/ml, 20mg/ml, 40mg/ml, 80mg/ml, and 100mg/ml was tested for its antibacterial activity against the bacteria as mentioned above using the agar well diffusion method. Erythromycin 0.125mg/ml was used as a positive control, whereas distilled water was used as a negative control. The Minimum inhibitory concentration (MIC) and Minimum bactericidal concentration (MBC) were determined by the broth dilution method. The results of this study have shown that the ethanol extract of S. acmella demonstrated concentration-dependent inhibition of bacterial growth (13-16mm diameter), with the highest concentration of 100mg/ml showing the strongest effect. The findings of this study support the use of the S. acmella plant extract in the treatment of dental caries and periodontal infection and suggest that it may be a viable alternative to traditional antimicrobial agents.

A comparative analysis of peptide-delivered antisense antibiotics using diverse nucleotide mimics.

Antisense oligomer (ASO)-based antibiotics that target mRNAs of essential bacterial genes have great potential for counteracting antimicrobial resistance and for precision microbiome editing. To date, the development of such antisense antibiotics has primarily focused on using phosphorodiamidate morpholino (PMO) and peptide nucleic acid (PNA) backbones, largely ignoring the growing number of chemical modalities that have spurred the success of ASO-based human therapy. Here, we directly compare the activities of seven chemically distinct 10mer ASOs, all designed to target the essential gene acpP upon delivery with a KFF-peptide carrier into Salmonella. Our systematic analysis of PNA, PMO, phosphorothioate (PTO)-modified DNA, 2'-methylated RNA (RNA-OMe), 2'-methoxyethylated RNA (RNA-MOE), 2'-fluorinated RNA (RNA-F), and 2'-4'-locked RNA (LNA) is based on a variety of in vitro and in vivo methods to evaluate ASO uptake, target pairing and inhibition of bacterial growth. Our data show that only PNA and PMO are efficiently delivered by the KFF peptide into Salmonella to inhibit bacterial growth. Nevertheless, the strong target binding affinity and in vitro translational repression activity of LNA and RNA-MOE make them promising modalities for antisense antibiotics that will require the identification of an effective carrier.