High Level Of Antibacterial Activity Research Articles

An insight into the bactericidal and phytochemical properties of leaf extract of Vernonia squarrosa and understanding antibacterial activity by molecular docking

IntroductionNumerous plants in the Vernonia genus are used in Traditional Chinese Medicine (TCM) to treat a wide range of illnesses, such as pityriasis rubra pilaris, infections, wounds, dermatitis, mastitis, diarrhoea, and colds. These genera also have antibacterial, antipyretic, and anti-inflammatory properties. The current work sought to investigate the bactericidal and phytochemical characteristics of Vernonia squarrosa leaf extract and comprehend antibacterial action using molecular docking. MethodsAn in vitro study was carried out to investigate the antibacterial capabilities of V. squarrosa. HRLCMS analysis was conducted to determine the phytoconstituents of the chloroform extract (LC). For molecular docking validation, PyRx, an Open Babel integrated Auto Dock programme, was used. ResultsPresent investigation reveals strong antibacterial activity against two tested gram-positive and gram-negative bacterial strains compared to other solvent extracts, LC at a higher concentration demonstrated a better response. Against Bacillus subtilis (20.05±0.88 mm) and Escherichia coli (20 ± 0.00 mm), the active components of the extracts formed the largest inhibitory zone followed by Pseudomonas aeruginosa (19.50±0.50 mm) and Staphylococcus aureus (14.33 ± 0.33 mm). The LC extract had lower minimum inhibitory concentrations (MIC) and stronger bactericidal activity than the other extracts. DiscussionV. squarrosa's LC showed higher levels of antibacterial activity against the tested bacterial strains than other solvent extracts, most likely as a result of the presence of 31 chemical components, including flavonoids, glycosides, alkaloids, phenolics, and triterpenoids. Developing unique TCM formulations assume significance in global healthcare scenarios to combat bacterial infections and in this context, the current paper underlines the importance of the potent antimicrobial properties of chloroform extract of V. squarrosa. This study revealed that chloroform extract of V. squarrosa has a great deal of antibacterial activity. ConclusionAccording to the study, V. squarrosa leaf chloroform extract possesses antibacterial properties because of its active phytocompounds. Its wide range of bioactive components makes it a prime choice for developing novel formulations to neutralize threats of newly emerging strains of harmful bacteria. The aforementioned discoveries may deepen our comprehension of phenomenal wisdom and deep science associated with the legendary TCM.

ANTIBACTERIAL ACTIVITY OF CLOVE ESSENTIAL OIL (SYZYGIUM AROMATICUM) AGAINST STRAINS OF ESCHERICHIA COLI, PSEUDOMONAS AERUGINOSA, AND SALMONELLA SSP

Background: The Clove (Syzygium aromaticum), a member of the Myrtaceae family, is cultivated in various countries across Asia, Africa, and the West. Eugenol, its primary volatile phenolic compound, imparts characteristic aroma and flavor, as well as possessing bactericidal properties. Objective: This study evaluated the antibacterial activity of clove essential oil (Syzygium aromaticum) against Escherichia coli, Pseudomonas aeruginosa, and Salmonella spp, isolated from food and water. Methods: To achieve this, the essential oil was extracted from the dried floral buds of cloves using the hydrodistillation method, using a Clevenger system. The susceptibility assessment of the strains took place using the disc diffusion method. Results: Escherichia coli and Salmonella, isolated from food, demonstrated sensitivity to the essential oil, with inhibition halos of 16 and 18 mm, respectively. The gram-negative strains Salmonella spp. and Salmonella isolated from sururu (Mytella guyanensis) were also sensitive to the oil, and the pattern with inhibition halos was 15 mm. However, strains of Pseudomonas aeruginosa, isolated from water, did not show activity against the essential oil. Discussion: The essential oil extracted from Syzygium aromaticum, known as clove, demonstrated a high level of antibacterial activity against two of the three tested bacterial strains (Escherichia coli and Salmonella spp), while exhibiting moderately effective activity against Pseudomonas aeruginosa. Conclusions: The microbiological study revealed that clove essential oil exhibited good antibacterial activity against the tested strains, with eugenol being the main compound responsible for this efficacy.

Biosynthesis of PbO nanoparticles via Adhatoda vesica (Justicia adhatoda) leaves extract for antimicrobial and photocatalytic applications

Research applications in biology and the environment can benefit greatly from nanoscience and nanotechnology. Aqueous leaf extract of Adhatoda vesica (AV) mediated the formation of lead oxide (PbO) nanoparticles in this study. A XRD analysis confirmed that the lead oxide nanoparticles (PbO NPs) synthesized from leaves extract have a crystalline structure. UV–vis spectroscopy study of colloidal PbO nanoparticles absorption revealed the greatest absorption bands, and the photoluminescence (PL) emission spectrum revealed a broad nature of visible emission peaks with high surface defects. By analyzing PbO nanoparticles using the fourier transform infrared method (FTIR), the leaf extract demonstrated the presence of functional peaks. It was evident from the SEM images that most of the PbO NPs had a spherical, irregular sponge-like shape. Additionally, the PbO nanostructures were tested for their antibacterial activity against Escherichia Coli, and a high level of antibacterial activity was observed, indicating their suitability for antimicrobial applications. PbO NPs have been evaluated for photocatalytic degradation of methylene blue dye (MB) under UV irradiation and have produced indications that the synthesized material is suitable for photocatalytic degradation. The Adhatoda vesica is used as medicine and enhances lead oxide nanomaterials' antibacterial properties. The research is focused on focusing on environmental pollution control and treatment of different diseases such as asthma, bronchitis, tuberculosis, and other diseases through applications of Ayurveda, Siddha, Homeopathy, and Unani. A study based on these findings revealed that Adhatoda vesica (Justicia adhatoda) leaves extract can be utilized as a cost-effective and environmentally friendly alternative to producing lead oxide nanoparticles.

INVESTIGATIONS AND SYNTHESIS OF SILVER-DOPED PHTHALIC ANHYDRIDE SINGLE CRYSTAL AND ITS EFFECT ON ANTIBACTERIAL ACTIVITY

The objective of this study was to introduce phthalic anhydride into Silver, to produce a novel substance having biological activity. The Fourier Transform Infrared Spectroscopy (FTIR), Powder X-ray Diffraction (PXRD), Ultraviolet-Visible Spectroscopy (UV-visible), and antimicrobial analyses collectively yielded compelling evidence indicating the occurrence of chemical alteration in the crystal structure. The obtained materials had a remarkable inhibitory action against K. pneumoniae and S. aureus, resulting in almost complete suppression. Additionally, they also hindered the growth of S. epidermidis. The derivatives exhibited the highest level of antibacterial activity, indicating that the addition of phthalic groups resulted in the hydrophobization of Silver, thereby improving the interaction between these compounds and the constituents of the bacterial cell wall. The Fourier Transform Infrared (FTIR) analysis yields data about the functional groups present in a sample, whilst the Ultraviolet (UV) examination provides insights into its optical properties. The present study presents a novel approach to introduce dopants into single crystals of phthalic anhydride, so greatly enhancing their potential for environmental applications.

Potential application of hydroxypropyl methylcellulose/shellac embedded with graphene oxide/TiO2-Nps as natural packaging film

Graphene oxide (GO), TiO2-NPs, HPMC, and shellac are environmentally green polymers and nanocomposites. This work aimed to create biodegradable composite films made of HPMC/shellac, HPMC/shellac-GO, and HPMC/shellac-GO/TiO2-NPs by film casting. TiO2-HPMC/shellac-GO matrix's dispersibility and mixing ability were characterized and observed using FTIR and XRD. XRD analysis shows that the crystallinity decreased within the composites due to breaking H-bonding. Compared to HPMC/shellac, TGA/DTG demonstrated the composite films' superior thermal stability. TiO2 (0.08–0.16 %) was cast into a composite film comprising HPMC, shellac, and GO. The homogeneity of TiO2 distribution in the composite film was shown using a SEM, which was also used to display the morphology of nanocomposite films. Nanocomposite films' thickness, air permeability, tensile strength, Young's modulus, and burst strength were examined. The results demonstrated that natural films prepared by a combination of shellac/GO with HPMC enhanced the fabricating of films' properties, the tensile strength increased by 231 % (from 16 to 53 MPa) in HPMC and HPSG2 (HPMC 1.9 g/shellac 0.25 g/GO 0.125 g in 100 mL) respectively, whereas the contact angle did not change. And after addition of TiO2-NPs, there were high enhancements in HPMC films' properties, such tensile strength increased by 212 % (from 16 to 50 MPa), burst strength increased by 20.96 % (3.1 to 3.75 Kg/cm2), and the contact angle by 60.86 % (48 to 74°) in HPMC and HPSGT2 respectively. Compared to HPMC films, films exhibited the highest levels of antibacterial activity against E. coli, B. mycoides, and C. albicans. So, the composite films from HPMC/shellac/GO/TiO2-NPs are promising potential packaging materials.

Coloration and antibacterial treatment of aramid fabric: a comprehensive review

Aramid fabric/fiber (AF), which possesses outstanding comprehensive qualities such as low density, high specific strength and high specific modulus, is widely used for body armor for defense. Different dyes and chemicals are required to give AF a specific coloration effect. AF is relatively difficult to dye due to its very crystalline structure and remarkable compactness. Different techniques, including supercritical carbon dioxide, microwave irradiation, liquid ammonia, ultraviolet treatment, copolymerization, high temperature, carrier method and ozone treatment, have already been utilized for the dyeing of AF. Some of these processes show excellent dyeing performance in terms of colorfastness against washing, rubbing and light. AF is also frequently used in harsh environments and cannot be cleaned in a timely manner. Bacteria that develop on its surface might pose a health concern, making AF with antibacterial properties extremely desirable. There have been a number of antibacterial treatments for AF to develop protection against Gram-positive and Gram-negative bacteria. The in situ treatment of AF using silver nanoparticles showed a high level of antibacterial activity. However, there are no reviews that discuss the coloration and antibacterial activity of AF. Therefore, this review summarizes the coloration and antibacterial activity of AF using different dyes and nanoparticles.

Garlic Extracts: Effect of pH on Inhibition of Helicobacter pylori.

The present work studies the influence of pH on the stability of thiosulfinates, compounds responsible for the bacteriostatic properties shown by ethanolic and acetonic garlic extracts (EGE and AGE) against the in vitro growth of Helicobacter pylori (Hp), a bacterium which is implicated in the etiology of diverse gastrointestinal diseases. The influence of pH and time on the stability of thiosulfinates and the microbiological activities of EGE and AGE has been evaluated at human body temperature (37 °C) and in a pH range of 0.9-4.7. A marked decrease in thiosulfinate concentration was observed in a relatively short time at pH values below 2.0. However, at pH values over 2.0, the samples maintained 70% of thiosulfinate concentration for 12 h. The inhibition halo diameters showed a maximum value at pH 2.50, with an inhibition halo of 28.94 ± 0.61 mm. The reduction in the activity at pH values below 2.0 was particularly remarkable. These results suggest that, for medical application, the pH of the selected extracts must only be maintained above 2 to maintain a high level of antibacterial activity. This fact would overcome the need for proton pump inhibitors and/or antibiotics during the treatment of Hp infections in human patients.

Laser-Induced Transferred Antibacterial Nanoparticles for Mixed-Species Bacteria Biofilm Inactivation.

In the present study, copper and silver nanoparticles with a concentration of 20 µg/cm2 were synthesized using the method of laser-induced forward transfer (LIFT). The antibacterial activity of the nanoparticles was tested against bacterial biofilms that are common in nature, formed by several types of microorganisms (mixed-species bacteria biofilms): Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The Cu nanoparticles showed complete inhibition of the bacteria biofilms used. In the course of the work, a high level of antibacterial activity was demonstrated by nanoparticles. This activity manifested in the complete suppression of the daily biofilm, with the number of bacteria decreasing by 5-8 orders of magnitude from the initial concentration. To confirm antibacterial activity, and determine reductions in cell viability, the Live/Dead Bacterial Viability Kit was used. FTIR spectroscopy revealed that after Cu NP treatment, there was in a slight shift in the region, which corresponded to fatty acids, indicating a decrease in the relative motional freedom of molecules.

Multicationic Quaternary Ammonium Compounds: A Framework for Combating Bacterial Resistance.

During previous stages of research, high biocidal activity toward microorganism archival strains has been used as the main indicator in the development of new antiseptic formulations. Although this factor remains one of the most important characteristics of biocide efficiency, the scale of antimicrobial resistance spread causes serious concern. Therefore, focus shifts toward the development of formulations with a stable effect even in the case of prolonged contact with pathogens. Here, we introduce an original isocyanuric acid alkylation method with the use of available alkyl dichlorides, which opened access to a wide panel of multi-QACs with alkyl chains of various lengths between the nitrogen atoms of triazine and pyridine cycles. We used a complex approach for the resulting series of 17 compounds, including their antibiofilm properties, bacterial tolerance development, and antimicrobial activity toward multiresistant pathogenic strains. As a result of these efforts, available compounds have shown higher levels of antibacterial activity against ESKAPE pathogens than widely used commercial QACs. Hit compounds possessed high activity toward clinical bacterial strains and have also demonstrated a long-term biocidal effect without significant development of microorganism tolerance. The overall results indicated a high level of antibacterial activity and the broad application prospects of multi-QACs based on isocyanuric acid against multiresistant bacterial strains.

High-throughput screening and molecular dynamics simulations of natural products targeting LuxS/AI-2 system as a novel antibacterial strategy for antibiotic resistance in Helicobacter pylori

The main goal of treating any Helicobacter pylori (H. pylori)-related gastrointestinal disease is completely eradicating infection. Falling eradication efficiency, off-target effects, and patient noncompliance with prolonged and broad spectrums have sparked clinical interest in exploring other effective, safer therapeutic choices. As natural substances are risk-free and privileged with high levels of antibacterial activity, most of these natural chemical’s specific modes of action are unknown. With the aid of in silico molecular docking-based virtual screening studies and molecular dynamic simulations, the current study is intended to gather data on numerous such natural chemicals and assess their affinity for the S-ribosyl homocysteine lyase (LuxS) protein of H. pylori. The ligand with the highest binding energy with LuxS, glucoraphanin, catechin gallate and epigallocatechin gallate were rationally selected for further computational analysis. The solution stability of the three compounds’ optimal docking postures with LuxS was initially assessed using long-run molecular dynamics simulations. Using molecular dynamics simulation, the epigallocatechin gallate was found to be the most stable molecule with the highest binding free energy, indicating that it might compete with the natural ligand of the inhibitors. According to ADMET analysis, his phytochemical was a promising therapeutic candidate for an antibacterial action since it had a range of physicochemical, pharmacokinetic, and drug-like qualities and had no discernible adverse effects. Additional in vitro, in vivo, and clinical trials are needed to confirm the drug’s precise efficacy during H. pylori infection. Communicated by Ramaswamy H. Sarma

Separation and Identification of an Antimicrobial Substance from Schisandra chinensis Extract against Streptococcus mutans KCCM 40105 Strain.

This study aimed to isolate and identify antibacterial compounds from Schisandra chinensis (S. chinensis) that are effective against the Streptococcus mutans KCCM 40105 strain. First, S. chinensis was extracted using varying concentrations of ethanol, and the resulting antibacterial activity was evaluated. The 30% ethanol extract of S. chinensis showed high activity. The fractionation and antibacterial activity of a 30% ethanol extract from S. chinensis were examined using five different solvents. Upon investigation of the antibacterial activity of the solvent fraction, the water and butanol fractions showed high activity, and no significant difference was found. Therefore, the butanol fraction was chosen for material exploration using silica gel column chromatography. A total of 24 fractions were obtained from the butanol portion using silica gel chromatography. The fraction with the highest antibacterial activity was Fr 7. From Fr 7, thirty-three sub-fractions were isolated, and sub-fraction 17 showed the highest level of antibacterial activity. A total of five peaks were obtained through the pure separation of sub-fraction 17 using HPLC. Peak 2 was identified as a substance exhibiting a high level of antibacterial activity. Based on the results of UV spectrometry, 13C-NMR, 1H-NMR, LC-MS, and HPLC analyses, the compound corresponding to peak number 2 was identified as tartaric acid.

The chemical composition of the secretions, their antibacterial activity, and the pygidial gland morphology of selected European Carabini ground beetles (Coleoptera: Carabidae)

The pygidial glands of carabids produce strong-smelling vapours. In this study, we examined the chemical composition of the gland secretions and the structure of the glands in five species of Carabini ground beetles (one species from the subtribe Calosomatina and four species from the subtribe Carabina): Calosoma (Calosoma) maderae (Fabricius, 1775), Carabus (Carabus) granulatus Linnaeus, 1758, C. (Limnocarabus) clathratus Linnaeus, 1760, C. (Carabus) ulrichii Germar, 1823, and C. (Procerus) gigas Creutzer, 1799. Additionally, we tested the antibacterial potential of the pygidial gland secretions of the two latter species against 11 bacterial strains. In order to detect the chemical content of the secretions, we used gas chromatography–mass spectrometry (GC–MS). The secretion extracts were applied against selected strains of medically important bacteria. We used bright-field microscopy to examine the morphology of the glands. We discovered a total of 11 chemical compounds in the pygidial gland extracts of the ground beetles we analysed. Ten of these compounds were identified as seven carboxylic acids, two hydrocarbons, and one aromatic aldehyde, while one chemical remained unidentified. Most of the components were isolated from the secretion of C. (L.) clathratus (nine), while the lowest number of compounds was found in C. (P.) gigas (two). Methacrylic acid was the most dominant compound by percentage in all five species, while angelic acid was also detected in all samples. As expected, salicylaldehyde was exclusively found in the species of the genus Calosoma Weber, 1801. The secretion of C. (P.) gigas was shown to achieve the highest level of antibacterial activity against Pseudomonas aeruginosa, Salmonella enterica, and S. typhimurium (even the same level as the positive control streptomycin), while the secretion of C. (C.) ulrichii achieved the highest antimicrobial potential against Staphylococcus epidermidis, S. aureus, Listeria monocytogenes, and Bacillus cereus. The most noticeable difference in the structure of the glands between the two genera is that the reservoir in Calosoma is more significantly narrowed as it leads into the efferent duct, compared to that of Carabus.

Tetramate derivatives by chemoselective Dieckmann ring closure of allo-phenylserines, and their antibacterial activity.

A general route which provides direct access to substituted bicyclic tetramates, making use of Dieckmann cyclisation of oxazolidine derivatives derived from allo-phenylserines, is reported. Of interest is the high level of diastereoselectivity observed for the N-acylation reaction of oxazolidines and the complete chemoselectivity of their ring closure in the Dieckmann cyclisation. Significantly, the sense of the chemoselectivity is different to earlier reported threo-phenylserine systems, showing the importance of steric bulk around the bicyclic ring system. The derived C7-carboxamidotetramates, but not C7-acyl systems, exhibited potent antibacterial activity against MRSA, with the most active compounds exhibiting well-defined physicochemical and structure-activity properties. This work clearly demonstrates that densely functionalised tetramates are both readily available and may exhibit high levels of antibacterial activity.

Evaluation of the Antibacterial Activity of the Jackfruit Parasite Leaf Plant Extract (Macrosolencochinchinensis (Lour.) van Tiegh) with Vitro and In Silico approach

In traditional Melayu Riau medicine, the jackfruit parasite plant, also known as Macrosolen cochinchinensis (Lour.) van Tiegh, has been utilized as a remedy for coughs, a treatment for cancer, a diuretic, and to speed up the recovery process after giving birth. Through in vitro and in silico testing, the purpose of this investigation is to learn more about the bioactive components and antibacterial activity of n-heksan, etilasetat, and etanol obtained from the extracts of the jackfruit parasite plant (Macrosolen cochinchinensis (Lour.) van Tiegh. The disc diffusion method was used for the in vitro testing, and the molecular docking method was used for the in silico testing, both of which were conducted against Staphylococcus aureus ATCC 12600 and Escherichia coli ATCC 25922. Each sample extract was prepared in three different concentrations (10%, 30%, and 50%), while chloramphenicol was used as the positive control. Inhibition zones of the extract against E. coli bacteria were found to be as follows: 6 mm, 8.4 mm, and 10.6 mm for the n-hexane extract; 8.2 mm, 10.7 mm, and 15.6 mm for the ethyl acetate extract; and 6 mm, 7.1 mm, and 14.1 mm for the methanol extract. The results of the test to determine the extract's antibacterial activity were as follows: The following is a list of the zones of inhibition that the extract has against S. aureus bacteria: 6 mm, 7.5 mm, and 13.7 mm in diameter for the extract of n-hexane; 12.8 mm, 14.2 mm, and 19.2 mm in diameter for the extract of ethyl acetate. Test results of 7.2 mm, 9.3 mm, and 15.3 mm were obtained for the methanol extract. In accordance with the findings of the study, the ethyl acetate extract of jackfruit parasite leaves exhibited the highest level of antibacterial activity, as measured by an inhibition zone diameter of 19.2 mm, when tested on S. aureus bacteria. In the meantime, the results of molecular docking of punicalin and rutin, which have been reported to have activity against proteins 6GOS.pdb and 1OJZ.pdb, have potential as antibacterials because they form 5 and 9 hydrogen bonds with important amino acids of the target protein, with cDOCKER values of -57.9239 and -88.3993, respectively. This suggests that punicalin and rutin have the ability to inhibit the growth of bacteria.

Antibacterial activity of metal-phenanthroline complexes against multidrug-resistant Irish clinical isolates: a whole genome sequencing approach.

Antimicrobial resistance (AMR) is one of the serious global health challenges of our time. There is now an urgent need to develop novel therapeutic agents that can overcome AMR, preferably through alternative mechanistic pathways from conventional treatments. The antibacterial activity of metal complexes (metal = Cu(II), Mn(II), and Ag(I)) incorporating 1,10-phenanthroline (phen) and various dianionic dicarboxylate ligands, along with their simple metal salt and dicarboxylic acid precursors, against common AMR pathogens were investigated. Overall, the highest level of antibacterial activity was evident in compounds that incorporate the phen ligand compared to the activities of their simple salt and dicarboxylic acid precursors. The chelates incorporating both phen and the dianion of 3,6,9-trioxaundecanedioic acid (tdda) were the most effective, and the activity varied depending on the metal centre. Whole-genome sequencing (WGS) was carried out on the reference Pseudomonas aeruginosa strain, PAO1. This strain was exposed to sub-lethal doses of lead metal-tdda-phen complexes to form mutants with induced resistance properties with the aim of elucidating their mechanism of action. Various mutations were detected in the mutant P. aeruginosa genome, causing amino acid changes to proteins involved in cellular respiration, the polyamine biosynthetic pathway, and virulence mechanisms. This study provides insights into acquired resistance mechanisms of pathogenic organisms exposed to Cu(II), Mn(II), and Ag(I) complexes incorporating phen with tdda and warrants further development of these potential complexes as alternative clinical therapeutic drugs to treat AMR infections.

Analisis uji daya hambat ekstrak lamun terhadap bakteri patogen di Pulau Bone Batang dan Barrang Lompo, Perairan Spermonde

Seagrass beds are a wealth of marine resources, one of the ecosystems found in coastal areas, capable of producing various secondary metabolites, and seagrasses are known to contain antibacterial active compounds. The purpose of this study was to determine the antibacterial potential of seagrass extracts from Zone I (large and small Lae-lae Island) and Zone II (Gusung Bone Batang and Barrang Lompo) against Staphylococcus aureus and Escherichia coli bacteria. The test method used is the agar diffusion method. The results showed that in Zone I, H. ovalis had an average inhibition of 7.9 mm and E. acoroides had an average inhibition of 8.15 mm, while in Zone II, E. acoroides was 2.5 mm, C Rotundata 1.18 mm, H. uninervis 1.53 mm, T. hemprichii 1.2 mm and H. ovalis 1.73 mm. The highest level of antibacterial activity was in the type of E. acoroides.

Antimicrobial activity of aqueous dispersions of silver nanoparticles against pathogens of purulent-inflammatory diseases

Currently, metal nanostructures are widely used in medical, microbiological, and veterinary practice. Silver nanoparticles are especially promising as antimicrobial agents, becauseno published data regarding antimicrobial resistance are available. Whiledeveloping preparations based on metal nanoparticles, an important remainingissue is the choice of a stabilizer, introduction of which during the synthesis ensures the preservation of structures at the nanoscale range, and, consequently, relevant main characteristics, including biocidal properties. The object of the study was to investigate silver nanoparticle aqueous dispersions stabilized by natural and synthetic polymeric compounds. Routine strains of Gram-positive and Gram-negative bacteria were used as experimental models: S. aureus 209 P, Escherichia coli ATCC 25922, Proteus mirabilis ATCC 3177 (O-form), Klebsiella pneumoniae ATCC 31488, obtained from the Scientific Centre for Expert Evaluation of Medicinal Products. The antimicrobial activity of diverse variants of silver nanoparticle aqueous dispersions was assessed by serial dilution platingon dense nutrient medium. In this work, we examined no effect of silver nanoparticles without stabilizers, because their absence led to rapid agglomeration of nanostructures and loss of nanoscale characteristics. The highest sensitivity of Gram-positive and Gram-negative bacteria was foundto the action of ansilver nanoparticle aqueous dispersions stabilized by polyazolidinammoniumand modified with iodine hydrate ions. Drug working concentrations ranging from 0.5 to 3% had a bactericidal effect against pathogens of purulent-inflammatory diseases, and the minimum working concentration of 0.125% led to decreased colony-forming units by 2057% for diverse bacterial strains. Silver nanoparticles stabilized with sodium dodecyl sulfate showed high efficiency against the studied test strainsprobably due to the high toxicity of the stabilizer used as was previously established during a comprehensive safety assessment using biotest objects and cell cultures. In this regard, its use as a component of antimicrobial preparations is not preferred. The results of the studies showed that among the variants of silver nanoparticle aqueous dispersions, preparations stabilized with polyvinyl alcohol and polyazolidinammonium modified with iodine hydrate ions are the most promising for use in biomedical practice, because they demonstrate a high level of antibacterial activity against both Gram-positive and Gram-negative bacteria as causative agents of purulent-inflammatory diseases and a low toxicity level. This allows us to recommend them as safe and effective antimicrobial components indisinfectants, as well as antiseptic preparations for prevention and treatment of skin and soft tissue infectious diseases.

Investigation of mechanical properties and antibacterial behavior of WE43 magnesium-based nanocomposite

The aim of this study is to develop a biodegradable magnesium-based nanocomposite with enhanced mechanical and antibacterial properties. To achieve this goal, nano- and micro-scale zinc oxide (ZnO) and copper-zinc oxide (Cu/ZnO) reinforcements were incorporated into WE43 magnesium alloy, as the matrix of the nanocomposite. High purity ZnO and Cu/ZnO were synthesized by solution combustion with citric acid fuel using conventional and microwave heating, resulting in nanometer and micrometer particles, respectively. Friction stir processing (FSP) was employed to develope the magnesium-based composites. ZnO and Cu/ZnO powders were implemented into the WE43 base plate with either drilling holes or machining grooves. Hole-inserted additives resulted in more uniform particle distribution than groove-inserted ones. In addition, nanoscale ZnO and Cu/ZnO particles showed more uniform distribution compared to microscale ZnO. The addition of Cu/ZnO particles yielded the highest level of antibacterial activity, compressive strength and micro hardness of the composite. The antibacterial performance of the composite was in line with the fact that Cu/ZnO powder showed more pronounced antibacterial properties than ZnO powders. In addition, groove-inserted Cu/ZnO composite showed compressive strength of 527 MPa and hardness of 90.7 Hv, which were significantly higher than the values of 300 MPa and 78.7 Hv obtained for groove-inserted ZnO composites. It should be noted that the un-processed monolithic WE43 alloy had a compressive strength of 138 MPa and hardness of 66.8 Hv.

Optimization of the synthesis of novel alginate-manganese oxide bionanocomposite by Taguchi design as antimicrobial dental impression material

Control of the infection transmission cycle in clinics and increase of drug resistance are among the current problems of the dental community. In this study, the optimization synthesis of the dental impression material of alginate-manganese oxide with the highest level of antibacterial activity was studied. For this purpose, alginate biopolymer and manganese oxide nanoparticles were synthesized by green synthesis using Azotobacter vinelandii and Bacillus sp, respectively. The in situ method was applied to synthesize alginate-manganese oxide nanocomposite. Nine experiments were designed to determine the antibacterial effects of the synthesized nanocomposites against Streptococcus mutans biofilm by the Taguchi method. Antibacterial activity of nanocomposite and its components were performed by the colony-forming unit (CFU) test. The results indicated that the synthesized nanocomposite by experiment 3 (50 mg/ml alginate, 4 mg/ml manganese oxide, and 90 min of stirring time) had the highest antibacterial activity (2.10 CFU/ml). The highest effect on streptococcus muntas bacteria survival was related to manganese oxide with an effect of 84.66%, stirring time of 6.58%, and alginate of 5.82%, respectively. Alginate at the first level and stirring time at the third level had the strongest interaction with each other and on the survival rate of streptococcus muntas bacteria at the amount 46.57%. Manganese oxide and stirring time at the third level showed a significant interaction on the survival rate of streptococcus muntas bacteria at the amount 13.68%. The lowest interaction intensity index was related to alginate at the first level and manganese oxide at the third level at the amount 2.85%. Characteristics of alginate-manganese oxide nanocomposite and its components evaluated by ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscope (TEM), and thermogravimetric analysis (TGA) confirmed the formation of the nanocomposite and the improvement of its properties.

Microbiological Evaluation of Novel Bis-Quaternary Ammonium Compounds: Clinical Strains, Biofilms, and Resistance Study.

This work is devoted to the investigation of biocidal properties of quaternary ammonium compounds (QACs) based on pyridine structures with aromatic spacers, and their widely known analogs, against clinically significant microorganisms. This study is focused on investigating their antimicrobial activity (minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs)), antibiofilm properties (minimum biofilm inhibitory concentrations (MBICs) and minimum biofilm eradication concentrations (MBECs)), synergetic effect with different alcohols in antiseptic formulations, and bacterial resistance development. It was shown that all combined analogue preparations had a higher level of antibacterial activity against the tested bacterial strains, with a 16- to 32-fold reduction in MICs and MBCs compared to previously used antiseptic preparations. Moreover, hit-QACs demonstrated a stable effect against Gram-negative E. coli, K. pneumoniae, and A. baumannii within a month of incubation. Overall results indicated a high level of antibacterial activity of pyridine-based QACs.