Nanoparticles in inhibiting Pantoea ananatis and to control maize white spot

ABSTRACT: Maize white spot (MWS) caused by Pantoea ananatis is one main maize leaf diseases, and nanoparticles (NPs) are an innovative approach for bacterial disease control. This research evaluated the toxicity of pure NPs and doped NPs with different elements in inhibiting bacterial growth and to control MWS. Pure NPs and ZnO NPs doped with silver (Ag), gold (Au), copper (Cu), iron (Fe), manganese (Mn), and nickel (Ni) at different concentrations were used to determine the toxicity for P. ananatis in vitro, evaluating the bacterial growth inhibition zone. To assess the control of MWS, in the preventive application, maize plants were sprayed with NPs of ZnO:0.1Cu, ZnO:0.05Fe, ZnO:0.2Mn and ZnO:0.7Ni at 10, 5 or 2.5 mg mL-1, and after 3 days, the plants were inoculated with bacterial suspension. To assess the curative application, plants were inoculated with the bacteria, and 3 days later sprayed with the NPs. The disease severity was assessed and the area under the disease-progress curve (AUDPC) was calculated. The doped ZnO NPs with different elements, and at different concentrations inhibited bacterial growth in vitro. NPs of ZnO:0.1Cu and ZnO:0.2Mn at 5 or 2.5 mg mL-1, in both applications reduced the severity of MWS, showing potential for use in the disease management.

New, Biocompatible, Chitosan-Gelled Microemulsions Based on Essential Oils and Sucrose Esters as Nanocarriers for Topical Delivery of Fluconazole

Biocompatible gel microemulsions containing natural origin excipients are promising nanocarrier systems for the safe and effective topical application of hydrophobic drugs, including antifungals. Recently, to improve fluconazole skin permeation, tolerability and therapeutic efficacy, we developed topical biocompatible microemulsions based on cinnamon, oregano or clove essential oil (CIN, ORG or CLV) as the oil phase and sucrose laurate (D1216) or sucrose palmitate (D1616) as surfactants, excipients also possessing intrinsic antifungal activity. To follow up this research, this study aimed to improve the adhesiveness of respective fluconazole microemulsions using chitosan (a biopolymer with intrinsic antifungal activity) as gellator and to evaluate the formulation variables’ effect (composition and concentration of essential oil, sucrose ester structure) on the gel microemulsions’ (MEGELs) properties. All MEGELs were evaluated for drug content, pH, rheological behavior, viscosity, spreadability, in vitro drug release and skin permeation and antifungal activity. The results showed that formulation variables determined distinctive changes in the MEGELs’ properties, which were nevertheless in accordance with official requirements for semisolid preparations. The highest flux and release rate values and large diameters of the fungal growth inhibition zone were produced by formulations MEGEL-FZ-D1616-CIN 10%, MEGEL-FZ-D1216-CIN 10% and MEGEL-FZ-D1616-ORG 10%. In conclusion, these MEGELs were demonstrated to be effective platforms for fluconazole topical delivery.

“Smart” Polylactic Acid Films with Ceftriaxone Loaded Microchamber Arrays for Personalized Antibiotic Therapy

Bacterial infections are a severe medical problem, especially in traumatology, orthopedics, and surgery. The local use of antibiotics-elution materials has made it possible to increase the effectiveness of acute infections treatment. However, the infection prevention problem remains unresolved. Here, we demonstrate the fabrication of polylactic acid (PLA) “smart” films with microchamber arrays. These microchambers contain ceftriaxone as a payload in concentrations ranging from 12 ± 1 μg/cm2 to 38 ± 8 μg/cm2, depending on the patterned film thickness formed by the different PLA concentrations in chloroform. In addition, the release profile of the antibiotic can be prolonged up to 72 h in saline. At the same time, on the surface of agar plates, the antibiotic release time increases up to 96 h, which has been confirmed by the growth suppression of the Staphylococcus aureus bacteria. The efficient loading and optimal release rate are obtained for patterned films formed by the 1.5 wt % PLA in chloroform. The films produced from 1.5 and 2 wt % PLA solutions (thickness—0.42 ± 0.12 and 0.68 ± 0.16 µm, respectively) show an accelerated ceftriaxone release upon the trigger of the therapeutic ultrasound, which impacted as an expansion of the bacterial growth inhibition zone around the samples. Combining prolonged drug elution with the on-demand release ability of large cargo amount opens up new approaches for personalized and custom-tunable antibacterial therapy.

Evaluation of Antimicrobial Activity of Several Medicinal Plants Against Clinically Isolated Staphylococcus Aureus from Humans and Sheep

Background: Continuous and indiscriminate use of chemical drugs causes an important phenomenon of resistance to microorganisms. Accordingly, the effect of medications is minimized or offset, increasing drug use and the need to study mixtures with more latest and powerful formulations. On the other hand, it has been reported that many plants essential oils have a significant inhibitory effect on pathogenic microorganisms. Objectives: This study aimed to evaluate the antimicrobial activity of some curative herbs against some clinical bacteria of humans and sheep. Methods: The leaves of chicory (Cichorium intybus L.), Hypericum perforatum L., Lavandula angustifolia, Thymus vulgaris L., and Taxus baccata L. were collected and determined in the botanical laboratory of the University of Zabol. Forty grams of dried leaves was used in 400 mL of ethanol (96%) to prepare the ethanolic extract. DPPH was used to determine the activity of reactive oxygen species (ROS) trapping. The antimicrobial effects were studied by the disk diffusion (6 mm) method in Müller-Hinton agar medium according to the method by Bauer et al. Results: The minimum inhibitory concentrations (MICs) of chicory, thyme, H. perforatum, French lavender, and yarrow extracts in human clinical Staphylococcus aureus were 6.25, 12.5, 3.1, 25, and 6.25 ppm, respectively, but, in sheep, clinical S. aureus, were 12.5, 6.25, 3.1, 12.5, and 25 ppm, respectively. The minimum bactericidal concentrations (MBCs) of chicory, thyme, H. perforatum, French lavender, and yarrow extracts in human clinical S. aureus were 12.5, 25, 6.25, 50, and 12.5 ppm, respectively, but, in sheep clinical S. aureus, were 25, 12.5, 6.25, 25, and 50 ppm, respectively. The most effective extract in inhibiting the growth of S. aureus was the H. perforatum L. extract with an 8.9-mm diameter growth inhibition zone. Conclusions: Regarding the side effects of artificial medications and antimicrobials, as well as the significant influence of healing herb extracts used in this study, it was found that H. perforatum was the most effective plant against S. aureus. It should be noted that plant extracts were more effective in human clinical S. aureus than in sheep clinical S. aureus.

Evaluation of the Antimicrobial Effect of Mineral Trioxide Aggregate Mixed with Fluorohydroxyapatite against E. faecalis In Vitro

Enterococcus faecalis is the dominant microorganism in chronic apical periodontitis. It is more resistant to local antiseptic agents than other endodontic microorganisms. Currently, mineral trioxide aggregate (MTA) is considered as an ideal material in many endodontic procedures. Some studies have shown that MTA has good antibacterial activity against E. faecalis. However, some studies have investigated the effect of incorporating some materials into MTA on its antibacterial activity against E. faecalis. No study has evaluated the effect of incorporating fluorohydroxyapatite nanoparticles (nano-FHA) on the antimicrobial activity of MTA. Therefore, the present study evaluated the antimicrobial effect of MTA mixed with nano-FHA on E. faecalis in vitro. The study was carried out on 18 samples in three groups: pure MTA, MTA mixed with 10 wt% of nano-FHA, and MTA mixed with 15 wt% of nan-FHA. The effect of nano-FHA on the antibacterial activity of MTA on E. faecalis was evaluated by evaluating the growth inhibition zone around each sample. The antimicrobial effect of samples on inhibiting E. faecalis biofilm formation and inhibiting microbial growth of E. faecalis in the planktonic phase was evaluated by disk agar diffusion (DAD), biofilm inhibition assay (BIA), and direct contact assay (DCA) tests, respectively. All the above tests were analyzed after 24 and 72 hours. Factorial designs were used for statistical analyses. Tukey tests were used for two-by-two comparisons. All the statistical analyses were carried out with SPSS 26. DAD results showed no formation of the growth inhibition zone in all the samples after 24 and 72 hours. The microbial colony counts in the BIA and DCA tests in the groups modified with FHA nanoparticles were significantly lower than the pure MTA group ( P < 0.05 ). The microbial colony counts increased in all the groups over time ( P < 0.05 ). Incorporating nano-FHA into MTA improved the antimicrobial activity of MTA against E. faecalis compared to pure MTA. The highest antimicrobial activity was achieved after incorporating 15 wt% of nano-FHA into MTA at the 72-hour interval.

Effects of Different Solvents to Extract Phytochemical Materials of Rhazya stricta Against Salmonella typhimurium Activity

Background: The use of plant extracts prepared from medicinal plants is common in the developing countries. Meanwhile, due to the resistance of microorganisms to antibiotics, researchers are looking to discover new antimicrobials. Medicinal plants play an essential role in this regard. Objectives: This study was aimed at investigating the antimicrobial properties of various extracts of Rhazya stricta plant against Salmonella typhimurium. Methods: Methanolic, aqueous, ethanolic, hydroalcoholic, and ethyl acetate extracts of R. stricta were prepared. S. typhimurium strains were isolated from poultry feces. The microdilution method was used to determine the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of this plant. The diameter of the growth inhibition zone using was determined using Whatman paper. Results: The lowest MIC against S. typhimurium was obtained from the hydroalcoholic solvent with 3.1 ppm. The most effective extraction solvent to inhibit the growth of S. typhimurium was the hydroalcoholic type with an average growth inhibition zone diameter of 12.25 mm, followed by the ethanolic extract with a growth inhibition zone diameter of 12.12 mm. Conclusions: According to the results of research and increasing resistance to synthetic antibacterial substances, it seems that R. stricta plant with the help of hydroalcoholic solvent, can be considered an effective plant in eliminating some bacteria, including S. typhimurium.

Evaluation of antimicrobial properties of nano-silver particles used in orthodontics fixed retainer composites: an experimental in-vitro study

Background. The present study evaluated the antimicrobial efficacy of composite resins containing nano-silver (NAg) particles used in fixed orthodontic retainers. Methods. Nano-composite resin samples with 1%, 2%, and 5% concentrations of NAg were prepared. The antimicrobial effectiveness of NAg was assessed against Streptococcus mutans, Streptococcus sanguis, and Lactobacillus acidophilus by the biofilm inhibition test (three-day-old biofilms), eluted components test (on days 3, 15, and 30), and disk-diffusion agar test after 48 hours. Measures of central tendency and index of dispersion were used to determine colony-forming units. Kruskal-Wallis test and Mann-Whitney U test were also used. Results. The biofilm inhibition test showed a significant decrease in the colonies of S. mutans (87.64%, 96.47%, and 99.76% decrease), S. sanguis (98.13%, 99.47%, and 99.93% decrease), and L. acidophilus (81.59%, 90.90%, and 99.61% decrease) at 1%, 2%, and 5% concentrations of Nag, respectively, compared to the control groups. The colony-forming unit (CFU)/mL of tested microorganisms continuously decreased with increased NAg concentration. In the eluted component test, no significant differences were noted in the 3rd, 15th, and 30th days between the different concentrations of Nag-containing composite resin disks and control samples. According to the disk-diffusion agar test, there was no growth inhibition zone for the composite resin disks containing 1% and 2% concentrations of Nag. However, the growth inhibition zone was seen with a 5% concentration, with a diameter of 9.5±0.71 mm for S. mutans, 8.5±0.71 mm for S. sanguis, and 8±1.41 for L. acidophilus. Conclusion. The incorporation of NAg into composite resins has antibacterial effects, possibly preventing dental caries around fixed orthodontic retainers.

Construction of metronidazole capped in gold nanoparticles against Helicobacter pylori: antimicrobial activity improvement

Introduction:Helicobacter pylori is considered a major agent causing gastritis and peptic ulcer disease. Unfortunately, the occurrence of increasing drug resistance to this bacterium would result in some difficulties in its treatment. Therefore, the application of nanotechnology has been suggested to resolve such problems. Nanoparticles usage in medical research has been expanded in recent years. Among nanometals, gold nanoparticles have exclusive features that can be used in such applications. Using nanotechnology in medical science could help mankind to solve this problem in the future. Aim: Our aim in this research was to investigate the antimicrobial effect of gold nanoparticles on H. pylori strains. Materials and methods: Gold nanoparticles were synthesized by the Turkevich method. Then, their size and dispersion were investigated using spectrophotometry, DLS, and TEM microscopy. Subsequently, the combination of metronidazole and gold nanoparticles was obtained by mixing method, and then the anti-helicobacter effects of the two were evaluated according to CLSI. Results: The highest size of gold nanoparticles was between 12 and 9 nm, and the maximum absorbance was 522 nm; however, in conjugated state, the maximum absorbance was 540 nm, which indicated the accumulation of drug-conjugated nanoparticles in the conjugate state. Some changes indicated the binding of metronidazole to gold nanoparticles. Antimicrobial testing of gold nanoparticles and metronidazole did not affect the Helicobacter pylori. Therefore, the combination of gold nanoparticles and metronidazole had a 17-mm growth inhibition zone. Conclusions: The anti-helicobacter effects of metronidazole significantly increased in conjugation with gold nanoparticles.

Antimicrobial properties, anti-virulence activities, and physico-mechanical characteristics of orthodontic adhesive containing C-phycocyanin: a promising application of natural products

Introduction: Antimicrobial orthodontic adhesives aim to reduce enamel demineralization, white spot lesions, and incipient tooth decay around bonded orthodontic brackets, but they should not imperil its mechanical properties.&nbsp; Aim: To evaluate the antimicrobial and physico-mechanical properties of acrylic containing different concentrations of C-phycocyanin on Streptococcus mutans, Lactobacillus acidophilus, and Candida albicans. Materials and methods: The mechanical properties of acrylic resins were measured by flexural strength test after preparation of acrylic resin samples with concentrations of 1%, 2%, 5%, 7.5%, and 10% of C-phycocyanin. Then we evaluated the antimicrobial effects of acrylic resin containing the maximum concentration of C-phycocyanin with clinically acceptable flexural strength and the changes in expression of virulence factors. Results: The highest and lowest means of flexural strength were obtained in acrylic resins containing 0% and 10% concentrations of C-phycocyanin at 50.2&plusmn;4.5 and 30.1&plusmn;3.3 MPa, respectively. Adding 1%, 2%, and 5% of C-phycocyanin showed no significant decrease in flexural strength (p>0.05). The maximum mean diameter of the growth inhibition zone was observed around discs containing 5% of C-phycocyanin. Until day 30 of the study, no microbial biofilms were formed on any acrylic disc. Only microbial biofilms of C. albicans were able to form on discs containing 5% of C-phycocyanin at 90 days. 5% C-phycocyanin could significantly decrease the expression levels of gtfB, hsp16, and ALS9 6.1-, 7.3-, and 3.9-fold, respectively. Conclusions: It can be concluded that the most acceptable concentration of C-phycocyanin in acrylic resin is 5% based on the results of flexural strength tests and antimicrobial activities of acrylic resin containing various concentrations of C-phycocyanin.

The biotechnological studies when developing lozenges with probiotics

Aim. To develop lozenges with probiotic components for the treatment and prevention of ENT diseases and analyze their effectiveness.Materials and methods. The study objects were lozenges based on xylitol and sorbitol of two compositions – based on live probiotic cultures and their metabolites. The following methods of control of the sample efficiency werechosen: determination of the number of viable lactobacilli in the study of their combined use with the drug components and the number of viable bacteria in finished oral probiotics by the Koch method (direct seeding on cups), as well as the method of diffusion into agar with the growth inhibition zone determination.Results and discussion. The studies of the properties of probiotic strains of L. fermentum 90-TC and L plantarum 8P-A3 have shown the prospects for their use in oral probiotics. It has been also proposed to use metabolitesof these strains as active components, which have a rather high antimicrobial potential to opportunistic pathogens that cause infectious ENT diseases. The oral probiotics in the form of lozenges of two compositions – based on live lactobacilli and their metabolites – have shown high efficiency, bacterial survival and antimicrobial properties, respectively.Conclusions. During the complex of the theoretical, technological and biotechnological studies, lozenges with a probiotic of two compositions (based on viable probiotic cultures and their metabolites) have been developed. After further research they can be recommended as a biologically active additive to support the oral microflora, stimulate the own immunity and as a therapeutic and prophylactic agent in infectious diseases of the oral cavity for use in both adults and children.