Thymol is a monoterpene phenolic derivative extracted from the Thymus vulgaris which has antimicrobial effects. In the present study, thymol-loaded chitosan nanogels were prepared and their physicochemical properties were characterized. The encapsulation efficiency of thymol into chitosan and its stability were determined. The in vitro antimicrobial and anti-biofilm activities of thymol-loaded chitosan nanogel (Ty-CsNG), free thymol (Ty), and free chitosan nanogel (CsNG) were evaluated against both Gram-negative and Grampositive multidrug-resistant (MDR) bacteria including Staphylococcus aureus, Acinetobacter baumanii, and Pseudomonas aeruginosa strains using the broth microdilution and crystal violet assay, respectively. After treatment of MDR strains with sub-minimum inhibitory concentration (Sub-MIC) of Ty-CsNG, free Ty and CsNG, biofilm gene expression analysis was studied. Moreover, cytotoxicity of Ty-CsNG, free Ty, and CsNG against HEK-293 normal cell line was determined using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) method. The average size of Ty-CsNG was 82.71 � 9.6 nm, encapsulation efficiency was 76.54 � 0.62 % with stability up to 60 days at 4 °C. Antibacterial activity test revealed that Ty-CsNG reduced the MIC by 4 -6 times in comparison to free thymol. In addition, the expression of biofilm-related genes including ompA, and pgaB were significantly down-regulated after treatment of strains with Ty-CsNG (P < 0.05). In addition, free CsNG displayed negligible cytotoxicity against HEK-293 normal cell lines and presented a biocompatible nanoscale delivery system. Based on the results, it can be concluded that Ty-CsNG can be considered a promising candidate for enhancing antimicrobial and anti-biofilm activities.

In the present study, the antibacterial and antibiofilm effects of Thymol-based chitosan nanogels were investigated. After clinical screening of MDR strains from the hospital environment, the morphological characteristics of the synthesized nanoparticles were identified using SEM, DLS, XRD and FTIR and the efficiency of encapsulation, stability and drug release were evaluated. The expression of OmpA and PgaB biofilm genes were determined by q-Real-Time PCR and the antibacterial and cytotoxic properties of the nanoparticles were determined by well diffusion and MTT methods, respectively. Nanoparticles with a size of 82.71 nm, encapsulation efficiency of 76.54% and stability up to 60 days at 4 °C were prepared. The results of the biological study showed strong antibacterial properties of Thymol-based chitosan nanoparticles by reducing the expression of OmpA and PgaB biofilm genes at a significant level of P ≤ 0.05 and reducing antibiotic resistance compared to the free drug thymol and chitosan nanogels. Thymol-based chitosan nanogels at concentrations of 0.125 to 256μg/mL showed the lowest cytotoxicity against HEK-293 compared to chitosan and free Thymol nanogels. The results showed very strong antibacterial properties of Thymol-based chitosan nanogels against MDR strains such as Staphylococcus, Acinetobacter and Pseudomonas as the challenging bacteria of the century.

In the present study, the antibacterial and antibiofilm effects of Thymol-based chitosan nanogels were investigated. After clinical screening of MDR strains from the hospital environment, the morphological characteristics of the synthesized nanoparticles were identified using SEM, DLS, XRD and FTIR and the efficiency of encapsulation, stability and drug release were evaluated. The expression of OmpA and PgaB biofilm genes were determined by q-Real-Time PCR and the antibacterial and cytotoxic properties of the nanoparticles were determined by well diffusion and MTT methods, respectively. Nanoparticles with a size of 82.71 nm, encapsulation efficiency of 76.54% and stability up to 60 days at 4 °C were prepared. The results of the biological study showed strong antibacterial properties of Thymol-based chitosan nanoparticles by reducing the expression of OmpA and PgaB biofilm genes at a significant level of P ≤ 0.05 and reducing antibiotic resistance compared to the free drug thymol and chitosan nanogels. Thymol-based chitosan nanogels at concentrations of 0.125 to 256μg/mL showed the lowest cytotoxicity against HEK-293 compared to chitosan and free Thymol nanogels. The results showed very strong antibacterial properties of Thymol-based chitosan nanogels against MDR strains such as Staphylococcus, Acinetobacter and Pseudomonas as the challenging bacteria of the century.

Background: We aim to assess the antibacterial and anti-biofilm properties of niosome-encapsulated meropenem. Methods: After isolating S. aureus isolates and determining their microbial sensitivity, their ability to form biofilms was examined using plate microtiter assay. Various formulations of niosome-encapsulated meropenem were prepared using the thin-film hydration method, Minimum Biofilm Inhibitory Concentration (MBIC) and Minimum Inhibitory Concentration (MIC) were determined, and biofilm genes expression was examined. Drug formulations’ toxicity effect on HDF cells were determined using MTT assay.Results: Out of the 162 separated Staphylococcus aureus, 106 were resistant to methicillin. 87 MRSA isolates were vancomycin-resistant, all of which could form biofilms. The F1 formulation of neoplastic meropenem with a size of 51.3 ± 5.84 and an encapsulation index of 84.86 ± 3.14 was detected, which prevented biofilm growth with a BDI index of 69% and reduced icaD, FnbA, Ebps biofilms’ expression with p ≤0.05 in addition to reducing MBIC and MIC by 4-6 times. Interestingly, F1 formulation of neoplastic meropenem indicated cell viability over 90% at all tested concentrations. Conclusions: Results of the present study indicate that niosome-encapsulated meropenem reduces the resistance of Staphylococcus aureus MRSA to antibiotics in addition to increasing its anti-biofilm and antibiotic activity, and could prove useful as a new strategy for drug delivery.

Introduction: The discovery of antibiotics for the treatment of bacterial infections was one of the most important advances in medical history, but unfortunately bacteria are highly adaptable, and overuse of antibiotics has made many bacteria resistant to antibiotics. In the present study, the antibacterial and antibiofilm effects of Thymol-based chitosan nanogels were investigated.Materials & Methods:After clinical screening of MDR strains from the hospital environment, the morphological characteristics of the synthesized nanoparticles were identified using SEM, DLS, XRD and FTIR and the efficiency of encapsulation, stability and drug release were evaluated. After determining the MIC concentration of nanoparticles, the expression of OmpA and PgaB biofilm genes were determined by q-Real-Time PCR and the antibacterial and cytotoxic properties of the nanoparticles were determined by well diffusion and MTT methods, respectively.Results:Three bacteria Pseudomonas, Acinetobacter and Staphylococcus were identified as MDR strains and the antibacterial and antibiofilm properties of nanoparticles with a size of 82.71 nm, encapsulation efficiency of 76.54% and stability up to 60 days at 4 °C were evaluated. The results of the biological study showed strong antibacterial properties of Thymol-based chitosan nanoparticles by reducing the expression of OmpA and PgaB biofilm genes at a significant level of P ≤ 0.05 and reducing antibiotic resistance compared to the free drug thymol and chitosan nanogels. Thymol-based chitosan nanogels at concentrations of 0.125 to 256μg/mL showed the lowest cytotoxicity against HEK-293 compared to chitosan and free Thymol nanogels.Discussion and Conclusion: The results of the study showed the very strong antibacterial properties of Thymol-based chitosan nanogels against MDR strains such as Staphylococcus, Acinetobacter and Pseudomonas as the challenging bacteria of the century. Therefore, the use of Thymol-based chitosan nanogels can be reported as a new application strategy with high potential in the pharmaceutical industry.

In the present study, the antibacterial and antibiofilm effects of Thymol-based chitosan nanogels were investigated. After clinical screening of MDR strains from the hospital environment, the morphological characteristics of the synthesized nanoparticles were identified using SEM, DLS, XRD and FTIR and the efficiency of encapsulation, stability and drug release were evaluated. The expression of OmpA and PgaB biofilm genes were determined by q-Real-Time PCR and the antibacterial and cytotoxic properties of the nanoparticles were determined by well diffusion and MTT methods, respectively. Nanoparticles with a size of 82.71 nm, encapsulation efficiency of 76.54% and stability up to 60 days at 4 °C were prepared. The results of the biological study showed strong antibacterial properties of Thymol-based chitosan nanoparticles by reducing the expression of OmpA and PgaB biofilm genes at a significant level of P ≤ 0.05 and reducing antibiotic resistance compared to the free drug thymol and chitosan nanogels. Thymol-based chitosan nanogels at concentrations of 0.125 to 256μg/mL showed the lowest cytotoxicity against HEK-293 compared to chitosan and free Thymol nanogels. The results showed very strong antibacterial properties of Thymol-based chitosan nanogels against MDR strains such as Staphylococcus, Acinetobacter and Pseudomonas as the challenging bacteria of the century.