In this research, a textile surface was modified by the sol–gel methodology with a new antimicrobial coating containing nanoparticles active against bacteria resistant to antibiotics. The effect of ultrasonic irradiation power (40 to 90 kHz), the concentration of reagents (nanoparticles, precursor and acids) and time (15 to 72 min) were investigated in relation to the structure, morphology and antimicrobial activity of coatings with zinc oxide nanoparticles. The relationship between the sonocatalytic performance and structure of the resultant modification was established by using various techniques, such as FTIR spectroscopy (FTIR) and scanning electron microscopy with an EDX detector (SEM-EDX), thin-layer chromatography (TLC) and antimicrobial effects were determined on selected model microorganisms. The homogeneity of layers with ZnO nanoparticles on samples was increased by increasing the ultrasonic irradiation power and time. The ultrasonic irradiation unify did not only unify both the structure and the morphology of samples, it also prevented the agglomeration of the nanoparticles. Moreover, under optimal conditions, an antimicrobial coating with ZnO nanoparticles, active against bacterial species S. aureus and E. coli was efficiently prepared. Results of the Time-kill methodology revieled excellent results starting after 6 hours of exposal to antimicrobialy functionalized cellulose polymer.

In this work the in vitro antimicrobial activity of colloidal solutions of nine different commercially available nanoparticles were investigated against Staphylococcus aureus strains, both methicillin-sensitive (MSSA) and methicillin-resistant (MRSA). Research covered antimicrobial investigation of different metal and metal-oxide nanoparticles, including Ag 10 nm, Ag 40 nm, Al₂O₃ 100 nm, Au 20 nm, Pt 4 nm, TiO₂ 100 nm, Y₂O₃ 100 nm, ZnO 100 nm and ZrO₂ 100 nm nanoparticles. Such materials were foreseen to be applied as coatings on 3D-printed biodegradable polymers: i.e., catheters, disposable materials, hospital bedding items, disposable antimicrobial linings and bandages for chronic wounds. Therefore, the antimicrobial activity of the nanoparticles was determined by agar well diffusion assays and serial microdilution broth assays. In addition, the chromatographic characterization of elements present in trace amounts was performed as a method for tracing the nanoparticles. Moreover, the potential of preparing the rough surface of biodegradable polymers for coating with antimicrobial nanoparticles was tested by 3D-printing fused deposition methodology. The in vitro results have shown that particular nanoparticles provided powerful antimicrobial effects against MSSA and MRSA strains, and can be easily applied on different biopolymers.

Aroylhydrazones 1–13 were screened for antimicrobial and antibiofilm activities in vitro. N′ -(2-hydroxy-phenylmethylidene)-3-pyridinecarbohydrazide ( 2 ), N′ -(5-chloro-2-hydroxyphenyl-methylidene)-3-pyridinecarbohydrazide ( 10 ), N′ -(3,5-chloro-2-hydroxyphenylmethylidene)-3-pyridinecarbohydrazide ( 11 ), and N′ -(2-hydroxy-5-nitrophenylmethylidene)-3-pyridinecarbohydrazide ( 12 ) showed antibacterial activity against Escherichia coli , with MIC values (in µmol mL ⁻¹ ) of 0.18–0.23, 0.11–0.20, 0.16–0.17 and 0.35–0.37, resp. Compounds 11 and 12 , as well as N′ -(2-hydroxy-3-methoxyphenylmethylidene)-3-pyridinecarbohydrazide ( 6 ) and N′ -(2-hydroxy-5- methoxyphenylmethylidene)-3-pyridinecarbohydrazide ( 8 ) showed antibacterial activity against Staphylococcus aureus , with the lowest MIC values of 0.005–0.2, 0.05–0.12, 0.06–0.48 and 0.17–0.99 µmol mL ⁻¹ . N′ -(2-hydroxy-5-methoxyphenylmethylidene)-3-pyridinecarbohydrazide ( 7 ) showed antifungal activity against both fluconazole resistant and susceptible C. albicans strains with IC ₉₀ range of 0.18–0.1 µmol mL ⁻¹ . Only compound 11 showed activity against C. albicans ATCC 10231 comparable to the activity of nystatin (the lowest MIC 4.0 ×10 ⁻² vs . 1.7 × 10 ⁻² µmol mL ⁻¹ ). Good activity regarding multi-resistant clinical strains was observed for compound 12 against MRSA strain ( MIC 0.02 µmol mL ⁻¹ ) and compounds 2 , 6 and 12 against ESBL+ E. coli MFBF 12794, with the lowest MIC for compound 12 ( IC ₅₀ 0.16 µmol mL ⁻¹ ). Anti-biofilm activity was found for compounds 2 ( MBFIC 0.015–0.02 µmol mL ⁻¹ against MRSA) and 12 ( MBFIC 0.013 µmol mL ⁻¹ against EBSL+ E. coli ). In the case of compound 2 against MRSA biofilm formation, MBFIC values were comparable to those of gentamicin sulphate, whereas in the case of compound 12 and EBSL+ E. coli even more favourable activity compared to gentamicin was observed.

Followed by a buildup of its phytochemical profile, Erodium cicutarium is being subjected to antimicrobial investigation guided with its ethnobotanical use. The results of performed in vitro screening on Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans strains, show that E. cicutarium has antimicrobial activity, with a particular emphasis on clinical S. aureus strains—both the methicillin sensitive (MSSA) and the methicillin resistant (MRSA) S. aureus. Experimental design consisted of general methods (the serial microdilution broth assay and the agar well diffusion assay), as well as observing bactericidal/bacteriostatic activity through time (the “time-kill” assay), investigating the effect on cell wall integrity and biofilm formation, and modulation of bacterial hemolysis. Observed antibacterial activity from above-described methods led to further activity-guided fractionation of water and methanol extracts using bioautography coupled with UHPLC-LTQ OrbiTrap MS⁴. It was determined that active fractions are predominantly formed by gallic acid derivatives and flavonol glycosides. Among the most active phytochemicals, galloyl-shikimic acid was identified as the most abundant compound. These results point to a direct connection between galloyl-shikimic acid and the observed E. cicutarium antibacterial activity, and open several new research approaches for future investigation.