Gram-negative Bacterial Strains Research Articles

Evaluation of Cladophora and Chlamydomonas microalgae for environmental sustainability: A comparative study of antimicrobial and photocatalytic dye degradation

The present study emphasizes exploring the potential of bioactive compounds such as polysaccharides, protein, pigments, antioxidants, and vitamins extracted from two microalgae species, Cladophora and Chlamydomonas. The extraction process was optimized for different periods, and the extracted bioactive compounds were characterized. These bioactive compounds showed significant antibacterial activity against gram-positive and gram-negative bacteria. Notably, Cladophora species exhibited a higher zone of inhibition than Chlamydomonas species against both gram-positive and gram-negative bacterial strains. Moreover, the photocatalytic activity of these bioactive compounds was investigated for the degradation of methylene blue and crystal violet dyes under different light conditions. The results demonstrated that Cladophora species exhibited superior photocatalytic activity under natural sunlight, UV light, and visible light sources compared to Chlamydomonas species. Moreover, Cladophora species achieved the highest dye degradation efficiencies of 78% and 72% for methylene blue and crystal violet, respectively, within 150 min compared to UV light and visible light sources.

Novel Coumarin Derivatives as Potential Urease Inhibitors for Kidney Stone Prevention and Antiulcer Therapy: From Synthesis to In Vivo Evaluation.

The presence of ammonium ions in urine, along with basic pH in the presence of urease-producing bacteria, promotes the production of struvite stones. This causes renal malfunction, which is manifested by symptoms such as fever, nausea, vomiting, and blood in the urine. The involvement of urease in stone formation makes it a good target for finding urease enzyme inhibitors, which have the potential to be developed as lead drugs against kidney stones in the future. The documented ethnopharmacology of coumarin 2-one against bacterial, fungal and viral strains encouraged us to synthesize new derivatives of coumarins by reacting aromatic aldehydes with 4-aminocoumarin. The synthesized compounds (2a to 11a) were evaluated for their antimicrobial, in vitro, and in silico properties against the urease enzyme. The study also covers in vivo determination of the synthesized compounds with respect to different types of induced ulcers. The molecular docking study along with extended MD simulations (100 ns each) and MMPBSA study confirmed the potential inhibitory candidates as evident from computed ∆Gbind (3a = -11.62 and 5a = -12.08 Kcal/mol) against the urease enzyme. The in silico analyses were augmented by an enzymatic assay, which revealed that compounds 3a and 5a had strong inhibitory action, with IC50 of 0.412 µM (64.0% inhibition) and 0.322 µM (77.7% inhibition), respectively, compared to standard (Thiourea) with 82% inhibition at 0.14 µM. Moreover, the most active compound, 5a, was further tested in vivo for antiulcer activity by different types of induced ulcers, including pyloric ligation-, ethanol-, aspirin-, and histamine-induced ulcers. Compound 5a effectively reduced gastric acidity, lipid peroxidation, and ulceration in a rat model while also inhibiting gastric ATPase activity, which makes it a promising candidate for ulcer treatment. As a result of the current research, 3a and 5a may be used as new molecules for developing potent urease inhibitors. Additionally, the compound 3a showed antibacterial activity against Staphylococcus aureus and Salmonella typhimurium, with zones of inhibition of 41 ± 0.9 mm and 35 ± 0.9 mm, respectively. Compound 7a showed antibacterial activity against Staphylococcus aureus and Salmonella typhimurium, with zones of inhibition of 30 ± 0.8 mm and 42 ± 0.8 mm, respectively. These results prove that the synthesized compounds also possess good antibacterial potential against Gram-positive and Gram-negative bacterial strains.

Synthesis, in silico Profiling, in vitro Anthelmintic and Antibacterial Activities of Novel 6-Bromo-2-Phenyl-3-Substituted Quinazolin-4(3H)-ones

In this study, eight novel derivatives of 6-bromo-2-phenyl-3-substituted quinazolin-4(3H)-ones were synthesized, which was achieved through the use of bromoanthranilic acid, benzoyl chloride, and different substituted amino synthons. The chemical structures of these compounds through IR spectroscopy, 1H NMR spectroscopy, and mass spectrometry were successfully characterized. By employing computational tools like PASS, Molinspiration, Osiris, and Swiss ADME, we made predictions about the properties of these molecules. These predictions encompassed factors such as anthelmintic and antibacterial traits, drug-likeness, bioactivity scores, toxicity, and potential molecular targets. Furthermore, we performed in vitro assays to evaluate the bioactivities of the synthesized compounds. For anthelmintic effectiveness, the conventional method of assessing paralysis and mortality in earthworms for each compound was followed. The antibacterial efficacy was tested against both Gram-positive and Gram-negative bacterial strains, using the agar cup plate technique. The results of these assays provide valuable insights into the potential of these compounds as agents with anthelmintic and antibacterial properties.

Synthesis, Characterization, Biological Activity of PEG Capped Silver Nanoparticles and Photocatalytic Degradation of Methylene Blue Dye using LC-MS Method

Silver nanoparticles (AgNPs) were prepared by co-precipitation method using a capping agent, PEG-4000 (polyethylene glycol). The synthesized AgNPs were characterized using UV-visible, FTIR, SEM, EDX and TEM techniques. The bandgap energy of snythesized nanoparticles was determined using UV-visible spectra and found to be 3.07 eV. The particle size of nanoparticles calculated from the TEM and XRD pattern was in the range of 10-23 nm. The degradation efficiency of PEG capped AgNPs towards methylene blue (MB) dye under solar radiation was 63.78%. The photocatalytic degradation of MB dye follows the pseudo-first-order kinetics with an apparent rate constant of 1.1 × 10-2 min-1. The degradation products of MB dye during the photocatalytic process were identified using liquid chromatography-mass spectrometry (LC-ESI-TOF-MS). The antibacterial activity of synthesized PEG capped AgNPs using a disc diffusion method against four different Gram-positive and Gram-negative bacterial strains. The results showed that the synthesized nanoparticles could exhibit antibacterial activity. The anticancer activity of synthesized PEG capped AgNPs was tested against cancer cell lines such as A549 and HepG2. The results revealed that the synthesized PEG capped AgNPs have also shown an excellent anticancer activity with increasing their concentration. The antidiabetic activity of PEG capped AgNPs was studied against the a- lucosidase enzyme. The results confirmed that the synthesized AgNPs were shown a-glucosidase inhibition to 45.08%. The ABTS and DPPH radical scavenging activities were used to assay the antioxidant activity of synthesized PEG capped AgNPs.

In vitro compositional and phytochemical analysis of green and black tea

The traditional beverage that people consume more after water is a tea. The ethanolic extract of green and black tea have antioxidant and antimicrobial activity and these activities may differ in their processing methods. In this study, physiochemical analysis of green and black tea was carried out. The physiochemical analysis showed that green tea has higher moisture content, crude fat and crude fiber except for crude protein and ash content which is found higher in black tea. The maceration process was used for extraction purposes. This extract was used to analyze the total phenolic and flavonoid content, antioxidant potential, and antimicrobial activity. A significant difference was found in the total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity of green and black tea. The flavonoids and phenolic content in T1 (ethanol 100%) acquired average and significant in the extract of green and black tea. The maximum value of TPC was observed in green tea extract 152.17a ± 0.28 mg GAE/g in treatment T1, and the value of TFC in green tea was found 40.26±11.387mg QE/g and the minimum value was found in black tea at 36.85±13.68 mg QE/g of extract. Antioxidant activity of green tea extract ranged from 90.64% to 69.07%, and black tea extract ranged from 89.05% to 50.93% in each extract. The parallel determination of the inhibitory effect of gram-negative and positive bacterial strains (Streptococcus pyogenes, Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa) was found sensitivity and resistivity towards extract of tea. The positive and negative effect was found in antimicrobial activity by using antibiotics against these bacterial strains.

Antimicrobial peptide 2K4L disrupts the membrane of multidrug-resistant Acinetobacter baumannii and protects mice against sepsis.

Antimicrobial peptides represent a promising therapeutic alternative for the treatment of antibiotic-resistant bacterial infections. 2K4L is a rationally-designed analog of a short peptide temporin-1CEc, a natural peptide isolated and purified from the skin secretions of the Chinese brown frog Rana chensinensis by substituting amino acid residues. 2K4L adopt an α-helical confirm in a membrane-mimetic environment and displayed an improved and broad-spectrum antibacterial activity against sensitive and multidrug-resistant Gram-negative and Gram-positive bacterial strains. Here, the action mechanism of 2K4L on multidrug resistant Acinetobacter baumannii (MRAB) and protection on MRAB-infected mice was investigated. The results demonstrated high bactericidal activity of 2K4L against both a multidrug resistant A. baumannii 0227 strain (MRAB 0227) and a sensitive A. baumannii strain (AB 22934), indicating a potential therapeutic advantage of this peptide. Strong positively-charged residues significantly promoted the electrostatic interaction on 2K4L with lipopolysaccharides (LPS) of the bacterial outer membrane. High hydrophobicity and an α-helical confirm endowed 2K4L remarkably increase the permeability of A. baumannii cytoplasmic membrane by depolarization of membrane potential and disruption of membrane integration, as well as leakage of fluorescein from the liposomes. Additionally, 2K4L at low concentrations inhibited biofilm formation and degraded mature 1-day-old MRAB 0227 biofilms by reducing the expression of biofilm-related genes. In an invasive A. baumannii infection model, 2K4L enhanced the survival of sepsis mice and decreased the production of the proinflammatory cytokines downregulating the phosphorylation level of signaling protein in MAPK and NF-κB signaling pathways, indicating that 2K4L represents a novel therapeutic antibiotic candidate against invasive multidrug-resistant bacterial strain infections.

Chemical Composition, Antibacterial Properties, and Anti-Enzymatic Effects of Eucalyptus Essential Oils Sourced from Tunisia.

This study was conducted to examine the chemical composition of the essential oils (EOs) from six Tunisian Eucalyptus species and to evaluate their anti-enzymatic and antibiofilm activities. The EOs were obtained through hydro-distillation of dried leaves and subsequently analyzed using GC/MS. The main class of compounds was constituted by oxygenated monoterpenes, particularly prominent in E. brevifolia (75.7%), E. lehmannii (72.8%), and E. woollsiana (67%). Anti-enzymatic activities against cholinesterases, α-amylase, and α-glucosidase were evaluated using spectrophotometric methods. Notably, the E. brevifolia, E. extensa, E. leptophylla, E. patellaris, and E. woollsiana EOs displayed potent acetylcholinesterase (AChE) inhibition (IC50: 0.25-0.60 mg/mL), with E. lehmannii exhibiting lower activity (IC50: 1.2 mg/mL). E. leptophylla and E. brevifolia showed remarkable α-amylase inhibition (IC50: 0.88 mg/mL), while E. brevifolia and E. leptophylla significantly hindered α-glucosidase (IC50 < 30 mg/mL), distinguishing them from other EOs with limited effects. Additionally, the EOs were assessed for their anti-biofilm properties of Gram-positive (Staphylococcus aureus and Listeria monocytogenes) and Gram-negative (Acinetobacter baumannii, Pseudomonas aeruginosa and Escherichia coli) bacterial strains. The E. extensa EO demonstrated the main antibiofilm effect against E. coli and L. monocytogenes with an inhibition > 80% at 10 mg/mL. These findings could represent a basis for possible further use of Eucalyptus EOs in the treatment of human microbial infections and/or as a coadjutant in preventing and treating Alzheimer's disease and/or diabetes mellitus.

Green multifunctional palladium nanoparticles from polysaccharide cordia myxa (CMY) gum: Synthesis, characterization, and antibacterial activity

BackgroundGreen synthesis has emerged as an environmentally friendly and highly effective method that has gained widespread application across various domains and biomedical research, particularly in healthcare. ObjectivesThe primary aim behind synthesizing CMY-PdNPs was to harness the potential of Cordia myxa gum to create multi-functional palladium nanoparticles, which could effectively prevent antimicrobial activity. MethodsIn this study, CMY-PdNPs were synthesized using Cordia myxa gum, a natural polysaccharide known for its non-toxic and environmentally friendly properties, marking the first reported instance of such green synthesis. Remarkably, this synthesis method demonstrated effectiveness in reaction time and nanoparticle stability, achieved without requiring external stabilizers or reducing agents. Green synthesized CMY-PdNPs characterization by different techniques, UV-Vis, FT-IR, FESEM, XRD, TEM, and XPS. ResultsThe synthesized CMY-PdNPs showed UV–Vis absorption maximum at around 278 nm. The crystalline nature of CMY-PdNPs was suggested by XRD patterns at (111), (200 (220), and (311) lattice planes, with a face-centered cubic structure depicting the formation of PdNPs. The chemical composition and product purity of green-produced CMY-PdNPs were determined by XPS analysis. As indicated by TEM micrographs, the uniform and spherical-shaped NPs with an average mean diameter of 15 nm were observed. The study investigated the antibacterial properties of PdNPs against Gram-positive and Gram-negative bacterial strains using the disc diffusion method to assess the zone of inhibition against various pathogenic microorganisms. ConclusionThis work demonstrates that eco-friendly technology can rival conventional physical/chemical methods for PdNP synthesis. Biogenic CMY-PdNPs show exceptional antimicrobial effectiveness and hold promise for biomedical applications, contributing significantly to medical research potential.

Bacterial multi-resistance to antibiotics in water from plant cavities (phytotelms) in a deep tropical forest from Costa Rica

Introduction: The spread of antimicrobial resistance in natural environments continues to be reported throughout the world; nevertheless, there is no study about phytotelms (water in the natural cavities of plants) in the deep understory of tropical cloud forests from Costa Rica. Objective: To detect phytotelm antibiotic-resistant bacterial strains in a Costa Rican forest and nearby town. Methods: We used the disk diffusion method to analyze the antimicrobial resistance of 10 gram-negative bacterial strains from phytotelm water collected from 10 bromeliads and 10 heliconias in both sites. Results: Three strains were multidrug resistant to more than three antibiotics in each site, and only one strain was susceptible to all antibiotics. Antibiotic resistance was similar in both environments. Conclusions: Phytotelm can be a rapid, cost-effective, and simple source for detecting antimicrobial resistance in unexplored environments.

Bioplastic (poly-3-hydroxybutyrate)-producing Massilia endophytica sp. nov., isolated from Cannabis sativa L. ‘Cheungsam’

A rod-shaped, motile, Gram-negative bacterial strain named DM-R-R2A-13T was isolated from the plant Cannabis sativa L. ‘Cheungsam’. The phylogenetic analysis of the 16S rRNA gene sequence revealed that strain DM-R-R2A-13T belongs to the family Oxalobacteraceae and is closely related to members of the genus Massilia, with Massilia flava (97.58% sequence similarity) and Massilia armeniaca (97.37% sequence similarity) being the closest members. The digital DNA-DNA hybridization (dDDH) values between strain DM-R-R2A-13T and Massilia flava CGMCC 1.10685T and Massilia armeniaca ZMN-3Twere 22.2% and 23.3%, while the average nucleotide identity (ANI) values were 78.85% and 79.63%, respectively. The DNA G+C content was measured to be 64.6 mol%. Moreover, the bacterium was found to contain polyhydroxyalkanoate (PHA) granules based on transmission electron microscopy, indicating its potential to produce bioplastic. Genome annotation revealed the presence of PHA synthase genes (phaC, phaR, phaP, and phaZ), and the biopolymer was identified as poly-3-hydroxybutyrate (PHB) based on nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR) analyses. Using maltose as a carbon source, the strain produced PHB of up to 58.06% of its dry cell weight. Based on the phenotypic, chemotaxonomic, and phylogenetic characteristics, it has been determined that DM-R-R2A-13T represents a novel species belonging to the genus Massilia. As such, the name Massilia endophytica sp. nov. is proposed for this newly identified species. The type strain is DM-R-R2A-13T (= KCTC 92072T = GDMCC 1.2920T).

Chemical, electrochemical and morphology studies of three di-cationic amphiphiles and their applications: Corrosion inhibitors for carbon steel in formation water during gas and oil production and as broad antimicrobial agents against standard microbial strains

In the present work, the previously synthesized di-cationic amphiphiles surfactants have displayed an excellent surface attitude in formation water, according to surface tension findings. The three di-cationic amphiphiles surfactants (CSI, CSII, and CSIII) were tested as corrosion inhibitors for carbon steel (CS) in the formation water during gas and oil production using weight loss (WL), Tafel polarization (TP) and electrochemical impedance spectroscopy (EIS) and surface morphology using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The obtained results demonstrated that the di-cationic amphiphiles surfactants are good corrosion inhibitors in the formation water.As the concentration of the inhibitors increased, the effectiveness of the dissuasion increased. The Tafel polarization results showed that, corrosion current densities (icorr) decreased whereas inhibition effecenicy (ηp) increased as the inhibitor concentration increased. EIS results showed that, the constant phase element (CPE) values decreased and the polarization resistance (RP) values increased with increasing the inhibitor concentrations. SEM & AFM photos exhibited a good CS surface in presence of the CSI, CSII & CSIII in opposite of the absence of them. Furthermore, the three di-cationic amphiphiles surfactants (CSI, CSII, and CSIII) were applied as broad antimicrobial agents against standard microbial strains (bacterial and candida strains). Results demonstrated a great broad antimicrobial activity of the three di-cationic amphiphiles surfactants with a zone of inhibitions ranging from (15–30) mm for the bacterial strains and (25–30) mm for the candida standard stain in comparison to the positive control antimicrobial agents. Moreover, the CSI, CSII & CSIII have displayed the highest antibacterial efficiency against the Gram-positive (27–30 mm) than the Gram-negative bacterial strains (15–19 mm).

“Antibacterial properties of nine indium(III) complexes of substituted pyrazoles/pyrazolate and the structural and solution characterization of the mer- and trans‑indium(III) complexes of 4-Me-pzH”

Two indium(III) complexes of formula mer-[InIIICl3(4-Me-pzH)3] and trans-[InIIICl2(4-Me-pzH)4]Cl·(4-Me-pzH)2·(H2O) were isolated from the same reaction mixture and crystallographically characterized. The two complexes exist in dynamic equilibrium and their dynamic behavior was probed by variable temperature 1H NMR spectroscopy in the 202 to 296 K range. Powder X-ray diffraction of the batch confirmed existence of both complexes in a 1:2 ratio. Antibacterial properties of both new complexes, in addition to seven other previously published indium(III) complexes, were investigated against three Gram-positive and four Gram-negative pathogenic bacterial strains. The results showed potential for the development of indium(III)-based antipseudomonal and antituberculosis drugs, with mer-[InCl3(4-Ph-pzH)3] being especially effective.

Ganoderma lucidum methanolic extract as a potent phytoconstituent: characterization, in-vitro antimicrobial and cytotoxic activity

Ganoderma lucidum methanolic extract (GLME) has attracted tremendous attention due to its exceptional antimicrobial and anticancer properties that can be delicately tuned by controlling the initial extraction's content and concentration. Herein, we detailed the characterization, antimicrobial, and cytotoxic performance of GLME as a potential multi-functional therapeutic agent. Accordingly, FTIR, XRD, FESEM, EDX, and HPLC analyses were employed to assess the samples, followed by disc diffusion and microdilution broth methods to test its antibacterial effects against four Gram-positive and Gram-negative bacterial strains, viz., Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. MTT assay was applied to determine the cytotoxic activity of GLME against PDL and Hek-293 normal cell lines and MCF-7 and K-562 cancer cell lines. The IC50 values of 598 µg mL-1 and 291 µg mL-1 were obtained for MCF-7 and K-562 cancer cell lines, which confirmed the stronger anticancer activity of the GLME against blood cancer cells than breast cancer cells. This is while the IC50 of normal Hek-293 cells is 751 µg mL-1, and the lowest toxicity was observed for normal PDL cells with more than 57% survival at a concentration of 3000 µg mL-1. The results showed that the antibacterial property of this product against E.coli bacteria was higher than streptomycin, so the zone of inhibition was observed as 44 ± 0.09 mm and 30 ± 0.11 mm, respectively. These data provide valuable insights into the therapeutic usage of GLME for treating breast and blood cancers. This work is motivated by research studies looking for pharmacological products to address chronic and acute diseases, where further resources and studies are required to explore such products' adverse effects and toxicity.

Superhydrophobic silicone/graphene oxide-silver-titania nanocomposites as eco-friendly and durable maritime antifouling coatings

In this work, a novel ecofriendly series of polydimethylsiloxane-polymethylmethacrylate (PDMS-PMMA) blend filled with silver nanospheres and titanium dioxide nanorods grafted on the graphene oxide surface (Ag–TiO2@GO) were produced by the catalytic hydrosilation method as outstanding marine antifouling coatings. Innovative Ag–TiO2@GO hybrid nanofillers, that would release fouling and confer surface robustness, were developed by a single-phase procedure. Ag nanospheres with 20 nm mean diameter were prepared by a controlled solvothermal method, while anatase TiO2 nanorods with 10 nm average diameter were grown by a hydrothermal technique. The solution casting method was used to distribute various Ag–TiO2@GO filler percentages throughout the silicone matrix. Atomic force microscopy, surface free energy, and water contact angle (WCA) were employed to examine the superhydrophobicity and roughness of the coatings. The mechanical durability and antifouling characteristics of the PDMS-PMMA nanocomposites filled with Ag–TiO2@GO composites were also investigated. Several microorganisms were employed to examine the fouling resistance of the coated specimens for 30 days. Trichogaster lalius fish and the bivalve Brachidontes variabilis species were used to examine the nanocomposites’ toxicity. Well-dispersion of Ag–TiO2@GO nanofillers in the PDMS-PMMA resin until 2.5 wt% exhibited the highest WCA (160° ± 2°), the lowest surface free energy (22.9 mN/m), rough topology, and improved bulk mechanical properties. Furthermore, the well-dispersed PDMSPMMA/Ag–TiO2@GO (2.5 wt%) nanocomposite presented the lowest biodegradability percentages and optical density against various gram-positive and gram-negative bacterial strains. Furthermore, it displayed non-toxicity against the tested species of fish and bivalve. The developed non-toxic and non-stick nanocoating exhibited various merits, including superhydrophobicity, mechanical robustness, and fouling retardancy, for using as maritime ship hull coatings.

Boosting photo-induced antimicrobial activity of lignin nanoparticles with curcumin and zinc oxide

Lignin nanoparticles have gained increasing attention as a potential antimicrobial agent due to their biocompatibility, biodegradability, and low toxicity. However, the limited ability of lignin to act as an antibacterial is a major barrier to its widespread use. Thus, it is crucial to develop novel approaches to amplify lignin's biological capabilities in order to promote its effective utilization. In this study, we modified lignin nanoparticles (LNPs) with photo-active curcumin (Cur), zinc oxide (ZnO), or a combination of both to enhance their antimicrobial properties. The successful modifications of LNPs were confirmed using comprehensive characterization techniques. The antimicrobial efficacy of the modified LNPs was assessed against both gram-positive and gram-negative bacterial strains. The results showed that the modification of LNPs with Cur and ZnO have much higher antibacterial and antibiofilm activities than unmodified LNPs. Moreover, photo illumination resulted in even higher antibacterial activity. Furthermore, atomic force microscopy revealed bacterial cells lysis and membrane damage by ZnO/Cur modified LNPs. Our research demonstrates that ZnO/Cur modified LNPs can serve as novel hybrid materials with enhanced antimicrobial capabilities. In addition, the photo-induced enhancement in antibacterial activity not only demonstrated the versatility of this hybrid material but also opened up interesting potential for bioinspired therapeutics agents.

Polymyxin B and fusidic acid, a novel potent synergistic combination against Klebsiella pneumoniae and Escherichia coli isolates with polymyxin B resistance.

The increasing prevalence of multidrug-resistant (MDR) Gram-negative bacteria and comparatively limited options of antibiotics pose a major threat to public health worldwide. Polymyxin B is the last resort against extensively resistant Gram-negative bacterial infections. However, a large number of Gram-negative bacteria exhibited high-level resistance to Polymyxin B, bringing challenges for antimicrobial chemotherapy. Combination therapies using polymyxins and other antibiotics are recommended to treat multidrug-resistant pathogens. In this study, we selected Gram-negative bacterial strains, including Klebsiella pneumoniae and Escherichia coli, to explore whether fusidic acid and polymyxin B have a synergistic killing effect. Through broth microdilution, we observed that minimum inhibitory concentrations (MICs) against polymyxin B in the isolates tested were significantly reduced by the addition of fusidic acid. Notably, chequerboard analysis indicated a synergistic effect between polymyxin B and fusidic acid. In addition, subsequent time-kill experiments showed that the combination of polymyxin B and fusidic acid was more effective than a single drug in killing bacteria. Finally, our investigation utilizing the murine model revealed a higher survival rate in the combination therapy group compared to the monotherapy group. Our research findings provide evidence of the synergistic effect between polymyxin B and fusidic acid. Fusidic acid was shown to increase the sensitivity of multi-drug resistant E. coli and K. pneumoniae to polymyxin B, thereby enhancing its bactericidal activity. This study provides new insights into a potential strategy for overcoming polymyxin B resistance, however, further investigations are required to evaluate their feasibility in real clinical settings.

Titanium Boston keratoprosthesis with corneal cell adhesive and bactericidal dual coating

The Boston keratoprosthesis (BKPro) is a medical device used to restore vision in complicated cases of corneal blindness. This device is composed by a front plate of polymethylmethacrylate (PMMA) and a backplate usually made of titanium (Ti). Ti is an excellent biomaterial with numerous applications, although there are not many studies that address its interaction with ocular cells. In this regard, despite the good retention rates of the BKPro, two main complications compromise patients' vision and the viability of the prosthesis: imperfect adhesion of the corneal tissue to the upside of the backplate and infections. Thus, in this work, two topographies (smooth and rough) were generated on Ti samples and tested with or without functionalization with a dual peptide platform. This molecule consists of a branched structure that links two peptide moieties to address the main complications associated with BKPro: the well-known RGD peptide in its cyclic version (cRGD) as cell pro-adherent motif and the first 11 residues of lactoferrin (LF1–11) as antibacterial motif. Samples were physicochemically characterized, and their biological response was evaluated in vitro with human corneal keratocytes (HCKs) and against the gram-negative bacterial strain Pseudomonas aeruginosa. The physicochemical characterization allowed to verify the functionalization in a qualitative and quantitative manner. A higher amount of peptide was anchored to the rough surfaces. The studies performed using HCKs showed increased long-term proliferation on the functionalized samples. Gene expression was affected by topography and peptide functionalization. Roughness promoted α-smooth muscle actin (α-SMA) overexpression, and the coating notably increased the expression of extracellular matrix components (ECM). Such changes may favour the development of unwanted fibrosis, and thus, corneal haze. In contrast, the combination of the coating with a rough topography decreased the expression of α-SMA and ECM components, which would be desirable for the long-term success of the prosthesis. Regarding the antibacterial activity, the functionalized smooth and rough surfaces promoted the death of bacteria, as well as a perturbation in their wall definition and cellular morphology. Bacterial killing values were 58 % for smooth functionalised and 68 % for rough functionalised samples. In summary, this study suggests that the use of the dual peptide platform with cRGD and LF1-11 could be a good strategy to improve the in vitro and in vivo performance of the rough topography used in the commercial BKPro.

Cu-vitamin B3 donut-like MOFs incorporated into TEMPO-oxidized bacterial cellulose nanofibers for wound healing

In this study, a novel multifunctional nanocomposite wound dressing was developed, consisting of TEMPO-oxidized bacterial cellulose (TOBC) nanofibers functionalized with donut-like copper-based metal–organic frameworks (CuVB3 MOFs). These CuVB3 MOFs were constructed using copper nodes linked by vitamin B3 molecules, resulting in a copper nicotinate crystal structure as confirmed by X-ray diffraction. Electron microscopy confirmed the presence of donut-like microstructures with uniform element distribution in the synthesized MOFs. Through the incorporation of CuVB3 MOFs into the TOBC nanofibers, innovative TOBC-CuVB3 nanocomposites were created. Biocompatibility testing using the MTT assay demonstrated enhanced cell viability of over 115% for the TOBC-CuVB3 nanocomposite. Acridine Orange staining revealed a ratio of 88–92% live cells on the wound dressings. Furthermore, fibroblast cells cultured on TOBC-CuVB3 exhibited expanded morphologies with long filopodia. The agar diffusion method exhibited improved antibacterial activity against both Gram-positive and Gram-negative bacterial strains, correlating with increased CuVB3 concentration in the samples. In vitro cellular scratch assays demonstrated excellent wound healing potential, with a closure rate of over 98% for wounds treated with the TOBC-CuVB3 nanocomposite. These findings underscore the synergistic effects of copper, vitamin B3, and TOBC nanofibers in the wound healing process.

Mono and binuclear cadmium complexes: X-ray crystal structures, Hirshfeld surface analysis and antimicrobial/antioxidant studies

A bidentate Schiff base ligand(L) and two new mono and binuclear cadmium(II) complexes formulated as [CdL2(NO3)](NO3) and [Cd2L2Cl4] were synthesized and their structures were characterized by physical and spectral techniques Moreover, the structures of the cadmium(II) complexes were identified using single crystal X-ray analysis. Hirshfeld surface analysis was used to characterize various interactions in the solid state framework. Thermal behaviors of the compounds were investigated from room temperature to 800 °C. Furthermore, the antimicrobial bioassays on the cadmium(II) complexes were performed in vitro against two gram-positive and two gram-negative bacterial strains and also against two fungal strains. Finally, the antioxidant capabilities of the Schiff base ligand and its complexes were investigated by means of two in vitro methods of ABTS and DPPH as compared with Trolox as a standard compound.

Antibactericidal Ir(III) and Ru(II) Complexes with Phosphine-Alkaloid Conjugate and Their Interactions with Biomolecules: A Case of N-Methylphenethylamine.

The phosphine ligand (Ph2 PCH2 N(CH3 )(CH2 )2 Ph, PNMPEA) obtained by the reaction of the (hydroxymethyl)diphenylphosphine with naturally occurring alkaloid N-methylphenethylamine, was used to synthesize the half-sandwich iridium(III) (Ir(η5 -Cp*)Cl2 Ph2 PCH2 N(CH3 )(CH2 )2 Ph, IrPNMPEA) and ruthenium(II) (Ru(η6 -p-cymene)Cl2 Ph2 PCH2 N(CH3 )(CH2 )2 Ph, RuPNMPEA) complexes. They were characterized using a vast array of methods, including 1D and 2D NMR, ESI(+)MS spectrometry, elemental analysis, cyclic voltammetry (CV), electron spectroscopy in the UV-Vis range (absorption, fluorescence) and density functional theory (DFT). The initial antimicrobial activity in vitro toward Gram-positive and Gram-negative bacterial strains was examined, indicating that both complexes are selective towards Gram-positive bacteria, e. g., Staphylococcus aureus, where the IrPNMPEA has been more bactericidal compared to RuPNMPEA. Additionally, the interactions of these compounds with various biomolecules, such as DNA (ctDNA, plasmid DNA, 9-ethylguanine (9-EtG), and 9-methyladenine (9-MeA)), nicotinamide adenine dinucleotide (NADH), glutathione (GSH), and ascorbic acid (Asc) were described. The results showed that both Ir(III) and Ru(II) complexes accelerate the oxidation process of NADH, GSH and Asc that appeared to occur by an electron transfer mechanism. Interestingly, only IrPNMPEA leads to the formation of various biomolecule adducts, which can explain its higher activity. Furthermore, RuPNMPEA and IrPNMPEA have been interacting with the DNA through weak noncovalent interactions.