Efficient Antimicrobial Activity Research Articles

Antimicrobial effect of coconut oil on Staphylococcus aureus: an implication of Staphylococcus epidermidis induced fermentation

Staphylococcus epidermidis is a commensal bacterium of human skin. S. epidermidis possesses lipolytic activity to digest skin surface lipids into the smallest unit of fatty acids (FAs). Most FAs hold antimicrobial properties essential for protecting skin from invading microorganisms. In this study, we were interested in virgin coconut oil (VCO), the source of several medium-chain fatty acids (MCFAs) such as lauric acid and caprylic acid. Those MCFAs products demonstrated remarkable antibacterial activity. Our results showed that crude supernatant from the culture medium of S. epidermidis with VCO fermentation exhibited the growth inhibition effect on Staphylococcus aureus. This bacterium causes a wide range of skin diseases. A co-culture of S. epidermidis and S. aureus in a rich medium with 2.5% (v/v) VCO significantly reduced the growth of S. aureus compared to those without VCO (p-value <0.05). Moreover, time-kill assays indicated that the supernatant from the culture medium of S. epidermidis with VCO fermentation showed an efficient antimicrobial activity against S. aureus after 18 hours of incubation. Our results concluded that the culture of S. epidermidis with VCO plausibly induced fermentation of natural lipid sources aiming the production of MCFAs with antibacterial activity, particularly suppression of skin pathogen S. aureus growth. The skin commensal bacterium S. epidermidis might help produce MCFAs from skin products containing VCO and make more benefits for skin infection protection.

Discovery of a Novel Antimicrobial Peptide, Temporin-PKE, from the Skin Secretion of Pelophylax kl. esculentus, and Evaluation of Its Structure-Activity Relationships.

Bacterial resistance against antibiotics has led to increasing numbers of treatment failures, and AMPs are widely accepted as becoming potential alternatives due to their advantages. Temporin-PKE is a novel peptide extracted from the skin secretion of Pelophylax kl. esculentus and it displays a strong activity against Gram-positive bacteria, with an extreme cytotoxicity. Incorporating positively charged residues and introducing D-amino acids were the two main strategies adopted for the modifications. The transformation of the chirality of Ile could reduce haemolytic activity, and an analogue with appropriate D-isoforms could maintain antimicrobial activity and stability. The substitution of hydrophobic residues could bring about more potent and broad-spectrum antimicrobial activities. The analogues with Lys were less harmful to the normal cells and their stabilities remained at similarly high levels compared to temporin-PKE. The optimal number of charges was three, and the replacement on the polar face was a better choice. Temporin-PKE-3K exerted dually efficient functions includingstrong antimicrobial and anticancer activity. This analogue showed a reduced possibility for inducing resistance in MRSA and Klebsiella pneumoniae, a rather strong antimicrobial activity in vivo, and it exhibited the highest therapeutic index such that temporin-PKE-3K has the potential to be developed as a clinical drug.

ICP-MS Determination of Antimicrobial Metals in Microcapsules.

Silver (Ag) and zinc (Zn) are very powerful antimicrobial metals. Therefore, in this research, a high-throughput, sensitive, and rapid method was developed for the determination of Ag and Zn in microcapsules using inductively coupled plasma mass spectrometry (ICP-MS). The sample preparation procedure employed simple microwave digestion of the microcapsules with 55.55% v/v HNO3 and 44.45% v/v H2O2. The method was applied to determine Ag and Zn in microcapsule samples of different sizes (120 and 450 μm) after their preparation with and without chitosan. Prepared microcapsules, after characterization, were bonded to a polymer carrier by sol-gel procedure and the materials were characterized by FTIR spectroscopy and high-resolution optical microscopy. Significant differences were found in Ag and Zn levels between microcapsules samples prepared with and without chitosan. The results have shown that samples with chitosan had up to 20% higher levels of Zn than Ag: 120 μm microcapsules contained 351.50 μg/g of Ag and 85.51 μg/g of Zn, respectively. In contrast, samples prepared without chitosan showed larger overall variability: In microcapsules with a diameter of 120 μm, the amounts of antimicrobial metals were 98.32 μg/g of Ag and 106.75 μg of Zn, respectively. Moreover, 450 μm microcapsules contained 190.98 μg/g of Ag and 121.35 μg/g of Zn. Those quantities are high enough for efficient antimicrobial activity of newly prepared microcapsules, enabling the application of microcapsules in different antimicrobial coatings.

Green coalescence of CuO nanospheres for efficient anti-microbial and anti-cancer conceivable activity

In this study, copper oxide nanospheres (CuO-NSs) were synthesized using Long pepper (Piper longum) extract. The biomolecules present in Piper longum extract are mainly responsible for reducing metal ions to metal nanoparticles. The synthesized CuO-NSs were characterized using SEM (scanning electron microscopy), TEM (transmission electron microscopy), XRD (X-ray diffraction), and UV-Vis spectroscopic techniques. SEM and TEM images indicated that the as-prepared CuO-NSs were floral spherical nanospheres shaped with a size distribution ranging from 4 to 400 nm. Besides, the synthesized CuO-NSs have shown crucial biological activity against pathogenic bacterial strains, viz. Klebsiella pneumonia, Bacillus subtilis, and Escherichia coli. The antimicrobial activity of CuO-NSs was scrutinized by an exemplary disk diffusion assay and minimum inhibitory concentration of CuO-NSs against various strains of bacteria. Furthermore, as-synthesized CuO-NSs was also applied as a potential material for hemolysis activity and determined its cytotoxicity effect on A549 cells. CuO-NSs has been tested in A549 cells, and the results of different characterization techniques confirmed that the synthesized CuO-NSs exhibited unique optical, morphological, antibacterial, and anticancer behaviors. The study elucidates the Piper longum effectiveness on uncontrolled cell division parameters, and different cancer reductions from in-vitro analysis. The Long pepper (Piper longum) extract with CuO-NSs could significantly stimulate carcinogenic conditions because of discrete standards that penetrate the target cells and good potential against the bacterial strains.

Antibacterial peptide NZ2114-loaded hydrogel accelerates Staphylococcus aureus-infected wound healing.

Wound infection caused by Staphylococcus aureus (S. aureus) is a great challenge which has caused significant burden and economic loss to the medical system. NZ2114, a plectasin-derived peptide, is an antibacterial agent for preventing and treating S. aureusinfection, especially for methicillin-resistant S. aureus (MRSA) infection. Here, three-dimensional reticulated antimicrobial peptide (AMP) NZ2114 hydrogels were developed based on hydroxypropyl cellulose (HPC) and sodium alginate (SA); they displayed sustained and stable release properties (97.88 ± 1.79% and 91.1 ± 10.52% release rate in 72h, respectively) and good short-term cytocompatibility and hemocompatibility. But the HPC-NZ2114 hydrogel had a smaller pore size (diameter 0.832 ± 0.420μm vs. 3.912 ± 2.881μm) and better mechanical properties than that of the SA-NZ2114 hydrogel. HPC/SA-NZ2114 hydrogels possess efficient antimicrobial activity in vitro and in vivo. In a full-thickness skin defect model, the wound closure of the 1.024mg/g HPC-NZ2114 hydrogel group was superior to those of the SA-NZ2114 hydrogel and antibiotic groups on day 7. The HPC-NZ2114 hydrogel accelerated wound healing by reducing inflammation and promoting the production of vascular endothelial growth factor (VEGF), endothelial growth factor (EGF) and angiogenesis (CD31) through histological and immunohistochemistry evaluation. These data indicated that the HPC-NZ2114 hydrogel is an excellent candidate for S. aureus infectionwound dressing. KEY POINTS: •NZ2114 hydrogels showed potential in vitro bactericidal activity against S. aureus •NZ2114 hydrogels could release continuously for 72h and had good biocompatibility •NZ2114 hydrogels could effectively promote S. aureus-infected wound healing.

Design and Comparative Evaluation of Vancomycin HCl-Loaded Rosin-Based In Situ Forming Gel and Microparticles.

Vancomycin hydrochloride (HCl) is a glycopeptide antibiotic used to treat serious or life-threatening infections, and it reduces plaque scores and gingivitis in periodontal patients. In this study, vancomycin HCl was incorporated into rosin in situ forming gel (ISG) and rosin in situ forming microparticles (ISM) to generate a local drug delivery system to treat periodontal disease. The physical properties of the ISG and ISM were measured, including pH, viscosity, injectability, adhesion properties, in-vitro transformation, and drug release. Moreover, the effectiveness of antimicrobial activity was tested using the agar-cup diffusion method against Staphylococcus aureus, Streptococcus mutans, Porphyromonas gingivalis, and Escherichia coli. Vancomycin HCl-loaded rosin-based ISG and ISM had a pH value in the range of 5.02–6.48 and exhibited the ease of injection with an injection force of less than 20 N. Additionally, the lubricity effect of the external oil phase of ISM promoted less work of injection than ISG and 40–60% rosin-based ISM showed good emulsion stability. The droplet size of emulsions containing 40%, 50%, and 60% rosin was 98.48 ± 16.11, 125.55 ± 4.75, and 137.80 ± 16.8 µm, respectively. Their obtained microparticles were significantly smaller in diameter, 78.63 ± 12.97, 93.81 ± 10.53, and 118.32 ± 15.61 µm, respectively, because the particles shrank due to the solvent loss from solvent exchange. Moreover, increasing the concentration of rosin increased the size of microparticles. After phase transformation, all formulations had better plasticity properties than elasticity; therefore, they could easily adapt to the specific shape of a patient’s gum cavity. Both developed ISG and ISM presented inhibition zones against S. mutans and P. gingivalis, with ISG presenting significantly more effectively against these two microbes (p < 0.05). The vancomycin HCl-loaded rosin ISG and ISM delayed drug release for 7 days with efficient antimicrobial activities; thus, they exhibit potential as the drug delivery systems for periodontitis treatment.

Kayısı Yaprak Özütü ile Sentezlenen Gümüş Nanopartiküllerin Antimikrobiyal Potansiyeli

Metallic nanoparticles are important substances in medicine. These particles could be prepared by various ways including green synthesis. The production of silver nanoparticles by plant extracts is widely used because of their environmentally friendly properties. In this study, silver nanoparticles have been synthesized by biological method and Apricot tree (Prunus armeniaca) leaf extract was used as reducing agent. The color change and formation of the characteristic absorption peak at 400-500 nm were the first indications of AgNP formation. XRD analysis showed the crystalline particles and obtained AgNPs were generally in spherical shape with the average particle size of 24 nm. Their antimicrobial activity studies against various pathogenic microorganisms showed that they have strong antibacterial activity against Escherichia coli and Staphylococcus aureus and antifungal activity against Candida albicans. The minimum inhibitory concentrations for E. coli, S. aureus and C. albicans were 0.125, 0.125 and 0.250 g/mL, respectively. The results confirmed that Prunus armeniaca leaf extract could be used to produce AgNPs with efficient antimicrobial activity.

Propolis in the control of bacterial bovine mastitis: a tool for the production of organic milk

Bovine mastitis is one of the main causes of economic damage in dairy farms. Therefore, the control and prevention of microorganisms involved in this disease, mainly Escherichia coli, Staphylococcus aureus, and Streptococcus agalactiae, are essential. One of the most important steps for the prevention of the disease is the use of antiseptic products before and after the milking process to avoid bacteria from infecting the udder of the animal. Currently, the most used antiseptic product in dairy farms is iodine-based, and organic dairy farms, which follow several strict regulations, including the use of natural products whenever possible, are often forced to adopt non-natural antiseptic products, such as iodine-based ones, because of the lack of natural alternatives. Propolis, a natural substance produced by honeybees, has been extensively studied for its various properties, one of which is antimicrobial activity. Therefore, a new natural antiseptic product containing 1% propolis in 10% hydroalcoholic solution for the pre-dipping, and 10% glycerol solution added with 0.2% citronella oil for the post-dipping was analyzed for its capacity to reduce bacteria in vivo in order to prevent bovine mastitis, allowing its use on organic dairy farms. A total of 128 samples were analyzed in terms of bacterial growth for Enterobacteriaceae and Staphylococcus spp. using the spreadplate technique. The reduction in the bacterial concentration after the application of the products was compared between two antiseptic solutions, an iodine-based solution as the control and a propolis-based one as the natural alternative. The results obtained show a similar efficiency for both products in terms of total bacterial reduction, indicating considerable antimicrobial activity against bacteria most commonly associated with bovine mastitis. Molecular analysis was carried out for the identification of Streptococcus agalactiae; the PCR results were negative for the presence of S. agalactiae in all samples, indicating that the animals most likely did not have any form of the disease. The efficiency of the natural antiseptic was satisfactory, indicating an important find facilitating organic milk production worldwide, showcasing a natural antiseptic solution with efficient antimicrobial activity.

Green synthesis of a MnO-GO-Ag nanocomposite using leaf extract of Fagonia arabica and its antioxidant and anti-inflammatory performance

This research work includes the green synthesis of silver and graphene oxide doped manganese oxide nanocomposites (NCs) using Fagonia arabica, which is commonly found in Asian countries and widely grown in deserts. Fagonia arabica is a medicinal herb used for the treatment of a variety of diseases. Fagonia arabica shows efficient anti-inflammatory, antimicrobial activity and antioxidant properties. Manganese oxide (MnO) NPs were synthesized by a green synthesis method using leaf extract of Fagonia arabica. The synthesized manganese oxide nanoparticles (NPs) were then used to form manganese oxide composites coupled with graphene oxide (GO) and silver (Ag). The main composite synthesized in this research work is MnO-GO-Ag NCs. All the synthesized NPs and composites were then characterized by SEM, XRD, EDX and ultra-violet–visible spectroscopy. The anti-inflammatory activity of the manganese oxide NPs and their MnO-GO and MnO-GO-Ag composites were checked by UV-visible spectroscopy and the obtained results were compared with the standard Diclofenac Sodium. The antioxidant activity of MnO-GO-Ag shows a higher scavenging potential than the standard ascorbic acid. SEM analysis was performed to check the size and morphology of the obtained product. The XRD analysis confirmed the purity and crystallinity of synthesized MnO-GO-Ag NCs. EDX spectra showed the peaks for C, O, Ag and Mn, indicating the presence of these elements in our desired composite. For anti-inflammatory activity, the MnO-GO-Ag NCs showed percentage inhibitions of 34.15 and 81.71%, having an IC50 values of 0.15 and 0.23, at 0.1 and 0.5 mg/mL concentrations, respectively. MnO-GO-Ag showed percentage scavenging efficiencies of 59.84 and 74.48% at concentrations of 0.3 and 0.5 mg/mL, respectively, while the standard (ascorbic acid) showed scavenging potentials of 44.22 and 58.42% at similar concentrations. The MnO-GO-Ag NCs showed lower IC50 values, thus exhibit the high efficiency of the NCs for anti-inflammatory and antioxidant activities.

Biosynthesis of selenium nanoparticles using combinations of plant extracts and their antibacterial activity

Antimicrobial resistance is a significant public health problem, and the use of nanotechnology to control bacterial growth has increased, including multidrug-resistant ones. In this context, nanoparticles of different elements, mainly metals, such as silver, gold, and iron, have been extensively researched due to their efficient antimicrobial activity. Another element that stands out is selenium, which nanoparticles have high bioactivity and antibacterial action, although few studies report its use as a metallic nanoparticle. Therefore, the objective of this study was to perform the synthesis of selenium nanoparticles (SeNPs) from extracts of three plants: Allium cepa (onion), Malpighia emarginata (acerola), and Gymnanthemum amygdalinum (boldo). The synthesized nanoparticles were characterized by Dynamic Light Scattering (DLS), scanning electron microscopy (SEM), Fourier-Transform Infrared Spectroscopy (FTIR) and X-Ray Diffraction (DRX). Antibacterial activity was evaluated by microdilution in broth, followed by the time-kill curve analysis. The bacterial strains tested were Streptococcus agalactiae, Staphylococcus aureus, methicillin-resistant S. aureus, Pseudomonas aeruginosa, and Escherichia coli. Hemolytic activity was also determined. The synthesized SeNPs had a size between 245 and 321 ​nm and mostly spherical morphology. Antimicrobial activity against all Gram-positive bacteria tested was observed, with minimal inhibitory concentrations ranging from 6.125 to 98 ​μg/ml, but without action in the tested Gram-negative bacteria. Low hemolytic capacity was observed, with CC50 ranging from 0.82 to 2.1 ​mg/ml. The antimicrobial activity and low hemolytic concentration indicate the possibility of use against Gram-positive bacteria, including multidrug-resistant ones, opening a wide variety of options for their applications.

Biological properties of novel mono and double-decker hexadeca-substituted metal phthalocyanines

This study reports chemical agents that exhibit efficient antibacterial photodynamic, antimicrobial, antioxidant, biofilm inhibition, and DNA cleavage activities.

Fluid properties and phase transition of antimicrobial eudragit RS/clove oil in situ forming depot

In situ forming depot (ISD) is a liquid drug delivery formulation generating solid depot after injection via a syringe into the body. The 5% w/w doxycycline hyclate (DH)-incorporated poly (ethyl acrylate, methyl methacrylate, trimethylammonioethyl methacrylate chloride) (Eudragit RS) ISD systems comprising clove oil (CO) dissolved in N-methyl pyrrolidone (NMP) were prepared and evaluated for their fluid properties (density, viscosity, injectability and thermal properties) and phase transition (depot formation, mechanical properties). The higher weight percentage of Eudragit RS and CO apparently enhanced the viscosity of the prepared ISDs. The rapid in vitro depot formation owing to solvent exchange was evident for ISD containing higher NMP amount whereas higher CO amount retarded the phase transition. The easier injectability and more efficient antimicrobial activities corresponded with lower viscosity of ISD comprising higher content of NMP and vice versa for CO content. ISDs exhibited a plastic deformation with rather low Fremaining/Fmax deformation ratio and efficiently inhibited the test bacteria and fungi. Thus, DH-loaded Eudragit RS /CO ISD shows as a potential local delivery system for periodontitis treatment.

Defensing role of novel piscidins from largemouth bass (Micropterus salmoides) with evidence of bactericidal activities and inducible expressional delineation

Micropterus salmoides is an economical important species of freshwater-cultured fish, the in-depth knowledge of its immune system is in urgent development to cope with serious infectious diseases. Piscidin is an important antimicrobial peptide (AMP) family existing in almost all teleosts. However, no piscidin has been reported in largemouth bass. In this study, three novel piscidins (MSPiscidin-1, -2, and -3) were firstly identified and characterized from the largemouth bass. The predicted mature peptides of MSPiscidin-1, -2, and -3 (consists of 24, 27, 25 amino acid residues, respectively) all adopted an amphipathic α-helical conformation representative of cationic AMPs that are important for membrane permeabilization and antibacterial activity. MSPiscidin-2 and -3 indeed displayed strong, broad-spectrum, and highly efficient antimicrobial activities in vitro against aquatic pathogens, but MSPiscidin-1 didn’t show direct antimicrobial activity. MSPiscidin-2 and -3 killed bacteria mainly by inducing membrane permeabilization, in addition, they also can interact with bacterial genomic DNA, which might influence the DNA replication and transcription. Besides, MSPiscidin-2 and -3 could effectively inhibit the formation of the bacterial biofilm and eliminate the preformed biofilms. In vivo, MSPiscidin-1−3 genes showed an inducible expression pattern in the tested tissues upon Vibrio harveyi infection, which further indicated the key roles of piscidins in innate immunity in largemouth bass. Overall, this study will supplement the understanding of M. salmoides innate immune system and provide candidates for the design of novel peptide antibacterial agents used in aquaculture.

Green Synthesis of Silver-Decorated Magnetic Particles for Efficient and Reusable Antimicrobial Activity.

Metal and metal hybrid nanostructures have shown tremendous application in the biomedical and catalytic fields because of their plasmonic and catalytic properties. Here, a green and clean method was employed for the synthesis of silver nanoparticle (Ag NP)-SiO2-Fe2O3 hybrid microstructures, and biomolecules from green tea extracts were used for constructing the hybrid structures. The SiO2-Fe2O3 structures were synthesized using an ethanolic green tea leaf extract to form Bio-SiO2-Fe2O3 (BSiO2-Fe2O3) structures. Biochemical studies demonstrated the presence of green tea biomolecules in the BSiO2 layer. Reduction of the silver ions was performed by a BSiO2 layer to form Ag NPs of 5–10 nm in diameter in and on the BSiO2-Fe2O3 microstructure. The reduction process was observed within 600 s, which is faster than that reported elsewhere. The antimicrobial activity of the Ag-BSiO2-Fe2O3 hybrid structure was demonstrated against Staphylococcus aureus and Escherichia coli, and the nanostructures were further visualized using confocal laser scanning microscopy (CLSM). The magnetic properties of the Ag-BSiO2-Fe2O3 hybrid structure were used for studying reusable antimicrobial activity. Thus, in this study, we provide a novel green route for the construction of a biomolecule-entrapped SiO2-Fe2O3 structure and their use for the ultra-fast formation of Ag NPs to form antimicrobial active multifunctional hybrid structures.

A novel combination therapy for multidrug resistant pathogens using chitosan nanoparticles loaded with β-lactam antibiotics and β-lactamase inhibitors

Antimicrobial resistance is one of the greatest global threats. Particularly, multidrug resistant extended-spectrum β-lactamase (ESBL)-producing pathogens confer resistance to many commonly used medically important antibiotics, especially beta-lactam antibiotics. Here, we developed an innovative combination approach to therapy for multidrug resistant pathogens by encapsulating cephalosporin antibiotics and β-lactamase inhibitors with chitosan nanoparticles (CNAIs). The four combinations of CNAIs including two cephalosporin antibiotics (cefotaxime and ceftiofur) with two β-lactamase inhibitors (tazobactam and clavulanate) were engineered as water-oil-water emulsions. Four combinations of CNAIs showed efficient antimicrobial activity against multidrug resistant ESBL-producing Enterobacteriaceae. The CNAIs showed enhanced antimicrobial activity compared to naïve chitosan nanoparticles and to the combination of cephalosporin antibiotics and β-lactamase inhibitors. Furthermore, CNAIs attached on the bacterial surface changed the permeability to the outer membrane, resulting in cell damage that leads to cell death. Taken together, CNAIs have provided promising potential for treatment of diseases caused by critically important ESBL-producing multidrug resistant pathogens.

Antibacterial, antibiofilm, anti-inflammatory, and wound healing effects of nanoscale multifunctional cationic alternating copolymers

Infectious diseases caused by new or unknown bacteria and viruses, such as anthrax, cholera, tuberculosis and even COVID-19, are a major threat to humanity. Thus, the development of new synthetic compounds with efficient antimicrobial activity is a necessity. Herein, rationally designed novel multifunctional cationic alternating copolymers were directly synthesized through a step-growth polymerization reaction using a bivalent electrophilic cross-linker containing disulfide bonds and a diamine heterocyclic ring. To optimize the activity of these alternating copolymers, several different diamines and cross-linkers were explored to find the highest antibacterial effects. The synthesized nanopolymers not only displayed good to excellent antibacterial activity as judged by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa, and Escherichia coli, but also reduced the number of biofilm cells even at low concentrations, without killing mammalian cells. Furthermore, in vivo experiments using infected burn wounds in mice demonstrated good antibacterial activity and stimulated wound healing, without causing systemic inflammation. These findings suggest that the multifunctional cationic nanopolymers have potential as a novel antibacterial agent for eradication of multidrug resistant bacterial infections.

Preparation and characterization of nanoclays-incorporated polyethylene/thermoplastic starch composite films with antimicrobial activity

Polyethylene (PE) composite films incorporated with nanoclays, organically modified montmorillonite (OMMT) and silver-loaded montmorillonite (Ag-MMT), and thermoplastic starch (TPS) were prepared using an extrusion blowing method, and their properties such as optical, tensile, thermal, water vapor barrier, oxygen gas barrier, and antimicrobial activity were tested. The composite films were flexible, homogeneous, smooth but yellowish, and less transparent than the neat PE film. Increasing the composite additive content (OMMT + Ag-MMT with TPS) did not improve the composite film's optical, tensile, thermal, and barrier properties. However, no significant differences were observed between the control film and the composite film in water contact angle, XRD pattern, and microstructure. The composite films showed strong antibacterial activity against Listeria monocytogenes and E. coli O157:H7. The PE/clay/TPS composite films with 2.5 wt% of the compounded additives had desirable physical properties and efficient antimicrobial activity for active food packaging applications.

In situ solvent removal-based Eudragit®L/dimethyl sulfoxide forming gel for periodontal pocket drug delivery

Periodontitis is a chronic inflammatorydisease of gum resulting from Porphyromonas gingivalis infectious at periodontal pockets. In situ forming gel (ISG) effectively delivers the antimicrobial agents to this targeted site. This study was to develop the dimethyl sulfoxide (DMSO) removal-based ISGs of Eudragit®L and their physicochemical properties were evaluated including the viscosity, rheological behavior, in vitro matrix formation, in vitro doxycycline hyclate (DH) release and antimicrobial activities. The ISGs showed the Newtonian flow which an increase in Eudragit®L amount enhanced a viscosity. They transformed into an opaque gel after exposure a simulated crevicular fluid and modulated the DH release longer than 3 days. The percentage of drug release from DMSO removal-based ISG containing 10, 15, 20 and 25% w/w of Eudragit®L was 95.9, 90.5, 79.8 and 70.0, respectively. Thus, DH release depended on the amount of Eudragit®L loading and corresponded with the polymeric matrix formation. The high Eudragit®L loading formulation retarded notably on the solvent removal owing to a thicker gel barrier. The DH-loaded in situ solvent removal-based Eudragit®L/ DMSO forming gels presented the efficient antimicrobial activities against Staphylococcus aureus, Escherichia coli, Candida albicans and Porphyromonas gingivalis. Therefore, Eudragit®L/DMSO ISG exhibited as a potential periodontal pocket drug delivery system based on solvent removal mechanism.

Pd-Cu nanoalloy for dual stimuli-responsive chemo-photothermal therapy against pathogenic biofilm bacteria

Photothermal therapy (PTT) is a promising strategy for antimicrobial therapy. However, the application of PTT to treat bacterial infections remains a challenge as the high temperature required for bacterial elimination can partly damage healthy tissues. Selecting the appropriate treatment temperature is therefore a key factor for PTT. In this work, we designed a near-infrared/pH dual stimuli-responsive activated procedural antibacterial system based on zeolitic imidazolate framework-8 (ZIF-8), which was bottom-up synthesized and utilized to encapsulate both Pd-Cu nanoalloy (PC) and the antibiotic amoxicillin (AMO). This procedural antibacterial therapy comprises chemotherapy (CT) and PTT. The former disrupts the bacterial cell wall by releasing AMO in an acidic environment, which depends on the sensitive response of ZIF-8 to pH value change. With the progression in time, the AMO release rate decreased gradually. The latter can then significantly stimulate drug release and further complete the antibacterial effect. This impactful attack consisted of two waves that constitute the procedural therapy for bacterial infection. Accordingly, the treatment temperature required for antibacterial therapy can be significantly lowered under this mode of treatment. This antibacterial system has a significant therapeutic effect on planktonic bacteria (G+/G−) and their biofilms and also has good biocompatibility; thus, it provides a promising strategy to develop an effective and safe treatment against bacterial infections. Statement of SignificanceWe have developed a near infrared/pH dual stimuli-responsive activated procedural antibacterial system that combines enhanced antibiotic delivery with photothermal therapy and has highly efficient antimicrobial activity. The antibacterial effect of this therapy was based on two mechanisms of action: chemotherapy, in which the bacterial cell wall was first destroyed, followed by photothermal therapy. After exposure to irradiation with an 808 nm laser, the inhibition rates were 99.8% and 99.1% for Staphylococcus aureus and Pseudomonas aeruginosa, respectively, and the clearance rates for their established biofilms were 75.3% and 74.8%, respectively. Thus, this procedural antibacterial therapy has shown great potentiality for use in the photothermal therapy of bacterial infectious diseases, including biofilm elimination.

Metallonucleases encompassing curcumin, 2-aminobenzothiazole and o-phenylenediamine: a search for new metallonucleases

A few novelmetallonucleases were synthesized from curcumin derived Schiff base incorporating 2-aminobenzothiazoleand o-phenylenediamine. By characterization, these complexes were found to have 1:1:1 stoichiometry [M:L:o-Ph]. They were inferred to be electrolytic in nature in accordance to the values of molar conductance. From the spectral data the proposed geometry of all the complexes was deduced to be square planar. The complexes were screened against a few pathogens for their antimicrobial activities which reveal that they are efficient antimicrobial activity than the free ligands. The interactions of CT-DNA were studied by UV spectrophotometric, viscosity and cyclic voltammetric techniques. The complexes with higher values of Kb are optional to have greater DNA binding propensity. They have potent interaction with the CT-DNA and hence they are proficient DNA cleavable linkers due to their importance in biotechnology and drug design. Furthermore, the copper(II) complex exhibits efficient DNA cleavage with supercoiled pBR322 involving hydrolytic cleavage pathway.