Effective Antibacterial Activity Research Articles

Green synthesis of silver nanoparticles for ultrafiltration membrane surface modification and antimicrobial activity

This study presents the application of biosynthesized silver nanoparticles (AgNPs) for modifying the surface of ultrafiltration membranes to confer antimicrobial properties. The AgNPs were synthesized using leaf extract of the medicinal plant Mimusops elengi L, and their characterization was carried out using UV spectroscopy, FTIR, XRD, FESEM, HRTEM, and AFM analyses. The optimal conditions for the synthesis of AgNPs were determined to be 240 min of reaction time, pH 9.5, 1:1 (v/v) ratio of initial concentration of precursor to bio-extract, and 323 K temperature. The synthesized AgNPs were found to be spherical with an average size of 20 nm and crystalline in nature. The AgNPs were then deposited on flat sheet polyether sulfone (PES) membranes (MWCO 30 kDa) using the dip coating technique. The deposition of AgNPs on the membrane surface was confirmed using FESEM and EDX analysis. The resulting AgNPs-incorporated membrane demonstrated effective antibacterial activity against E.coli. These findings highlight the potential of biosynthesized AgNPs for developing functionalized ultrafiltration membranes with antimicrobial properties.

In silico Studies, Synthesis and Antibacterial Activity of Heterocyclic Compounds with Mannich Bases

Aim The present study aimed to identify the potent 123-triazole derivatives for synthesis and also assess their anti-bacterial activity.Methodology In silico design of novel analogues was carried out for ten derivatives using Auto Dock Vina and compared with standard drug Ciprofloxacin. Swiss ADME software was used to analyze lsquoLipinski Rule of Fiversquo and drug likeness properties. Three derivatives which obeyed rule of five having desired physicochemical properties and highest docking score were synthesized PDB code 2K35. The synthesis was carried out in two step process to determine their antibacterial activity. The synthesized compounds were structurally elucidated using Fourier-transform infrared spectroscopy FTIR Nuclear Magnetic Resonance 1H NMR and Mass spectroscopy .Results Antibacterial activity of different compounds was observed by disc diffusion method against two organisms E. coli and Streptococcus. Among the tested compounds 4A showed significant antibacterial activity. Compounds 6A and 8A also exhibited appreciable antibacterial activity against E. coli while compound 6A showed appreciable antibacterial activity against Streptococcus.Conclusion According to data obtained from the present study piperazine incorporated triazole derivatives were found to possess effective antibacterial activity. Further modifications of triazole based compounds at different positions to generate new molecules with potent anti-tumor activities will be described in future.

Phytochemical analysis, antioxidant, and antibacterial activities of Cyperus rotundus L. rhizomes

Cyperus rotundus L. is a ubiquitous weed, commonly found in tropical, subtropical, and temperate regions around the world, belonging to the Cyperaceae family. This slender, erect, perennial sedge propagates through a fibrous root system, enabling it to thrive in diverse habitats. The rhizomes initially appear black, transitioning to a darker shade as they mature. This plant is a traditional medicinal herb renowned for treating stomach ailments, nausea, vomiting, intestinal parasites, food poisoning, indigestion, and bowel irritation. Phytochemical screening of the ethanolic crude extract of C. rotundus L. rhizomes was conducted, revealing the presence of flavonoids, polyphenols, terpenoids, tannins, steroids, carbohydrates, and fixed oils. The total phenolic content was measured at 51.48 ± 1.77 mg GAE/g, 159.63 ± 2.28 mg GAE/g, and 17.90 ± 2.64 mg GAE/g in the ethanolic crude extract, ethyl acetate, and hexane fractions, respectively. Similarly, the total flavonoid content in the ethanolic crude extract, ethyl acetate, and hexane fractions was determined as (21.00 ± 1.51), (118.07 ± 5.06), and (10.67 ± 2.53) mg GAE/g, respectively. The ethyl acetate fraction of C. rotundus L. rhizomes exhibited significant antioxidant activity with an IC50 value of 27.11 ± 1.46 µg/mL. Furthermore, the ethanolic crude extract of C. rotundus L. rhizomes displayed effective antibacterial activity against gram-positive bacteria Staphylococcus aureus, with a zone of inhibition (ZOI) of 8 mm.

Green Synthesis of AuNPs by Crocus caspius—Investigation of Catalytic Degradation of Organic Pollutants, Their Cytotoxicity, and Antimicrobial Activity

Biogenic methods are an effective alternative to chemical methods in the preparation of nanoparticles. Our study used Crocus caspius extract to synthesize gold nanoparticles (CC-AuNPs) in a green manner. The eco-friendly synthesis of AuNPs was conducted by optimizing the temperature and concentration of HAuCl4 and extract. Synthesized CC-AuNPs were characterized using TEM, SEM, EDX, XRD, FTIR, and UV–Vis spectroscopy. The prepared CC-AuNPs were detected with a size of around 22.66 ± 1.67 nm. The FT-IR analysis of the biomolecules involved in synthesizing CC-AuNPs was performed. Additionally, these biomolecules capped on the AuNPs were revealed by TG/DTA analysis. The EDX study demonstrated the existence of elemental gold. The biosynthesized CC-AuNPs were effectively applied as green catalysts to reduce three organic pollutant dyes—methyl orange (MO), methylene blue (MB), and 4-nitrophenol. In the biological evaluations, the free radical scavenging activity of the eco-friendly CC-AuNPs (DPPH assay) indicated an IC50 value of 29.22 ± 0.47 µg/mL. They displayed effective antibacterial activity against several bacterial strains. Their anticancer activity against AGS and MCF-7 cells showed IC50 concentrations at 48.2 µg/mL and 51.76 µg/mL, respectively. Furthermore, CC-AuNPs presented excellent antileishmanial activity (IC50 = 13.92 µg/mL). Therefore, the green AuNPs are efficient in biomedicine and nanobiotechnology.

Green synthesis of Silver Nanoparticles using Premna tomentosa leaf extract and its effective antibacterial activity

Green synthesis of silver nanoparticles was done at room temperature using Premna tomentosa leaf extract. Silver nanoparticle formation was preliminarily confirmed through UV Spectroscopy and characterized by FTIR, XRD, TEM and SEM. The λmax was observed at 424nm in UV spectroscopy results. The XRD and EDAX spectrum confirmed the presence of silver ions and the crystalline nature of synthesized silver nanoparticles. The synthesized silver nanoparticles were spherical, hexagonal and irregular in shape. FTIR results have revealed the functional groups present in the synthesized nanoparticles such as C-N stretch, N-O symmetric stretch, C-H stretch, N-H bend, C-H group, O-H stretch and H bond. TEM and SEM results showed a clear image of nanoparticles in the size range 100nm and 200nm. In the application part, we focused on the antibacterial activity of synthesized nanoparticles on six pathogens namely Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, Vibrio parahaemolyticus and Proteus mirabilis. The maximum zone of inhibition was found in Vibrio parahaemolyticus followed by Staphylococcus aureus and Pseudomonas aeruginosa.

A cost-effective, fast cooling, and efficient anti-inflammatory multilayered topological hydrogel patch for burn wound first aid

First-aid burn wound patches play an essential role in reducing mortality by preventing hyperthermia and resisting wound infection. However, existing products still suffer from inferior cooling performance, limited therapeutic effect, weaker wound protection, and/or high cost, which hinder their widespread application in market. Herein, we design and fabricate a cost-effective multilayered topological hydrogel-based first-aid burn wound patch (FBP) for rapid cooling, efficient anti-inflammation, and wound protection. Such a hydrogel patch is fabricated from a polyacrylamide-chitosan (PAAm-CS) hydrogel as the soft antibacterial layer integrated with a topological poly(vinyl alcohol)-chitosan (PVA-CS) hydrogel as the stretchable cooling layer, as well as thin polyethylene films as encapsulated layers to prevent dehydration. As-fabricated FBP exhibits a unique combination of intriguing mechanical, thermal, and biological properties, including softness (Young’s modulus of 83 kPa), stretchability (fracture stain over 106%), high thermal conductivity (0.54 W m−1 K−1), instant cooling, effective antibacterial activity (96.2% for S. aureus, 92.2% for E. coli), and excellent biocompatibility (94.04% cell viability at 20 mg mL−1 extract in 24 h). A second-degree scald rat model further demonstrates that fast-cooling and anti-inflammatory FBP can effectively reduce the tissue damage and inflammation levels by showing less edema formation and higher collagen/blood vessel ratios. With a set of these interesting performances, the FBP may be useful as a first-aid burn wound product to alleviate patients’ sufferings and even rescue more lives in critical situation.

Bio-Mediated Zinc Oxide Nanoparticles through Tea Residue: Ecosynthesis, Characterizations, and Biological Efficiencies

Recent advances in nanotechnology have placed a major emphasis on environmentally friendly processes that encourage sustainable growth by using moderate reaction conditions and non-toxic precursors. In the present study, a simple, inventive, and affordable green technique was applied to generate bio-augmented ZnO nanoparticles using an aqueous extract of tea residue as a reducing and stabilizing component. Numerous methods, including UV-Vis, XRD, FT-IR, FE-SEM with EDAX and TEM were used to analyze ZnO nanoparticles that were generated. The antimicrobial capabilities of biomediated ZnO nanoparticles against pathogenic organisms were examined using an agar well method. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT assay) and flow cytometry analysis was utilized to explore cytotoxic effects and apoptosis, and methylene blue dye was used to examine photocatalytic activity. The ZnO nanoparticles demonstrated considerable anticancer activity in human lung cancer cells (A549) as well as highly effective antibacterial activity against several different microbial pathogens. Furthermore, the greatest degradation percentage of methylene blue obtained was found to be 86% after 140 min. Therefore, it is concluded that the chosen nanoparticle combination enhanced antimicrobial, anticancer and photocatalytic activities. The combination may represent a useful tool for removing dye pollution from wastewater and, ideally, be used in the pharmaceutical sector to combat lung cancer.

Morphology biased pharmacological and mechanical properties of nanosized block copolymers of PNIPAM with polyethylene oxide and polyaminoacids in presence of polycaprolactone

AbstractThis work targets to develop amphiphilic self‐assembled PEO‐b‐PAAs‐b‐PNIPAM and PEO‐b‐PAAs‐b‐PNIPAM@PCL nanosized block copolymers (NBCPs) of poly N‐isopropyl acrylamide (PNIPAM) with polyethylene oxide (PEO), and poly amino acids (PAAs) with and without polycaprolactone (PCL) via ring‐opening and condensation polymerization methods. The interesting ring necklace and petunia bell‐shaped flower‐like morphology play an important role in both mechanical behavior and pharmacological actions. The PEO‐b‐PAAs‐b‐PNIPAM@PCL NBCP exhibits a notable antibacterial activity against gram‐negative (Escherichia coli) and gram‐positive (Staphylococcus aureus) with ZOI of 20 ± 4 mm and 18 ± 3 mm, respectively, with MIC 250 μg/ml. The mechanical properties of the NBCPs are measured at room temperature. The PEO‐b‐PAAs‐b‐PNIPAM@PCL NBCP possesses a higher value in each case compared to the neat polymer with the UTS 1.4651 MPa, Y 0.0050 MPa, Tensile strength at yield (1.4048 MPa), TS at break (1.4640 MPa), % elongation at yield (23.5%), elongation % at break (124%) and proportional limit (1.0082 MPa at 8%), respectively. With the improved mechanical strength, effective antibacterial activities along with sustainable drug release rate, the designed material can be used as a potential material for different biomedical applications.

Branched AuAg nanoparticles coated by metal–phenolic networks for treating bacteria-induced periodontitis via photothermal antibacterial and immunotherapy

Periodontitis is an inflammatory disease caused by bacteria. The prolonged and repeated occurrence of this disease results from immune system disorders and leads to the destruction of surrounding tissues. Research on new antibacterial materials that can regulate autoimmunity and promote repair can effectively treat periodontal inflammation. Hence, metal–phenolic networks (MPNs) were loaded onto the surface of branched AuAg nanoparticles (NPs), denoted as AuAg@PC-Fe. The procyanidin (PC)-Fe network not only enhanced the photothermal properties of AuAg NPs to achieve effective photothermal antibacterial activity against periodontal pathogens but also alleviated oxidative stress and excessive inflammation. The mechanism of action is as follows: AuAg@PC-Fe promotes the polarisation of alternatively activated macrophages by activating the phosphoinositide 3-kinase/protein kinase B signaling pathway and upregulates nuclear factor erythroid 2-related factor 2, scavenging reactive oxygen species and subsequently inhibiting the nuclear factor kappa-B signaling pathway to regulate immunity. The ability of periodontal inflammatory tissue to repair was improved in vivo. This design provides new ideas for applying MPNs to photothermal therapy and immunotherapy. It presents a new therapeutic platform for treating periodontitis and other infectious diseases.

Molecular Insights into the Mode of Action of Antibacterial Peptides Derived from Chicken Plasma Hydrolysates.

Due to the overuse and abuse of antibiotics, several antibiotic resistant bacteria have emerged. Antimicrobial peptides (AMPs) have gained attention as alternative antimicrobial agents because of their unique mode of action that impedes bacterial resistance. Two novel antibacterial peptides were isolated from Alcalase-hydrolyzed chicken plasma by size exclusion and reverse-phase chromatography. They were identified by LC-MS/MS to be VSDH and CCCPKAF, which showed effective antibacterial activity toward Bacillus cereus DMST 5040, with varied modes of action. The peptide CCCPKAF caused cell membrane disintegration, as evidenced by propidium iodide (PI) uptake. In contrast, the peptide VSDH targeted intracellular molecules, including proteins and nucleic acids, as revealed by Synchrotron-based Fourier Transform Infrared (SR-FTIR). The secondary structure of intracellular proteins increased to a β-sheet structure concomitant with a decrease in the α-helix structure when exposed to 0.5 mM VSDH. Molecular docking analysis revealed that VSDH showed high binding affinity for the active sites of the various enzymes involved in DNA synthesis. In addition, it showed good affinity for a chaperone protein (Dnak), resulting in the misfolding of intracellular proteins. Nuclear magnetic resonance (NMR) and molecular dynamics simulations also indicated that VSDH chelated well with Mg2+, which could partly contribute to its antibacterial activity.

The Roots of Deguelia nitidula as a Natural Antibacterial Source against Staphylococcus aureus Strains.

Deguelia nitidula (Benth.) A.M.G.Azevedo & R.A.Camargo (Fabaceae) is an herbaceous plant distributed in the Brazilian Amazon, and it is called "raiz do sol" (sun roots). On Marajó Island, quilombola communities use its prepared roots to treat skin diseases commonly caused by fungi, viruses, and bacteria. Thus, in this study, the extract, and its fractions from D. nitidula roots were used to perform in vitro cytotoxic and antibacterial assays against Staphylococcus aureus strains. Thereafter, liquid chromatography-mass spectrometry (LC-MS) was used for the metabolite annotation process. The ethanolic extract of D. nitidula roots show significant bactericidal activity against S. aureus with IC50 82 μg.mL-1 and a selectivity index (SI) of 21.35. Furthermore, the SREFr2 and SREFr3 fractions show a potent bactericidal activity, i.e., MIC of 46.8 μg.mL-1 for both, and MBC of 375 and 93.7 μg.mL-1, respectively. As showcased, SREFr3 shows safe and effective antibacterial activity mainly in respect to the excellent selectivity index (SI = 82.06). On the other hand, SREFr2 shows low selectivity (SI = 6.8), which characterizes it as not safe for therapeutic use. Otherwise, due to a limited amount of reference MS2 spectra in public libraries, up to now, it was not possible to perform a complete metabolite annotation. Despite that, our antibacterial results for SREFr3 and correlated substructures of amino acid derivatives show that the roots of D. nitidula are a natural source of specialized metabolites, which can be isolated in the future, and then used as a support for further bio-guided research, as well as natural drug development.

The Antibacterial Activity of Kaempferol Combined with Colistin against Colistin-Resistant Gram-Negative Bacteria.

Social hygiene is seriously threatened by the rise in colistin (COL) resistance against Gram-negative bacteria (GNB). With resistance to last-line antibiotics such as COL becoming more common, it is imperative to identify alternative treatment options. In our work, we sought to determine if COL plus kaempferol (KP) present synergistic effects on the antibacterial and antibiofilm activities against colistin-resistant (Col-R) GNB in vivo and in vitro. Twenty-four Col-R GNB were collected as the experimental strains. The synergistic activity of COL and KP was evaluated by checkerboard method, time-killing assays, and the Galleria mellonella experiment. The antibiofilm effectiveness of the COL/KP combination against Col-R GNB was assessed using biofilm inhibition and eradication assays and scanning electron microscopy (SEM). Cytotoxicity tests were performed to detect the toxicity of KP monotherapy or combination therapy. There is synergistic antibacterial activity of COL and KP combination in vitro. KP combined with COL could inhibit the formation of bacterial biofilms. The amalgamation of COL and KP considerably reduced the amount of bacteria in the biofilm, according to the SEM findings. The COL/KP combination improved the survivorship of infected larvae in the G. mellonella in vivo infection model. In addition, the combination of KP and COL showed no cytotoxicity at synergistic combined concentrations according to cytotoxicity assays. This represents the first account of the antibacterial and antibiofilm activities of KP in combination with COL against Col-R GNB. Therefore, our results may provide an effective alternative route to combat Col-R GNB infections. IMPORTANCE COL is one of the few antibiotics effective against clinical isolates of GNB. However, in recent years, GNB resistance to colistin has been increasing. As a result, the combined application of colistin in conjunction with nonantibacterial medications has garnered considerable interest. In this work, the KP/COL combination showed effective antibacterial and antibiofilm activities in vitro and in vivo. The synergistic effect of combined application may be attributed to membrane permeability. Due to the low cytotoxicity of the combined concentration, the combination exhibits a promising future for use in clinical anti-infection treatments. This finding might broaden the potential applications for COL.

FORMULASI SEDIAAN CREAM DAN UJI AKTIVITAS ANTIBAKTERI PADA EKSTRAK ETANOL KOMBINASI KULIT PISANG (Musa paradisiaca) DAN KULIT NANAS (Ananas comosus) TERHADAP BAKTERI PENYEBAB JERAWAT Propionibacterium acnes

Background: Acne vulgaris is a chronic inflammatory skin disease with a complex pathogenesis, involving sebaceous glands, follicular hyperkeratosis, bacterial overgrowth, immune and inflammatory responses. Objective: This formulate the ethanol extract of banana peel and pineapple peel into cream preparations and to test the effective antibacterial activity of the combination of banana peel and pineapple peel ethanol extract cream against Propionibacterium acnes. Methods: This research was conducted experimentally with maceration extraction using 70% ethanol as solvent. Acne cream is made with a concentration ratio between (Banana peel: Pineapple peel) namely F1 (Cream Base), F2 (5%:15%), F3 (7.5%:12.5%), F4 (10%:10% ), F5 (12.5%:7.5%), F6 (15%;5%), F7 (20%:0%) and F8 (0%;20%). Then, the physical stability test was carried out in the form of organoleptic test, viscosity test, pH test, homogeneity test, spreadability test and cream type test. Followed by testing the bacteria Propionibacterium acnes in Na media. Results: The antibacterial activity test on F3 showed that the diameter of 20.18 mm was relatively larger than F1 of 0mm, F2 of 18.63 mm, F4 of 18.38 mm, F5 of 16.48 mm, F6 of 18.28 mm, F7 of 13.91 mm and The F8 is 16.11 mm. Conclusion: Cream preparations from formula 1 to formula 8 the cream stability organoleptic test, viscosity test, pH test, homogeneity test, test spreadability and cream type test. The cream preparation in formula 3 has the widest diameter for antibacterial activity compared to other formulas.

Green Synthesis of Chitosan Nanoparticles Using of Martynia annua L. Ethanol Leaf Extract and Their Antibacterial Activity

The herbal-based drug isolation-related research has increased recently around the globe. Accordingly, the current study was designed to evaluate the phytochemical content of ethanol extract of Martynia annua and its chitosan nanoparticles (MA-CNPs) antibacterial activity against bacterial pathogens such as Bacteroides fragilis, Streptococcus oralis MTCC 2696, Propionibacterium acnes MTCC 1951, Pseudomonas aeruginosa MTCC 424, Staphylococcus aureus MTCC 2940, E. coli MTCC 443, Bacillus cereus MTCC 441, Streptococcus mutans MTCC 890, Aeromonas hydrophila MTCC 12301, and Streptococcus faecalis by agar well diffusion methods. The obtained results showed that the ethanol extract of M. annua contains more pharmaceutically valuable phytochemicals than other solvent extracts and its mediated chitosan nanoparticles showed effective antibacterial activities. The ethanol extract also effectively reduced, capped, and stabilized the chitosan into MA-CNPs. The green synthesized MA-CNPs were characterized and confirmed through UV-visible spectrophotometer, FT-IR, SEM, and DLS analyses. The MA-CNPs exhibited considerable antibacterial activity in the order of Bacteroides fragilis > Streptococcus oralis > Propionibacterium acnes > Pseudomonas aeruginosa > Staphylococcus aureus > E. coli > Bacillus cereus > Streptococcus mutans > Aeromonas hydrophila> Streptococcus faecalis. Finally, the results strongly recommended that the ethanol extract of M. annua-mediated chitosan nanoparticles could be considered an effective nanomaterial to control microbial pathogens. Further, therapeutical uses of MA-CNPs need in vitro and in vivo investigation.

Synergistic Wound Healing by Novel Ag@ZIF-8 Nanostructures

In this paper, novel zeolitic imidazolate framework-8 (ZIF-8) functionalized with Ag (Ag@ZIF-8) nanoparticles were synthesized through a green, facile and environmental-friendly process for wound dressing applications. X-ray diffraction revealed that the ZIF-8 and Ag@ZIF-8 were successfully synthesized by green solvents at ambient temperature. Field-emission scanning electron microscopy indicated a homogeneous porous blend of ∼30 nm chitosan/bacterial cellulose (CS/BC) nanofibers embedded with ∼80–110 nm nanoparticles of the ZIF-8 and Ag@ZIF-8. Transmission electron microscopy revealed the Ag@ZIF-8 nanostructures consist of ZIF-8 cores that are covered by 5–20 nm Ag nanoparticles. MTT assay indicated excellent cell viability values of ∼115 and 109% for the CS/BC nanocomposites reinforced by ZIF-8 and Ag@ZIF-8 nanoparticles, respectively. The Ag-containing wound dressings showed 52–300% of effective antibacterial activities. Animal studies demonstrated excellent healing for the wound treated by CS/BC-25%Ag@ZIF-8 nanocomposite with ∼91% of wound closure after 14 days of treatment. Hematoxylin and eosin (H&E) staining revealed successful healing and tissue regeneration for the wounds treated using the CS/BC-Ag@ZIF-8 nanocomposites. This kind of nanocomposites with synergistic antimicrobial and bioactivity properties can be a promising candidate for regenerative medicine.

Antibacterial activities and biosynthesis of nanoparticles using hemp extracts

Background: The use of plants in the biosynthesis of nanoparticles is a fast-growing technique and has gained much interest from researchers over the years.Aim: This study reported the utilisation of leaf extracts of Cannabis sativa L. (hemp) for the biosynthesis of silver nanoparticles (AgNPs).Methods: In this study, techniques such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) microanalysis and Fourier transform infrared (FT-IR) were carried out for the synthesis and characterisation of nanoparticles. The antibacterial efficacy of the synthesised nanoparticles was evaluated by using the agar diffusion and macrobroth dilution methods. The antibacterial properties of the biosynthesised AgNPs were evaluated against both Gram-negative and Gram-positive bacteria.Results: The formation of AgNPs was confirmed by colour change in plant extracts and further characterised by Ultraviolet-visible (UV-Vis) spectrophotometry TEM, SEM, EDX and FT-IR analyses. Fourier transform infrared analysis revealed the efficient capping and stabilisation properties of these particles and the nature of the capping agent. Silver nanoparticles prepared from leaf extracts showed effective antibacterial activity against Escherichia coli.Conclusion: Biosynthesised AgNPs showed a broad-spectrum antimicrobial susceptibility range and therefore represent promising antimicrobial agents. This is the first reported study for hemp leaf extracts and contributes to the environmentally friendly and cost-effective technique of biosynthesising nanoparticles for drug development.Contribution: This study contributes to the current medicinal properties of cannabis. Furthermore, it reflects that cannabis can also be utilized at a nanoscale with effective antibacterial efficacy.

Synthesizing Ag2Ox(3 wt%)-loaded ZnFe2O4 photocatalysts for efficiently saving polluted aquatic ecosystems

Herein, we report an Ag2Ox (3 wt%)-loaded ZnFe2O4 photocatalysts synthesized by co-precipitation and incipient wet impregnation approach for acetamiprid degradation, antibacterial, antioxidant, and toxicity assay. Initially, bare ZnFe2O4 nanostructures were made through a simple co-precipitation method. In the second step, 3 wt% of various transition metal oxides (CuOx, ZrOx, and Ag2Ox) were embedded on the surface of ZnFe2O4 photocatalysts via a wet impregnation method. Further, the prepared photocatalysts were systematically characterized using XRD, FTIR, FE-SEM, BET, HRTEM, and XPS analysis. The optimum Ag2Ox (3 wt%)-loaded ZnFe2O4 photocatalysts revealed higher degradation efficiencies for acetamiprid under sunlight irradiation. Additionally, the Ag2Ox (3 wt%)-loaded ZnFe2O4 photocatalysts showed more effective antioxidant and antibacterial activity than blank and bare ZnFe2O4 nanomaterials. The enriched catalytic efficiency can be accredited to the 3 wt% of Ag2Ox NPs loaded on ZnFe2O4 nanomaterials, possibly due to the boosted transport properties of the electron-hole pairs. This study will provide a new avenue for the development of simple and effective photocatalysts for efficiently saving polluted aquatic ecosystems.

SECONDARY METABOLITES OF ANTAGONISTIC BACTERIAL STRAIN Cytobacillus firmus TCP1 EXERT ANTIBACTERIAL AND ANTICANCER ACTIVITY AGAINST LUNG CANCER A549 CELLS

Marine bacteria are abundant producers of many different kinds of bioactive substances. In this study, we isolated the antagonistic marine bacterial strain Cytobacillus firmus TCP1 from soil samples collected from the shoreline and evaluated the antibacterial and anticancer effects of its crude secondary metabolites. The potent antagonistic bacterial isolate C. firmus was identified using 16S rRNA sequencing analysis. The secondary metabolites from strain C. firmus were extracted by centrifugation with ethanol, and the agar well diffusion method was used to evaluate them for antibacterial activity against respiratory tract bacterial pathogens. This study demonstrated that the metabolic extract of the TCP1 effectively inhibited the growth of respiratory tract bacterial pathogens. Moreover, it established concentration-dependent cytotoxicity on A549 lung cancer cells. The administration of metabolic extract of the TCP1 showed an effective inhibitory effect on colony formation of A549 cells, increased lipid peroxidation, and decreased the antioxidant activity in A549 cells. The results showed that the metabolic extract of the TCP1 showed effective antibacterial and anticancer activity. Therefore, upon additional clinical testing, the secondary metabolites of strain C. firmus TCP1 may be exploited to create potent antibiotics and anticancer drugs for lung cancer.

PH-responsive drug release and antibacterial activity of chitosan-coated core/shell borate glass-hydroxyapatite microspheres

Multifunctional drug delivery system that can treat bone infection and concurrently accelerate bone tissue regeneration is highly desirable. In this study, we developed a pH-responsive local drug carrier in which a core/shell microsphere consisting of a borate glass core and a mesoporous hydroxyapatite HA shell (BG-HA) was coated with glutaraldehyde-crosslinked chitosan (CS). At neutral pH, a negligible concentration of vancomycin was released from the BG-HA@CS microspheres. However, in an acidic environment, the pores on the HA shell were uncapped due to the swelling of CS, thus accelerating the drug release. The advantage of the BG-HA@CS was evidenced by comparing with HA@CS that was prepared by fully converting borate glass followed by CS coating. The dissolution of the unconverted borate glass core upon immersing in PBS led to an increase in the local pH. This change of pH regulated the swelling/de-swelling behaviours of CS, thereby realizing more sustained drug release. Furthermore, it revealed that the vancomycin-loaded BG-HA@CS provided highly effective antibacterial activity against S. aureus and E. coli, while the vancomycin-loaded HA@CS did not show inhibitory effect on E. coli. The results indicated that the BG-HA@CS would be a promising multifunctional delivery system that can achieve self-regulated drug release, control the acidic environment of bone infection sites and promote bone tissue regeneration.

PH-sensitive alginate hydrogel for synergistic anti-infection

This work designed a pH-sensitive sodium alginate hydrogel for combating bacterial infection caused by tissue damage. The antibacterial hydrogels were prepared using sodium alginate, citric acid, and vancomycin by one-step in situ method. Vancomycin (Van) was loaded into hydrogels via reversible imine bonds for controlled drug delivery. The morphology, swelling properties, and antibacterial activity of hydrogel were characterized. The hydrogel shown strong water absorbent behavior and pH-dependent performance. The result under weak acid conditions, the drug release rate of van-loaded gel was faster than neutral and alkaline conditions and followed zero-order kinetic release model, and the cumulative release amount could reach 86.7 % over 320 min. The van-loaded gel had highly effective antibacterial activity in a weak acid environment, the combination of citric acid and vancomycin had a synergistic therapeutic effect for acute infection. The drug-loaded hydrogel shows good biocompatibility. Compared with gauze, the drug-loaded hydrogel exhibited good coagulation properties, high platelet adhesion, high fluid absorption capacity, and proper balance of fluid on the wound bed. This work proposed this simple alginate-based drug delivery system has potential applications in the field of clinical treatment of infections.