Diamond Nanoparticles-Porphyrin mTHPP Conjugate as Photosensitizing Platform: Cytotoxicity and Antibacterial Activity

Conjugation of photosensitizers (PS) with nanoparticles has been largely used as a strategy to stabilize PS in the biological medium resulting in photosensitizing nanoparticles of enhanced photoactivity. Herein, (Meso-5, 10, 15, 20-tetrakis (3-hydroxyphenyl) phorphyryn (mTHPP) was conjugated with diamond nanoparticles (ND) by covalent bond. Nanoconjugate ND-mTHPP showed suitable stability in aqueous suspension with 58 nm of hydrodynamic diameter and Zeta potential of −23 mV. The antibacterial activity of ND-mTHPP was evaluated against Escherichia coli for different incubation times (0–24 h). The optimal activity was observed after 2 h of incubation and irradiation (660 nm; 51 J/cm2) performed right after the addition of ND-mTHPP (100 μg/mL) to the bacterial suspension. The inhibitory activity was 56% whereas ampicillin at the same conditions provided only 14% of bacterial growth inhibition. SEM images showed agglomerate of ND-mTHPP adsorbed on the bacterial cell wall, suggesting that the antimicrobial activity of ND-mTHPP was afforded by inducing membrane damage. Cytotoxicity against murine embryonic fibroblast cells (MEF) was also evaluated and ND-mTHPP was shown to be noncytotoxic since viability of cells cultured for 24 h in the presence of the nanoconjugate (100 μg/mL) was 78%. Considering the enhanced antibacterial activity and the absence of cytotoxic effect, it is possible to consider the ND-mTHPP nanoconjugate as promising platform for application in antimicrobial photodynamic therapy (aPDT).

Download Full-text

Effects of Synthetic Procedures and Postsynthesis Incubation pH on Size, Shape, and Antibacterial Activity of Copper (I) Oxide Nanoparticles

Journal of Chemistry ◽

10.1155/2020/9541934 ◽

2020 ◽

Vol 2020 ◽

pp. 1-10

Author(s):

Vinh Tien Nguyen ◽

Khanh Son Trinh

Keyword(s):

Antibacterial Activity ◽

High Surface ◽

Size Variation ◽

Reaction Rates ◽

Bacterial Suspension ◽

Oxide Nanoparticles ◽

Surface Charges ◽

Fast Reaction ◽

Sem Images ◽

Etching Effect

Copper (I) oxide nanoparticles (Cu2O NP) were synthesized by reducing CuSO4 with glucose in the presence of polyvinyl alcohol as a capping agent. We used three different synthetic procedures with a fast reaction (procedure 1p), a fast-then-slow reaction (procedure 2p), and a slow-then-fast reaction (procedure 3p). The reaction rates were controlled by changing the temperature and the speed of adding reagents. The synthesized Cu2O NP were subsequently incubated for 24 h in a pH 6 solution (Cu2O NP6) or a pH 8 solution (Cu2O NP8) at 5°C. XRD and SEM images analysis revealed that the 1p procedure produced smaller NP, while the 2p procedure produced larger but more uniform NP. The 3p procedure produced the largest NP with a higher size variation. The 24-hour acidic postsynthesis incubation resulted in an etching effect, which reduced the size and size variation of Cu2O NP6. To evaluate the antibacterial activity, E. coli suspensions were mixed with the obtained Cu2O NP (32, 96, or 160 ppm) for different time intervals (1 or 24 h) and then grown on Petri dishes at 37°C for 24 h. Higher doses, smaller sizes of Cu2O NP, and longer contact times with the bacterial suspension resulted in higher inactivation efficiencies. Cu2O NP6 showed higher antibacterial effects at low doses, possibly due to the etching effect and the positive surface charge. Increasing the Cu2O doses from 32 to 96 and 160 ppm noticeably increased the antibacterial effect of the Cu2O NP8, but not significantly for Cu2O NP6. We suggested that the Cu2O NP6 suffered from agglomeration at high doses due to their high surface activity and low surface charges.

Download Full-text

Evaluating the Antibacterial Activity and Mode of Action of Thymol-Loaded Chitosan Nanoparticles Against Plant Bacterial Pathogen Xanthomonas campestris pv. campestris

Frontiers in Microbiology ◽

10.3389/fmicb.2021.792737 ◽

2022 ◽

Vol 12 ◽

Author(s):

Sarangapani Sreelatha ◽

Nadimuthu Kumar ◽

Tan Si Yin ◽

Sarojam Rajani

Keyword(s):

Electron Microscopy ◽

Antibacterial Activity ◽

Xanthomonas Campestris ◽

Membrane Damage ◽

Chitosan Nanoparticles ◽

Bacterial Pathogen ◽

Electron Microscopy Analysis ◽

Rot Disease ◽

The Impact

The bacterium Xanthomonas campestris pv. campestris (Xcc) causes black rot disease in cruciferous crops, resulting in severe yield loss worldwide. The excessive use of chemical pesticides in agriculture to control diseases has raised significant concern about the impact on the environment and human health. Nanoparticles have recently gained significant attention in agriculture owing to their promising application in plant disease control, increasing soil fertility and nutrient availability. In the current study, we synthesized thymol-loaded chitosan nanoparticles (TCNPs) and assessed their antibacterial activity against Xcc. The synthesis of TCNPs was confirmed by using ultraviolet–visible spectroscopy. Fourier-transform infrared spectroscopy, transmission electron microscopy, and scanning electron microscopy analysis revealed the functional groups, size, and shape of TCNPs, with sizes ranging from 54 to 250 nm, respectively. The antibacterial activity of TCNPs against Xcc was investigated in vitro by liquid broth, cell viability, and live dead staining assay, and all of them demonstrated the antibacterial activity of TCNPs. Furthermore, TCNPs were found to directly inhibit the growth of Xcc by suppressing the growth of biofilm formation and the production of exopolysaccharides and xanthomonadin. The ultrastructure studies revealed membrane damage in TCNP-treated Xcc cells, causing a release of intracellular contents. Headspace/gas chromatography (GC)–mass spectrometry (MS) analysis showed changes in the volatile profile of Xcc cells treated with TCNPs. Increased amounts of carbonyl components (mainly ketones) and production of new volatile metabolites were observed in Xcc cells incubated with TCNPs. Overall, this study reveals TCNPs as a promising antibacterial candidate against Xcc.

Download Full-text

Plant defensin antibacterial mode of action against Pseudomonas species

10.21203/rs.2.20753/v1 ◽

2020 ◽

Author(s):

Andrew Edward Sathoff ◽

Shawn Lewenza ◽

Deborah A. Samac

Keyword(s):

Gene Expression ◽

Antibacterial Activity ◽

Outer Membrane ◽

Pseudomonas Syringae ◽

Mode Of Action ◽

Fluorescent Microscopy ◽

Insertion Site ◽

Membrane Damage ◽

Plant Defensin ◽

Plant Defensins

Abstract Background: Though many plant defensins exhibit antibacterial activity, little is known about their antibacterial mode of action (MOA). Antimicrobial peptides with a characterized MOA induce the expression of multiple bacterial outer membrane modifications, which are required for resistance to these membrane-targeting peptides. Mini-Tn5-lux mutant strains of Pseudomonas aeruginosa with Tn insertions disrupting outer membrane protective modifications were assessed for sensitivity against plant defensin peptides. These transcriptional lux reporter strains were also evaluated for lux gene expression in response to sublethal plant defensin exposure. Also, a plant pathogen, Pseudomonas syringae pv. syringae was modified through transposon mutagenesis to create mutants that are resistant to in vitro MtDef4 treatments.Results: Plant defensins displayed specific and potent antibacterial activity against strains of P. aeruginosa. A defensin from Medicago truncatula, MtDef4, induced dose-dependent gene expression of the aminoarabinose modification of LPS and surface polycation spermidine production operons. The ability for MtDef4 to damage bacterial outer membranes was also verified visually through fluorescent microscopy. Another defensin from M. truncatula, MtDef5, failed to induce lux gene expression and limited outer membrane damage was detected with fluorescent microscopy. The transposon insertion site on MtDef4 resistant P. syringae pv. syringae mutants was sequenced, and modifications of ribosomal genes were identified to contribute to enhanced resistance to plant defensin treatments. Conclusions: MtDef4 damages the outer membrane similar to polymyxin B, which stimulates antimicrobial peptide resistance mechanisms to plant defensins. MtDef5, appears to have a different antibacterial MOA. Additionally, the MtDef4 antibacterial mode of action may also involve inhibition of translation.

Download Full-text

A Comparison of Antibacterial Activity of Selected Thyme (Thymus) Species by Means of the Dot Blot Test with Direct Bioautographic Detection

Journal of AOAC International ◽

10.5740/jaoacint.sge5-orlowska ◽

2015 ◽

Vol 98 (4) ◽

pp. 871-875 ◽

Cited By ~ 2

Author(s):

Marta Orłowska ◽

Teresa Kowalska ◽

Mieczysław Sajewicz ◽

Wioleta Jesionek ◽

Irena M Choma ◽

...

Keyword(s):

Antibacterial Activity ◽

Detection Method ◽

Cost Effective ◽

Polar Fraction ◽

Dot Blot ◽

Inhibition Zones ◽

Chromatographic Plate ◽

Direct Bioautography ◽

Bacterial Growth Inhibition ◽

Different Origin

Abstract Bioautography carried out with the aid of thin-layer chromatographic adsorbents can be used to assess antibacterial activity in samples of different origin. It can either be used as a simple and cost-effective detection method applied to a developed chromatogram, or to the dot blot test performed on a chromatographic plate, where total antibacterial activity of a sample is scrutinized. It was an aim of this study to compare antibacterial activity of 18 thyme (Thymus) specimens and species (originating from the same gardening plot and harvested in the same period of time) by means of a dot blot test with direct bioautography. A two-step extraction of herbal material was applied, and at step two the polar fraction of secondary metabolites was obtained under the earlier optimized extraction conditions [methanol–water (27 + 73, v/v), 130°C]. This fraction was then tested for its antibacterial activity against Bacillus subtilis bacteria. It was established that all investigated extracts exhibited antibacterial activity, yet distinct differences were perceived in the size of the bacterial growth inhibition zones among the compared thyme species. Based on the results obtained, T. citriodorus “golden dwarf” (sample No. 5) and T. marschallianus (sample No. 6) were selected as promising targets for further investigations and possible inclusion in a herbal pharmacopeia, which is an essential scientific novelty of this study.

Download Full-text

Hydroxyapatite-ciprofloxacin delivery system: Synthesis, characterisation and antibacterial activity

Acta Pharmaceutica ◽

10.2478/acph-2018-0011 ◽

2018 ◽

Vol 68 (2) ◽

pp. 129-144 ◽

Cited By ~ 3

Author(s):

Maria-Viorica Ciocilteu ◽

Andreea Gabriela Mocanu ◽

Adriana Mocanu ◽

Catalin Ducu ◽

Oana Elena Nicolaescu ◽

...

Keyword(s):

Antibacterial Activity ◽

Chemical Precipitation ◽

Precipitation Method ◽

Synthesis Process ◽

Diffusion Controlled ◽

Ft Ir ◽

Inhibition Zones ◽

Bacterial Growth Inhibition ◽

Local Release

Abstract The main objective of this study was to synthesize hydroxyapatite-ciprofloxacin composites using a chemical precipitation method and to evaluate the properties and in vitro release profile of the drug from the hydroxyapatite-ciprofloxacin composites. Composite characterization was achieved by FT-IR, XRD and DLS. Ciprofloxacin determination was accomplished by HPLC, resulting in good incorporation efficiency of the drug (18.13 %). The in vitro release study (Higuchi model C = K t1/2 and Ritger-Peppas model, C = K t0.6) showed a diffusion-controlled mechanism. The antibacterial activity showed that the bacterial growth inhibition zones were approximately equal for the synthesis composites and for the mechanical mixture on the Staphylococcus aureus germ. The use of hydroxyapatite, which is a biocompatible, bioactive and osteoconductive material, with ciprofloxacin, which has good antibacterial activity in this composite, makes it suitable for the development of bone grafts. Furthermore, the synthesis process allows a slow local release of the drug.

Download Full-text

A Synergistic Antimicrobial Mechanism of GO: Why Oxidative Stress Can Inactivate E. coli

NANO ◽

10.1142/s179329202050054x ◽

2020 ◽

Vol 15 (04) ◽

pp. 2050054 ◽

Cited By ~ 1

Author(s):

Xin Li ◽

Haoqi Zhao ◽

Shidong Wang ◽

Weiwu Zou ◽

Peiyan Yang ◽

...

Keyword(s):

Oxidative Stress ◽

Antibacterial Activity ◽

Mammalian Cells ◽

Water Solubility ◽

Direct Interaction ◽

Medical Application ◽

Future Application ◽

Sem Images ◽

E Coli ◽

Low Cytotoxicity

Graphene oxide (GO), a 2D nanomaterial, is a promising material for medical application, thanks to its water solubility, antibacterial activity and relatively low cytotoxicity. However, many factors, such as lateral dimension, purity and surface chemistry, may influence its antibacterial activity, its exact mechanism is still unknown. In this work, E. coli was used as model bacterium to determine the antibacterial activity of well-dispersed GO which was obtained by a modified Hummer method and dialyzed to remove the salts and acid used in the oxidation process. After co-culture with GO for 2[Formula: see text]h, up to 90% E. coli cells were inactivated when GO concentration at 8[Formula: see text][Formula: see text]g/mL. The direct interaction was not detected in FE-SEM images and the results of [Formula: see text] potential showed that the interaction between GO and E. coli are repulsive[Formula: see text] Our results showed that GO can produce ROS and inactivate SOD and CAT enzymes in low concentration after co-cultured with E. coli which explained the antibacterial activity of GO in aqueous solution. Meanwhile, GO, with high purity, showed low cytotoxicity towards mammalian cells and did not cause any observable hemoglobin after co-cultured with blood cells. The data presented here prove that GO is effectively inhibit E. coli through inactivating SOD, CAT enzymes and the oxidative stress produced by ROS. Furthermore, the good biocompatibility promised its future application.

Download Full-text

Antibacterial Activity and Mechanism of Ginger Essential Oil against Escherichia coli and Staphylococcus aureus

Molecules ◽

10.3390/molecules25173955 ◽

2020 ◽

Vol 25 (17) ◽

pp. 3955 ◽

Cited By ~ 1

Author(s):

Xin Wang ◽

Yi Shen ◽

Kiran Thakur ◽

Jinzhi Han ◽

Jian-Guo Zhang ◽

...

Keyword(s):

Escherichia Coli ◽

Staphylococcus Aureus ◽

Antibacterial Activity ◽

Essential Oil ◽

Cell Membrane ◽

Bacterial Cell ◽

Tricarboxylic Acid Cycle ◽

Inhibition Zone ◽

Underlying Mechanism ◽

Bacterial Suspension

Though essential oils exhibit antibacterial activity against food pathogens, their underlying mechanism is understudied. We extracted ginger essential oil (GEO) using supercritical CO2 and steam distillation. A chemical composition comparison by GC-MS showed that the main components of the extracted GEOs were zingiberene and α-curcumene. Their antibacterial activity and associated mechanism against Staphylococcus aureus and Escherichia coli were investigated. The diameter of inhibition zone (DIZ) of GEO against S. aureus was 17.1 mm, with a minimum inhibition concentration (MIC) of 1.0 mg/mL, and minimum bactericide concentration (MBC) of 2.0 mg/mL. For E. coli, the DIZ was 12.3 mm with MIC and MBC values of 2.0 mg/mL and 4.0 mg/mL, respectively. The SDS-PAGE analysis revealed that some of the electrophoretic bacterial cell proteins bands disappeared with the increase in GEO concentration. Consequently, the nucleic acids content of bacterial suspension was raised significantly and the metabolic activity of bacteria was markedly decreased. GEO could thus inhibit the expression of some genes linked to bacterial energy metabolism, tricarboxylic acid cycle, cell membrane-related proteins, and DNA metabolism. Our findings speculate the bactericidal effects of GEO primarily through disruption of the bacterial cell membrane indicating its suitability in food perseveration.

Download Full-text

The Effect of Modification of Hydroxyapatite Whisker with Zinc Acetate via Sol-Gel Technology

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.364.655 ◽

2013 ◽

Vol 364 ◽

pp. 655-659 ◽

Cited By ~ 1

Author(s):

Jian Feng Jin ◽

Wen Ying Liu ◽

Wen Yun Zhang ◽

Qing Hua Chen ◽

Yan Bo Yuan ◽

...

Keyword(s):

Zinc Oxide ◽

Antibacterial Activity ◽

Zinc Acetate ◽

Ph Value ◽

Antibacterial Property ◽

Sol Gel ◽

Annealing Treatment ◽

Sem Images ◽

Different Shapes

Antibacterial activity of zinc oxide (ZnO) or strengthening of hydroxylapatite whisker (HAPw) had been studied and applied widely. However, antibacterial property of ZnO-HAPw was scarcely researched nowadays. The aim of this study was to further investigate several kinds of morphologies of ZnO-HAPw prepared by sol-gel technology at different pondus hydrogenii (pH) value and temperature. Four kinds of morphologies of ZnO-HAPw were granule, triangle, short rod and gongs nail at 70°C and pH=6.4, 37°C and pH=6.6, 70°C and pH=6.6, 70°C and pH=6.6. The SEM images of HAPw and ZnO-HAPw samples showed that the HAPw surface was smooth and no difference after annealing treatment. In addition, different shapes of nanoZnO fused uniformly on the HAPw surface. The EDS indicates nanoZnO fuses on HAPw surface.

Download Full-text

Effect of Morphology-based Defect Structure of ZnO Nanostructures in Photo-Degradation of Organic Dye

MRS Proceedings ◽

10.1557/opl.2014.727 ◽

2014 ◽

Vol 1672 ◽

Cited By ~ 1

Author(s):

Reza Shidpour ◽

Manouchehr Vosoughi ◽

Abdolreza Simchi ◽

Faegheh Ghanbari

Keyword(s):

Defect Structure ◽

Aqueous Suspension ◽

Organic Dye ◽

Zno Nanostructures ◽

Photocatalytic Efficiency ◽

Porous Network ◽

Sem Images ◽

Photo Degradation ◽

Annealing Temperatures ◽

Zinc Oxides

ABSTRACTThe fabrication of strong photocatalysts applied to the degradation of organic pollutants is necessary in environmental applications. In a single-stage method, acetate precursor and poly vinyl pyrolydine are used to produce ZnO nanostructures with various morphologies in annealing temperatures ranging from 300 °C to 900 oC. The physical properties of the prepared nanostructures were characterized by SEM, XRD and PL spectroscopy. The SEM images exhibit a variety of the as-prepared hexagonal zinc oxides including wires, rods, particles and porous network of welded particles of ZnO nanoparticles. The results of the photocatalytic degradation of methylene blue as an organic dye in aqueous suspension showed that the morphology of ZnO nanostructures influences on the photocatalytic efficiency of ZnO nanostructures, greatly. For the best result, the highest MB degradation occurs by ZnO nanowires within 16 minutes and in others samples, degradation of higher than 95 percent occurs within 20 minutes. The XRD and PL spectroscopy revealed neither VZn nor Oi are in all of samples but only VO−, VO2− and Zni exist in ZnO nanostructures.

Download Full-text

Investigation of Ultrasonic Treatment on Physicochemical, Structural and Morphological Properties of Sodium Alginate/AgNPs/Apple Polyphenol Films and Its Preservation Effect on Strawberry

Polymers ◽

10.3390/polym12092096 ◽

2020 ◽

Vol 12 (9) ◽

pp. 2096

Author(s):

Wenting Lan ◽

Siying Li ◽

Shiti Shama ◽

Yuqing Zhao ◽

Dur E. Sameen ◽

...

Keyword(s):

Antibacterial Activity ◽

Composite Film ◽

Sodium Alginate ◽

Food Packaging ◽

Base Material ◽

Morphological Properties ◽

Vapor Permeability ◽

Sem Images ◽

Active Food Packaging ◽

Ultrasonic Time

An antibacterial and anti-oxidation composite film was prepared by a casting method using sodium alginate (SA) and apple polyphenols (APPs) as the base material and glycerol as the plasticizer. Silver nanoparticles (AgNPs) were deposited by ultrasonic-assisted electrospray method. The degree of influence of the addition ratio of SA and AgNPs and different ultrasonic time on the mechanical properties, barrier properties, optical properties, and hydrophilicity of the composite film was explored. The composite films were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the SA: AgNPs ratio of 7:3 and the ultrasonic time for 30 min have the best comprehensive performance, and SA/AgNPs/APP films showed the lowest water vapor permeability value of 0.75 × 10−11 g/m·s·Pa. The composite film has good strength and softness, with tensile strength (TS) and elongation at break (E) at 23.94 MPa and 29.18%, respectively. SEM images showed that the surface of the composite film was smooth and the AgNPs’ distribution was uniform. The composite film showed broad antibacterial activity, and the antibacterial activity of Escherichia coli (92.01%) was higher than that of Staphylococcus aureus (91.26%). However, due to the addition of APP, its antioxidant activity can reach 98.39%, which has a synergistic effect on antibacterial activity. For strawberry as a model, the results showed that this composite film can prolong the shelf life of strawberries for about 8 days at 4 °C, effectively maintaining their storage quality. Compared with the commonly used PE(Polyethylene film) film on the market, it has a greater fresh-keeping effect and can be used as an active food packaging material.

Download Full-text