Nanofibrous Membrane with Encapsulated Glucose Oxidase for Self-Sustained Antimicrobial Applications

Polyvinyl alcohol (PVA) nanofibrous membrane, consisting of separately encapsulated glucose oxidase (GOx) and glucose (Glu) nanofibers, was prepared via simultaneously electrospinning PVA/GOx and PVA/Glu dopes. The as-prepared pristine membrane could self-sustainably generate hydrogen peroxide (H2O2) only in contact with an aqueous solution. The H2O2 production level was well maintained even after storing the dry membrane at room temperature for 7 days. Cross-linking the membrane via reaction with glutaraldehyde (GA) vapor could not only prevent the nanofibrous membrane from dissolving in water but also prolonged the release of H2O2. The sustained release of H2O2 from the membrane achieved antimicrobial capability equivalent to that of 1% H2O2 against both Escherichia coli and Staphylococcus aureus. Gram(+) S. aureus cells were more susceptible to H2O2 than Gram(−) E. coli and >99% of S. aureus were killed after 1 h incubation with the membrane. Pristine and GA-crosslinked nanofibrous membrane with in situ production of H2O2 were self-sterilized in which no microorganism contamination on the membrane could be detected after 2 weeks incubation on an agar plate. The GOx/Glu membrane may find potential application as versatile antimicrobial materials in the field of biomedicine, in the food and health industries, and especially challenges related to wound healing in diabetic patients.

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Atmospheric Pressure Microplasma for Antibacterial Silver Nanoparticle/Chitosan Nanocomposites With Tailored Properties

10.26434/chemrxiv.9849806.v1 ◽

2019 ◽

Author(s):

Daye Sun ◽

Jonathan Turner ◽

Nan Jiang ◽

Songsong Zhu ◽

Li Zhang ◽

...

Keyword(s):

Silver Nanoparticle ◽

Atmospheric Pressure ◽

Room Temperature ◽

Polymer Network ◽

Antibacterial Properties ◽

Bacterial Strains ◽

E Coli ◽

Modified Chitosan ◽

First Time

Room temperature atmospheric pressure microplasma (APM) was deployed for the first time for the in situ synthesis of anti-bacterial silver nanoparticle / chitosan (AgNP/CS) nanocomposites. The plasma induced liquid chemistry plays a role in the in situ formation of AgNP, the size distribution of which depends on the silver salt precursor concentration. The microplasma process has also simultaneously tailored the physical properties of the composites, rendering more crosslinked chitosan polymer network with shorter molecular chains. The formation of AgNP within the in situ modified chitosan has led to nanocomposites with overall improved mechanical properties and better stability in simulated body fluid. Our plasma synthesized AgNP/CS nanocomposites also demonstrate effective antibacterial properties against E. Coli and S. Aureus bacterial strains, showing their promise in potential antimicrobial applications.

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Quaternary ammonium salt–modified polyacrylonitrile/polycaprolactone electrospun nanofibers with enhanced antibacterial properties

Textile Research Journal ◽

10.1177/0040517521997187 ◽

2021 ◽

pp. 004051752199718

Author(s):

Hongnan Zhang ◽

Tingting Zhang ◽

Qiaohua Qiu ◽

Xiaohong Qin

Keyword(s):

Antibacterial Properties ◽

Electrospun Nanofibers ◽

Tensile Tests ◽

Nanofibrous Membrane ◽

E Coli ◽

Small Pore Size ◽

Small Pore ◽

Inhibition Zones ◽

Nanofibrous Membranes ◽

And Staphylococcus Aureus

In this experiment, octadecyltrimethylammonium chloride (STAC), a cationic antibacterial agent, was designed to modify hydrolyzed polyacrylonitrile (PAN) through tight electrostatic attraction. Then, the modified PAN was successfully electrospun with polycaprolactone (PCL) to obtain PCL/PAN-STAC nanofibrous membranes with enhanced mechanical properties. The modified PAN was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis and elemental analysis. The morphological, mechanical and antibacterial properties of nanofibrous membranes were investigated. The blended nanofibrous membrane presented a uniform and stable structure with small pore size. Tensile tests indicated that the mechanical property of PCL/PAN-STAC nanofibrous membrane was obviously enhanced by blending. Disk diffusion tests showed that the inhibition zones of PCL/PAN-STAC against Escherichia coli and Staphylococcus aureus were 7.56 ± 0.05 mm and 15.37 ± 0.34 mm, respectively. Shaking method indicated that the antibacterial activity against E. coli was as high as 96.20 ± 0.89% when the use of PCL/PAN-STAC reached 9 mg. Therefore, this antibacterial nanofibrous membrane is very favorable for applications such as protective filtration masks and wound dressing.

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Atmospheric Pressure Microplasma for Antibacterial Silver Nanoparticle/Chitosan Nanocomposites With Tailored Properties

10.26434/chemrxiv.9849806 ◽

2019 ◽

Author(s):

Daye Sun ◽

Jonathan Turner ◽

Nan Jiang ◽

Songsong Zhu ◽

Li Zhang ◽

...

Keyword(s):

Silver Nanoparticle ◽

Atmospheric Pressure ◽

Room Temperature ◽

Polymer Network ◽

Antibacterial Properties ◽

Bacterial Strains ◽

E Coli ◽

Modified Chitosan ◽

First Time

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Antibacterial properties of a novel nano-silver loaded poly(styrene-co-acrylic) composites

Polymers and Polymer Composites ◽

10.1177/09673911211037499 ◽

2021 ◽

pp. 096739112110374

Author(s):

Ruge Cao ◽

Xuqing Zhai ◽

Xueyang Li ◽

Xiaoyu Zhao

Keyword(s):

Silver Nanoparticles ◽

Antibacterial Properties ◽

Underlying Mechanism ◽

Nano Silver ◽

E Coli ◽

Transmission Electron ◽

Antibacterial Material ◽

Inhibition Zones ◽

And Staphylococcus Aureus

To prevent microbial contamination in foods and medical tools, we prepared a novel antibacterial material nano-silver loaded poly(styrene-co-acrylic) (nAg-PSA) composites by in situ reductions. The nAg-PSA was characterized by scanning electron microscope, transmission electron microscopy, energy dispersive X-ray spectroscopy and thermogravimetric analysis. The antibacterial properties of nAg-PSA against Escherichia coli and Staphylococcus aureus were systematically evaluated, and the underlying mechanism was investigated. Results showed that the silver nanoparticles were successfully loaded onto PSA microspheres, highly dispersed on the surface of nAg-PSA nanoparticles. The nAg-PSA nanoparticles all showed significant antibacterial effects, among which nAg-PSA4 had maximum diameters of inhibition zones against the Gram-negative E. coli (1.18 mm) and the Gram-positive S. aureus (1.29 mm), respectively, which closely related to the size and density of silver nanoparticles covered on the surface.

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In situ Forming Hyperbranched PEG—Thiolated Hyaluronic Acid Hydrogels With Honey-Mimetic Antibacterial Properties

Frontiers in Bioengineering and Biotechnology ◽

10.3389/fbioe.2021.742135 ◽

2021 ◽

Vol 9 ◽

Author(s):

Jeddah Marie Vasquez ◽

Ayesha Idrees ◽

Irene Carmagnola ◽

Aa Sigen ◽

Sean McMahon ◽

...

Keyword(s):

Enzyme Activity ◽

Hyaluronic Acid ◽

Glucose Oxidase ◽

Gram Positive ◽

Antibiotic Resistant ◽

Gram Negative ◽

E Coli ◽

Gram Positive Bacteria

The rapidly increasing resistance of bacteria to currently approved antibiotic drugs makes surgical interventions and the treatment of bacterial infections increasingly difficult. In recent years, complementary strategies to classical antibiotic therapy have, therefore, gained importance. One of these strategies is the use of medicinal honey in the treatment of bacterially colonized wounds. One of the several bactericidal effects of honey is based on the in situ generation of hydrogen peroxide through the activity of the enzyme glucose oxidase. The strategy underlying this work is to mimic this antibacterial redox effect of honey in an injectable, biocompatible, and rapidly forming hydrogel. The hydrogel was obtained by thiol–ene click reaction between hyperbranched polyethylene glycol diacrylate (HB PEGDA), synthesized using reversible addition-fragmentation chain transfer (RAFT) polymerization, and thiolated hyaluronic acid (HA-SH). After mixing 500 µL HB PEGDA (10%, w/w) and 500 µL HA-SH (1%, w/w) solutions, hydrogels formed in ∼60 s (HB PEGDA/HA-SH 10.0–1.0), as assessed by the tube inverting test. The HB PEGDA/HA-SH 10.0–1.0 hydrogel (200 µL) was resistant to in vitro dissolution in water for at least 64 days, absorbing up to 130 wt% of water. Varying glucose oxidase (GO) amounts (0–500 U/L) and constant glucose content (2.5 wt%) were loaded into HB PEGDA and HA-SH solutions, respectively, before hydrogel formation. Then, the release of H2O2 was evaluated through a colorimetric pertitanic acid assay. The GO content of 250 U/L was selected, allowing the formation of 10.8 ± 1.4 mmol H2O2/L hydrogel in 24 h, under static conditions. The cytocompatibility of HB PEGDA/HA-SH 10.0–1.0 hydrogels loaded with different GO activities (≤ 500 U/L) at a constant glucose amount (2.5 wt%) was investigated by in vitro assays at 24 h with L929 and HaCaT cell lines, according to DIN EN ISO 10993-5. The tests showed cytocompatibility for GO enzyme activity up to 250 U/L for both cell lines. The antibacterial activity of HB PEGDA/HA-SH 10.0–1.0 hydrogels loaded with increasing amounts of GO was demonstrated against various gram-positive bacteria (S. aureus and S. epidermidis), antibiotic-resistant gram-positive bacteria (MRSA and MRSE), gram-negative bacteria (P. aeruginosa, E. coli, and A. baumanii), and antibiotic-resistant gram-negative strains (P. aeruginosa and E. coli) using agar diffusion tests. For all gram-positive bacterial strains, increasing efficacy was measured with increasing GO activity. For the two P. aeruginosa strains, efficacy was shown only from an enzyme activity of 125 U/L and for E. coli and A. baumanii, efficacy was shown only from 250 U/L enzyme activity. HB PEGDA/HA-SH 10.0–1.0 hydrogels loaded with ≤250 U/L GO and 2.5 wt% glucose are promising formulations due to their fast-forming properties, cytocompatibility, and ability to produce antibacterial H2O2, warranting future investigations for bacterial infection treatment, such as wound care.

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Otoconia perfect/imperfect crystals

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100167949 ◽

1994 ◽

Vol 52 ◽

pp. 42-43

Author(s):

César D. Fermin ◽

Dale Martin

Keyword(s):

Image Processing ◽

Room Temperature ◽

Phosphotungstic Acid ◽

Gallus Domesticus ◽

Crystal Matrix ◽

Organic Templates ◽

Image Processing Algorithms ◽

Processing Algorithms ◽

Diffraction Patterns

Otoconia of higher vertebrates are interesting biological crystals that display the diffraction patterns of perfect crystals (e.g., calcite for birds and mammal) when intact, but fail to produce a regular crystallographic pattern when fixed. Image processing of the fixed crystal matrix, which resembles the organic templates of teeth and bone, failed to clarify a paradox of biomineralization described by Mann. Recently, we suggested that inner ear otoconia crystals contain growth plates that run in different directions, and that the arrangement of the plates may contribute to the turning angles seen at the hexagonal faces of the crystals.Using image processing algorithms described earlier, and Fourier Transform function (2FFT) of BioScan Optimas®, we evaluated the patterns in the packing of the otoconia fibrils of newly hatched chicks (Gallus domesticus) inner ears. Animals were fixed in situ by perfusion of 1% phosphotungstic acid (PTA) at room temperature through the left ventricle, after intraperitoneal Nembutal (35mg/Kg) deep anesthesia. Negatives were made with a Hitachi H-7100 TEM at 50K-400K magnifications. The negatives were then placed on a light box, where images were filtered and transferred to a 35 mm camera as described.

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In Situ Localization of PPAR Gamma and Uncoupling Protein in Mouse Embryo Sections Using Digoxigenin-Labeled Riboprobes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100162624 ◽

1996 ◽

Vol 54 ◽

pp. 32-33

Author(s):

C. Jennermann ◽

S. A. Kliewer ◽

D. C. Morris

Keyword(s):

Alkaline Phosphatase ◽

Room Temperature ◽

Uncoupling Protein ◽

Ppar Gamma ◽

Nuclear Hormone Receptor ◽

Full Length ◽

Northern Analysis ◽

Peroxisome Proliferator

Peroxisome proliferator-activated receptor gamma (PPARg) is a member of the nuclear hormone receptor superfamily and has been shown in vitro to regulate genes involved in lipid metabolism and adipocyte differentiation. By Northern analysis, we and other researchers have shown that expression of this receptor predominates in adipose tissue in adult mice, and appears first in whole-embryo mRNA at 13.5 days postconception. In situ hybridization was used to find out in which developing tissues PPARg is specifically expressed.Digoxigenin-labeled riboprobes were generated using the Genius™ 4 RNA Labeling Kit from Boehringer Mannheim. Full length PPAR gamma, obtained by PCR from mouse liver cDNA, was inserted into pBluescript SK and used as template for the transcription reaction. Probes of average size 200 base pairs were made by partial alkaline hydrolysis of the full length transcripts. The in situ hybridization assays were performed as described previously with some modifications. Frozen sections (10 μm thick) of day 18 mouse embryos were cut, fixed with 4% paraformaldehyde and acetylated with 0.25% acetic anhydride in 1.0M triethanolamine buffer. The sections were incubated for 2 hours at room temperature in pre-hybridization buffer, and were then hybridized with a probe concentration of 200μg per ml at 70° C, overnight in a humidified chamber. Following stringent washes in SSC buffers, the immunological detection steps were performed at room temperature. The alkaline phosphatase labeled, anti-digoxigenin antibody and detection buffers were purchased from Boehringer Mannheim. The sections were treated with a blocking buffer for one hour and incubated with antibody solution at a 1:5000 dilution for 2 hours, both at room temperature. Colored precipitate was formed by exposure to the alkaline phosphatase substrate nitrobluetetrazoliumchloride/ bromo-chloroindlylphosphate.

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Cross-linked nonwoven fibers produced by room temperature cure blowing and in situ photopolymerization: 'Greener' approach to high performance nonwovens

10.1021/scimeetings.0c01646 ◽

2020 ◽

Author(s):

Aditya Banerji ◽

Kailong Jin ◽

Mahesh Mahanthappa ◽

Christopher J Ellison

Keyword(s):

High Performance ◽

Room Temperature ◽

Nonwoven Fibers

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Single Crystal Growth of High-Pressure Phases of Ice and Salt Hydrate Far Below the Original Melting Point by Mixing Alcohol: Crystal Structure Determination of Magnesium Chloride Heptahydrate

10.26434/chemrxiv.11345063.v2 ◽

2020 ◽

Author(s):

Keishiro Yamashita ◽

Kazuki Komatsu ◽

Hiroyuki Kagi

Keyword(s):

Crystal Structure ◽

High Pressure ◽

Crystal Growth ◽

Single Crystal ◽

Room Temperature ◽

Growth Technique ◽

Salt Hydrate ◽

X Ray

An crystal-growth technique for single crystal x-ray structure analysis of high-pressure forms of hydrogen-bonded crystals is proposed. We used alcohol mixture (methanol: ethanol = 4:1 in volumetric ratio), which is a widely used pressure transmitting medium, inhibiting the nucleation and growth of unwanted crystals. In this paper, two kinds of single crystals which have not been obtained using a conventional experimental technique were obtained using this technique: ice VI at 1.99 GPa and MgCl2·7H2O at 2.50 GPa at room temperature. Here we first report the crystal structure of MgCl2·7H2O. This technique simultaneously meets the requirement of hydrostaticity for high-pressure experiments and has feasibility for further in-situ measurements.

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Optics-Free Visualization of Proteins in Single Cells by Time of Flight-Secondary Ion Mass Spectrometry Coupled with Genetically Encoded Chemical Tags

10.26434/chemrxiv.12046125 ◽

2020 ◽

Author(s):

Feifei Jia ◽

Jie Wang ◽

Yanyan Zhang ◽

Qun Luo ◽

Luyu Qi ◽

...

Keyword(s):

Mass Spectrometry ◽

Secondary Ion Mass Spectrometry ◽

Single Cells ◽

Time Of Flight ◽

E Coli ◽

Tof Sims ◽

Ion Mass Spectrometry ◽

Chemical Tags ◽

Secondary Ion

In situ visualization of proteins of interest at single cell level is attractive in cell biology, molecular biology and biomedicine, which usually involves photon, electron or X-ray based imaging methods. Herein, we report an optics-free strategy that images a specific protein in single cells by time of flight-secondary ion mass spectrometry (ToF-SIMS) following genetic incorporation of fluorine-containing unnatural amino acids as a chemical tag into the protein via genetic code expansion technique. The method was developed and validated by imaging GFP in E. coli and human HeLa cancer cells, and then utilized to visualize the distribution of chemotaxis protein CheA in E. coli cells and the interaction between high mobility group box 1 protein and cisplatin damaged DNA in HeLa cells. The present work highlights the power of ToF-SIMS imaging combined with genetically encoded chemical tags for in situ visualization of proteins of interest as well as the interactions between proteins and drugs or drug damaged DNA in single cells.

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