scholarly journals Tubular Electrospun Vancomycin-Loaded Vascular Grafts: Formulation Study and Physicochemical Characterization

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2073
Author(s):  
Rossella Dorati ◽  
Enrica Chiesa ◽  
Mariella Rosalia ◽  
Silvia Pisani ◽  
Ida Genta ◽  
...  
Keyword(s):  
Methylene Chloride ◽  
Physicochemical Characterization ◽  
Fiber Surface ◽  
Solvent System ◽  
Burst Release ◽  
Sem Images ◽  
Composition And Structure ◽  
Medical Healthcare ◽  
Local Release ◽  
Preformulation Study

This work aimed at formulating tubular grafts electrospun with a size < 6 mm and incorporating vancomycin as an antimicrobial agent. Compared to other papers, the present study succeeded in using medical healthcare-grade polymers and solvents permitted by ICH Topic Q3C (R4). Vancomycin (VMC) was incorporated into polyester synthetic polymers (poly-L-lactide-co-poly-ε-caprolactone and poly lactide-co-glycolide) using permitted solvents; moreover, a surfactant was added to the formulation in order to avoid the precipitation of VMC on fiber surface. A preliminary preformulation study was carried out to evaluate solubility of VMC in different aqueous and organic solvents and its stability. To reduce size of fibers and their orientation, we studied a solvent system based on methylene chloride and acetone (DCM/acetone), at different ratios (80:20, 70:30, and 60:40). Considering conductivity of solutions and their spinnability, solvent system at a 80:20 ratio was selected for the study. SEM images demonstrated that size of fibers, their distribution, and their orientation were affected by the incorporation of VMC and surfactant into polymer solution. Surfactant allowed for the reduction of precipitates of VMC on fiber surface, which are responsible of the high burst release in the first six hours; the release was mainly dependent on graft structure porosity, number of pores, and graft absorbent capability. A controlled release of VMC was achieved, covering a period from 96 to 168 h as a function of composition and structure; the concentration of VMC was significantly beyond VMC minimum inhibitory concentration (MIC, 2 ug/mL). These results indicated that the VMC tubular electrospun grafts not only controlled the local release of VMC, but also avoided onset of antibiotic resistance.

scholarly journals Antimicrobial Properties and Release Profile of Ampicillin from Electrospun Poly(εepsilon;-caprolactone) Nanofiber Yarns

2010 ◽  
Vol 5 (4) ◽  
pp. 155892501000500 ◽  
Author(s):  
Hang Liu ◽  
Karen K. Leonas ◽  
Yiping Zhao
Keyword(s):  
In Vitro Release ◽  
Antimicrobial Properties ◽  
Fiber Surface ◽  
Electrospun Nanofibers ◽  
Release Profile ◽  
Burst Release ◽  
Spun Yarns ◽  
Surgical Sutures ◽  
Release Model

Poly(εepsilon;-caprolactone) (PCL) electrospun fibers containing ampicillin sodium salt have been produced and twisted into nanofiber yarns. The fiber diameters and crystallinity, the in vitro antimicrobial properties of the yarns, and the in vitro release of ampicillin from yarns containing various ampicillin concentrations are studied. Decreased fiber diameters and reduced diameter variation are observed with the addition of ampicillin salt into the polymer solution. The results from the zone of inhibition test of the yarns against both gram-positive Staphylococcus aureus and gram-negative Klebsiella pneumoniae indicate that the released ampicillin retains its effectiveness after the production processes, therefore the as-spun yarns are antimicrobial active. A burst release of ampicillin from the yarns has been observed in the first hour, and the release is almost completed in 96 hours. The burst release is believed to be due to the low compatibility of ampicillin with PCL, the accumulation of ampicillin on fiber surface and the small fiber diameters. An empirical release model is developed to describe the release profile. The results indicate that the electrospun nanofibers yarns will have a great potential to be used for biomaterials, such as surgical sutures, to decrease the surgical site infection rate.

Improving the efficiency of enzymatic hydrolysis of Eucalyptus residues with a modified aqueous ammonia soaking method

2018 ◽  
Vol 33 (2) ◽  
pp. 165-174 ◽  
Author(s):  
Dan Huo ◽  
Qiulin Yang ◽  
Guigan Fang ◽  
Qiujuan Liu ◽  
Chuanling Si ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Enzymatic Hydrolysis ◽  
Aqueous Ammonia ◽  
Pulp Mill ◽  
Fiber Surface ◽  
Raw Material ◽  
Sem Images ◽  
Aqueous Ammonia Soaking ◽  
Guaiacyl Lignin ◽  
Hydrolysis Of

Abstract Eucalyptus residues from pulp mill were pretreated with aqueous ammonia soaking (AAS) method to improve the efficiency of enzymatic hydrolysis. The optimized condition of AAS was obtained by response surface methodology. Meanwhile, hydrogen peroxide was introduced into the AAS system to modify the AAS pretreatment (AASP). The results showed that a fermentable sugar yield of 64.96 % was obtained when the eucalypt fibers were pretreated at the optimal conditions, with 80 % of ammonia (w/w) for 11 h and keeping the temperature at 90 °C. In further research it was found that the addition of H2O2 to the AAS could improve the pretreatment efficiency. The delignification rate and enzymatic digestibility were increased to 64.49 % and 73.85 %, respectively, with 5 % of hydrogen peroxide being used. FTIR analysis indicated that most syringyl and guaiacyl lignin and a trace amount of xylan were degraded and dissolved during the AAS and AASP pretreatments. The CrI of the raw material was increased after AAS and AASP pretreatments, which was attributed to the removal of amorphous portion. SEM images showed that microfibers were separated and explored from the initial fiber structure after AAS pretreatment, and the AASP method could improve the destructiveness of the fiber surface.

scholarly journals Quantitative Analysis of Sulpiride and Impurities of 2-Aminomethyl-1-Ethylpyrrolidine and Methyl-5-Sulphamoyl-2-Methoxybenzoate in Pharmaceuticals by High-Performance Thin-Layer Chromatography and Scanning Densitometry

1999 ◽  
Vol 82 (4) ◽  
pp. 825-829 ◽  
Author(s):  
Danica Agbaba ◽  
Tatjana Miljkovic ◽  
Valentina Marinkovic ◽  
Dobrila Zivanov-Stakic ◽  
Sote Vladimirov
Keyword(s):  
Quantitative Analysis ◽  
Thin Layer ◽  
High Performance ◽  
Methylene Chloride ◽  
Solvent System ◽  
Ammonia Solution ◽  
Dosage Forms ◽  
Raw Material ◽  
Layer Chromatography

Abstract A simple and reliable thin-layer chromatographic method for determining sulpiride and impurities of 2-aminomethyl-1-ethylpyrrolidine and methyl-5-sulphamoyl-2-methoxybenzoate was developed and validated. A methylene chloride–methanol–ammonia solution (25%; 18 + 2.8 + 0.4, v/v) solvent system is used for separation and quantitative evaluation of chromatograms. The chromatographic plate is first scanned at 240 nm to locate chromatographic zones corresponding to sulpiride and methyl-5-sulphamoyl-2-methoxybenzoate. Then 2-aminomethyl-1-ethylpyrrolidine is derivatized in situ with ninhydrin, and resulting colored spots are measured at 500 nm. The method is reproducible and convenient for quantitative analysis and purity control of sulpiride in its raw material and in its dosage forms.

scholarly journals Fabrication and Characterization of Strontium-Substituted Hydroxyapatite-CaO-CaCO3 Nanofibers with a Mesoporous Structure as Drug Delivery Carriers

Pharmaceutics ◽  
2018 ◽  
Vol 10 (4) ◽  
pp. 179 ◽  
Author(s):  
Shiao-Wen Tsai ◽  
Wen-Xin Yu ◽  
Pai-An Hwang ◽  
Sheng-Siang Huang ◽  
Hsiu-Mei Lin ◽  
...  
Keyword(s):  
Drug Carrier ◽  
Drug Loading ◽  
Average Pore Size ◽  
Sol Gel ◽  
Mesoporous Structure ◽  
Drug Carriers ◽  
Burst Release ◽  
Doping Amount ◽  
Sem Images ◽  
Average Pore

Hydroxyapatite (HAp) is the main inorganic component and an essential part of hard bone and teeth. Due to its excellent biocompatibility, bioactivity, and osteoconductivity, synthetic HAp has been widely used as a bone substitute, cell carrier, and therapeutic gene or drug carrier. Recently, numerous studies have demonstrated that strontium-substituted hydroxyapatite (SrHAp) not only enhances osteogenesis but also inhibits adipogenesis in mesenchymal stem cells. Mesoporous SrHAp has been successfully synthesized via a traditional template-based process and has been found to possess better drug loading and release efficiencies than SrHAp. In this study, strontium-substituted hydroxyapatite-CaO-CaCO3 nanofibers with a mesoporous structure (mSrHANFs) were fabricated using a sol–gel method followed by electrospinning. X-ray diffraction analysis revealed that the contents of CaO and CaCO3 in the mSrHANFs decreased as the doping amount of Sr increased. Scanning electron microscopy (SEM) images showed that the average diameter of the mSrHANFs was approximately 200~300 nm. The N2 adsorption–desorption isotherms demonstrated that the mSrHANFs possessed a mesoporous structure and that the average pore size was approximately 20~25 nm. Moreover, the mSrHANFs had excellent drug- loading efficiency and could retard the burst release of tetracycline (TC) to maintain antibacterial activity for over 3 weeks. Hence, mSrHANFs have the potential to be used as drug carriers in bone tissue engineering.

Fabrication of Polyacrylonitrile Nanofiber Membranes Functionalized With Metal Organic Framework for CO2 Capturing

2015 ◽  
Author(s):  
Wahiduzzaman ◽  
Mujibur Khan ◽  
Saheem Absar ◽  
Spencer Harp ◽  
Kyle Edwards ◽  
...  
Keyword(s):  
Gas Adsorption ◽  
Metal Organic Framework ◽  
Fiber Surface ◽  
Precursor Solution ◽  
Electrospun Nanofibers ◽  
Primary Component ◽  
Secondary Process ◽  
Sem Images ◽  
Filter System ◽  
Metal Organic

Crystalline particles known as Metal Organic Frameworks (MOF’s) are known for their large surface area and high adsorption and storage capacity for CO2 gas. Electrospun nanofibers are considered as ideal substrates for synthesizing the MOF particles on the fiber surface. In this project, Polyacrylonitrile (PAN) and a Cu-based MOF known as HKUST-1 were selected as substrate fibers and adsorbent particles respectively. A precursor solution of PAN polymer hybridized with HKUST-1 particles dissolved in Dimehtylformamide (DMF) is used as the primary component solution for electrospinning. SEM images of the electrospun fibers showed small MOF particles formation into the fiber structure. A secondary solvothermal process of MOF particles growing on the fibers was then executed to increase the amount of MOF particles for effectual gas adsorption. The secondary process consists of multiple growth cycles and SEM images showed uniform distribution of porous MOF particles of 2–3μm in size on the fiber surface. EDS report of the fiber confirmed the presence of MOF particles through identification of characteristic Copper elemental peaks of HKUST-1. Thermogravitmetric analysis (TGA) of HKUST-1 doped PAN fiber displayed 32% of total weight loss between 180°C and 350°C thus proving the as-synthesized MOF particles are thermally stable within the mentioned temperature range. A comparative IR spectroscopic result between the gas-treated and gas-untreated fiber samples showed the presence of characteristic peak in the vicinity of 2300 and 2400cm−1 which corroborates the assertion of adsorption of CO2 on the system. Further step involved is to investigate the gas adsorption capacity of the filter system in an experimental test bench. Non-dispersive Infrared (NDIR) CO2 sensors will be used at the gas inlet and outlet parts to measure the concentration of CO2 and determine the amount of gas uptake by the filter system.

OMG Neutral Deinking Technical Conditions and Mechanism

2011 ◽  
Vol 236-238 ◽  
pp. 1351-1354 ◽  
Author(s):  
Xiao Lin Zhang ◽  
Ru Min Wang
Keyword(s):  
Electron Microscopy ◽  
Fiber Surface ◽  
Single Factor ◽  
Sem Images ◽  
Operation Conditions ◽  
Microscope Images ◽  
Before And After ◽  
Distribution State ◽  
Single Factor Experiment ◽  
Scanning Electron

Single factor experiment was used to investigate neutral deinking technology of old magazine paper (OMG) by self-compounded NTM-2 deinking agent. Olympus inverted biological microscope were used to research distribution state of ink particles in the secondary pulp before and after deinking treatment. Scanning electron microscopy (SEM) was used to analyze fiber surface changing during neutral deinking and ink particles dispersing behaviors in the paper. The results showed that NTM-2 deinking agent had a good deinking effect to OMG, optimum operation conditions of neutral deinking was NTM-2 0.5%, deinking temperature 50°C, deinking time 40min, repulper time 25s, pulp consistence 1.0%, and floatation time 6 min. Under these conditions, brightness of the deinked pulp increased 8.4%SBD, and the ink removal efficiency reached by 90%. Olympus inverted biological microscope images showed that there were a large number of ink particles in the un-treated pulp, and these ink particles integrated with fibers tightly. After treated by neutral deinking, most of ink particles were separated from the fiber, dispersed and suspended in the pulp evenly. SEM images indicated that there were little ink particles in the secondary paper, the fiber surface turned more smoother, and the clean degree would nearly corresponding to the effect of alkaline deinking.

Susceptibility of Strawberries, Blackberries, and Cherries to Aspergillus Mold Growth and Aflatoxin Production

1982 ◽  
Vol 65 (3) ◽  
pp. 659-664 ◽  
Author(s):  
Gerald C Llewellyn ◽  
Thomas Eadie ◽  
William V Dashek
Keyword(s):  
Acetic Acid ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Mycelial Growth ◽  
Methylene Chloride ◽  
Aflatoxin Production ◽  
Solvent System ◽  
Mold Growth ◽  
Tlc Plates ◽  
Layer Chromatography

Abstract The susceptibility of blackberries, cherries, and strawberries to Aspergillus growth and aflatoxin production has been examined. Three aflatoxigenic isolates of Aspergillus, A. flavus ATCC 15548 and NRRL 3251 as well as A. parasiticus NRRL 2999, were cultured on homogenates of the fruits for 14 days at 28 ± 2°C. Percent mycelial growth and spore infestation were determined each day with a calibrated grid. At day 14 each culture was frozen at –5°C until aflatoxins were extracted with methylene chloride and water. Aflatoxins were separated by thin layer chromatography (TLC) with benzene-methanol-acetic acid (90 + 5 + 5). This extraction and solvent system provided satisfactory separations of the aflatoxins and was free of background interference on the TLC plates. Although all fruits served as substrates for both Aspergillus growth and aflatoxin production, cherries appeared to be a more favorable substrate than did blackberries, and the latter was more favorable than strawberries. Whereas A. flavus produced both B1 and G1 on all substrates, it yielded B2 and G2 only on cherries. Although A. parasiticus NRRL 2999 synthesized B1, B2, G1, and G2 on both blackberries and cherries, no aflatoxins were detected on strawberries. In contrast, A. flavus NRRL 3251 failed to produce detectable levels of aflatoxin on any substrate. All substrates supported both mycelial growth and subsequent sporulation with cherries &gt; blackberries &gt; strawberries.

Isomerization of Retinyl Palmitate Using Conventional Lipid Extraction Solvents

1983 ◽  
Vol 66 (3) ◽  
pp. 746-750
Author(s):  
Mary C Mulry ◽  
Ronald H Schmidt ◽  
James R Kirk
Keyword(s):  
High Performance ◽  
Methylene Chloride ◽  
Lipid Extraction ◽  
Chlorinated Solvents ◽  
Solvent System ◽  
Retinyl Palmitate ◽  
Fluorometric Detection ◽  
Butyl Ether ◽  
Water Solvent ◽  
Extraction Solvents

Abstract The use or a chlorotorm-ethanol-water solvent system for the direct extraction of retinyl palmitate isomers from fortified food products was previously shown to be unsuitable because significant isomerization of all-trans-retinyl palmitate occurred during the extraction. This study investigated the extent of isomerization of retinyl palmitate in various extraction solvents when subjected to gold fluorescent laboratory light. Purified solutions of all-trans-retinyl palmitate in hexane were diluted with methyl t-butyl ether, hexane, methylene chloride, and stabilized chloroform and subjected to gold fluorescent laboratory light for 2, 4, and 6.5 h. Similar solutions were subjected to light or kept in the dark for 3.5 h. All-trans-, 9-cis-, and 13-cis-retinyl palmitate esters in the solutions were determined by using normal phase high performance liquid chromatography with fluorometric detection. Results demonstrated a noticeable increase in the 9-cis-retinyl palmitate concentration and a corresponding decrease in all-trans-retinyl palmitate concentration with time, in chloroform and methylene chloride compared with hexane. Chlorinated solvents in the absence of light did not promote isomerization of retinyl palmitate. Use of chlorinated solvents for the extraction of vitamin A esters should be avoided because they promote isomerization of retinyl palmitate when subjected to light, including gold fluorescent laboratory light.

scholarly journals Fabrication of Air Freshening Spongy Three Dimensional Electrospun Membrane

2018 ◽  
Vol 14 (1) ◽  
pp. 14-21
Author(s):  
Purnima Mulmi ◽  
Hem Raj Pant
Keyword(s):  
Essential Oil ◽  
Three Dimensional ◽  
Solvent System ◽  
Porous Membrane ◽  
Electrospinning Process ◽  
Potential Candidate ◽  
Oil Uptake ◽  
Electrospun Membrane ◽  
Sem Images ◽  
Fragrance Release

 In this work, air freshening spongey 3D nanofibrous membrane of nylon-6 (N6) is fabricated via electrospinning process. Viscous N6 solution dissolved in formic acid/acetic acid solvent system was allowed for electrospinning to obtain 2D membrane. As-fabricated 2D membrane is converted into 3D one by using gas foaming technique. Lemon grass essential oil as a fragrance was incorporated through 2D and 3D porous membrane by evaporating essential oil at 60°C for 5 hours. The morphology of different membranes was examined from FE-SEM images which showed that 3D membrane is far porous than 2D one. The control fragrance release from the 3D spongy membrane was evaluated from the weight loss of oil-loaded membrane for 60 days which showed that the 3D membrane had more oil uptake and the controlled release of oil over the studied time. FT-IR spectra of oil-incorporated 3D membrane at different interval of times indicated the presence of fragrance even after the 60 days. The result showed that as-fabricated sponge 3D membrane may be a potential candidate for the future air freshening materials.Journal of the Institute of Engineering, 2018, 14(1): 14-21

Beta-carotene determined in serum by liquid chromatography with an internal standard.

1983 ◽  
Vol 29 (6) ◽  
pp. 1042-1044 ◽  
Author(s):  
W J Driskell ◽  
M M Bashor ◽  
J W Neese
Keyword(s):  
Liquid Chromatography ◽  
High Performance ◽  
Methylene Chloride ◽  
Internal Standard ◽  
Beta Carotene ◽  
Solvent System ◽  
Peak Height ◽  
Reversed Phase ◽  
Human Populations ◽  
Relationship Of

Abstract We describe a procedure for quantitative determination of beta-carotene in human serum. The 0.1-mL serum sample is precipitated with ethanol containing the internal standard, dimethyl-beta-carotene, then extracted with hexane. This extract is injected onto a reversed-phase, "high-performance" liquid-chromatography column, and the carotenes are resolved and eluted with an acetonitrile/methylene chloride isocratic solvent system. They are quantified from the peak-height ratios of their absorbance at 450 nm. About 14 min is required for each chromatogram. The procedure has excellent precision and is appropriate for routine use in analysis of large numbers of samples. The method should be particularly useful for clinical studies on the relationship of serum beta-carotene and cancer incidence in human populations.

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