scholarly journals Production and enzymatic degradation of poly(ε-caprolactone)/graphene oxide composites

2020 ◽  
Vol 10 (6) ◽  
pp. 866-876
Author(s):  
V. Martínez-Ramón ◽  
I. Castilla-Cortázar ◽  
A. Vidaurre ◽  
A. J. Campillo-Fernández
Keyword(s):  
Graphene Oxide ◽  
Enzymatic Degradation ◽  
Morphological Changes ◽  
Phosphate Buffer Solution ◽  
Oxide Content ◽  
Buffer Solution ◽  
Scanning Calorimetry ◽  
Weight Loss Data ◽  
Mixing Method ◽  
Oxide Composites

Poly(ε-caprolactone) (PCL) based composites containing different graphene oxide (GO) contents (0.1, 0.2 and 0.5 wt%) were produced by the solution mixing method followed by compression molding and enzymatically degraded in a pH 7.4 phosphate buffer solution containing Pseudomonas lipase at 37 °C. Morphological changes, molecular weight, calorimetric and mechanical properties were analyzed according to graphene oxide content. The study of tensile properties showed that the composites increased their Young’s modulus, while tensile strength and elongation at break decreased to significantly less than that of neat PCL. PCL composite crystallinity was evaluated by differential scanning calorimetry (DSC). It was found that incorporating GO can reduce nucleation activity as well as crystallization rates, from 67.6% for neat PCL to 50.6% for a composite with 0.5 wt% GO content. For enzymatic degradation, the weight loss data showed that incorporating GO into the PCL significantly altered enzymatic degradation. The presence of GO did not alter PCL’s hydrolysis mechanism, but did slow down composite enzymatic degradation in proportion to the percentage of filler content.

Surface Morphological Changes Accompanying Dissolution of Bioactive Glass: Effect of Residual Stress

2008 ◽  
Vol 47-50 ◽  
pp. 1302-1306 ◽  
Author(s):  
John A. Nychka ◽  
Ding Li
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Bioactive Glass ◽  
Morphological Changes ◽  
Phosphate Buffer Solution ◽  
Buffer Solution ◽  
Mechanochemical Effect ◽  
Dissolution Behaviour ◽  
Glass Surfaces

We report our observations concerning the time evolution of surface morphology occurring during the in vitro immersion of bioactive glass surfaces in contact with phosphate buffer solution. We compare regions under intentionally produced residual stresses via micro-indentation to those where no indentation was performed. The sign of the residual stress is shown to be important for predicting dissolution behaviour; compression retards dissolution, whereas tension enhances dissolution. We analyze our results with a simple model for the work of bond dissociation. We report that a highly constrained residual compressive stress state, such as in an indent, leads to a work deficit in comparison to tension, which accounts for the slower dissolution rate of compressed bioactive glass. Such a mechanochemical effect suggests that the presence of residual stresses from the manufacture of biomedical implants and devices could lead to accelerated or delayed dissolution and that careful control of residual stresses should be sought for predictable performance in dissolvable materials.

scholarly journals Synthesis, Characterization, and Biodegradation Studies of Poly(1,4-cyclohexanedimethylene-adipate-carbonate)s

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Ajay S. Chandure ◽  
Ganesh S. Bhusari ◽  
Suresh S. Umare
Keyword(s):  
Weight Loss ◽  
Enzymatic Degradation ◽  
Hydrolytic Degradation ◽  
Phosphate Buffer Solution ◽  
Film Surface ◽  
Solution Viscosity ◽  
Buffer Solution ◽  
Sem Images ◽  
Titanium Butoxide ◽  
Soil Burial

Aliphatic/alicyclic poly(1,4-cyclohexanedimethylene-adipate-carbonate)s (PCACs) were synthesized by a transesterification from 1,4-cyclohexamethylendimethanol (1,4-CHDM), adipic acid (AA), diethyl carbonate (DEC), and titanium butoxide Ti(OBu)4 as a transesterification catalyst. The synthesized PCACs were characterized by the Fourier transform infrared (FTIR), X-ray diffraction analysis (XRD), solubility, solution viscosity, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscope (SEM) for their structural, physical, thermal, and morphological investigation. The structure of synthesized PCACs was confirmed by FTIR. All TGA curves of PCACs shows 10% weight loss above 270°C, and they reveal good thermal stability. Biodegradability of PCACs was investigated by hydrolytic degradation at (pH 7.2 and 11.5), enzymatic degradation using Rhizopus delemar lips at 37°C in phosphate buffer solution (PBS), and soil burial degradation at 30°C. The hydrolytic degradation shows the greater rate of weight loss in PBS at pH-11.5 than pH-7.2. The hydrolytic and soil burial degradation shows faster rate of weight loss as compared to enzymatic degradation. Biodegradation rate of PCACs follows the order: PCAC-20 > PCAC-40 > PCAC-60. SEM images show that degradation occurred all over the film surface, creating holes and cracks. These biodegradable PCACs may be able to replace conventional polymer in the fabrication of packaging film in near future.

The role of graphene oxide content on the adsorption-enhanced photocatalysis of titanium dioxide/graphene oxide composites

2011 ◽  
Vol 170 (1) ◽  
pp. 226-232 ◽  
Author(s):  
Thuy-Duong Nguyen-Phan ◽  
Viet Hung Pham ◽  
Eun Woo Shin ◽  
Hai-Dinh Pham ◽  
Sunwook Kim ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Graphene Oxide ◽  
Oxide Content ◽  
Oxide Composites

Chiral Separation of Racemic Naproxen by High-Performance Liquid Chromatography with β-CD/SiO2 as the Chiral Stationary Phase

2014 ◽  
Vol 97 (1) ◽  
pp. 121-127 ◽  
Author(s):  
Lili Wang ◽  
Jian Deng ◽  
Xuezhen Ji ◽  
Wanbin Liu ◽  
Jun Liang ◽  
...  
Keyword(s):  
Stationary Phase ◽  
Chiral Separation ◽  
Photoelectron Spectroscopy ◽  
High Performance ◽  
Chiral Stationary Phase ◽  
Separation Efficiency ◽  
Phosphate Buffer Solution ◽  
Buffer Solution ◽  
Scanning Calorimetry ◽  
Column Temperature

Abstract A novel derivative β-cyclodextrin (β-CD) bonded silica gel (β-CD/SiO2) was prepared via carbodiimide activation and used as a chiral stationary phase (CSP). The β-CD/SiO2 CSP was characterizedby X-ray photoelectron spectroscopy and FTIR spectroscopy to prove the successful immobilization of β-CD onto the surface of the silica gel.The thermal behavior of the CSP was studied by differential scanning calorimetry and then used forthe chiral separation of racemic naproxen using HPLC. Several factors affecting the separation efficiency of naproxen enantiomers were investigatedsystematically. The following parameters were selected: methanol–0.01 M phosphate buffer solution (85 + 15, v/v, pH 3.5) was the mobile phase, the flow rate was 1.0 mL/min, and the column temperature was 35°C. Under optimal conditions, the racemic naproxen was efficiently separated with a resolution factor (RS) of 1.70 and a separation factor (α) of 1.25. This method was successfully used for the enantiomeric separation and purity assessment of naproxen in commercial naproxen sustained release tablets.

scholarly journals Temperature-Sensitive Poly(N-isopropylacrylamide)/Konjac Glucomannan/Graphene Oxide Composite Membranes with Improved Mechanical Property, Swelling Capability, and Degradability

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Guohong Zou ◽  
Juan Shen ◽  
Peizhen Duan ◽  
Xu Xia ◽  
Rigui Chen ◽  
...  
Keyword(s):  
Mechanical Property ◽  
Graphene Oxide ◽  
Enzymatic Degradation ◽  
Composite Membranes ◽  
Konjac Glucomannan ◽  
Temperature Sensitive ◽  
Scanning Calorimetry ◽  
Solution Blending ◽  
Phase Transition Temperatures ◽  
Potential Applications

Temperature-sensitive poly(N-isopropylacrylamide)/konjac glucomannan/graphene oxide (PNIPAM/KGM/GO) composite membranes were prepared by solution blending using calcium ions as a cross-linker. The composite membranes were characterized by Fourier-transform infrared spectroscopy (FT-IR), field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Raman spectroscopy (Raman), and differential scanning calorimetry (DSC). The swelling, mechanical property, phase transformation behaviors, and enzymatic degradation activities were also determined. Results revealed that the phase transition temperatures of all the composite membranes were approximately 35°C. The PNIPAM/KGM/GO composite membranes showed enhanced mechanical property. The swelling behavior and enzymatic degradation of the PNIPAM/KGM/GO composite membranes improved compared with those of conventional PNIPAM hydrogel and PNIPAM/KGM composite membranes. Thus, the PNIPAM/KGM/GO composite membranes have potential applications in the biomedical field as skin dressings.

scholarly journals Determining the Optimal Conditions for the Production by Supercritical CO2 of Biodegradable PLGA Foams for the Controlled Release of Rutin as a Medical Treatment

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1645
Author(s):  
Diego Valor ◽  
Antonio Montes ◽  
Marilia Monteiro ◽  
Ignacio García-Casas ◽  
Clara Pereyra ◽  
...  
Keyword(s):  
Controlled Release ◽  
Drug Release ◽  
Mercury Intrusion Porosimetry ◽  
Phosphate Buffer Solution ◽  
Polymer Foam ◽  
Expansion Factor ◽  
Buffer Solution ◽  
Scanning Calorimetry ◽  
High Pressure And Temperature ◽  
Supercritical Foaming

Poly(D,L,-lactide-co-glycolide) (PLGA) foam samples impregnated with rutin were successfully produced by supercritical foaming processes. A number of parameters such as pressure (80–200 bar), temperature (35–55 °C), depressurization rate (5–100 bar/min), ratio lactide:glycolide of the poly(D,L,-lactide-co-glycolide) (50:50 and 75:25) were studied to determine their effect on the expansion factor and on the glass transition temperature of the polymer foams and their consequences on the release profile of the rutin entrapped in them. The impregnated foams were characterized by scanning electron microscopy, differential scanning calorimetry, and mercury intrusion porosimetry. A greater impregnation of rutin into the polymer foam pores was observed as pressure was increased. The release of rutin in a phosphate buffer solution was investigated. The controlled release tests confirmed that the modification of certain variables would result in considerable differences in the drug release profiles. Thus, five-day drug release periods were achieved under high pressure and temperature while the depressurization rate remained low.

scholarly journals Electrochemical sensor for determination of hydroxylamine using functionalized Fe3O4 nanoparticles and graphene oxide modified screen-printed electrode

2021 ◽  
Author(s):  
Hamed Tashakkorian ◽  
Behnaz Aflatoonian ◽  
Peyman Mohammadzadeh Jahani ◽  
Mohammad Reza Aflatoonian
Keyword(s):  
Graphene Oxide ◽  
Electrochemical Sensor ◽  
Fe3o4 Nanoparticles ◽  
Phosphate Buffer Solution ◽  
Electrochemical Process ◽  
Screen Printed Electrode ◽  
Buffer Solution ◽  
Solution Ph ◽  
Screen Printed

A simple strategy for determination of hydroxylamine based on Fe3O4 nanoparticles function­nalized by [2-(4-((3-(trimethoxysilyl)propylthio)methyl)1-H1,2,3-triazol-1-yl)acetic­acid] (FNPs) and graphene oxide (GO) modified screen-printed electrode (SPE), denoted as (Fe3O4 FNPs/GO/SPE), is reported. The electrochemical behavior of hydroxylamine was investigated at Fe3O4FNPs/GO/SPE by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and chro­noamperometry (CHA) techniques in phosphate buffer solution (pH 7.0). Fe3O4 FNPs/GO/SPE as a novel electrochemical sensor exhibited catalytic activity toward the oxidation of hydroxyl­ami­ne. The potential of hydroxylamine oxidation was shifted to more negative potentials, and its oxidation peak current increased on the modified electrode, also indicating that under these conditions, the electrochemical process is irreversible. The electrocatalytic current of hydroxyl­amine showed a good relationship in the concentration range of 0.05–700.0 μM, with a detection limit of 10.0 nM. The proposed electrode was applied for the determination of hydroxyl­amine in water samples, too.

scholarly journals Morphology, Crystallinity, and Molecular Weight of Poly(ε-caprolactone)/Graphene Oxide Hybrids

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1099 ◽  
Author(s):  
Castilla-Cortázar ◽  
Vidaurre ◽  
Marí ◽  
Campillo-Fernández
Keyword(s):  
Molecular Weight ◽  
Graphene Oxide ◽  
Biomedical Applications ◽  
Morphological Changes ◽  
Gel Permeation Chromatography ◽  
Biological Properties ◽  
Intermolecular Hydrogen Bonds ◽  
Depth Study ◽  
Apparent Reduction ◽  
Mixing Method

A study was carried out to determine the effects of graphene oxide (GO) filler on the properties of poly(ε-caprolactone) (PCL) films. A series of nanocomposites were prepared, incorporating different graphene oxide filler contents (0.1, 0.2, and 0.5 wt%) by the solution mixing method, and an in-depth study was made of the morphological changes, crystallization, infrared absorbance, molecular weight, thermal properties, and biocompatibility as a function of GO content to determine their suitability for use in biomedical applications. The infrared absorbance showed the existence of intermolecular hydrogen bonds between the PCL’s carbonyl groups and the GO’s hydrogen-donating groups, which is in line with the apparent reduction in molecular weight at higher GO contents, indicated by the results of the gel permeation chromatography (GPC), and the thermal property analysis. Polarized optical microscopy (POM) showed that GO acts as a nucleating point for PCL crystals, increasing crystallinity and crystallization temperature. The biological properties of the composites studied indicate that adding only 0.1 wt% of GO can improve cellular viability and that the composite shows promise for use in biomedical applications.

Preparation and Characterization of Chitosan-Gelatin Films with Na2SO4 Cross-Linked for Controlled-Release of Nitrofurantoin

2017 ◽  
Vol 757 ◽  
pp. 78-82 ◽  
Author(s):  
Weenawan Somphon ◽  
Siriporn Samnaree
Keyword(s):  
Controlled Release ◽  
Water Absorption ◽  
Drug Carrier ◽  
Phosphate Buffer Solution ◽  
Absorption Capacity ◽  
Antibacterial Drug ◽  
Buffer Solution ◽  
Scanning Calorimetry ◽  
Solution Ph ◽  
Nausea And Emesis

This work prepared and characterized of chitosan (Cs)-gelatin (Gel) films for the controlled release of the nitrofurantoin (NF) antibacterial drug. The side effects of NF are nausea and emesis due to its high absorption rate immediately after oral administration. The use of Cs-Gel films enables economic production of the drug carrier system. Cs-Gel films were prepared by mixing Cs with Gel at different ratios and were cross-linked with Na2SO4 with different concentrations. NF was loaded into the films by soaking of drug solution. Films were characterized by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and evaluated for thickness, water absorption capacity, swelling behaviour and invitro NF drug release in phosphate buffer solution pH 5.8 and pH 7.4. The results indicated that additional amount of gelatin and sulfate ion cross-linked to the films increased the swelling, water absorption ability and also improved NF release.

Sign in / Sign up

Export Citation Format

Share Document