Objectives: Reversible addition-fragmentation chain transfer (RAFT) polymerization belongs to the controlled/living radical polymerization methods and is highly efficient in the preparation of ...well-defined drug and gene delivery vesicles. Methods: Via RAFT Polymerization different amphlphilic block copolymers consisting of poly(N- acryloyl morpholine) or poly(N-isopropytacrylamide) and poly2-hydroxyethyl methacrylate-block-poly( epsilon -caprolactone) have been prepared. Two different trithiocarbonate RAFT agents have been used and AIBN acted as initiator. As fluorescence marker in cell imaging Fluorescein methacrylate was copolymerized in the hydrophobic block. Micelles were formed by dialysis and their hydrodynamic diameter was characterized by dynamic light scattering (DLS). Results We successfully prepared well-defined amphiphilic block copolymers with low polydispersity indices by RAFT polymerization. They are composed of poly(N-acryloyl morpholine) and poly(N-isopropylacrylamide) as hydrophilic part and biodegradable poly2-hydroxyethyl methacrylate-poly( epsilon -caprolactone) in the hydrophobic part The ability of these block copolymers to self assemble into micelles in an aqueous surrounding was determined by DLS. The uptake of the micelles into living cells was shown by fluorescence imaging. Further modification of the block copolymers is possible due to succinimide units in the polymer backbone. Conclusions Based on biodegradable amphiphilic block copolymers we designed new smart drug carriers, which can assemble into micelles. Because of succinimide groups in the hydrophobic part these block copolymers are able to bind drugs with an amino functionality. The fluorescein moiety included in the polymer backbone allows to monitor the cellular drug uptake by fluorescence imaging. Enzymatic degradation studies of the micelles are currently ongoing.
Objectives: Biodegradable fibers with controlled properties may meet the requirements for medical applications. Poly(lactic acid) (PLA) is a biodegradable linear aliphatic thermoplastic polyester. ...PLA fibers with five type spin finishes were prepared and assayed for in vitro cytotoxic activities. Methods: The PLA fibers were prepared by a two-step melt-spinning process. The PLA Polymer 6201D, fiber grade with nominal MFI=15-30 g/10min, a NatureWorks LLC product was used. PLA fibers were coated with 5 types of spin finishes: PLA 24 with 2.4% of Glicerol Ph Eur, PLA 25 - 0.40% of Lurol PL 801, PLA 26-0.61% of Stantex 6457, PLA 27-0.36% of Lurol PT-L216, PLA28-0.62% of Estesol PF 790. The fibers with linear density 2.2 - 4.8 dtex, tenacity 35-39 cN/tex, elongation similar to 50% were obtained. To determine if they can affect cells, line cultures L929 (ATCC CCL1) was used. The cells (2x10 super(8) cells/mL) were incubated with fibers for 24h, 48h and 72h (37 degree C, 5% CO sub(2). Cell growth, morphology and viability were determined. Results: After 72h incubation, the level of cytotoxicity of PLA 24 fibers was 2 (% dead-38), PLA 25 - 3 (% dead-100), PLA 27 - 3 (% dead-100), PLA 28 - 0 (% dead-99), control fenol-3 (% dead-94), L929-0 (% dead-3). Conclusions: Fibroblast cultures after contact with the four of PLA fibres showed cytotoxity effects. The cells were dead with hanged morphologie and lower proliferation. The result of the testing of PLA fibers with Estesol spin finish did not show any cytotoxicity effects and may be promising candidate for medical applications.
Biodegradable plastics (BDP) are expected to mineralize easily, in particular under conditions of technical composting. However, the complexity of the sample matrix has largely prevented degradation ...studies under realistic conditions. Here composts and fertilizers from state-of-the-art municipal combined anaerobic/aerobic biowaste treatment plants were investigated for residues of BDP. We found BDP fragments > 1 mm in significant numbers in the final composts intended as fertilizer for agriculture and gardening. Compared to pristine compostable bags, the recovered BDP fragments showed differences in their material properties, which potentially renders them less prone to further biodegradation. BDP fragments < 1 mm were extracted in bulk and came up to 0.43 wt% of compost dry weight. Finally, the liquid fertilizer produced during the anaerobic treatment contained several thousand BDP fragments < 500 µm per liter. Hence, our study questions, if currently available BDP are compatible with applications in areas of environmental relevance, such as fertilizer production.
Tungsten disulphide inorganic nanotubes (INT-WS sub(2)) were used to prepare advanced biodegradable polymer nanocomposites. The biopolymer matrix employed, poly(3-hydroxybutyrate) (PHB), is one of ...the most extensively researched and utilized biodegradable and renewable thermoplastic polyesters. Results from differential scanning calorimetry (DSC) and time-resolved synchrotron X-ray diffraction demonstrate that the crystallization and melting behaviour of PHB/INT-WS sub(2) nanocomposites is dependent on both the INT-WS sub(2) concentration and the cooling rate. The addition of low INT-WS sub(2) loadings strongly increases the crystallization rate of PHB, reducing the activation energy with as little as 0.1 wt.% INT, which is very important for the processing of PHB. The nucleating activity of INT-WS sub(2) in the orthorhombic phase of PHB reaches very low values ( phi = 0.45), indicating that INT-WS sub(2) actually acts as a highly efficient nucleating agent for the crystallization of PHB. This corresponds to the lowest value observed to date for PHB formulations using specific nucleating agents or nano-sized fillers, which is of significant importance for extending the practical applications of these biodegradable polymer nanocomposites.
The reactive oxygen species (ROS) originated from endogenous and exogenous sources play a dominant role in the initiation and propagation of several diseases. It is therefore an urgent need to ...explore substances capable of encountering the ROS and resist the damage caused by ROS. The present paper deals with various aspects of generation and implications of ROS in the management of myocardial infarction. The use of biosynthetic amphiphilic biodegradable hydrogels in the control and management of ROS in myocardial infarction was studied using a biosynthetic hydrogel (PA-PEGDA) comprising poly(propylene fumarate)-co-alginate copolymer cross-linked with calcium and polyethylene glycol diacrylate (PEGDA). The effect of ROS on the cell growth was studied using H sub( 2)O sub( 2) as model ROS molecule. The present hydrogel resists the penetration of ROS in the cell which was evident from the live/dead assay, increased intra cellular GSH levels when compared with the H sub( 2)O sub( 2) treated positive and curcumin treated negative control cells. The Comet assay reveals genomic integrity of the cells exposed to the present hydrogel. The hydrogel is a promising injectable material for the management of myocardial infarction and ischemia.
Poly(ethylene glycol) (PEG) hydrogels are water-swellable, non-toxic, non-immunogenic, and biocompatible. In this paper, we describe the generation of biodegradable PEG hydrogels by cross-linking ...biotinylated PEG oligomers containing intrinsic disulfide bonds via biotin-avidin interactions. The biotinylated PEG oligomers were synthesized by the condensation reaction between PEG and 3,3'-dithiodipropionic acid, followed by the reaction with biotin. This methodology obviates the need for potentially toxic chemical cross-linking agents that are usually used in the common preparation of hydrogels. Therefore it may be particularly useful in biomedical or pharmaceutical applications.
Simple measurements of H sub(2)O sub(2) concentration or CO sub(2) evolution were used to evaluate the effectiveness of the use of Fenton's reagent to mineralize organic compounds in water and soil ...contaminated by crude petroleum. This methodology is suitable for application in small treatment and remediation facilities. Reagent concentrations of H sub(2)O sub(2) and Fe super(2) super(+) were found to influence the reaction time and temperature, as well as the degree of mineralization and biodegradability of the sample contaminants. Some H sub(2)O sub(2)/Fe super(2) super(+) combinations (H sub(2)O sub(2) greater than 10% and Fe super(2) super(+) greater than 50mM) resulted in a strong exothermic reaction, which causes peroxide degradation and violent gas liberation. Up to 75% TOC removal efficiency was attained in water and 70% in soil when high H sub(2)O sub(2) (20%) and low Fe super(2) super(+) (1mM) concentrations were used. Besides increasing the degree of mineralization, the Fenton's reaction enhances the biodegradability of petroleum compounds (BOD sub(5)/COD ratios) by a factor of up to 3.8 for contaminated samples of both water and soil. Our experiments showed that low reagent concentrations (1% H sub(2)O sub(2) and 1mM Fe super(2) super(+)) were sufficient to start the degradation process, which could be continued using microorganisms. This leads to a decrease in reagent costs in the treatment of petroleum-contaminated water and soil samples. The simple measurements of H sub(2)O sub(2) concentration or CO sub(2) evolution were effective to evaluate the Fenton's reaction efficiency.
Textile wastewater containing a high level of color and refractory chemical oxidation demand (COD) is difficult to treat using traditional wastewater treatment processes. Typically, a chemical ...process was suggested as a pretreatment to remove color and increase biodegradability of refractory organic materials. A biological process was then used to remove organic materials and reduce chemical costs for textile wastewater treatment. Fenton oxidation is one of the most effective chemical processes for removing color and COD for textile wastewater. In Fenton processes, oxidations by generated hydroxyl radical are the key factor for color removal in textile wastewaters; thus, monitoring oxidation reduction potential (ORP) should have high potential in Fenton dosage control for color removal in textile wastewater treatment. The main object of this study is to build a Fenton dosage control strategy that uses ORP monitoring and artificial neural network (ANN) models for removing color from textile wastewaters. Two wastewaters, synthetic and real textile, were used in this study. Experimental results have shown that the ANN models precisely represent the correlation between monitoring ORP, Fenton doses, color removal efficiency, and effluent color value, and therefore can be used to control Fenton doses for removing color from textile wastewater. Finally, another series of Fenton dose-control experiments for different color removal control targets were conducted to evaluate this proposed Fenton dose control strategy. Experimental results indicate that the proposed control strategy precisely controls the required Fenton doses for different control targets for both synthetic and real textile wastewaters, and result in reduced chemical costs.
Celotno besedilo
Dostopno za:
DOBA, FGGLJ, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Skin wound healing is an important lifesaving issue for massive lesions. A novel porous scaffold with collagen, hyaluronic acid and gelatin was developed for skin wound repair. The swelling ratio of ...this developed scaffold was assayed by water absorption capacity and showed a value of over 20 g water/g dried scaffold. The scaffold was then degraded in time- and dose-dependent manners by three enzymes: lysozyme, hyaluronidase and collagenase I. The average pore diameter of the scaffold was 132.5 plus or minus 8.4 mu m measured from SEM images. With human skin cells growing for 7 days, the SEM images showed surface fractures on the scaffold due to enzymatic digestion, indicating the biodegradable properties of this scaffold. To simulate skin distribution, the human epidermal keratinocytes, melanocytes and dermal fibroblasts were seeded on the porous scaffold and the cross-section immunofluorescent staining demonstrated normal human skin layer distributions. The collagen amount was also quantified after skin cells seeding and presented an amount 50% higher than those seeded on culture wells. The in vivo histological results showed that the scaffold ameliorated wound healing, including decreasing neutrophil infiltrates and thickening newly generated skin compared to the group without treatments.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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