Papers by Keyword: Micro-Sphere

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Authors: Q. Qiu, Paul Ducheyne, P.S. Ayyaswamy
Authors: Ai Min Chen, Pei Gu, Jun Hu
Abstract: In this paper, we report a simple strategy for fabricating mesoporous magnesium borate (2MgO·B2O3) microspheres. We employed sodium dodecyl sulfate (SDS) in one system, as a template for the controlled growth of mesoporous 2MgO·B2O3 microspheres. The products were characterized by XRD, SEM, TEM, EDS, N2 sorption and FT-IR. SEM and TEM observations indicate magnesium borate products are composed of a large number of hollow microspheres, with diameters of 1.0~1.5 μm, which are in fact built from fibers with lengths of 100~150 nm. The N2 sorption results show that the products have meso-structures. The average pore diameter is 27 nm. The BET surface area is about 53.03 m2/g, and the pore volume is 0.37 m3/g. It was found that SDS plays a key role for the formation of mesoporous structure. A possible mechanism was proposed to interpret the formation of the mesoporous structure. The mesopores will endow the hierarchical microspheres with novel application potentials.
Authors: Hui Wang, Hao Liang, Qi Peng Yuan, Tian Xin Wang
Abstract: Sulforaphane (SF) has been proved to be an effective anticancer agent according to its experiments both in vitro and in vivo. To date, there is few reported method to deliver SF for increasing its bioactivity and stability. In this study, a novel pH-sensitive microsphere composed of water-soluble carboxymethylated chitosan (CMCS) and alginate mixed with sodium sulfate was developed for SF delivery. Swelling studies and release characteristics under different pH values of microspheres were investigated. Then, the release of SF from test microspheres was studied in simulated gastric and segmented intestinal media. It has been found that the SF cumulated release in 5h was increased from 55.89% to 76.73% when the microspheres mixed with sodium sulfate. In addition, the stability of SF embedded in CMCS/alginate microspheres was also significantly improved. Under pH 7.4, free SF had a severe degradation of approximate 100% within 210 min, whereas the change of the SF in microspheres was only a decrease of about 10%. The results suggested that the microspheres of CMCS and alginate could be a suitable pH-sensitive carrier to increase the stability of SF in the segmented intestine.
Authors: Shi Jun Wei, Meng Zhang, Lei Li, Lu Lu
Abstract: Multi-membrane hydrogels are newly promising carriers in biomedical fields for their gentle gel condition and excellent biocompatibilities. In this study we focused on the dual control release property of alginate-based onion-like multi-membrane hydrogels hybrid with polylactic acid microspheres. The results indicated that the PLA microspheres evenly distributed in each of the hydrogel membranes. And the drug delivery in physiological saline is well controlled which can be promising in transport drugs, genes, protein, etc.
Authors: An Na Wang, Li Gen Wu, Lin Lu Jia, Xiu Ling Li, Yu Dan Sun
Abstract: Tea polyphenol loaded alginate-chitosan microspheres were prepared by ionic gelation method for controlling tea polyphenol release by using various combinations of chitosn and Ca2+ as cation and alginate as anion.Scanning electron microscopy were used to investigate the surface characteristics of tea polyphenol loaded microspheres. These microencapsulated beads were evaluated as a pH-sensitive system for delivery of tea polyphenol. The main advantage of this system is that all procedures used were performed in aqueous medium which may preserve the tea polyphenol bioactivity. At pH7.4, the amounts of tea polyphenol released increased significantly as compared to those released at pH1.2. It is evident that the rate of tea polyphenol release could be controlled by changing the chitosan and the calcium chloride concentrations.
Authors: Mamoru Aizawa, Toshiki Ohno, N. Kanomata, K. Yano, M. Emoto
Authors: C.C. Barrias, C.C. Ribeiro, M.C.L. Martins, Mario A. Barbosa, D. Rodrigues, M.C. Sá Miranda
Abstract: The ability of calcium titanium phosphate (CTP) and hydroxyapatite (HAp) microspheres to reversibly adsorb the enzyme glucocerebrosidase (GCR) while preserving its biological activity, and efficiently deliver it to Gaucher disease (GD) fibroblasts was investigated. CTP microspheres adsorbed ca. 3.6-fold more GCR than HAp microspheres. The activity of adsorbed GCR was higher than the free enzyme in the case of CTP microspheres and lower when HAp was used. GCR release from both types of microspheres was characterized by the initial elution of a large percentage of enzyme followed by a delayed release that extended for at least 30 days. Released GCR was internalized by GD fibroblasts increasing their intracellular enzymatic activity. In cells treated with the same amount of GCR-loaded CTP microspheres or free-GCR a higher intracellular activity was detected in the former case, suggesting an improved efficacy.
Authors: Jing Hui, Xiao Jie Yu, Yue Zhang, Feng Qing Hu
Abstract: Poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) is one of the components of polyhydroxyalkanoates (PHAs) and some of its mechanical properties have been shown to improve over poly (3-hydroxybutyrate) (PHB) and poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). The investigation of PHBHHx microspheres as a drug delivery system was prepared by emulsion-solvent evaporation method for the sustained release of anti-cancer drug 5-fluorouracil (5-FU) and cyclosporin A (CsA). The mean diameter of the PHBHHx microspheres ranged from 5.24 to 22.10 μm dependent on the different processing parameters. The PHBHHx concentration, emulsifier concentration, anti-cancer drug dosage, and agitation speed, were optimized according to the encapsulation efficiency of 4% PHBHHx, 0.5% SDS, 10 mg anti-cancer drug, and 500 rpm. Under optimized conditions, the encapsulation efficiency of 5-FU and CsA microspheres were 7.19% and 96.44%, respectively. The morphologies of scanning electron microscope (SEM) suggested that PHBHHx microspheres were relatively smooth that provided better dispersion compared to PHB microspheres. The in vitro release profiles indicated 32.42% of 5-FU and 30.61% of CsA were released from PHBHHx microspheres during the initial burst phase, and the drug release from PHBHHx microsphere could be detected even after one month. The characteristics of PHBHHx microspheres demonstrated the feasibility of PHBHHx microsphere as a novel matrix for drug release system. With positive maintenance of the therapeutic concentrations of the drug, side effects can be reduced and patient compliance can be improved.
Authors: Xin Hua Zhou, Qi Hai Liu, Guo Qiang Ying, Ying De Cui
Abstract: With Ca2+ ions as cross-link agent, chlorpyrifos-loaded attapulgite/sodium alginate hybrid microspheres were prepared by extrusion method. The hybrid microspheres were characterized by FITR, DSC, SEM techniques to gain insights into the structural and morphological features of the microspheres. Meanwhile, the release properties of the drug-loaded hydrogel microspheres for chlorpyrifos were tested. The experimental results indicate that, chlorpyrifos were loaded in calcium alginate microspheres in the forms of partial differential aggregation and molecular disperse, and there exists hydrogen bond between sodium alginate and attapulgite. The release effect of hybrid gel microspheres for chlorpyrifos can be divided into two stages, namely, the burst release and the sustained release. With the increasing of the attapulgite content, the release rate during the sustained-release phase and the amount of pesticide during burst release will be significantly reduced. The introduction of attapulgite can change the micro-phase structure of the drug-loaded sodium alginate gel, which is conducive to improve the release effect of gel microspheres for pesticides, thus promoting the release performance of drug-loaded sodium alginate microspheres.
Authors: Imre Norbert Orbulov, Árpád Németh, János Dobránszky
Abstract: This paper presents the possibility of composite block production by using pressure infiltration technology. This method uses the pressure of an inert gas (usually argon or nitrogen) to force the melted matrix material to infiltrate the reinforcing elements. Three types of materials were considered: open cell metallic foam, metal matrix syntactic foam and carbon fiber reinforced metal matrix composite. Physical and mechanical investigations – such as SEM and compression tests – were performed. The results of measurements were summarized briefly.
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