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Drug Carriers (drug + carrier)
Kinds of Drug Carriers Selected AbstractsChitosan per os: from Dietary Supplement to Drug CarrierFOCUS ON ALTERNATIVE AND COMPLEMENTARY THERAPIES AN EVIDENCE-BASED APPROACH, Issue 3 2000MH Pittler [source] Synthesis of Magnetic, Up-Conversion Luminescent, and Mesoporous Core,Shell-Structured Nanocomposites as Drug CarriersADVANCED FUNCTIONAL MATERIALS, Issue 7 2010Shili Gai Abstract The synthesis (by a facile two-step sol,gel process), characterization, and application in controlled drug release is reported for monodisperse core,shell-structured Fe3O4@nSiO2@mSiO2@NaYF4: Yb3+, Er3+/Tm3+ nanocomposites with mesoporous, up-conversion luminescent, and magnetic properties. The nanocomposites show typical ordered mesoporous characteristics and a monodisperse spherical morphology with narrow size distribution (around 80,nm). In addition, they exhibit high magnetization (38.0,emu g,1, thus it is possible for drug targeting under a foreign magnetic field) and unique up-conversion emission (green for Yb3+/Er3+ and blue for Yb3+/Tm3+) under 980,nm laser excitation even after loading with drug molecules. Drug release tests suggest that the multifunctional nanocomposites have a controlled drug release property. Interestingly, the up-conversion emission intensity of the multifunctional carrier increases with the released amount of model drug, thus allowing the release process to be monitored and tracked by the change of photoluminescence intensity. This composite can act as a multifunctional drug carrier system, which can realize the targeting and monitoring of drugs simultaneously. [source] Degradable, Surfactant-Free, Monodisperse Polymer-Encapsulated Emulsions as Anticancer Drug CarriersADVANCED MATERIALS, Issue 18 2009Sri Sivakumar Anticancer emulsions: Degradable, surfactant- free, micrometer- to sub-micrometer-sized polymer-encapsulated emulsions loaded with lipophilic drugs (doxorubicin and 5-fluorouracil) are prepared. In vitro drug-release studies demonstrate controlled release under redox conditions and incubation with human colorectal cancer cells triggers cell death with greater efficiency (,106 fold) than the free drug. [source] Synthesis of Nonwoven Nanofibers by Electrospinning , A Promising Biomaterial for Tissue Engineering and Drug Delivery,ADVANCED ENGINEERING MATERIALS, Issue 8 2010N. Naveen PHB nanofibers are synthesized by electrospinning of a PHB solution prepared using HFIP as the solvent. The nanofibrous scaffold supports rapid cell growth with normal morphology and attains a viability of 87% after 48,h. Kanamycin sulphate-loaded PHB nanofiber mats are synthesized, with the antibiotic on the surface and sandwiched within the nanofiber mats: their antimicrobial property is proved by the good zone of inhibition tested against Staphylococcus aureus. The drug shows more than 95% release within 8,h. These results indicate that nanofibers loaded with the antibiotic have potential applications as a template for tissue engineering and as a drug carrier. [source] Charge-Reversal Drug Conjugate for Targeted Cancer Cell Nuclear Drug DeliveryADVANCED FUNCTIONAL MATERIALS, Issue 22 2009Zhuxian Zhou Abstract DNA-toxin anticancer drugs target nuclear DNA or its associated enzymes to elicit their pharmaceutical effects, but cancer cells have not only membrane-associated but also many intracellular drug-resistance mechanisms that limit their nuclear localization. Thus, delivering such drugs directly to the nucleus would bypass the drug-resistance barriers. The cationic polymer poly(L -lysine) (PLL) is capable of nuclear localization and may be used as a drug carrier for nuclear drug delivery, but its cationic charges make it toxic and cause problems in in-vivo applications. Herein, PLL is used to demonstrate a pH-triggered charge-reversal carrier to solve this problem. PLL's primary amines are amidized as acid-labile , -carboxylic amides (PLL/amide). The negatively charged PLL/amide has a very low toxicity and low interaction with cells and, therefore, may be used in vivo. But once in cancer cells' acidic lysosomes, the acid-labile amides hydrolyze into primary amines. The regenerated PLL escapes from the lysosomes and traverses into the nucleus. A cancer-cell targeted nuclear-localization polymer,drug conjugate has, thereby, been developed by introducing folic-acid targeting groups and an anticancer drug camptothecin (CPT) to PLL/amide (FA-PLL/amide-CPT). The conjugate efficiently enters folate-receptor overexpressing cancer cells and traverses to their nuclei. The CPT conjugated to the carrier by intracellular cleavable disulfide bonds shows much improved cytotoxicity. [source] Injectable Superparamagnetic Ferrogels for Controlled Release of Hydrophobic DrugsADVANCED MATERIALS, Issue 13 2009Jian Qin A ferrogel for magnetically controlled release of drugs is prepared by integration of superparamagnetic iron oxide nanoparticles and Pluronic F127 gels. The hydrophobic drug indomethacin is loaded in the ferrogel owing to the oil-in-water micellar structure. The characteristic sol,gel transition property renders the ferrogel an injectable drug carrier that will be, in principle, free from surgical implant procedure. [source] pH-sensitive alginate/soy protein microspheres as drug transporterJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2007Hua Zheng Abstract The complex microspheres based on alginate (AL) and soy protein isolate (SPI) were prepared by solution blending and then Ca2+ crosslinking, and their function as drug carrier was explored as well. The effects of composition on the structures of microspheres were studied, and the XRD results proved the miscibility between components. Meanwhile, FTIR results suggested that such miscibility was driven by strong hydrogen bonding. Especially, the complex microsphere with equal content of AL and SPI had the best miscibility by morphological analysis, shown as a smooth and uniform surface of SEM images. The controlled release function of the complex microspheres was verified using theophylline as a drug model, that is, the swelling and drug release were affected by pH conditions and showed obvious differences under given pH of stomach, intestine, and colon. Moreover, the intestine and colon may be optimal site for prompt release of drugs. Except for the attribution of AL component to pH sensitivity, the complex microspheres also inherited the bioactivity of SPI component, which may lower irritants of drug to the tissues in body. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 [source] Calcium-carboxymethyl chitosan hydrogel beads for protein drug delivery systemJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2007Zonghua Liu Abstract In this study, carboxymethyl chitosan (CMC) hydrogel beads were prepared by crosslinking with Ca2+. The pH-sensitive characteristics of the beads were investigated by simulating gastrointestinal pH conditions. As a potential protein drug delivery system, the beads were loaded with a model protein (bovine serum albumin, BSA). To improve the entrapment efficiency of BSA, the beads were further coated with a chitosan/CMC polyelectrolyte complex (PEC) membrane by extruding a CMC/BSA solution into a CaCl2/chitosan gelation medium. Finally, the release studies of BSA-loaded beads were conducted. We found that, the maximum swelling ratios of the beads at pH 7.4 (17,21) were much higher than those at pH 1.2 (2,2.5). Higher entrapment efficiency (73.2%) was achieved in the chitosan-coated calcium-CMC beads, compared with that (44.4%) in the bare calcium-CMC beads. The PEC membrane limited the BSA release, while the final disintegration of beads at pH 7.4 still leaded to a full BSA release. Therefore, the chitosan-coated calcium-CMC hydrogel beads with higher entrapment efficiency and proper protein release properties were a promising protein drug carrier for the site-specific release in the intestine. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3164,3168, 2007 [source] Synthesis and use of pHEMA microbeads with human EA.hy 926 endothelial cellsJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2009Hervé Nyangoga Abstract Cancer has become a major problem in public health and the resulting bone metastases a worsening factor. Facing it, different strategies have been proposed and mechanisms involved in tumor angiogenesis are being studied. Enhanced permeability retention (EPR) effect is a key step in designing new anticancer drugs. We have prepared poly 2-hydroxyethyl methacrylate (pHEMA) microbeads to target human endothelial EA.hy 926 cells, a cell line derived from human umbilical vein endothelial cells. Microbeads were synthesized by emulsion precipitation method and carried positive or negative charges. EA.hy 926 cells were cultured in 24-well plates and microbeads were deposited on cells at various times. Scanning and transmission electron microscopy, flow cytometry, confocal microscopy, and three-dimensional (3D) reconstruction were used to characterize microbeads and their location outside and inside cells. Microbeads were uptaken by endothelial cells with a better internalization for negatively charged microbeads. 3D reconstruction of confocal optical sections clearly evidenced the uptake and internalization of microbeads by endothelial cells. pHEMA microbeads could represent potential drug carrier in tumor model of metastases. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009 [source] Effects of insulin-mimetic vanadyl-poly(,-glutamic acid) complex on diabetic rat modelJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 7 2010Rongzhang Hu Abstract Poly-,-glutamic acid (,-PGA) prepared by fermentation of microbe was used as drug carrier for vanadium sulfate to obtain vanadyl-poly-,-glutamic acid (VO-,-PGA) complex. The FI-IR spectrum of the complex demonstrated that the expected VO-,-PGA complex is formed by the coordination of VO2+ through the side chain carboxylic groups of the ,-PGA. Studies of the complex in treating type I diabetes were carried out on alloxan induced diabetes rats. The results of treating the rats in 2 weeks and then stopping administration for 10 days showed that VO-,-PGA can effectively lower blood glucose levels of diabetic rats during administration. But after ceasing treatment there were no differences between groups in blood glucose level and water intake. The results of oral glucose tolerance and some serum parameters also demonstrated that VO-,-PGA was more effective than vanadium sulfate in treating diabetic rats. © 2010 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:3041,3047, 2010 [source] Solid-state stability and characterization of hot-melt extruded poly(ethylene oxide) filmsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 10 2005Suneela Prodduturi Abstract Poly(ethylene oxide) (PEO) was used to prepare thin polymer films containing clotrimazole (CT) utilizing hot-melt extrusion (HME) technology. Films containing PEOs of two different molecular weights and the drug were investigated for solid-state characteristics, moisture-sorption, bioadhesivity, mechanical properties, release characteristics, and physical and chemical stability of the drug within the HME films. The solid-state characterization of the drug and the polymer were performed utilizing differential scanning calorimetry and X-ray diffractometry. A Texture analyzer was utilized to study the bioadhesive and mechanical properties of the HME films. Physical and chemical stability of the films, stored at 25°C/60% RH, was studied for up to 12 months. XRD profiles indicated that the drug was physically unstable (recrystallization of the drug occurred) after storage for 3 months at 25°C/60% RH. Based on the DSC studies, it has been proposed that the recrystallization of the drug may be due to the folding (due to HME) and unfolding (upon storage) of the linear PEO chains. Desirable bioadhesive, mechanical, and thermoplastic properties of PEO qualify it as a promising and potential drug carrier. However, further investigation is necessary to enhance the physical stability of these PEO,drug systems. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:2232,2245, 2005 [source] Enlarging the library of poly-(L -lysine citramide) polyelectrolytic drug carriersJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 20 2001Anne-Claude Couffin-Hoarau Abstract Poly-(L -lysine citramide) is a degradable drug carrier of the polyelectrolyte type that is composed of citric acid and L -lysine building blocks. In a previous work, poly-(L -lysine citramide) was synthesized by the interfacial polycondensation of ,-hydroxy acid protected citryl dichloride with COOH-protected lysine diamine. Because of head-to-head and head-to-tail and tail-to-tail linkages in the chains as well as various side reactions such as deprotection of the ,-hydroxy acid moieties and intramolecular imide ring formation, a very large family of degradable polyelectrolyte copolymers was obtained. All the members of this family hydrolytically degrade to the same end products. In this study, another route was explored based on the polycondensation of ,-hydroxy acid protected citric acid pentafluorophenyl diesters, namely, citrobenzal dipentafluorophenyl and citrochloral dipentafluorophenyl with N - N,-trimethylsilylated COOH-protected L -lysine. The resulting polymers were characterized by IR, NMR, and size exclusion chromatographic analyses. The resulting chain structures and repeat units were identified from these characterizations and are discussed as compared with characteristics exhibited by analogous polymers resulting from interfacial polycondensation. Differences observed at the intermediate stage involving protected polymers were largely erased during the final deprotection stage because of imide formation during final hydrolysis under the selected conditions. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3475,3484, 2001 [source] Temperature-Triggered Nanosphere Formation Through Self-Assembly of Amphiphilic PolyphosphazeneMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 14 2006Jian Xiang Zhang Abstract Summary: An amphiphilic graft polyphosphazene with a molar ratio of poly(N -isopropylacrylamide) (PNIPAm) to ethyl glycinate (GlyEt) of 0.54:1 was synthesized. This copolymer in aqueous solution exhibited two temperature induced phase transitions at 17.2 and 33.7,°C, which correspond to the transformation of primary aggregate morphology (at Tph1) and the collapse of PNIPAm chains (at Tph2) respectively. Network micelles were assembled in water at lower temperature (far below Tph1), and then narrowly dispersed nanoparticles were formed above Tph1, while inter-nanoparticle aggregation occurred due to the collapse of PNIPAm chains surrounding the GlyEt core when the temperature was above Tph2. Through solubilization of the hydrophobic drug ibuprofen into polymeric aggregates at lower temperature, drug loaded nanospheres were prepared successfully. In vitro release revealed that sustained drug release was achieved with this novel delivery system. These results suggest that this novel copolymer could be used as a potential drug carrier, especially for the delivery of hydrophobic biocompounds through parenteral administration. Schematic illustration of the temperature-triggered self-assembly process of PNIPAm/GlyEt-PPP in aqueous solution. [source] Relationship among drug delivery behavior, degradation behavior and morphology of copolylactones derived from glycolide, l -lactide and ,-caprolactonePOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 2 2002Qing Cai Abstract A series of copolylactones was synthesized by ring-opening copolymerization of glycolide, L -lactide and ,-caprolactone, using stannous octoate as catalyst. The in vitro degradation behaviors of them were studied and data demonstrated different degradation rates which mainly depended on the compositions. Investigation of the 5-fluorouracil (5-Fu) release from these copolylactones revealed that the composition, degradation rate and the morphology of the polymeric matrix played an important role on the drug release kinetics. A sustained 5-Fu release without initial time lag was obtained from random poly(lactide-co-glycolide-co-caprolactone) (r-PGLC) drug carrier, and it differed from the cases of polylactide (PLA) or random poly(lactide-co-glycolide) (PLGA), which usually showed an initial time lag or biphasic drug release behavior. It was due to the low glass transition temperature (Tg) of the r-PGLC and the drug would diffuse faster in rubbery state under the experimental temperature. Furthermore, a significant change in the drug release behavior of r-PGLC was observed when the temperatures were changed around the Tg of the drug carrier, which implied that the drug release behavior could be regulated by adjusting the morphology of the drug carrier. Copyright © 2002 John Wiley & Sons, Ltd. [source] Facile synthesis of functional polyperoxides by radical alternating copolymerization of 1,3-dienes with oxygenTHE CHEMICAL RECORD, Issue 5 2009Eriko Sato Abstract We have developed a facile synthesis of degradable polyperoxides by the radical alternating copolymerization of 1,3-diene monomers with molecular oxygen at an atmospheric pressure. In this review, the synthesis, the degradation behavior, and the applications of functional polyperoxides are summarized. The alkyl sorbates as the conjugated 1,3-dienes gave a regiospecific alternating copolymer by exclusive 5,4-addition during polymerization and the resulting polyperoxides decomposed by the homolysis of a peroxy linkage followed by successive , -scissions. The preference of 5,4-addition was well rationalized by theoretical calculations. The degradation of the polyperoxides occurred with various stimuli, such as heating, UV irradiation, a redox reaction with amines, and an enzyme reaction. The various functional polyperoxides were synthesized by following two methods, one is the direct copolymerization of functional 1,3-dienes, and the other is the functionalization of the precursor polyperoxides. Water soluble polyperoxides were also prepared, and the LCST behavior and the application to a drug carrier in the drug delivery system were investigated. In order to design various types of degradable polymers and gels we developed a method for the introduction of dienyl groups into the precursor polymers. The resulting dienyl-functionalized polymers were used for the degradable gels. The degradable branched copolymers showed a microphase-separated structure, which changed owing to the degradation of the polyperoxide segments. © 2009 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 9: 000,000; 2009: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.200900009 [source] Development and characterization of a fusion protein between thermally responsive elastin-like polypeptide and interleukin-1 receptor antagonist: Sustained release of a local antiinflammatory therapeuticARTHRITIS & RHEUMATISM, Issue 11 2007Mohammed F. Shamji Objective Interleukin-1 receptor antagonist (IL-1Ra) has been evaluated for the intraarticular treatment of osteoarthritis. Such administration of proteins may have limited utility because of their rapid clearance and short half-life in the joint. The fusion of a drug to elastin-like polypeptides (ELPs) promotes the formation of aggregating particles that form a "drug depot" at physiologic temperatures, a phenomenon intended to prolong the presence of the drug. The purpose of this study was to develop an injectable drug depot composed of IL-1Ra and ELP domains and to evaluate the properties and bioactivity of the recombinant ELP-IL-1Ra fusion protein. Methods Fusion proteins between IL-1Ra and 2 distinct sequences and molecular weights of ELP were overexpressed in Escherichia coli. Environmental sensitivity was demonstrated by turbidity and dynamic light scattering as a function of temperature. IL-1Ra domain activity was evaluated by surface plasmon resonance, and in vitro antagonism of IL-1,mediated lymphocyte and thymocyte proliferation, as well as IL-1,induced tumor necrosis factor , (TNF,) expression and matrix metalloproteinase 3 (MMP-3) and ADAMTS-4 messenger RNA expression in human intervertebral disc fibrochondrocytes. IL-1Ra immunoreactivity was assessed before and after proteolytic degradation of the ELP partner. Results Both fusion proteins underwent supramolecular aggregation at subphysiologic temperatures and slowly resolubilized at 37°C. Interaction with IL-1 receptor was slower in association but equivalent in dissociation as compared with the commercial antagonist. Anti,IL-1 activity was demonstrated by inhibition of lymphocyte and thymocyte proliferation and by decreased TNF, expression and ADAMTS-4 and MMP-3 transcription by fibrochondrocytes. ELP domain proteolysis liberated a peptide of comparable size and immunoreactivity as the commercial IL-1Ra. This peptide was more bioactive against lymphocyte proliferation, nearly equivalent to the commercial antagonist. Conclusion The ELP-IL-1Ra fusion protein proved to retain the characteristic ELP inverse phase-transitioning behavior as well as the bioactivity of the IL-1Ra domain. This technology represents a novel drug carrier designed to prolong the presence of bioactive peptides following intraarticular delivery. [source] Evaluation of enantioselective binding of antihistamines to human serum albumin by ACEELECTROPHORESIS, Issue 15 2007María Amparo Martínez-Gómez Abstract The drug binding to plasma and tissue proteins is a fundamental factor in determining the overall pharmacological activity of a drug. HSA, together with ,1 -acid glycoprotein, are the most important plasma proteins, which act as drug carriers, with implications on the pharmacokinetic of drugs. Among plasma proteins, HSA possesses the highest enantioselectivity. In this paper, a new methodology for the study of enantiodifferentiation of chiral drugs with HSA is developed and applied to evaluate the possible enantioselective binding of four antihistamines: brompheniramine, chlorpheniramine, hydroxyzine and orphenadrine to HSA. This study includes the determination of affinity constants of drug enantiomers to HSA and the evaluation of the binding sites of antihistamines on the HSA molecule. The developed methodology includes the ultrafiltration of samples containing HSA and racemic antihistaminic drugs and the analysis of the free or bound drug fraction using the affinity EKC-partial filling technique and HSA as chiral selector. The results shown in this paper represent the first evidence of the enantioselective binding of antihistamines to HSA, the major plasmatic protein. [source] Hydrophobic Functional Group Initiated Helical Mesostructured Silica for Controlled Drug Release,ADVANCED FUNCTIONAL MATERIALS, Issue 23 2008Lei Zhang Abstract In this paper a novel one-step synthetic pathway that controls both functionality and morphology of functionalized periodic helical mesostructured silicas by the co-condensation of tetraethoxysilane and hydrophobic organoalkoxysilane using achiral surfactants as templates is reported. In contrast to previous methods, the hydrophobic interaction between hydrophobic functional groups and the surfactant as well as the intercalation of hydrophobic groups into the micelles are proposed to lead to the formation of helical mesostructures. This study demonstrates that hydrophobic interaction and intercalation can promote the production of long cylindrical micelles, and that the formation of helical rod-like morphology is attributed to the spiral transformation from bundles of hexagonally-arrayed and straight rod-like composite micelles due to the reduction in surface free energy. It is also revealed that small amounts of mercaptopropyltrimethoxysilane, vinyltrimethoxysilane, and phenyltrimethoxysilane can cause the formation of helical mesostructures. Furthermore, the helical mesostructured silicas are employed as drug carriers for the release study of the model drug aspirin, and the results show that the drug release rate can be controlled by the morphology and helicity of the materials. [source] A Biomolecular "Ship-in-a-Bottle": Continuous RNA Synthesis Within Hollow Polymer Hydrogel AssembliesADVANCED MATERIALS, Issue 6 2010Andrew D. Price The use of micrometer-sized, monodisperse polymer hydrogel capsules that act as both microreactors and drug carriers for de novo synthesized RNA is demonstrated (see figure). These capsules are expected to have broad impact as biophysical tools for the study of encapsulated RNA and as new biocompatible delivery vehicles for the cellular delivery of RNA therapeutics. [source] Entering and Lighting Up Nuclei Using Hollow Chitosan,Gold Hybrid NanospheresADVANCED MATERIALS, Issue 36 2009Yong Hu Functional hollow CS,PAA,Au-hybrid nanospheres are prepared in aqueous solution via a one-pot route. These hollow hybrid nanospheres can not only act as drug carriers for intracellular and intranuclear drug delivery, but also act as a contrast agent in cancer-cell imaging, and light up the nucleus. This results in a nanosphere that can execute tumor-cell imaging and anticancer drug delivery at the same time. [source] In vitro degradability and stability of hydrophobically modified pH-sensitive micelles using MPEG-grafted poly(,-amino ester) for efficient encapsulation of paclitaxelJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Min Sang Kim Abstract Methoxypoly(ethylene glycol)-grafted poly(,-amino ester) was synthesized for the fabrication of pH-sensitive micelles, and these micelles were modified with deoxycholic acid to facilitate the hydrophobic interaction between the micellar core and paclitaxel. The micelle properties were studied by dynamic light scattering and fluorescence spectrometry. An in vitro degradation study showed that the synthesized polymers degraded hydrolytically within 24 h under physiological conditions. The stability of paclitaxel-loaded pH-sensitive micelles was evaluated in vitro. The introduced deoxycholic acid more stabilized the micelles at pH 7.4 compared to the micelles without modification. But the pH-sensitive region of the micelles was lowered from pH 6.8 to pH 5.8. These results indicate that pH-sensitive micelles with improved stability have great potential as hydrophobic drug carriers for tumor targeting. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Hollow, pH-sensitive calcium,alginate/poly(acrylic acid) hydrogel beads as drug carriers for vancomycin releaseJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2010Hong-Ru Lin Abstract In this study, hollow calcium,alginate/poly(acrylic acid) (PAA) hydrogel beads were prepared by UV polymerization for use as drug carriers. The hollow structure of the beads was fortified by the incorporation of PAA. The beads exhibited different swelling ratios when immersed in media at different pH values; this demonstrated that the prepared hydrogel beads were pH sensitive. A small amount (<9%) of vancomycin that had been incorporated into the beads was released in simulated gastric fluid, whereas a large amount (,67%) was released in a sustained manner in simulated intestinal fluid. The observed drug-release profiles demonstrated that the prepared hydrogel beads are ideal candidate carriers for vancomycin delivery into the gastrointestinal tract. Furthermore, the biological response of cells to these hydrogel beads indicated that they exhibited good biological safety and may have additional applications in tissue engineering. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Biodegradable blend films based on two polysaccharide derivatives and their use as ibuprofen-releasing matricesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007Ju-Zhen Yi Abstract Differential scanning calorimetry (DSC), FTIR, X-ray diffraction (XRD), and viscosity methods were used to examine the miscibility, interaction, and degradability of cationic guar gum (GG) and sodium carboxymethylcellulose (NaCMC) in their blend films. The experiment results prove that there exist electrostatic interactions and hydrogen bonding between GG and NaCMC. Blend films degrade quicker than pure GG or NaCMC film. Furthermore, the degradation rate of blend films is related to the interactions between GG and NaCMC. Based on the research of blend films as the drug carriers for Ibuprofen, it is found that the blend composition, initial drug concentration, and pH value affect the drug release and the GG/NaCMC blend films have good sustained release performance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3553,3559, 2007 [source] Nanoparticles as tools to study and control stem cellsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 4 2009L. Ferreira Abstract The use of nanoparticles in stem cell research is relatively recent, although very significant in the last 5 years with the publication of about 400 papers. The recent advances in the preparation of some nanomaterials, growing awareness of material science and tissue engineering researchers regarding the potential of stem cells for regenerative medicine, and advances in stem cell biology have contributed towards the boost of this research field in the last few years. Most of the research has been focused in the development of new nanoparticles for stem cell imaging; however, these nanoparticles have several potential applications such as intracellular drug carriers to control stem cell differentiation and biosensors to monitor in real time the intracellular levels of relevant biomolecules/enzymes. This review examines recent advances in the use of nanoparticles for stem cell tracking, differentiation and biosensing. We further discuss their utility and the potential concerns regarding their cytotoxicity. J. Cell. Biochem. 108: 746,752, 2009. © 2009 Wiley-Liss, Inc. [source] Multifunctioning pH-responsive nanoparticles from hierarchical self-assembly of polymer brush for cancer drug deliveryAICHE JOURNAL, Issue 11 2008Youqing Shen Abstract Polymer nanoparticles are extensively explored as drug carriers but they generally have issues of premature burst drug release, slow cellular uptake, and retention in acidic intracellular compartments. Herein, we report multifunctioning three-layered nanoparticles (3LNPs) that can overcome these problems. The 3LNPs have a poly(,-caprolactone) (PCL) core, a pH-responsive poly[2-(N,N-diethylamino)ethyl methacrylate](PDEA) middle layer and a polyethylene glycol (PEG) outer layer. The pH-responsive PDEA layer is insoluble at pH above 7 but becomes positively charged and soluble via protonation at pH lower than 6.5. Thus, this layer has three functions: it covers on the PCL core inhibiting the premature burst drug release at the physiological pH, becomes positively charged and thus promotes endocytosis for fast cellular internalization in the acidic interstitium of solid tumors, and is highly positively charged in lysosomes to disrupt the lysosomal membrane and release the nanoparticle into the cytosol. The multifunctioning nanoparticles are an efficient carrier for cancer cytosolic drug delivery. © 2008 American Institute of Chemical Engineers AIChE J, 2008 [source] Thermally associating polypeptides designed for drug delivery produced by genetically engineered cellsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 3 2007David S. Hart Abstract Thermally associating polymers, including gelatin, cellulose ethers (e.g., Methocels® and poloxamers (e.g., Pluronics®) have a long history of use in pharmacy. Over the past 20 years, significant advances in genetic engineering and the understanding of protein secondary and tertiary structures have been made. This has led to the development of a variety of polypeptides that do not occur naturally but can be expressed in recombinant cells and have useful properties that lend themselves to novel applications where current materials cannot perform. The most intensively studied motifs are derived from the consensus repeats of elastin and silk, as well as coiled-coil helices. Many of these designed polypeptides or ,artificial proteins' are thermally associating materials. This property can be exploited to develop solid dosage forms, injectable drug delivery systems, micro- or nanoparticle drug carriers, triggered or targeted release systems, or as a means of simplifying the purification process and thus reducing costs of production of these materials. This review focuses on the development and characterization of this novel class of biomaterials and examines their potential for pharmaceutical applications. © 2006 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci [source] Formulation, preparation and evaluation of flunarizine-loaded lipid microspheresJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 3 2007Yan Jiao Wang The aim of this study was to investigate the feasibility of preparing flunarizine-loaded lipid microspheres. Lipid microspheres (LMs) are excellent drug carriers for drug delivery systems (DDS) and are relatively stable and easily mass-produced. They have no particular adverse effects. LMs have been widely studied as drug carriers for water-soluble drugs, lipid-soluble drugs and inadequately soluble (in water or in lipid) drugs, in that they have a lipid layer, a water layer and an emulsifier layer. Flunarizine (FZ), a poorly water-soluble drug, was incorporated in lipid microspheres to reduce side effects by avoiding the use of supplementary agents, compared with solution injection. After investigation, the final formulation was as follows: 10% oil phase (long-chain triglyceride (LCT); medium-chain fatty acid (MCT) = 50:50); 1.2% egg lecithin; 0.2% Tween-80; 2.5% glycerin; 0.3% dl-,-tocopherol; 0.02% EDTA; 0.03% sodium oleate; 0.1% FZ and double-distilled water to give a total volume of 100 mL. Homogenization was the main method of preparation and the best conditions were a temperature of 40°C, a pressure of 700,800 bar and a suitable cycle frequency of about 10. The particle size distribution, zeta-potential and entrapment efficacy were found to be 198.7 ± 54.0 nm, ,26.4mV and 96.2%, respectively. Its concentration in the preparation was 1.0mg mL,1. The lipid microspheres were stable during storage at 4°C, 25°C and 37°C for 3 months. Pharmacokinetic studies were performed in rats using a dose of 1.0 mg kg,1. The pharmacokinetic parameters were as follows: AUC0-t 6.13 ,g h mL,1, t½ 5.32 h and Ke 0.16 Lh,1. The preparation data fitted a two-compartment model estimated by using 3p87 analysis software. From the observed data, FZ encapsulated in LMs did not significantly alter the pharmacokinetic characteristic compared with the FZ solution injection and did not produce a delayed release effect, when it was released in-vivo in rats. However, the availability of the drug was increased. These results suggested that this LM system is a promising option for the preparation of the liquid form of FZ for intravenous administration. [source] Inhibition of serum angiotensin-converting enzyme in rabbits after intravenous administration of enalaprilat-loaded intact erythrocytesJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 9 2001Mehrdad Hamidi Encapsulation of drugs in intact erythrocytes, because of the profound characteristics of these natural microspheres, has gained considerable attention in recent years. In this study, the inhibition time courses of serum angiotensin-converting enzyme (ACE) activity after intravenous administration of enalaprilat encapsulated in intact erythrocytes was evaluated and compared with free drug, in a rabbit model. Three groups of animals each received free drug, drug-loaded erythrocytes or sham-encapsulated erythrocytes. Serum ACE activity was determined in each case using the synthetic substrate hippuryl-histidyl-leucine and quantitation of the hippuric acid released by a developed and validated HPLC method. The serum ACE inhibition profiles in the three groups showed that the encapsulated drug inhibited the serum ACE more slowly, more efficiently, over a considerably longer time and in a more reproducible manner, than the free drug or sham-encapsulated erythrocytes. We conclude that the erythrocytes can serve as efficacious slow-release drug carriers for enalaprilat in circulation. [source] Triton-X-100-modified polymer and microspheres for reversal of multidrug resistanceJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 6 2001Zhi Liu Triton X-100 is a non-ionic detergent capable of reversing multidrug resistance (MDR) due to its interaction with cell membranes. However, it interacts with cells in a non-specific way, causing cytotoxicity. This work aimed to develop polymeric chemosensitizers that possess the ability to reverse MDR and lower toxic side effects. When being delivered to tumours, the polymeric chemosensitizers may also have longer retention times in tumours than the free detergent. Triton-X-100-immobilized dextran microspheres (T-MS) and inulin (T-IN) were prepared and characterized. Their cytotoxicity against multidrug-resistant Chinese hamster ovary cells (CHRC5) was compared with that of free Triton X-100 solutions. The in-vitro effect of the products on 3H-vinblastine accumulation by CHRC5 cells was determined. Both T-MS and T-IN showed a marked decrease in the cytotoxicity, as compared with free Triton solutions at equivalent concentrations. Drug accumulation by CHRC5 cells was increased over two fold in the presence of T-MS or T-IN. These results suggest that polymeric drug carriers with MDR-reversing capability and lower cytotoxicity may be prepared by immobilization of chemosensitizers. [source] An efficient approach to synthesize polysaccharides- graft -poly(p -dioxanone) copolymers as potential drug carriersJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 20 2009Fang Lu Abstract Starch and poly(p -dioxanone) (PPDO) are the natural and synthetic biodegradable and biocompatible polymers, respectively. Their copolymers can find extensive applications in biomedical materials. However, it is very difficult to synthesize starch- graft -PPDO copolymers in common organic solvents with very good solubility. In this article, well-defined polysaccharides- graft -poly(p -dioxanone) (SAn -PPDO) copolymers were successfully synthesized via the ring-opening polymerization of p -dioxanone (PDO) with an acetylated starch (SA) initiator and a Sn(Oct)2 catalyst in bulk. The copolymers were characterized via Fourier transform infrared spectroscopy, 1H NMR, gel permeation chromatography, thermogravimetric analysis (TG), differential scanning calorimetry, and wide angle x-ray diffraction. The in vitro degradation results showed that the introduction of SA segments into the backbone chains of the copolymers led to an enhancement of the degradation rate, and the degradation rate of SAn -PPDO increased with the increase of SA wt %. Microspheres with an average volume diameter of 20 ,m, which will have potential applications in controlled release of drugs, were successfully prepared by using these new copolymers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5344,5353, 2009 [source] | ||||||||||||||||||||||||||||||||||