The Experts below are selected from a list of 15723 Experts worldwide ranked by ideXlab platform
Andreas Lendlein - One of the best experts on this subject based on the ideXlab platform.
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evaluation of a degradable shape memory polymer network as matrix for Controlled Drug Release
Journal of Controlled Release, 2009Co-Authors: Christian Wischke, Susi Steuer, Axel T Neffe, Andreas LendleinAbstract:Degradable shape-memory polymers are multifunctional materials with broad applicability for medical devices. They are designed to acquire their therapeutically relevant shape and mechanical properties after implantation. In this study, the potential of a completely amorphous shape-memory polymer matrix for Controlled Drug Release was comprehensively characterized according to a four step general strategy which provides concepts for validating multifunctional materials for pharmaceutical applications. Independent functionalities are thereby crucial for fully exploiting the potential of the materials. The copolyester urethane network was synthesized by crosslinking star-shaped tetrahydroxy telechelics of oligo[(rac-lactide)-co-glycolide] with an aliphatic diisocyanate. In step 1 of the four step characterization procedure, this material showed the thermal and mechanical properties, which are required for the shape-memory effect under physiological conditions. Shape recovery could be realized by a one-step or a multi-step methodology. In step 2, feasibility of Drug loading of pre-formed shape-memory networks has been demonstrated with Drugs of different hydrophobicities. The presence of Drugs did not disturb the material's functionalities directly after loading (step 3) and under Release conditions (step 4). A predictable Release of about 90% of the payload in 80 days was observed. Overall, the synthesized amorphous polymer network showed three independent functionalities, i.e., a shape-memory effect combined with biodegradability and Controlled Drug Release.
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Evaluation of a degradable shape-memory polymer network as matrix for Controlled Drug Release
Journal of Controlled Release, 2009Co-Authors: Christian Wischke, Susi Steuer, Axel T Neffe, Andreas LendleinAbstract:Degradable shape-memory polymers are multifunctional materials with broad applicability for medical devices. They are designed to acquire their therapeutically relevant shape and mechanical properties after implantation. In this study, the potential of a completely amorphous shape-memory polymer matrix for Controlled Drug Release was comprehensively characterized according to a four step general strategy which provides concepts for validating multifunctional materials for pharmaceutical applications. Independent functionalities are thereby crucial for fully exploiting the potential of the materials. The copolyester urethane network was synthesized by crosslinking star-shaped tetrahydroxy telechelics of oligo[(rac-lactide)-co-glycolide] with an aliphatic diisocyanate. In step 1 of the four step characterization procedure, this material showed the thermal and mechanical properties, which are required for the shape-memory effect under physiological conditions. Shape recovery could be realized by a one-step or a multi-step methodology. In step 2, feasibility of Drug loading of pre-formed shape-memory networks has been demonstrated with Drugs of different hydrophobicities. The presence of Drugs did not disturb the material's functionalities directly after loading (step 3) and under Release conditions (step 4). A predictable Release of about 90% of the payload in 80??days was observed. Overall, the synthesized amorphous polymer network showed three independent functionalities, i.e., a shape-memory effect combined with biodegradability and Controlled Drug Release. ?? 2009 Elsevier B.V. All rights reserved.
Wuli Yang - One of the best experts on this subject based on the ideXlab platform.
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synthesis of discrete and dispersible hollow mesoporous silica nanoparticles with tailored shell thickness for Controlled Drug Release
Journal of Materials Chemistry, 2012Co-Authors: Yunfeng Jiao, Shun Shen, Baisong Chang, Yahong Zhang, Xinguo Jiang, Wuli YangAbstract:By employing poly (tert-butylacrylate) (PTBA) nanospheres as the dissolvable core templates, we develop a new method to synthesize hollow mesoporous silica nanoparticles (HMSN). Both the PTBA core and the structure-directing surfactant, cetyltrimethylammonium bromide (CTAB), can be easily and synchronously removed through solvent extraction in ethanol, which ensures the complete structure and ideal dispersibility of the products compared with the previous template synthesis that often needs calcination to remove the templates. Given that hollow core diameter and shell thickness are the key properties of HMSN, the hollow core diameter and shell thickness can be tailored precisely. In addition, as novel inorganic nanomaterials with a tuned structure, HMSN show notable biocompatibility and efficient doxorubicin (DOX) loading. In in vitro tests, the Release rate of DOX-loaded HMSN exhibit a surprising shell-thickness-dependent and a pH responsive Drug Release character, suggesting that HMSN are a very promising Drug delivery system for shell-thickness-Controlled Drug Release. The results of intracellular tracking and cytotoxicity assays further demonstrate the potential and efficiency of HMSN as a Drug delivery system.
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thermo and ph dual responsive polymer shell coated magnetic mesoporous silica nanoparticles for Controlled Drug Release
Journal of Materials Chemistry, 2011Co-Authors: Baisong Chang, Yunfeng Jiao, Changchun Wang, Wuli YangAbstract:In this paper, a kind of core–shell composite microsphere was prepared based on poly(N-isopropylacrylamide-co-methacrylic acid) (P(NIPAM-co-MAA)) coated magnetic mesoporous silica nanoparticles (M-MSN) via precipitation polymerization. The composite microsphere presented a thermo/pH-coupling sensitivity and the volume phase transition could be precisely regulated by the molar ratio of MAA to NIPAM or the concentration of NaCl. At physiological conditions (37 °C, 0.15 M NaCl), the P(NIPAM-co-MAA) shell underwent a distinct transition from a swollen state in pH 7.4 to a collapsed state in pH 5.0, so that the polymer shell was active in moderating the diffusion of embedded Drugs in-and-out of the pore channels of MSN. Doxorubicin hydrochloride (DOX) was applied as a model Drug and the behaviors of Drug storage/Release were investigated. The Drug loaded behavior was pH-dependent, and the composite microsphere had a Drug embed efficiency of about 91.3% under alkaline conditions. The cumulative in vitro Release of the DOX-loaded composite microsphere showed a low level of leakage below the volume phase transition temperature (VPTT) and was significantly enhanced above its VPTT, exhibiting an apparent thermo/pH-response Controlled Drug Release. The cytotoxicity assay of a blank carrier to normal cells indicated that the composite microspheres were suitable as Drug carriers, while the DOX-loaded composite microspheres had a similar cytotoxicity to HeLa cells compared with free DOX. Therefore, the thermo/pH-sensitive composite microsphere could, in principle, be used for in vivo cancer therapy with a low premature Drug Release during blood circulation whilst having a rapid Release upon reaching tumor tissues.
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magnetic mesoporous silica microspheres with thermo sensitive polymer shell for Controlled Drug Release
Journal of Materials Chemistry, 2009Co-Authors: Wuli Yang, Jianhua Hu, Changchun Wang, Shoukuan FuAbstract:A Controlled Drug Release system was designed based on the combination of three advantages into one entity, which was composed of Fe3O4 magnetic nanoparticle as the core, mesoporous silica as the sandwiched layer, and thermo-sensitive P(NIPAM-co-NHMA) copolymer as the outer shell. The hydrophilic comonomer content affected the volume phase-transition temperature (VPTT) of this composite microsphere and the behavior of the temperature-triggered Drug Release. Zn(II) phthalocyanine tetrasulfonic acid (ZnPcS4), a well-known photodynamic therapy (PDT) Drug, was used as a model Drug to assess the Release system. The results demonstrated that the Drug Release behavior was dependent on the temperature and had a close correlation with the VPTT. Above the VPTT, the Drug Release rate was much faster than that below the VPTT, which showed a great potential application in tumor therapy.
Jianmei Lu - One of the best experts on this subject based on the ideXlab platform.
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Near-infrared light-Controlled Drug Release and cancer therapy with polymer-caged upconversion nanoparticles
RSC Advances, 2015Co-Authors: Qingjian Xing, Jiaying Xu, Najun Li, Qingfeng Xu, Dongyun Chen, Yang Jiao, Jianmei LuAbstract:Herein, a core–shell nanocomposite was fabricated by self-assembly of the photo-responsive copolymer with silica-coated upconversion nanoparticles for near-infrared light-Controlled Drug Release and cancer therapy. Firstly, lanthanide upconversion nanoparticles (UCNPs) co-doped with Yb3+ and Tm3+ were encapsulated with mesoporous silica as the core (MUCNPs). Then a folate conjugated light-responsive copolymer (PSMN-FA) was synthesized and coated on MUCNP as the shell via self-assembly. Anti-cancer Drugs could be loaded into the mesopores of the silica layer before polymer coating. Upon near-infrared (NIR) light irradiation at 980 nm, the caged UCNPs emitted luminescence in the UV region, which could change the structure of the amphiphilic copolymer and separate it from the MUCNPs, immediately followed by the Release of the pre-loaded Drugs to the targeted cancer cells. Our model experiments in vitro verified that the nanocarrier MUCNPs@C18@PSMN-FAcan provide active tumor targeting to folate receptor over-expressed (FR+) tumor cells. Both in vitro and in vivo studies were carried out to evaluate the NIR-Controlled Drug Release strategy and the promising application in anticancer therapy based on the polymer-UCNPs nanocomposites.
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light responsive amphiphilic copolymer coated nanoparticles as nanocarriers and real time monitors for Controlled Drug Release
Journal of Materials Chemistry B, 2014Co-Authors: Qingjian Xing, Xiuxiu Qi, Najun Li, Qingfeng Xu, Dongyun Chen, Yang Jiao, Jianmei LuAbstract:Herein, light-responsive nanocarriers based on hollow mesoporous silica (HMS) nanoparticles modified with spiropyran-containing light-responsive copolymer (PRMS-FA) were fabricated via a simple self-assembly process. HMS modified with long-chain hydrocarbon octadecyltrimethoxysilane was an ideal base material owing to its good biocompatibility and Drug capability. The spiropyran-containing amphiphilic copolymer could shift its hydrophilic–hydrophobic balance to become hydrophilic upon UV (λ = 365 nm) irradiation and then break away from the hydrophobic surface of the HMS core, followed by the uncaging and Release of the pre-loaded anticancer Drug. Simultaneously, the fluorescence resonance energy transfer (FRET) process based on the structural transformation of PRMS-FA was observed, which could act as a real-time monitor for the light-Controlled Drug Release. Our model experiments in vitro tested and verified that this composite nanocarrier has good biocompatibility, active tumour targeting to the folate receptor over-expressed in tumour cells, is non-toxic to normal cells and that light-Controlled Drug Release with real-time monitoring can be achieved.
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A facile preparation of targetable pH-sensitive polymeric nanocarriers with encapsulated magnetic nanoparticles for Controlled Drug Release
Journal of Materials Chemistry, 2012Co-Authors: Shun Bin Yang, Xiuxiu Qi, Xiao Mei, Najun Li, Qingfeng Xu, Dongyun Chen, Hua Li, Jianmei LuAbstract:Novel multifunctional nanocomposites were successfully prepared for the Controlled Release of anticancer Drug and magnetic resonance imaging (MRI) via a simple self-assembly process. In this strategy, superparamagnetic iron oxide nanoparticles (SPIONPs) were "fixed" between the hydrophobic segment of the pH-sensitive amphiphilic polymer (HAMAFA-b-DBAM) and the surface of hollow mesoporous silica nanoparticles (HMS) which were modified by the long-chain hydrocarbon octadecyltrimethoxysilane (C18). Since the amphiphilic polymer was conjugated with a folic acid (FA) group, the nanocomposites could target the folic acid receptor (FR) of over-expressed tumor cells efficiently. Moreover, high Drug loading content was obtained simultaneously due to the hollow core of HMS. The loaded Drug could Release from the HMS core triggered by the mildly acidic pH environment in the cancer cells due to the hydrolysis of the pH-sensitive polymer shell. The targeting process of the nanocomposites could be easily tracked by MRI due to the magnetism of the SPIONPs. Therefore, a nanocarrier with high Drug-loading capacity and Controlled Drug Release property for tumor diagnosis and therapy was obtained via the self-assembly of HMS core, magnetic Fe3O4 nanoparticles and targetable pH-sensitive polymer shell.
Christian Wischke - One of the best experts on this subject based on the ideXlab platform.
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evaluation of a degradable shape memory polymer network as matrix for Controlled Drug Release
Journal of Controlled Release, 2009Co-Authors: Christian Wischke, Susi Steuer, Axel T Neffe, Andreas LendleinAbstract:Degradable shape-memory polymers are multifunctional materials with broad applicability for medical devices. They are designed to acquire their therapeutically relevant shape and mechanical properties after implantation. In this study, the potential of a completely amorphous shape-memory polymer matrix for Controlled Drug Release was comprehensively characterized according to a four step general strategy which provides concepts for validating multifunctional materials for pharmaceutical applications. Independent functionalities are thereby crucial for fully exploiting the potential of the materials. The copolyester urethane network was synthesized by crosslinking star-shaped tetrahydroxy telechelics of oligo[(rac-lactide)-co-glycolide] with an aliphatic diisocyanate. In step 1 of the four step characterization procedure, this material showed the thermal and mechanical properties, which are required for the shape-memory effect under physiological conditions. Shape recovery could be realized by a one-step or a multi-step methodology. In step 2, feasibility of Drug loading of pre-formed shape-memory networks has been demonstrated with Drugs of different hydrophobicities. The presence of Drugs did not disturb the material's functionalities directly after loading (step 3) and under Release conditions (step 4). A predictable Release of about 90% of the payload in 80 days was observed. Overall, the synthesized amorphous polymer network showed three independent functionalities, i.e., a shape-memory effect combined with biodegradability and Controlled Drug Release.
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Evaluation of a degradable shape-memory polymer network as matrix for Controlled Drug Release
Journal of Controlled Release, 2009Co-Authors: Christian Wischke, Susi Steuer, Axel T Neffe, Andreas LendleinAbstract:Degradable shape-memory polymers are multifunctional materials with broad applicability for medical devices. They are designed to acquire their therapeutically relevant shape and mechanical properties after implantation. In this study, the potential of a completely amorphous shape-memory polymer matrix for Controlled Drug Release was comprehensively characterized according to a four step general strategy which provides concepts for validating multifunctional materials for pharmaceutical applications. Independent functionalities are thereby crucial for fully exploiting the potential of the materials. The copolyester urethane network was synthesized by crosslinking star-shaped tetrahydroxy telechelics of oligo[(rac-lactide)-co-glycolide] with an aliphatic diisocyanate. In step 1 of the four step characterization procedure, this material showed the thermal and mechanical properties, which are required for the shape-memory effect under physiological conditions. Shape recovery could be realized by a one-step or a multi-step methodology. In step 2, feasibility of Drug loading of pre-formed shape-memory networks has been demonstrated with Drugs of different hydrophobicities. The presence of Drugs did not disturb the material's functionalities directly after loading (step 3) and under Release conditions (step 4). A predictable Release of about 90% of the payload in 80??days was observed. Overall, the synthesized amorphous polymer network showed three independent functionalities, i.e., a shape-memory effect combined with biodegradability and Controlled Drug Release. ?? 2009 Elsevier B.V. All rights reserved.
Yuichi Ohya - One of the best experts on this subject based on the ideXlab platform.
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Biodegradable shape-memory polymers exhibiting sharp thermal transitions and Controlled Drug Release
Biomacromolecules, 2009Co-Authors: Koji Nagahama, Yuichi Ueda, Tatsuro Ouchi, Yuichi OhyaAbstract:Biodegradable shape-memory polymer networks prepared by cross-linking star shape branched oligo(ε-caprolactone) (bOCL) with hexamethylene diisocyanate are introduced. The thermal and mechanical properties of these networks were investigated using differential scanning calorimetry and tensile testing, respectively, and the morphology of the phase structure was characterized by polarized optical microscopy. The shape-memory properties of the networks were quantified using thermomechanical tensile experiments and showed strain fixity rates R(f) higher than 97% and strain recovery rates R(r) as high as 100%. Of note, networks of OCL segments with a lower degree of polymerization (DP; 10) exhibited significantly improved temperature-sensitive shape recovery: 90% of the permanent shape was recovered upon heating to within a 2 °C range (37-39 °C). The networks exhibited complete shape recovery to the permanent shape within 10 s at 42 °C. Theophylline-loaded (10 and 20 wt %) shape-memory materials, prepared by cross-linking bOCL with hexamethylene diisocyanate in the presence of theophylline, are also described as a model for a Controlled Drug Release device. The 10 wt % loaded material was sufficiently soft and flexible for complex shape transformation and also showed high R(f) (98%) and R(r) (99%). Sustained Release of loaded theophylline was achieved over 1 month without initial burst-Release in a phosphate buffer solution (PBS; pH 7.4) at 37 °C.