-
Journal of Controlled Release 11/2011; 152 Suppl 1:e17-8. · 5.73 Impact Factor
-
Journal of Controlled Release 11/2011; 152 Suppl 1:e57-8. · 5.73 Impact Factor
-
Journal of Controlled Release 11/2011; 152 Suppl 1:e52-4. · 5.73 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: An intelligent drug delivery nanosystem has been developed based on biodegradable supramolecular polymer micelles (SMPMs). The drug release can be triggered from SMPMs responsively by a bioactive agent, L-phenylalanine in a controlled fashion. The SMPMs are constructed from ethylcellulose-graft-poly(ε-caprolactone) (EC-g-PCL) and α-cyclodextrin (α-CD) derivate via host-guest and hydrophobic interactions. It has been found that these SMPMs have disassembled rapidly in response to an additional L-phenylalanine, due to great affinity discrepancy to α-CD between L-phenylalanine and PCL. Experiments have been carried out on trigger-controlled in vitro drug release of the SMPMs loaded with a model porphyrin based photosensitizer THPP. The result shows that the SMPMs released over 85% THPP in 6 h, which is two orders magnitudes faster than that of control. Also investigated is the photodynamic therapy (PDT) of THPP-loaded SMPMs with and without L-phenylalanine on MCF-7 carcinoma cell line. An effective trigger-concentration dependent lethal effect has been found showing promise in clinical photodynamic therapy.
Macromolecular Rapid Communications 03/2011; 32(6):540-5. · 4.60 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Novel pH-responsive polyglycerol (PG)-based hydrogels were successfully synthesized through the reaction of epichlorohydrin with L-lactic acid (LLA) in the presence of sodium hydroxide (NaOH), and cetyltrimethylammonium bromide as a phase transfer catalyst at room temperature, followed by hydrolysis, polymerization, and crosslinking reactions. The resultant gel was characterized by carbon nuclear magnetic resonance spectroscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared measurement, and it was found that incorporated LLA was bound to PG network as a pendant acidic substituent by the hydroxyl group of LLA (PGL gel). The PGL hydrogels with different LLA contents and equilibrium swelling ratios (ESRs) were prepared by changing the feed ratios of materials. The results determined by chemical titration showed that under the applied conditions the efficiency of introducing the carboxyl group into PG network was about 86% and the amount of LLA in the hydrogel reached to about 17 wt %. The swelling behavior of the hydrogels in different environmental mediums was investigated, and the results showed that the hydrogels are pH-, ionic strength-, and cationic charge-responsive. The hydrogels also have the reversible swelling/deswelling properties. These pH-responsive PG-based hydrogels will have potential applications in biomedical and related areas. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Journal of Applied Polymer Science 02/2009; 112(6):3209 - 3216. · 1.29 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: According to the concept of green chemistry and sustainable development, a new biodegradable copolymer comprised of hydrophobic poly(l-lactide) (PLLA) segments and hydrophilic cellulose segment (cellulose-g-PLLA) was designed and synthesized. The structure of the copolymer was characterized by (1)H NMR, FT-IR, (13)C NMR, DSC and WAXD. The cytotoxicity study shows that cellulose-g-PLLA exhibits good biocompatibility. The copolymer can self-assemble into micelles in water with the hydrophobic PLLA segments at the cores of micelles and the hydrophilic cellulose segments as the outer shells. Transmission electron microscopy (TEM) shows that the micelles exhibit nanospheric morphology within a size range of 30-80nm. The drug loaded micelles formed by the copolymer in aqueous media show sustained drug release which indicates their potential applicability in drug carrier.
Colloids and Surfaces B Biointerfaces 06/2008; 66(1):26-33. · 3.46 Impact Factor
-
Angewandte Chemie International Edition 02/2008; 47(30):5573-6. · 13.45 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Cisplatin conjugated onto macromolecules or loaded in micelles can be preferentially delivered to tumors to minimize its toxicity to healthy tissues and increase its drug efficacy. Herein, we report cisplatin-containing nanogels possibly useful for targeted delivery of cisplatin. Carboxylic acid-functionalized poly(beta -aminoester)graft-poly(ethylene glycol) copolymers were synthesized by cocondensation polymerization of piperazine with 2,2-bis(acryloxymethyl)propionic acid, PEG 2,2-bis(acryloxymethyl)propionate macromonomer (mPEG). The graft copolymers formed 100-200 nm nanogels with low size-distribution by the complexation of their carboxylic groups with cisplatin. The nanogels were negatively charged and had a PEG outer layer. Thus, they had "stealth properties" suitable for in vivo applications. The nanogels had significantly lower in vitro cytotoxicity to SKOV-3 ovarian cancer cells than free cisplatin, but similar anticancer activity toward SKOV-3 tumors xenografted to immunocompromised mice.
Drug Delivery 08/2007; 14(5):279-86. · 1.46 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Poly(vinyl alcohol)-initiated microwave-assisted ring opening polymerization of ε-caprolactone in bulk was investigated, and a series of poly(vinyl alcohol)-graft-poly(ε-caprolactone) (PVA-g-PCL) copolymers were prepared, with the degree of polymerization (DP) of PCL side chains and the degree of substitution (DS) of PVA by PCL being in the range of 3–24 and 0.35–0.89, respectively. The resultant comb-like PVA-g-PCL copolymers were confirmed by means of FTIR, 1H NMR, and viscometry measurement. The introduction of hydrophilic backbone resulted in the decrease in both melting point and crystallization property of the PVA-g-PCL copolymers comparing with linear PCL. With higher microwave power, the DP of PCL side chains and DS of PVA backbone were higher, and the polymerization reaction proceeded more rapidly. Both the DP and monomer conversion increased with irradiation time, while the DS increased first and then remained constant. With initiator in low concentration, the DP and DS were higher, while the monomer was converted more slowly. Microwaves dramatically improved the polymerization reaction in comparison of conventional heating method. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104, 3973–3979, 2007
Journal of Applied Polymer Science 03/2007; 104(6):3973 - 3979. · 1.29 Impact Factor
-
Macromolecular Rapid Communications 02/2007; 28(4):411 - 416. · 4.60 Impact Factor
-
Macromolecular Rapid Communications 11/2006; 27(24):2060 - 2064. · 4.60 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Poly(epsilon-caprolactone)-poly(ethylene glycol)-poly(epsilon-caprolactone) triblock co-polymers with number-average molar mass (Mn) over 20000 g/mol were prepared by ring-opening polymerization of epsilon-caprolactone initiated by poly(ethylene glycol) under microwave irradiation. This method was proposed as a means to improve in vivo compatibility as no harmful chemicals were involved in the polymerization except epsilon-caprolactone and poly(ethylene glycol). The resulting tri-block co-polymers were characterized by FT-IR, H-NMR, GPC and WAXD. Their Mn and their composition was controlled by the amount and the chain length of the poly(ethylene glycol) macromers involved in the feed. The ability of poly(epsilon-caprolactone)-poly(ethylene glycol)-poly(epsilon-caprolactone) co-polymers to entrap and deliver drugs was investigated with ibuprofen as a model drug. The release of ibuprofen was significantly influenced by the co-polymer composition and the extent of loading. The in vitro release of ibuprofen was sustained from 3 to 15 days for 10% loading, depending on the ratio of epsilon-caprolactone to ethylene glycol-derived subunits in co-polymer chains. This ratio ranged from 0.97 to 9.78. In the case of the co-polymer whose epsilon-caprolactone molar ratio to ethylene glycol-derived subunits was 2.49, the ibuprofen release was sustained for 2 to 24 days for ibuprofen loads going from 5 to 20 wt%.
Journal of Biomaterials Science Polymer Edition 02/2005; 16(8):957-71. · 1.69 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The micro construction of poly(epsilon-caprolactone) (PCL) and poly(L-lactic acid) (PLLA) blend films fabricated by solution casting under microwave irradiation was investigated by selective enzymatic degradation and scanning electron microscopy (SEM). The results were totally different from the blends obtained by conventional methods. The blend was more homogeneous and the PCL continuous phase more compact as no spherulites and tiny zone separation were observed from the film surface and no PCL network was observed inside the film, and the degradation of a PCL plank by Pseudomonas lipase was significantly retarded. The distributed PLLA micro spheres were enlarged and amorphous. The thermal behavior of the blend by microwave heating revealed that PCL and PLLA underwent a melting process, which induced the variations of the PCL phase and PLLA spheres. The weight loss caused by degradation of the PCL/PLLA blend obtained by conventional methods (B50c) is greater than that of the blend obtained by microwave methods (B50m), which reflects the change in morphology from a loose PCL network (B50c) to a dense PCL plank (B50m).
Macromolecular Bioscience 08/2004; 4(7):656-64. · 3.89 Impact Factor
-
Macromolecular Rapid Communications 07/2004; 25(15):1402 - 1405. · 4.60 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Acid-initiated ring-opening polymerization (ROP) of epsilon-caprolactone (epsilon-CL) was conducted under microwave irradiation (MI) at 2.45 GHz. At this frequency, metallic catalysts were no longer necessary. The effects of microwave power, irradiation time, epsilon-CL: acid molar ratio and acidity of acid on the polymerization were investigated. Both the rate of polymerization and the molar mass of polymer obtained were enhanced in comparison with conventional thermal method. Poly(epsilon-caprolactone) (PCL) with weight-average molar mass (Mw) over 12000 g/mol and Mw/Mn below 1.6 was synthesized in the presence of carboxylic acids such as maleic acid (MA), succinic acid (SA) and adipic acid (AA). The polymerization was also carried out when the monomer contained a certain amount of ibuprofen (IBU), by which, the IBU-PCL controlled release system was prepared directly. The release of IBU from the system was sustained from 12 h to 9 days with IBU content in weight increasing from 5 to 20%. It seems that this is a promising method to prepare drug controlled release systems.
Journal of Biomaterials Science Polymer Edition 02/2003; 14(3):241-53. · 1.69 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A polymer (Mw3000 g mol−1 with Mw/Mn 1.2) was obtained by the copper-catalyzed nitrogen-elimination of allyl diazoacetate. Its structure was determined as poly(carballyloxycarbene) (PCACB) by 1H and 13C NMR and IR spectroscopy.© 2002 Society of Chemical Industry
Polymer International 10/2002; 51(10):1047 - 1049. · 1.90 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Poly(epsilon-caprolactone) was blended with various polylactide-based polymers and processed to films by the solution casting method. Blends of 25/75, 50/50, 75/25, 90/10, and 95/5 (w/w) poly(epsilon-caprolactone)/poly(l-lactide), a 95/5 (w/w) blend of poly(epsilon-caprolactone) with a poly(d-lactide), a 50/50 (w/w) poly(l-lactide)-poly(d-lactide) mixture, and a poly(l-lactide-co-epsilon-caprolactone) copolymer were considered comparatively. The various phase-separated films were allowed to degrade in the presence of Pseudomonas lipase, biodegradation being monitored by proton nuclear magnetic resonance, size exclusion chromatography, differential scanning calorimetry, X-ray diffraction, and environmental scanning electron microscopy. The formation of separated phases during solvent evaporation and their morphologies are discussed. The introduction of poly(l-lactide) dramatically decreased the degradation rate of poly(epsilon-caprolactone)/poly(l-lactide) blends. The higher the percentage of poly(l-lactide), the slower the degradation, while the presence of cracks and increasing the lipase concentration acted in favor of the enzymatic degradation. Long-term enzymatic degradation of the various 95/5 blends was investigated over 480 h. The poly(epsilon-caprolactone) phase was enzymatically degraded by the lipase regardless of the blend type, the degradation rate depending on the nature of the co-components.
Biomacromolecules 4(2):372-7. · 5.48 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A powerful and highly efficient direct solvent, 1-allyl-3-methylimidazolium chloride ([AMIM]Cl), has been used for the dissolution of starch and the homogeneous ring opening graft polymerization (ROGP) of ε-caprolactone (ε-CL) onto starch granules. The ROGP carried out smoothly and the grafting efficiency of PCL reached 24.42% when the ROGP proceeded at 110 °C for 28 h with ε-CL/starch 1:1 (wt/wt) and stannous octoate (Sn(Oct)2) as a catalyst, which was calculated according to a standard curve newly created by an FT-IR method. The structure of starch grafted poly(ε-caprolactone) (starch-g-PCL) was characterized by FT-IR, DSC, WAXD and 13C NMR, the good adhesion between the two components was evidenced by SEM observations. The homo-polymerization of ε-CL and the disconnection of grafted PCL from starch-g-PCL were the main competition reactions. A new homogeneous modification of starch by the ROGP of ε-CL in [AMIM]Cl was investigated, as well as a new FT-IR method to calculate the grafting efficiency of PCL.
Carbohydrate Polymers.
