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102
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Loh XJ, Tan YX, Li Z, Teo LS, Goh SH, Li J. Biodegradable thermogelling poly(ester urethane)s consisting of poly(lactic acid)--thermodynamics of micellization and hydrolytic degradation. Biomaterials 2008; 29:2164-72. [PMID: 18276002 DOI: 10.1016/j.biomaterials.2008.01.016] [Citation(s) in RCA: 139] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2007] [Accepted: 01/23/2008] [Indexed: 11/25/2022]
Abstract
Multiblock poly(ether ester urethane)s comprising of poly(lactic acid) (PLA), poly(ethylene glycol) (PEG), and poly(propylene glycol) (PPG) segments were synthesized, and their aqueous solutions exhibited thermogelling behavior at critical gelation concentrations (CGC) ranging from 7 to 9 wt%. The chemical structures and molecular characteristics of the copolymers were studied by GPC, 1H NMR, 13C NMR and FTIR. The thermal stability of the poly(PEG/PPG/PLA urethane)s was studied by thermogravimetry analysis (TGA), and the PLA contents were calculated based on the thermal degradation profile. The results were in good agreement with those obtained from the 1H NMR measurements. The critical micellization concentration (CMC) of these water-soluble poly(ether ester urethane)s was determined at different temperatures using a dye solubilization method. The thermodynamic parameters for micelle formation were calculated, indicating that the process is largely entropy-driven. Interestingly, it appears that there exists a requirement for the system to possess a minimum gain in entropy before the thermogelling effect can be observed. Dilute copolymer solutions showed a lower critical solution temperature (LCST) behavior similar to pNIPAM dissolved in aqueous solutions. The thermogels hydrolytically degraded to polymer fragments corresponding to the constituent segment blocks within 3 months.
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Affiliation(s)
- Xian Jun Loh
- NUS Graduate School for Integrative Sciences & Engineering (NGS), National University of Singapore, Centre for Life Sciences, 28 Medical Drive, Singapore 117456, Singapore
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103
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Kim IY, Seo SJ, Moon HS, Yoo MK, Park IY, Kim BC, Cho CS. Chitosan and its derivatives for tissue engineering applications. Biotechnol Adv 2008; 26:1-21. [PMID: 17884325 DOI: 10.1016/j.biotechadv.2007.07.009] [Citation(s) in RCA: 843] [Impact Index Per Article: 52.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2007] [Accepted: 07/25/2007] [Indexed: 12/16/2022]
Abstract
Tissue engineering is an important therapeutic strategy for present and future medicine. Recently, functional biomaterial researches have been directed towards the development of improved scaffolds for regenerative medicine. Chitosan is a natural polymer from renewable resources, obtained from shell of shellfish, and the wastes of the seafood industry. It has novel properties such as biocompatibility, biodegradability, antibacterial, and wound-healing activity. Furthermore, recent studies suggested that chitosan and its derivatives are promising candidates as a supporting material for tissue engineering applications owing to their porous structure, gel forming properties, ease of chemical modification, high affinity to in vivo macromolecules, and so on. In this review, we focus on the various types of chitosan derivatives and their use in various tissue engineering applications namely, skin, bone, cartilage, liver, nerve and blood vessel.
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Affiliation(s)
- In-Yong Kim
- School of Agricultural Biotechnology, Seoul National University, Seoul 151-921, South Korea
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104
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Kim IY, Yoo MK, Kim BC, Park IY, Lee HC, Cho CS. Thermogelling behaviors of poly(caprolactone-b-ethylene glycol-b-caprolactone) triblock copolymer in the presence of hyaluronic acid. ACTA ACUST UNITED AC 2008. [DOI: 10.1002/pola.22702] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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105
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106
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Jun YJ, Kim JH, Choi SJ, Lee HJ, Jun MJ, Sohn YS. A tetra(l-lysine)-grafted poly(organophosphazene) for gene delivery. Bioorg Med Chem Lett 2007; 17:2975-8. [PMID: 17428658 DOI: 10.1016/j.bmcl.2007.03.069] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2007] [Revised: 03/17/2007] [Accepted: 03/22/2007] [Indexed: 10/23/2022]
Abstract
In order to develop a new gene delivery vector, a novel cationic poly(organophosphazene) was synthesized by stepwise nucleophilic substitutions of poly(dichlorophosphazene) with a hydrophilic methoxy-poly(ethylene glycol) (MPEG) as a shielding group and a branched tetra(L-lysine), LysLys(LysEt)(2), as a cationic moiety. The cationic polymer has shown to form a polyplex by DNA condensation and very low in vitro cytotoxicity probably due to the shielding effect of MPEG, which provides a basis for improving the low gene transfection yield of cationic polyphosphazenes.
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Affiliation(s)
- Yong Joo Jun
- Division of Nano Science BK 21, Ewha Womans University, 11-1 Daehyun-Dong, Seodaemun-Gu, Seoul 120-750, Republic of Korea
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107
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Watanabe E, Tomoshige N, Uyama H. New Biodegradable and Thermoresponsive Polymers Based on Amphiphilic Poly(asparagine) Derivatives. ACTA ACUST UNITED AC 2007. [DOI: 10.1002/masy.200750428] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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108
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Lee Y, Park SY, Chung HJ, Park TG. New Sol-Gel Transition Hydrogels Based on Pluronic-Mimicking Copolymers Grafted with Oligo(lactic acids). ACTA ACUST UNITED AC 2007. [DOI: 10.1002/masy.200750322] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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109
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Synthesis of Stimuli-Responsive Polymers by Living Polymerization: Poly(N-Isopropylacrylamide) and Poly(Vinyl Ether)s. ADVANCES IN POLYMER SCIENCE 2007. [DOI: 10.1007/12_2007_120] [Citation(s) in RCA: 177] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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110
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Chitkara D, Shikanov A, Kumar N, Domb AJ. Biodegradable Injectable In Situ Depot-Forming Drug Delivery Systems. Macromol Biosci 2006; 6:977-90. [PMID: 17128422 DOI: 10.1002/mabi.200600129] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The scope of drug-delivery systems has expanded significantly in recent years providing new ways to deliver life saving therapeutics to patients. The development of new injectable drug-delivery systems has provided new vistas and opened up unexplored horizons in the field of science, particularly in controlled drug delivery since these systems possess unique advantages over traditional ones, which include ease of application, and localized and prolonged drug delivery. In the past few years, an increasing number of such systems has been reported in the literature for various biomedical applications, including drug delivery, cell encapsulation, and tissue repair. These are injectable fluids that can be introduced into the body in a minimally invasive manner prior to solidifying or gelling within the desired site. For this purpose both natural (chitosan, alginates) as well as synthetic polymers (PEGylated polyesters, ricinoleic acid-based polymers) have been utilized. These systems have been explored widely for the delivery of various therapeutic agents ranging for anti-neoplastic agents like paclitaxel to proteins and peptides such as insulin, almost covering every segment of the pharmaceutical field. This manuscript focuses on the recent advancements in the area of in situ forming biodegradable polymeric drug-delivery systems.
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Affiliation(s)
- Deepak Chitkara
- Department of Pharmaceutics, National Institute of Pharmaceutical Education and Research, Sec. 67, SAS Nagar, Mohali 160062, India
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111
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Controlled nanoparticles formation by self-assembly of novel amphiphilic polyphosphazenes with poly (N-isopropylacrylamide) and ethyl glycinate as side groups. REACT FUNCT POLYM 2006. [DOI: 10.1016/j.reactfunctpolym.2006.06.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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112
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Jo S, Kim J, Kim SW. Reverse Thermal Gelation of Aliphatically Modified Biodegradable Triblock Copolymers. Macromol Biosci 2006; 6:923-8. [PMID: 17099865 DOI: 10.1002/mabi.200600127] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A simple aliphatic modification demonstrated how to turn a water-soluble biodegradable triblock copolymer synthesized from PEG, L-lactide, and epsilon-caprolactone into a thermoreversible polymer of which aqueous solution underwent a sol-to-gel phase transition upon a mild temperature rise. Thermogelling behavior of the aliphatically modified polymer was dependent on the degree of aliphatic modification and polymer concentration. When the polymer solutions were subcutaneously injected into rats, immediate depot formation has been observed. The polymeric gel depots have lasted for two weeks in vivo. This aliphatically modified thermogelling polymer can find applications in drug delivery.
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Affiliation(s)
- Seongbong Jo
- Center for Controlled Chemical Delivery, Department of Pharmaceutics and Pharmaceutical Chemistry, 30 S 2000 E RM 201, University of Utah, Salt Lake City, UT 84112-5820, USA
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113
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Kang GD, Cheon SH, Khang G, Song SC. Thermosensitive poly(organophosphazene) hydrogels for a controlled drug delivery. Eur J Pharm Biopharm 2006; 63:340-6. [PMID: 16527468 DOI: 10.1016/j.ejpb.2006.01.001] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2005] [Revised: 01/19/2006] [Accepted: 01/19/2006] [Indexed: 11/23/2022]
Abstract
Thermosensitive poly(organophosphazenes) were synthesized for a controlled release of hydrophilic polymeric model drugs such as dextran and albumin in this study. The solutions of the present polymers bearing both hydrophobic side groups of L-isoleucine ethyl ester (IleOEt) and hydrophilic groups of alpha-amino-omega-methoxy-PEG (Mw 550) (AMPEG550) exhibited reversible sol-gel transition behaviors with changes of temperature. Viscometric measurement indicated that the thermosensitive hydrogels with good strength could be formed from the solutions in the range of the concentrations of 7-15 wt% around body temperature. For increasing their biodegradabililites, depsipeptides of ethyl-2-(O-glycyl)lactate (GlyLacOEt) were also introduced to the polymer, showing enhanced degradation of hydrogels. In vitro release behaviors of hydrophilic FITC-dextran (Mw 71,600) and human serum albumin from these polymer hydrogels were sustained for about 2 weeks while those from poloxamer (Pluronic F-127) hydrogel showed a distinct initial burst. The release of FITC-dextran exhibited concentration-dependent behavior ranging from 7 to 15 wt% of the polymer solution while it was almost independent of the concentration of FITC-dextran.
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Affiliation(s)
- Gyung Don Kang
- Division of Life Science, Korea Institute of Science and Technology, Seoul, Republic of Korea
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114
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Zhang JX, Qiu LY, Jin Y, Zhu KJ. Thermally responsive polymeric micelles self-assembled by amphiphilic polyphosphazene with poly(N-isopropylacrylamide) and ethyl glycinate as side groups: Polymer synthesis, characterization, andin vitro drug release study. J Biomed Mater Res A 2006; 76:773-80. [PMID: 16345095 DOI: 10.1002/jbm.a.30604] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Thermally responsive amphiphilic poly(N-isopropylacrylamide) (PNIPAm)-grafted-polyphosphazene (PNIPAm-g-PPP) was synthesized by stepwise cosubstitution of chlorine atoms on polymer backbones with amino-terminated NIPAm oligomers and ethyl glycinate (GlyEt). Polymer structure was confirmed by FT-IR, (1)H NMR, elemental analysis, and GPC. The thermosensitivity of PNIPAm-g-PPP aqueous solution was investigated by turbidity method. The lower critical solution temperature (LCST) of PNIPAm-g-PPP was observed to be approximately 30 degrees C in water, while it was 24 degrees C in 0.1M PBS (pH 7.4). Micellization behavior of PNIPAm-g-PPP in aqueous solution was characterized by fluorescence probe technique, TEM, and DLS. The critical micelle concentration (CMC), thus, determined was 0.0187 g/L. Both TEM and DLS measurement suggested that the diameter of micelles was approximately 190 nm at 20 degrees C. Diflunisal (DIF)-loaded micelles were prepared by dialysis method. In vitro release test at various temperatures was also performed to study the effect of temperature on the drug release profiles. It was demonstrated that DIF release from PNIPAm-g-PPP micelles was slower at the temperature of 37 degrees C than that at 4 degrees C.
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Affiliation(s)
- Jian Xiang Zhang
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310031, China
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115
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Cho YW, An SW, Song SC. Effect of Inorganic and Organic Salts on the Thermogelling Behavior of Poly(organophosphazenes). MACROMOL CHEM PHYS 2006. [DOI: 10.1002/macp.200500483] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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116
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Abstract
Polymers occupy a major portion of materials used for controlled release formulations and drug-targeting systems because this class of materials presents seemingly endless diversity in topology and chemistry. This is a crucial advantage over other classes of materials to meet the ever-increasing requirements of new designs of drug delivery formulations. The polymer architecture (topology) describes the shape of a single polymer molecule. Every natural, seminatural, and synthetic polymer falls into one of categorized architectures: linear, graft, branched, cross-linked, block, star-shaped, and dendron/dendrimer topology. Although this topic spans a truly broad area in polymer science, this review introduces polymer architectures along with brief synthetic approaches for pharmaceutical scientists who are not familiar with polymer science, summarizes the characteristic properties of each architecture useful for drug delivery applications, and covers recent advances in drug delivery relevant to polymer architecture.
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Affiliation(s)
- Li Yan Qiu
- Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, 421 Wakara Way, Suite 315, Salt Lake City, Utah 84108, USA
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117
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Cho YW, Lee JR, Song SC. Novel Thermosensitive 5-Fluorouracil−Cyclotriphosphazene Conjugates: Synthesis, Thermosensitivity, Degradability, and in Vitro Antitumor Activity. Bioconjug Chem 2005; 16:1529-35. [PMID: 16287251 DOI: 10.1021/bc049697u] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A novel thermosensitive macromolecular prodrug of 5-fluorouracil (5-FU) was synthesized using cyclotriphosphazene, and its thermosensitivity, degradability, and in vitro antitumor activity were studied. A series of alpha-substituted glycine derivatives of 5-FU containing carboxylic groups were prepared, and cyclotriphosphazenes with amino groups were synthesized via the stepwise substitution of hexachlorocyclotriphosphazene (NPCl(2))(3) with methoxy-poly(ethylene glycol) (MPEG) or alkoxy ethylene oxide and lysine ethyl ester (LysOEt). The coupling reaction of the two derivatives, and their subsequent deprotection, yielded a thermosenstive 5-FU-cyclotriphosphazene conjugate, which exhibited a unique octopus-shaped molecular structure, in which the three hydrophilic PEG groups (or alkoxy ethylene oxides) were oriented in one direction, opposing the other three hydrophobic groups containing 5-FU, with respect to the trimer ring plane. This conjugate exhibited a reversible and thermosensitive phase transition in an aqueous medium, from soluble to insoluble states. The lower critical solution temperature (LCST) of the conjugate was controlled by substitution with different hydrophilic/hydrophobic side groups, and a few of the conjugates displayed LCSTs which were just below body temperature. This, of course, implies possible applications for local drug delivery by direct intratumoral injection. The conjugate exhibited gradual degradation at 37 degrees C in both neutral and acidic buffer solutions, and high temperature significantly facilitated its hydrolytic degradation. All of the conjugates displayed dose-dependent cytotoxicity against the leukemia L1210 cell line and exhibited more pronounced cytotoxic effects than did 5-FU.
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Affiliation(s)
- Yong Woo Cho
- Division of Life Science, Korea Institute of Science and Technology, Seoul 130-650, Korea
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118
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Kang GD, Heo JY, Jung SB, Song SC. Controlling the Thermosensitive Gelation Properties of Poly(organophosphazenes) by Blending. Macromol Rapid Commun 2005. [DOI: 10.1002/marc.200500472] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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119
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Kim JK, Toti US, Song R, Sohn YS. A macromolecular prodrug of doxorubicin conjugated to a biodegradable cyclotriphosphazene bearing a tetrapeptide. Bioorg Med Chem Lett 2005; 15:3576-9. [PMID: 15982876 DOI: 10.1016/j.bmcl.2005.05.057] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2005] [Revised: 05/12/2005] [Accepted: 05/16/2005] [Indexed: 11/24/2022]
Abstract
A new biodegradable water-soluble phosphazene trimer-doxorubicin conjugate was synthesized, in which equimolar hydrophilic methoxy-poly(ethylene glycol) with a molecular weight of 350 (MPEG350) and a tumor-specific tetrapeptide (Gly-Phe-Leu-Gly) were grafted to cyclotriphosphazene. The present conjugate exhibited cytotoxicity lower than that of free doxorubicin (IC50=0.10 microM) but a reasonably higher in vitro cytotoxicity (IC50=1.1 microM) against the leukemia L1210 cell line probably due to its enzymatically controlled release.
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Affiliation(s)
- Jin Kyu Kim
- Department of Chemistry, Division of Nano Science, Ewha Womans University, Seoul 120-750, South Korea
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120
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Ruel-Gariépy E, Leroux JC. In situ-forming hydrogels--review of temperature-sensitive systems. Eur J Pharm Biopharm 2005; 58:409-26. [PMID: 15296964 DOI: 10.1016/j.ejpb.2004.03.019] [Citation(s) in RCA: 825] [Impact Index Per Article: 43.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2004] [Accepted: 03/08/2004] [Indexed: 10/26/2022]
Abstract
In the past few years, an increasing number of in situ-forming systems have been reported in the literature for various biomedical applications, including drug delivery, cell encapsulation, and tissue repair. There are several possible mechanisms that lead to in situ gel formation: solvent exchange, UV-irradiation, ionic cross-linkage, pH change, and temperature modulation. The thermosensitive approach can be advantageous for particular applications as it does not require organic solvents, co-polymerization agents, or an externally applied trigger for gelation. In the last 2 decades, several thermosensitive formulations have been proposed. This manuscript focuses on aqueous polymeric solutions that form implants in situ in response to temperature change, generally from ambient to body temperature. It mainly reviews the characterization and use of polysaccharides, N-isopropylacrylamide copolymers, poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) (poloxamer) and its copolymers, poly(ethylene oxide)/(D,L-lactic acid-co-glycolic acid) copolymers, and thermosensitive liposome-based systems.
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Affiliation(s)
- Eve Ruel-Gariépy
- Canada Research Chair in Drug Delivery, Faculty of Pharmacy, University of Montreal, Montreal, Que, Canada
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121
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Song R, Joo Jun Y, Ik Kim J, Jin C, Sohn YS. Synthesis, characterization, and tumor selectivity of a polyphosphazene–platinum(II) conjugate. J Control Release 2005; 105:142-50. [PMID: 15894394 DOI: 10.1016/j.jconrel.2005.03.016] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2005] [Revised: 03/26/2005] [Accepted: 03/28/2005] [Indexed: 11/21/2022]
Abstract
A new amphiphilic poly(organophosphazene) was synthesized by stepwise nucleophilic substitutions with a hydrophilic methoxy poly(ethylene glycol) with an average molecular weight of 350 (MPEG350) and a hydrophobic glycyl-L-glutamate as side groups, and then an antitumor (dach)platinum(II) (dach: trans-(+/-)-1,2-diaminocyclohexane) moiety was conjugated to the polymer using the dipeptide as a spacer. This polymeric platinum conjugate was found to be accumulated in the tumor tissue to a remarkably greater extent than in the normal tissue (tumor/tissue ratio >4), probably due to the excellent EPR effect and the long circulating properties of the polymer conjugate (t1/2beta=6.2 h and AUC=4020 nmol h/ml) compared with carboplatin (t1/2beta=0.42 h and AUC=120 nmol h/ml). The polymer conjugate also exhibited high in vitro cytotoxicity comparable to cisplatin against several human tumor cells tested.
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Affiliation(s)
- Rita Song
- Department of Chemistry, Division of Nano Science, Ewha Womans University, Seoul 120-750, South Korea
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122
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Seong JY, Jun YJ, Jeong B, Sohn YS. New thermogelling poly(organophosphazenes) with methoxypoly(ethylene glycol) and oligopeptide as side groups. POLYMER 2005. [DOI: 10.1016/j.polymer.2005.04.024] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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123
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Takeuchi Y, Uyama H, Tomoshige N, Watanabe E, Tachibana Y, Kobayashi S. Injectable thermoreversible hydrogels based on amphiphilic poly(amino acid)s. ACTA ACUST UNITED AC 2005. [DOI: 10.1002/pola.21189] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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124
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Zhang T, Cai Q, Wu ZP, Li CQ, Jin RG. Nucleophilic cosubstitution of poly(dichlorophosphazene) with alkyl ether and amino acid ester. ACTA ACUST UNITED AC 2005. [DOI: 10.1002/pola.20722] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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125
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Ahn JS, Suh JM, Lee M, Jeong B. Slow eroding biodegradable multiblock poloxamer copolymers. POLYM INT 2005. [DOI: 10.1002/pi.1780] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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126
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127
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Shimokuri T, Kaneko T, Akashi M. Specific thermosensitive volume change of biopolymer gels derived from propylated poly(?-glutamate)s. ACTA ACUST UNITED AC 2004. [DOI: 10.1002/pola.20384] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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128
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Tachibana Y, Kurisawa M, Uyama H, Kobayashi S. Thermo- and pH-responsive biodegradable poly(alpha-N-substituted gamma-glutamine)s. Biomacromolecules 2003; 4:1132-4. [PMID: 12959575 DOI: 10.1021/bm034123y] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
New double stimuli-responsive poly(alpha-N-substituted gamma-glutamine) has been developed, which was synthesized by the reaction of poly(gamma-glutamic acid) with amino alcohols. Appropriate combinations of the amino alcohols provided the biodegradable poly(amino acid) exhibiting a sharp lower critical solution temperature (LCST) in water. Furthermore, the phase transition temperature was highly sensitive to pH changes.
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Affiliation(s)
- Yoichi Tachibana
- Department of Materials Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
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129
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