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Altering of lower critical solution temperature of environmentally responsive poly (N-isopropylacrylamide-co-acrylic acid-co-vanillin acrylate) affected by acrylic acid, vanillin acrylate, and post-polymerization modification. Colloid Polym Sci 2021. [DOI: 10.1007/s00396-021-04882-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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2
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Poly(N-isopropylacrylamide-co-2-((diethylamino)methyl)-4-methylphenyl acrylate) thermo-ph responsive copolymer: trend in the lower critical solution temperature optimization of Poly (N-isopropyylacrylamide). JOURNAL OF POLYMER RESEARCH 2021. [DOI: 10.1007/s10965-021-02574-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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3
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Yılmaz Aykut D, Yolaçan Ö, Deligöz H. pH stimuli drug loading/release platforms from LbL single/blend films: QCM-D and in-vitro studies. Colloids Surf A Physicochem Eng Asp 2020. [DOI: 10.1016/j.colsurfa.2020.125113] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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4
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Influence of vanillin acrylate and 4-acetylphenyl acrylate hydrophobic functional monomers on phase separation of N-isopropylacrylamide environmental terpolymer: fabrication and characterization. Polym Bull (Berl) 2019. [DOI: 10.1007/s00289-019-02890-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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5
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Abdelaty MSA. Poly( N-isopropylacrylamide- co-2-((diethylamino)methyl)-4-formyl-6-methoxyphenyl acrylate) Environmental Functional Copolymers: Synthesis, Characterizations, and Grafting with Amino Acids. Biomolecules 2018; 8:E138. [PMID: 30404234 PMCID: PMC6316684 DOI: 10.3390/biom8040138] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Revised: 10/29/2018] [Accepted: 10/30/2018] [Indexed: 11/29/2022] Open
Abstract
Vanillin was used to synthesize a new derivative with an active aldehyde group and response to pH. It is named 2-((diethylamino) methyl)-4-formyl-6-methoxyphenyl acrylate, abbreviated to DEAMVA. The chemical structures were evaluated by ¹H, 13C nuclear magnetic resonance (NMR), infrared (IR), and UV-Vis-spectroscopy, and all results demonstrated good statement. In order to achieve the dual responsive behavior thermo-pH with functionality, free radical polymerization of N-isopropylacrylamide with DEAMVA in different molar ratios (5, 10, 15 mol%) has been used, with azobisisobutyronitrile (AIBN) as the initiator. The chemical structure of the polymers was investigated by ¹H NMR and IR. The dual responsive functional copolymer was exposed to a grafted process with tryptophan and tyrosine, both of which were also evaluated by ¹HNMR and IR. Copolymers before and after grafting were physically investigated by size exclusion chromatography (SEC) for estimation of the molecular weight, the glass transition temperature by differential scanning calorimeter (DSC) and scanning electron microscope (SEM) for the surface morphology. The phase separation or lower critical solution temperature (LCST) (Tc) of the polymer solution was determined not only by a turbidity method using the change in the transmittance with temperature, but also by micro-DSC. The conversion to an amino acid-grafted polymer was detected through Beer's law for the absorption of the ⁻CH=N- imine group by UV-Vis-Spectroscopy.
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Affiliation(s)
- Momen S A Abdelaty
- Polymer and Biopolymer Lap, Department of Biology, Collage of Haql, Faculty of Science, University of Tabuk, Tabuk 71491, Saudi Arabia.
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Rwei SP, Chiang WY, Way TF, Tuan HNA, Chang YC. Study of theThermo-/pH-Sensitivity of Stereo-Controlled Poly( N-isopropylacrylamide-co-IAM) Copolymers via RAFT Polymerization. Polymers (Basel) 2018; 10:polym10050512. [PMID: 30966546 PMCID: PMC6415441 DOI: 10.3390/polym10050512] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 05/05/2018] [Accepted: 05/06/2018] [Indexed: 12/03/2022] Open
Abstract
In this work, a smart copolymer, Poly(nipam-co-IAM) was synthesized by copolymerization of N-isopropylacrylamide (nipam) and itaconamic acid (IAM) through reversible addition-fragmentation chain-transfer (RAFT) polymerization. Poly(nipam-co-IAM) has been studied previously synthesized via radical polymerization without stereo-control, and this work used cumyl dithiobenzoate and Ytterbium(III) trifluoromethanesulfonate as RAFT and stereo-control agents, respectively. The stereo-control result in this work shows that tacticity affects the lower critical solution temperature (LCST) and/or the profile of phase separation of Poly(nipam-co-IAM). In the pH 7 and pH 10 buffer solutions, the P(nipam-co-IAM) copolymer solutions showed soluble–insoluble–soluble transitions, i.e., both LCST and upper critical solution temperature (UCST) transitions, which had not been found previously, and the insoluble to soluble transition (redissolved behavior) occurred at a relatively low temperature. The insoluble to soluble transition of P(nipam-co-IAM) in alkaline solution occurred at a temperature of less than 45 °C. However, the redissolved behavior of P(nipam-co-IAM) was found only in the pH 7 and pH 10 buffer solutions and this redissolved behavior was more prominent for the atactic copolymers than in the isotactic-rich ones. In addition, the LCST results under our experimental range of meso content did not show a significant difference between the isotactic-rich and the atactic P(nipam-co-IAM). Further study on the soluble-insoluble-soluble (S-I-S) transition and the application thereof for P(nipam-co-IAM) copolymers will be conducted.
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Affiliation(s)
- Syang-Peng Rwei
- Institute of Organic and Polymeric Materials and Research and Development Center for Smart Textile Technology, National Taipei University of Technology, Taipei 106, Taiwan.
| | - Whe-Yi Chiang
- Institute of Organic and Polymeric Materials and Research and Development Center for Smart Textile Technology, National Taipei University of Technology, Taipei 106, Taiwan.
| | - Tun-Fun Way
- Institute of Organic and Polymeric Materials and Research and Development Center for Smart Textile Technology, National Taipei University of Technology, Taipei 106, Taiwan.
| | - Huynh Nguyen Anh Tuan
- Institute of Organic and Polymeric Materials and Research and Development Center for Smart Textile Technology, National Taipei University of Technology, Taipei 106, Taiwan.
| | - Ya-Chin Chang
- Institute of Organic and Polymeric Materials and Research and Development Center for Smart Textile Technology, National Taipei University of Technology, Taipei 106, Taiwan.
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7
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Abdelaty MSA, Kuckling D. Synthesis and Characterization of New Functional Photo Cross-Linkable Smart Polymers Containing Vanillin Derivatives. Gels 2016; 2:E3. [PMID: 30674135 PMCID: PMC6318687 DOI: 10.3390/gels2010003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 12/02/2015] [Accepted: 12/18/2015] [Indexed: 11/17/2022] Open
Abstract
The synthesis of new functional monomers based on vanillin is reported. The monomers further were used in the synthesis of different temperature-responsive photo cross-linkable polymers via free radical polymerization with N-isopropyl acrylamide and a maleimide photo cross-linker. These polymers were characterized by NMR, FTIR and UV spectroscopy, as well as gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). Critical solution temperatures were determined by UV spectroscopy. Hydrogel thin films were formed by spin coating of a polymer solution over gold with adhesion promotor followed by cross-linking by UV irradiation. The swelling properties were determined by surface plasmon resonance coupled with optical waveguide spectroscopy. The swelling behavior of the hydrogel films was determined as a function of temperature. The incorporation of a dialkyl amino group compensated the hydrophobic effect of the vanillin monomer. Transition temperatures in the physiological range could be obtained.
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Affiliation(s)
- Momen S A Abdelaty
- Chemistry Department, University of Paderborn, Warburger Straße 100, D-33098 Paderborn, Germany.
- Polymer Lap, Chemistry Department, Faculty of Science, Al-Azhar University, Assiut 71524, Egypt.
| | - Dirk Kuckling
- Chemistry Department, University of Paderborn, Warburger Straße 100, D-33098 Paderborn, Germany.
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8
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Rwei SP, Way TF, Chang SM, Chiang WY, Lien YY. Thermo- and pH- responsive copolymers: Poly(n-Isopropylacrylamide-co-IAM) copolymers. J Appl Polym Sci 2015. [DOI: 10.1002/app.42367] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Syang-Peng Rwei
- Department of Molecular Science and Engineering, National Taipei University of Technology; Taipei, Taiwan Republic of China
| | - Tun-Fun Way
- Material and Chemical Research Laboratories, Industrial Technology Research Institute; Taiwan Republic of China
| | - Shu-Mei Chang
- Department of Molecular Science and Engineering, National Taipei University of Technology; Taipei, Taiwan Republic of China
| | - Whe-Yi Chiang
- Department of Molecular Science and Engineering, National Taipei University of Technology; Taipei, Taiwan Republic of China
| | - Yi-Yin Lien
- Department of Molecular Science and Engineering, National Taipei University of Technology; Taipei, Taiwan Republic of China
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9
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Ebara M. Shape-memory surfaces for cell mechanobiology. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2015; 16:014804. [PMID: 27877747 PMCID: PMC5036502 DOI: 10.1088/1468-6996/16/1/014804] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Revised: 01/15/2015] [Accepted: 01/17/2015] [Indexed: 06/06/2023]
Abstract
Shape-memory polymers (SMPs) are a new class of smart materials, which have the capability to change from a temporary shape 'A' to a memorized permanent shape 'B' upon application of an external stimulus. In recent years, SMPs have attracted much attention from basic and fundamental research to industrial and practical applications due to the cheap and efficient alternative to well-known metallic shape-memory alloys. Since the shape-memory effect in SMPs is not related to a specific material property of single polymers, the control of nanoarchitecture of polymer networks is particularly important for the smart functions of SMPs. Such nanoarchitectonic approaches have enabled us to further create shape-memory surfaces (SMSs) with tunable surface topography at nano scale. The present review aims to bring together the exciting design of SMSs and the ever-expanding range of their uses as tools to control cell functions. The goal for these endeavors is to mimic the surrounding mechanical cues of extracellular environments which have been considered as critical parameters in cell fate determination. The untapped potential of SMSs makes them one of the most exciting interfaces of materials science and cell mechanobiology.
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Affiliation(s)
- Mitsuhiro Ebara
- Biomaterials Unit, International Center for Materials Nanoarchitectonics (WPI-MANA), Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
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10
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Preparation of thermo- and pH-responsive star copolymers via ATRP and its use in drug release application. Colloid Polym Sci 2014. [DOI: 10.1007/s00396-014-3436-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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11
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Techawanitchai P, Idota N, Uto K, Ebara M, Aoyagi T. A smart hydrogel-based time bomb triggers drug release mediated by pH-jump reaction. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2012; 13:064202. [PMID: 27877529 PMCID: PMC5099762 DOI: 10.1088/1468-6996/13/6/064202] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2012] [Accepted: 08/31/2012] [Indexed: 05/23/2023]
Abstract
We demonstrate a timed explosive drug release from smart pH-responsive hydrogels by utilizing a phototriggered spatial pH-jump reaction. A photoinitiated proton-releasing reaction of o-nitrobenzaldehyde (o-NBA) was integrated into poly(N-isopropylacrylamide-co-2-carboxyisopropylacrylamide) (P(NIPAAm-co-CIPAAm)) hydrogels. o-NBA-hydrogels demonstrated the rapid release of protons upon UV irradiation, allowing the pH inside the gel to decrease to below the pKa value of P(NIPAAm-co-CIPAAm). The generated protons diffused gradually toward the non-illuminated area, and the diffusion kinetics could be controlled by adjusting the UV irradiation time and intensity. After irradiation, we observed the enhanced release of entrapped L-3,4-dihydroxyphenylalanine (DOPA) from the gels, which was driven by the dissociation of DOPA from CIPAAm. Local UV irradiation also triggered the release of DOPA from the non-illuminated area in the gel via the diffusion of protons. Conventional systems can activate only the illuminated region, and their response is discontinuous when the light is turned off. The ability of the proposed pH-jump system to permit gradual activation via proton diffusion may be beneficial for the design of predictive and programmable devices for drug delivery.
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Affiliation(s)
- Prapatsorn Techawanitchai
- Department of Materials Engineering, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577, Japan
- Biomaterials Unit, International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan
| | - Naokazu Idota
- Biomaterials Unit, International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan
| | - Koichiro Uto
- Biomaterials Unit, International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan
| | - Mitsuhiro Ebara
- Biomaterials Unit, International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan
| | - Takao Aoyagi
- Department of Materials Engineering, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577, Japan
- Biomaterials Unit, International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan
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12
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Burova TV, Grinberg NV, Dubovik AS, Zhang G, Grinberg VY. Interpolyelectrolyte complexes of soybean peroxidase with thermoresponsive copolymers. POLYMER SCIENCE SERIES A 2012. [DOI: 10.1134/s0965545x12060090] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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13
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Maharjan P, Hearn MT, Jackson WR, De Silva K, Woonton BW. Development of a temperature-responsive agarose-based ion-exchange chromatographic resin. J Chromatogr A 2009; 1216:8722-9. [DOI: 10.1016/j.chroma.2009.04.037] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2008] [Revised: 04/01/2009] [Accepted: 04/14/2009] [Indexed: 11/24/2022]
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14
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Burova TV, Grinberg NV, Grinberg VY, Tang Y, Zhang G, Khokhlov AR. Binding Energetics of Lysozyme to Copolymers ofN-Isopropylacrylamide with Sodium Sulfonated Styrene. Macromol Biosci 2009; 9:543-50. [DOI: 10.1002/mabi.200800313] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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15
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Choi WI, Kim M, Tae G, Kim YH. Sustained release of human growth hormone from heparin-based hydrogel. Biomacromolecules 2008; 9:1698-704. [PMID: 18457449 DOI: 10.1021/bm701391b] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Won Il Choi
- Research Center for Biomolecular Nanotechnology and Department of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju, Korea
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16
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Burova TV, Grinberg NV, Grinberg VY. Conformational and phase transitions in lysozyme-thermosensitive polyelectrolyte complexes. POLYMER SCIENCE SERIES A 2006. [DOI: 10.1134/s0965545x06030102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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17
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Radiation induced synthesis and swelling characterization of thermo-responsive N-isopropylacrylamide-co-ionic hydrogels. Eur Polym J 2006. [DOI: 10.1016/j.eurpolymj.2005.08.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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18
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Liang HF, Hong MH, Ho RM, Chung CK, Lin YH, Chen CH, Sung HW. Novel Method Using a Temperature-Sensitive Polymer (Methylcellulose) to Thermally Gel Aqueous Alginate as a pH-Sensitive Hydrogel. Biomacromolecules 2004; 5:1917-25. [PMID: 15360306 DOI: 10.1021/bm049813w] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A novel method using a temperature-sensitive polymer (methylcellulose) to thermally gel aqueous alginate blended with distinct salts (CaCl2, Na2HPO4, or NaCl), as a pH-sensitive hydrogel was developed for protein drug delivery. It was noted that the salts blended in hydrogels may affect the structures of an entangled network of methylcellulose and alginate and have an effect on their swelling characteristics. The methylcellulose/alginate hydrogel blended with 0.7 M NaCl (with a gelation temperature of 32 degrees C) demonstrated excellent pH sensitivity and was selected for the study of release profiles of a model protein drug (bovine serum albumin, BSA). In the preparation of drug-loaded hydrogels, BSA was well-mixed to the dissolved aqueous methylcellulose/alginate blended with salts at 4 degrees C and then gelled by elevating the temperature to 37 degrees C. This drug-loading procedure in aqueous environment at low temperature may minimize degradation of the protein drug while achieving a high loading efficiency (95-98%). The amount of BSA released from test hydrogels was a function of the amount of alginate used in the hydrogels. The amount of BSA released at pH 1.2 from the test hydrogel with 2.5% alginate was relatively low (20%), while that released at pH 7.4 increased significantly (86%). In conclusion, the methylcellulose/alginate hydrogel blended with NaCl could be a suitable carrier for site-specific protein drug delivery in the intestine.
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Affiliation(s)
- Hsiang-Fa Liang
- Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan 30013, Republic of China
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Soppimath KS, Aminabhavi TM, Dave AM, Kumbar SG, Rudzinski WE. Stimulus-responsive "smart" hydrogels as novel drug delivery systems. Drug Dev Ind Pharm 2002; 28:957-74. [PMID: 12378965 DOI: 10.1081/ddc-120006428] [Citation(s) in RCA: 205] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Recently, there has been a great deal of research activity in the development of stimulus-responsive polymeric hydrogels. These hydrogels are responsive to external or internal stimuli and the response can be observed through abrupt changes in the physical nature of the network. This property can be favorable in many drug delivery applications. The external stimuli can be temperature, pH, ionic strength, ultrasonic sound, electric current, etc. A majority of the literature related to the development of stimulus-responsive drug delivery systems deals with temperature-sensitive poly(N-isopropyl acrylamide) (pNIPAAm) and its various derivatives. However, acrylic-based pH-sensitive systems with weakly acidic/basic functional groups have also been widely studied. Quite recently, glucose-sensitive hydrogels that are responsive to glucose concentration have been developed to monitor the release of insulin. The present article provides a brief introduction and recent developments in the area of stimulus-responsive hydrogels, particularly those that respond to temperature and pH, and their applications in drug delivery.
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Affiliation(s)
- K S Soppimath
- Center of Excellence in Polymer Science, Karnatak University, Dharwad 580 003, India
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Mun GA, Nurkeeva ZS, Khutoryanskiy VV, Sergaziyev AD, Rosiak JM. Radiation synthesis of temperature-responsive hydrogels by copolymerization of [2-(methacryloyloxy)ethyl]trimethylammonium chloride with N-isopropylacrylamide. Radiat Phys Chem Oxf Engl 1993 2002. [DOI: 10.1016/s0969-806x(02)00205-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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21
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Iskakov RM, Kikuchi A, Okano T. Time-programmed pulsatile release of dextran from calcium-alginate gel beads coated with carboxy-n-propylacrylamide copolymers. J Control Release 2002; 80:57-68. [PMID: 11943387 DOI: 10.1016/s0168-3659(01)00551-x] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Time-programmed release of macromolecular drugs was achieved by utilization of calcium-alginate gel beads modified with coated copolymer layers. Modified calcium-alginate gel beads coated with poly(carboxy-n-propylacrylamide-co-dimethylacrylamide) [poly(CNPAAm-co-DMAAm)] (22.7 mol% of CNPAAm) of varying coating thickness from 25 to 125 microm were developed as drug carriers. Model macromolecular drugs used were fluorescein isothiocyanate (FITC)-labeled dextrans with different molecular weights ranging from 9400 to 145000. FITC-dextran release was strongly dependent on both copolymer coating thicknesses and the dextran molecular weights. Release of FITC-dextran (MW 9400) followed Fickian diffusion according to t(1/2) dependence, indicating that the drug diffusion is the main driving force for release of dextran MW 9400. Release of higher molecular weight FITC-dextrans (71,00 and 145,00) exhibited a burst-effect preceded by a preset lag time. These release profiles were governed by the dissociation of calcium ions from polyguluronate sequences in alginate molecules along with the diffusion of sodium ions into the gel bead core. This created osmotic pressure inside the gel, inducing breakage of the coated copolymer layer and accelerated drug release. Burst release of macromolecular drugs thus occurred after a certain lag period. The lag time was regulated by the copolymer coat thickness. A pulsatile release of FITC-dextran was demonstrated by combining a series of modified alginate gel beads in a single batch.
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Affiliation(s)
- Rinat M Iskakov
- Institute of Advanced Biomedical Engineering and Science, Tokyo Women's Medical University, 8-1 Kawadacho, Shinjuku-ku, Tokyo 162-8666, Japan
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