201
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Abstract
Hollow nanoparticles represent an emerging area of development for the encapsulation of active ingredients. Expanding the capabilities of these nanomaterials will require continued efforts to infill properties such as size control, biodegradability, and environmental responsiveness. Acid-labile poly(N-vinylformamide) (PNVF) nanocapsules were synthesized by free radical polymerization of N-vinylformamide on the surface of silica nanoparticles. Polymerization in the presence of a novel crosslinker that contains an acid-labile ketal facilitated stable etching of silica nanoparticle templates using sodium hydroxide and recovery of degradable PNVF nanocapsules. The formamido side group of PNVF was then hydrolyzed by extended exposure to sodium hydroxide to produce polyvinylamine (PVAm) micro- and nanocapsules. Both capsule types demonstrated an increasing dissolution rate as pH decreased. In addition, PVAm nanocapsules exhibited swelling in proportion to the relative charge density of the PVAm network (a function of the degree of formamide hydrolysis and pH), presumably due to the repulsion of positively charged amino groups within the elastic shell network. The synthetic approaches reported provide methods to endow nanocapsules with key attributes such as size control, pH sensitive degradation, swelling in response to pH, and amine functionality.
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Affiliation(s)
- Lianjun Shi
- Department of Chemical and Petroleum Engineering, The University of Kansas, Lawrence, KS 66047
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202
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Li H, Ng TY, Yew YK, Lam KY. Meshless Modeling of pH-Sensitive Hydrogels Subjected to Coupled pH and Electric Field Stimuli: Young Modulus Effects and Case Studies. MACROMOL CHEM PHYS 2007. [DOI: 10.1002/macp.200600620] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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203
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Tae G, Kim YJ, Choi WI, Kim M, Stayton PS, Hoffman AS. Formation of a novel heparin-based hydrogel in the presence of heparin-binding biomolecules. Biomacromolecules 2007; 8:1979-86. [PMID: 17511500 DOI: 10.1021/bm0701189] [Citation(s) in RCA: 121] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An injectable, heparin-based hydrogel system with the potential to be gelled with cells was developed. First, heparin was modified to have thiol groups by the modification of carboxylic groups of heparin with cysteamine using carbodiimide chemistry. Thiol functionalization of heparin carboxylic groups was controlled from 10% to 60% of the available COOH groups, and the retained bioactivity of the modified heparin, characterized by its binding affinity to antithrombin III, decreased with increasing functionalization. Then, the thiol-functionalized heparin was reacted with poly(ethylene glycol) diacrylate to form a hydrogel. The gelation kinetics and mechanical properties of the final gel state could be tuned by controlling cross-link density. Fibroblast cell encapsulation using this hydrogel revealed the nontoxicity of the present system. Cell proliferation inside the hydrogel was observed, and it was significantly enhanced (more than 5-fold) by the addition of fibrinogen into the hydrogel during gelation.
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Affiliation(s)
- Giyoong Tae
- Research Center for Biomolecular Nanotechnology and Department of Materials Science and Engineering, Gwangju Institute of Science and Technology, 1 Oryong-dong, Buk-gu, Gwangju 500-712, South Korea.
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204
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Rzaev ZM, Dinçer S, Pişkin E. Functional copolymers of N-isopropylacrylamide for bioengineering applications. Prog Polym Sci 2007. [DOI: 10.1016/j.progpolymsci.2007.01.006] [Citation(s) in RCA: 445] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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205
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Mercadé-Prieto R, Falconer RJ, Paterson WR, Wilson DI. Swelling and Dissolution of β-Lactoglobulin Gels in Alkali. Biomacromolecules 2007; 8:469-76. [PMID: 17243763 DOI: 10.1021/bm060553n] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
It is well documented in the literature that during the dissolution of whey protein gels in alkali, the gels swell to a great extent. However, the relevance of the swelling step in the dissolution process of the protein gel remains unknown. In the present article we present a systematic study on the swelling of beta-lactoglobulin gels at different alkaline pH and ionic strengths. The equilibrium swelling degree at different conditions has been modeled using a simple model developed for polyelectrolyte gels, modified to take into account the ionization of the residues in a protein. The model can describe the swelling behavior of the gels over a wide range of conditions, but it underpredicts the equilibrium swelling under conditions close to those when dissolution is observed. Dissolution is only noticeable above pH 11.5-12 and only for those gels that are swollen over a minimum degree, suggesting the existence of a dissolution threshold.
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Affiliation(s)
- Ruben Mercadé-Prieto
- Department of Chemical Engineering, University of Cambridge, New Museums Site, Pembroke Street, Cambridge CB2 3RA, United Kingdom
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206
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Clapper JD, Guymon CA. Physical Behavior of Cross-Linked PEG Hydrogels Photopolymerized within Nanostructured Lyotropic Liquid Crystalline Templates. Macromolecules 2007. [DOI: 10.1021/ma0622377] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jason D. Clapper
- Department of Chemical and Biochemical Engineering, The University of Iowa, Iowa City, Iowa 52242
| | - C. Allan Guymon
- Department of Chemical and Biochemical Engineering, The University of Iowa, Iowa City, Iowa 52242
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207
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Griffin JM, Robb I, Bismarck A. Preparation and characterization of surfactant-free stimuli-sensitive microgel dispersions. J Appl Polym Sci 2007. [DOI: 10.1002/app.25873] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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208
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Çaykara T, Akçakaya İ. Swelling behaviors of ionic poly(N,N-dimethylacrylamide-co-acrylamide) hydrogels in various media. J Appl Polym Sci 2007. [DOI: 10.1002/app.24313] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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209
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Synthesis and characterization of pH/temperature-sensitive block copolymers via atom transfer radical polymerization. POLYMER 2007. [DOI: 10.1016/j.polymer.2006.11.040] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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210
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Saito H, Taguchi T, Aoki H, Murabayashi S, Mitamura Y, Tanaka J, Tateishi T. pH-responsive swelling behavior of collagen gels prepared by novel crosslinkers based on naturally derived di- or tricarboxylic acids. Acta Biomater 2007; 3:89-94. [PMID: 17055791 DOI: 10.1016/j.actbio.2006.08.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2006] [Revised: 07/14/2006] [Accepted: 08/16/2006] [Indexed: 10/24/2022]
Abstract
The aim of this study was to compare the physicochemical properties of alkali-treated collagen (AlCol) gels prepared using two kinds of naturally derived crosslinkers made from citric and malic acids (CAD and MAD, respectively) that we have developed. From the crosslinking reaction between active ester groups and amino groups of AlCol, we successfully obtained AlCol gels, named AlCol-CAD and AlCol-MAD, prepared using CAD and MAD, respectively. The gelation time of the AlCol solution containing CAD initially decreased with increasing CAD concentration up to 70 mM, and then increased as the CAD concentration increased further. The gelation time reached its minimum and began to increase. On the other hand, for AlCol-MAD solution, gelation occurred within 40s at any MAD concentration. Moreover, the residual amino groups in AlCol-CAD and AlCol-MAD were found to decrease with increasing CAD or MAD concentrations, whereas increased residual carboxyl groups were detected only in the case of AlCol-CAD. The swelling ratio of AlCol-CAD significantly increased at CAD concentrations above 50mM. On the other hand, AlCol-MAD showed little increase in swelling ratio with increasing MAD concentration. Also, AlCol-CAD was swollen when the gels were immersed in a solution with high pH. On the other hand, no significant increase in swelling ratio was observed when AlCol-MAD was immersed in a similar solution. These results suggest that the different amounts of carboxyl groups in AlCol-CAD affected the swelling behavior of gels and that this pH-responsive AlCol-CAD has potential for drug delivery systems and tissue engineering.
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Affiliation(s)
- Hirofumi Saito
- Graduate School of Information Science and Technology, The University of Hokkaido, N-14 W-9, Kita-ku, Sapporo 060-0814, Japan; Furuuchi Chemical Corporation, 6-17-17 Minami-oi, Shinagawa-ku, Tokyo 140-0013, Japan
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211
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Lin CC, Metters AT. Hydrogels in controlled release formulations: network design and mathematical modeling. Adv Drug Deliv Rev 2006; 58:1379-408. [PMID: 17081649 DOI: 10.1016/j.addr.2006.09.004] [Citation(s) in RCA: 1040] [Impact Index Per Article: 57.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2006] [Accepted: 09/04/2006] [Indexed: 10/24/2022]
Abstract
Over the past few decades, advances in hydrogel technologies have spurred development in many biomedical applications including controlled drug delivery. Many novel hydrogel-based delivery matrices have been designed and fabricated to fulfill the ever-increasing needs of the pharmaceutical and medical fields. Mathematical modeling plays an important role in facilitating hydrogel network design by identifying key parameters and molecule release mechanisms. The objective of this article is to review the fundamentals and recent advances in hydrogel network design as well as mathematical modeling approaches related to controlled molecule release from hydrogels. In the first section, the niche roles of hydrogels in controlled release, molecule release mechanisms, and hydrogel design criteria for controlled release applications are discussed. Novel hydrogel systems for drug delivery including biodegradable, smart, and biomimetic hydrogels are reviewed in the second section. Several mechanisms have been elucidated to describe molecule release from polymer hydrogel systems including diffusion, swelling, and chemically-controlled release. The focus of the final part of this article is discussion of emerging hydrogel delivery systems and challenges associated with modeling the performance of these devices.
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Affiliation(s)
- Chien-Chi Lin
- Department of Bioengineering, Clemson University, Clemson, SC 29634, USA
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212
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Affiliation(s)
- Oluwasijibomi Okeowo
- Department of Chemical Engineering, Colorado School of Mines, Golden, Colorado 80401
| | - John R. Dorgan
- Department of Chemical Engineering, Colorado School of Mines, Golden, Colorado 80401
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213
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Shah NM, Pool MD, Metters AT. Influence of Network Structure on the Degradation of Photo-Cross-Linked PLA-b-PEG-b-PLA Hydrogels. Biomacromolecules 2006; 7:3171-7. [PMID: 17096548 DOI: 10.1021/bm060339z] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Triblock copolymers of functionalized poly(lactic acid)-b-poly(ethylene glycol)-b-poly(lactic acid) (PLA-b-PEG-b-PLA) have been widely investigated as precursors for fabricating resorbable polymeric drug delivery vehicles and tissue engineering scaffolds. Previous studies show degradation and erosion behavior of PLA-b-PEG-b-PLA hydrogels to rely on macromer chemistry as well as structural characteristics of the cross-linked networks. In this research, the degradation kinetics of diacrylated PLA-b-PEG-b-PLA copolymers as soluble macromers and cross-linked gels are directly compared as a function of macromer concentration, buffer pH, and ionic strength. The pseudo first-order rate constants for degradation of soluble macromers increase with water concentration and show a minimum at intermediate pH values, but are insensitive to ionic strength. The degradation rate constants for covalently cross-linked gels display a greater sensitivity to local water concentration and a minimum at lower pH values than corresponding soluble macromers. In addition, ionic strength significantly affects the rate of gel degradation due to the direct correlation between the degree of network ionization and gel water content.
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Affiliation(s)
- Nihar M Shah
- Department of Bioengineering and Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, South Carolina 29634, USA
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214
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Ng TY, Li H, Yew YK, Lam KY. Effects of Initial-Fixed Charge Density on pH-Sensitive Hydrogels Subjected to Coupled pH and Electric Field Stimuli: A Meshless Analysis. J Biomech Eng 2006; 129:148-55. [PMID: 17408319 DOI: 10.1115/1.2472370] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In this paper, we study the effects of initial fixed-charge density on the response behavior of pH-sensitive hydrogels subjected to coupled stimuli, namely, solution pH and externally applied electric field. This is the first instance in which a coupled stimuli numerical analysis has been carried out for these polymer gels, which are used as active sensing/actuating elements in advanced biomicroelectromechanical systems devices. In this work, a chemo-electro-mechanical formulation, termed the multi-effect-coupling pH-stimulus (MECpH) model, is first presented. This mathematical model takes into account the ionic species diffusion, electric potential coupling, and large mechanical deformation. In addition, a correlation between the diffusive hydrogen ions and fixed-charge groups on the hydrogel polymeric chains is established based on the Langmuir absorption isotherm, and incorporated accordingly into the MECpH model. To solve the resulting highly nonlinear and highly coupled partial differential equations of this mathematical model, the Hermite-Cloud method, a novel true meshless technique, is employed. To demonstrate the accuracy and robustness the MECpH model, computed numerical results are compared with experimental data available from literature. Following this validation, several numerical studies are carried out to investigate the effects of initial fixed-charge density on the volumetric variations of these pH-stimulus-responsive hydrogels when immersed in buffered solutions.
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Affiliation(s)
- T Y Ng
- School of Mechanical & Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798.
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215
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Paulino AT, Guilherme MR, Reis AV, Campese GM, Muniz EC, Nozaki J. Removal of methylene blue dye from an aqueous media using superabsorbent hydrogel supported on modified polysaccharide. J Colloid Interface Sci 2006; 301:55-62. [PMID: 16740270 DOI: 10.1016/j.jcis.2006.04.036] [Citation(s) in RCA: 163] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2006] [Revised: 04/15/2006] [Accepted: 04/17/2006] [Indexed: 10/24/2022]
Abstract
The removal of methylene blue (MB) in water with the superabsorbent hydrogel (SH) formed by modified gum arabic, polyacrylate, and polyacrylamide was investigated. The SH exhibited excellent performance in MB absorption. The maximum absorption capacity was 48 mg of the dye per g of SH, representing 98% of the MB removed. Experimental parameters were used as follows: pH 8, hydrogel mass 50 mg, and initial concentration of MB 50 mg L(-1). In a procedure with an individual solution of orange II, an opposite effect related to the MB was observed: the hydrogel only absorbed water, resulting in an orange II-richer solution. The orange II concentration in solution increased about 50 times (relative to the initial concentration). In another experiment using an aqueous mixture of orange II and MB, the SH absorbed the MB exclusively. Compared to the MB, the orange II is separated from water by SH selectivity-absorption through an inverse process. This effect was attributed to the formation of a ionic complex between the imine groups of MB and the ionized carboxylic groups of SH.
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Affiliation(s)
- Alexandre T Paulino
- Chemistry Department, Maringa State University, Av. Colombo 5790, CEP 87020-900, Maringa, Parana, Brazil
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216
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Çaykara T, Akçakaya İ. Synthesis and network structure of ionic poly(N,N-dimethylacrylamide-co-acrylamide) hydrogels: Comparison of swelling degree with theory. Eur Polym J 2006. [DOI: 10.1016/j.eurpolymj.2006.01.001] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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217
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Pal K, Banthia AK, Majumdar DK. Development of carboxymethyl cellulose acrylate for various biomedical applications. Biomed Mater 2006; 1:85-91. [PMID: 18460761 DOI: 10.1088/1748-6041/1/2/006] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The purpose of this work is to prepare a pH-sensitive hydrogel membrane of sodium carboxymethyl cellulose acrylate for drug delivery and other biomedical applications. The hydrogel was made by esterification of sodium carboxymethyl cellulose (SCMC) and acryloyl chloride (ACl). The esterified product was characterized by FTIR spectroscopy and XRD. Swelling, hemocompatibility, water vapor transmission rate, contact angle and diffusional studies were also done. Biocompatibility of the membrane was established by quantification of cell growth of L929 cells and mice splenocytes. The FTIR spectrum of the hydrogel suggested the formation of ester bonds between the hydroxyl groups of sodium carboxymethyl cellulose and the carbonyl group of acryloyl chloride. Water vapor transmission rate, hemocompatibility, contact angle and swelling studies indicated that the hydrogel can be tried as a wound dressing material. The hydrogel showed pH-dependent swelling behavior arising from the acidic pendant group in the polymer network. The permeability of the hydrogel membrane produced, as shown by salicylic acid diffusion, increased in response to an increase in pH of the external medium. The hydrogel membrane was permeable to salicylic acid at pH 7.2 but not at pH 2.0 (0.01N HCl). The effect of changes of pH on the hydrogel's permeability was found to be reversible. The hydrogel membrane was found to be compatible with the L929 mice fibroblast cell line and mice splenocytes. The esterified product of SCMC and ACl swells on increase of pH indicating its possible use in a pH-sensitive drug delivery system and as a wound dressing material.
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Affiliation(s)
- Kunal Pal
- Materials Science Centre, Indian Institute of Technology, Kharagpur 721302, India
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218
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Casolaro M, Bottari S, Ito Y. Vinyl Polymers Based on l-Histidine Residues. Part 2. Swelling and Electric Behavior of Smart Poly(ampholyte) Hydrogels for Biomedical Applications. Biomacromolecules 2006; 7:1439-48. [PMID: 16677025 DOI: 10.1021/bm0509671] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Hydrogels based on the uncharged N-isopropylacrylamide and the ionic ampholyte N-acryloyl-L-histidine showed a reversible multiple-responsive volume change and volume phase transition behavior in aqueous solution. The phase transition phenomenon was induced by the temperature, the pH, the salt-type concentration, and the electric potential. The kind of cation (Na+, K+, Cs+, Mg2+, Ca2+, Sr2+) and anion (Cl-, ClO4-, NO3-, SO4(2-)) strongly influenced the critical concentration that improved the phase separation of the gels. The volume of the collapsed gel can be hundred times smaller than that of the swollen one. The oscillatory swelling of the gels in response to temperature and pH (4 and 9) changes was fast and reversible, while the contractile behavior in the electric field showed response only at pH 9, i.e., when the amount of negative charges on the L-histidine residues predominated. The electrically induced anisotropic gel deswelling was attributed to the syneresis of water from the gel. The nontoxicity against the RAW264 cell line and the low osmotic pressure exhibited by the swollen gels make these compounds useful scaffolds for human organs. The ability to load and release an ionizable drug molecular model (ferulic acid) from the hydrogels was shown also at different pH values.
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Affiliation(s)
- Mario Casolaro
- Dipartimento di Scienze e Tecnologie Chimiche e dei Biosistemi, Via Aldo Moro 2, Università degli Studi di Siena, I-53100 Siena, Italy.
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219
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Liu G, Zhao X. Study on the electrodriven action of gelatin hydrogel in silicone oil. J Appl Polym Sci 2006. [DOI: 10.1002/app.23831] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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220
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Turan E, Demirel G, Zengin M, Şimsek D, Çaykara T. PH-dependent swelling behavior and network parametes of ionic poly(N-t-butylacrylamide-co-acrylamide) hydrogels. J Appl Polym Sci 2006. [DOI: 10.1002/app.23945] [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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221
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Kim SJ, Spinks GM, Prosser S, Whitten PG, Wallace GG, Kim SI. Surprising shrinkage of expanding gels under an external load. NATURE MATERIALS 2006; 5:48-51. [PMID: 16380727 DOI: 10.1038/nmat1553] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2004] [Accepted: 11/17/2005] [Indexed: 05/05/2023]
Abstract
Hydrogels are fascinating and useful in that they can show large volume changes in response to various stimuli, such as temperature or chemical environment. Here we report the peculiar observation that chemically crosslinked hydrogels that normally expand owing to a change in electrolyte pH can be made to shrink in certain circumstances. Specifically, these hydrogels contract when tested at a constant compressive force and subjected to a pH change that causes expansion in the absence of the applied load. When tested under tension, the gels always expand. Although the effects of external stress on the swelling of gels is known, the concomitant change in gel mechanical properties during pH switching was found to be a more dominant effect in our studies. However, existing mechanical models used to predict dimensional changes in actuator materials could not explain both the tensile and compression results. In addition, we show that the friction between metal plates of the apparatus and the gel is a key factor in explaining the contractile actuation under compressive loads. The observations reported in this paper are important for the successful design and use of hydrogel actuators in devices such as valves for microfluidics.
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Affiliation(s)
- Seon Jeong Kim
- Department of Biomedical Engineering, Hanyang University, Seoul 133-791, South Korea
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222
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Lee WF, Yeh YC. Effect of porosigen and hydrophobic monomer on the fast swelling–deswelling behaviors for the porous thermoreversible copolymeric hydrogels. J Appl Polym Sci 2006. [DOI: 10.1002/app.23143] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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223
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Bellot JC, Tarantino RV, Condoret JS. Thermodynamic modeling of multicomponent ion-exchange equilibria of amino acids. AIChE J 2006. [DOI: 10.1002/aic.690450617] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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224
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Xu S, Wu R, Huang X, Cao L, Wang J. Effect of the anionic-group/cationic-group ratio on the swelling behavior and controlled release of agrochemicals of the amphoteric, superabsorbent polymer poly(acrylic acid-co-diallyldimethylammonium chloride). J Appl Polym Sci 2006. [DOI: 10.1002/app.23990] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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225
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Xu S, Cao L, Wu R, Wang J. Salt and pH responsive property of a starch-based amphoteric superabsorbent hydrogel with quaternary ammonium and carboxyl groups (II). J Appl Polym Sci 2006. [DOI: 10.1002/app.23722] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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226
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Swelling Behaviors of a New Zwitterionic N-carboxymethyl-N, N-dimethyl-N-allylammonium/acrylic Acid Hydrogel. JOURNAL OF POLYMER RESEARCH 2005. [DOI: 10.1007/s10965-005-9002-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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227
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Noomrio MH, Zhang R, Eisenthal R, Hubble J. Characterisation of Hydrogel Gel Swelling by Molecular Exclusion. Biotechnol Lett 2005; 27:1587-90. [PMID: 16245178 DOI: 10.1007/s10529-005-1801-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2005] [Revised: 07/28/2005] [Accepted: 07/28/2005] [Indexed: 10/25/2022]
Abstract
A facile method for the characterization of hydrogel swelling is described which is based on the determination of changes in the liquid phase concentration of an excluded tracer as gel swells in a constant volume system. The utility of this approach is demonstrated with two responsive hydrogel preparations, one where swelling is influenced by system pH, the other by changes in specific solute concentration.
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Affiliation(s)
- M H Noomrio
- Department of Chemistry, Shah Abdul Latif University, Khairpur, Pakistan
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228
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Swelling Characteristics of pH- and Thermo-Sensitive Crosslinked Poly(Vinyl Alcohol) Grafts. JOURNAL OF POLYMER RESEARCH 2005. [DOI: 10.1007/s10965-005-9004-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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229
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Lim YM, Lee YM, Nho YC. Preparation and characterization of pH-sensitive poly(ethylene oxide) grafted methacrylic acid and acrylic acid hydrogels by γ-ray irradiation. Macromol Res 2005. [DOI: 10.1007/bf03218461] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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230
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Zhang R, Tang M, Bowyer A, Eisenthal R, Hubble J. A novel pH- and ionic-strength-sensitive carboxy methyl dextran hydrogel. Biomaterials 2005; 26:4677-83. [PMID: 15722138 DOI: 10.1016/j.biomaterials.2004.11.048] [Citation(s) in RCA: 199] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2004] [Accepted: 11/23/2004] [Indexed: 11/16/2022]
Abstract
A fast and simple method for the preparation of pH-sensitive hydrogel membranes for drug delivery and tissue engineering applications has been developed using carbodiimide chemistry. The hydrogels were formed by the intermolecular cross-linking of carboxymethyl dextran (CM-dextran) using 1-ethyl-(3-3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). Infrared spectra of the hydrogels suggest the formation of ester bonds between the hydroxyl and carboxyl groups in the CM-dextran. The porosity of the hydrogels produced, as shown by protein diffusion, increases in response to changes in the pH and the ionic strength of the external medium. The results show pH-dependent swelling behaviour arising from the acidic pedant groups in the polymer network. The diffusion of the protein lysozyme through the hydrogel membranes increased with increases in both pH (5.0-9.0) and ionic strength. The effect of changes of pH and ionic strength on the hydrogel's permeability was shown to be reversible. Scanning electron microscopy of these hydrogels showed that pH-dependent changes in permeability are mirrored by morphological changes in gel structure.
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Affiliation(s)
- Rhongsheng Zhang
- Department of Chemical Engineering, University of Bath, Claverton Down Bath, Banes BA2 7AY, UK
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231
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Zhang Y, Wu F, Li M, Wang E. pH switching on-off semi-IPN hydrogel based on cross-linked poly(acrylamide-co-acrylic acid) and linear polyallyamine. POLYMER 2005. [DOI: 10.1016/j.polymer.2005.05.121] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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232
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Li H, Ng TY, Yew YK, Lam KY. Modeling and simulation of the swelling behavior of pH-stimulus-responsive hydrogels. Biomacromolecules 2005; 6:109-20. [PMID: 15638511 DOI: 10.1021/bm0496458] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The modulation of the swelling ability of the hydrogel matrix by pH-stimulus enables the dynamic control of the swelling forces, thereby obtaining effective diffusivity and permeability of the solutes, or mechanical energy from the hydrogel. In this work, a chemo-electro-mechanical model describing hydrogel behavior, based on multi-field effects, is developed to simulate the swelling and shrinking of these fascinating bio-materials, and it is termed the multi-effect-coupling pH-stimulus (MECpH) model. This model accounts for the ionic fluxes within both the hydrogel and solution, the coupling between the electric field, ionic fluxes, and mechanical deformations of the hydrogel. The main contribution of this model is to incorporate the relationship between the concentrations of the ionized fixed-charge groups and the diffusive hydrogen ion, which follows a Langmuir isotherm, into the Poisson-Nernst-Planck system. To validate this MECpH model, one-dimensional steady-state simulations under varying pH solution are carried out via a meshless Hermite-Cloud methodology, and the numerical results are compared with available experimental data. It is shown that the presently developed MECpH model is accurate, efficient, and numerically stable.
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Affiliation(s)
- Hua Li
- Institute of High Performance Computing, National University of Singapore, 1 Science Park Road, #01-01 The Capricorn, Singapore Science Park II, Singapore 117528.
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233
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Li H, Yew Y, Ng T, Lam K. Meshless steady-state analysis of chemo-electro-mechanical coupling behavior of pH-sensitive hydrogel in buffered solution. J Electroanal Chem (Lausanne) 2005. [DOI: 10.1016/j.jelechem.2005.03.034] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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234
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Meng FB, Zhang BY, Li QY, Qi J. Cholesteric Liquid-Crystalline Elastomers Prepared from Ionic Bis–Olefinic Crosslinking Units. Polym J 2005. [DOI: 10.1295/polymj.37.277] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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235
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Jabbari E. Release characteristics of a model plasmid DNA encapsulated in biodegradable poly(ethylene glycol fumarate)/acrylamide hydrogel microspheres. J Microencapsul 2005; 21:525-38. [PMID: 15513759 DOI: 10.1080/02652040410001729296] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Biodegradable hydrogel microspheres were synthesized by free radical suspension copolymerization of poly(ethylene glycol fumarate) macromer with bisacrylamide (PEGF/PAM). The acidic initiator ammonium persulphate in combination with the basic accelerator, N,N,N',N'-tetramethyethylenediamine, were used to form the PEGF/PAM hydrogel at a neutral pH. The equilibrium water content of the microspheres was greater than 90% w/w. A model double stranded plasmid DNA (dsDNA) coding for the enhanced green fluorescence protein (pEGFP) gene was encapsulated in the hydrogel and the effect of loading and water content before swelling on release kinetics was investigated. Fluorescent confocal microscopy demonstrated that the encapsulated dsDNA was in the biologically active double stranded configuration. The highest loading of 0.81 mg ml(-1) resulted in the best encapsulation efficiency of 95%. For that loading, 6% of the dsDNA was released in 25 days at a rate of 16 ng ml(-1). The highest water content of 70% resulted in the highest burst release of 27% and 14% of the dsDNA was released in 25 days at a rate of 30 ng ml(-1). For elucidating the release mechanism, the network mesh size was compared with the radius of gyration (Rg) of the dsDNA plasmid. The mesh size was 7 nm, which was less than Rg of the dsDNA (31 nm) but greater than the chain diameter of 1.1 nm. Since the mesh size was less than Rg, the release mechanism was by reptation of the segments of dsDNA within the tube formed by the network chains between crosslinks. These results indicate that the hydrogel mesh size and the size of the plasmid control the release mechanism.
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Affiliation(s)
- E Jabbari
- Department of Bioengineering, Rice University, 6100 Main, Houston, TX 77005-1892, USA.
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236
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Lopez VC, Hadgraft J, Snowden MJ. The use of colloidal microgels as a (trans)dermal drug delivery system. Int J Pharm 2005; 292:137-47. [PMID: 15725560 DOI: 10.1016/j.ijpharm.2004.11.040] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2004] [Revised: 11/16/2004] [Accepted: 11/24/2004] [Indexed: 10/25/2022]
Abstract
A co-polymer of poly(N-isopropylacrylamide) (85%) co-butyl acrylate (10%) co-methacrylic acid (5%) (NIPAM/BA/MAA) (85/10/5) microgel was synthesised and investigated as a potential pH and temperature sensitive transdermal delivery device. Three compounds having different octanol/water partition coefficients and solubilities were incorporated into the microgel, namely: salicylamide (SA), methyl paraben (MP) and propyl paraben (PP). Physico-chemical characterisation of these microgel-drug complexes showed that microgels incorporating MP and SA have smaller volumes after changing environmental pH or temperature when compared with the co-polymer NIPAM/BA/MAA (85/10/5) alone. This reduction in volume could be attributed to the incorporation of the compounds into the microgel particles, having a shielding effect on the charged groups present within the network. Diffusion studies, across human skin, were performed at 305K in the range of pH 3-7 for saturated solutions of SA, MP and PP, and for microgel particles incorporating the three compounds. The transport rate for these microgels incorporating MP was reduced by 2/3-fold compared to the saturated solution, by one order of magnitude for PP, meanwhile the transport rate for these microgels incorporating SA is the same order of magnitude as that for the corresponding saturated solutions. Transdermal release studies of the saturated colloidal dispersions indicated that pH control of the drug release was marginal. The incorporation of compounds into the pH/temperature sensitive co-polymer NIPAM/BA/MAA (85/10/5) and the subsequent release depends on the octanol/water partition coefficient and solubility of the respective compound.
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Affiliation(s)
- V Castro Lopez
- Medway Sciences, University of Greenwich at Medway, Chatham Maritime, Kent ME4 4TB, UK
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237
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Effect of functional crosslinking agents on preparation and swelling properties of dextran hydrogels. Carbohydr Polym 2005. [DOI: 10.1016/j.carbpol.2004.08.025] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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238
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Madrigal González B, Christie G, Davidson CA, Blyth J, Lowe CR. Divalent metal ion-sensitive holographic sensors. Anal Chim Acta 2005. [DOI: 10.1016/j.aca.2004.03.029] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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239
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Liu G, Zhao X. Electromechanochemical Behavior of Gelatin Hydrogel Under Electric Field. JOURNAL OF MACROMOLECULAR SCIENCE PART A-PURE AND APPLIED CHEMISTRY 2005. [DOI: 10.1081/ma-200040958] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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240
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Li H, Yew Y, Lam K, Ng T. Numerical simulation of pH-stimuli responsive hydrogel in buffer solutions. Colloids Surf A Physicochem Eng Asp 2004. [DOI: 10.1016/j.colsurfa.2004.08.068] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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241
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Çaykara T, Doǧmuş M, Kantoǧlu Ö. Network structure and swelling-shrinking behaviors of pH-sensitive poly(acrylamide-co-itaconic acid) hydrogels. ACTA ACUST UNITED AC 2004. [DOI: 10.1002/polb.20129] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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242
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Pacios IE, Horta A, Renamayor CS. Macroporous Gels of Poly(N,N-dimethylacrylamide) Obtained in the Lamellar System AOT/Water. Macromolecules 2004. [DOI: 10.1021/ma049758j] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- I. E. Pacios
- Departamento CC. y TT. Fisicoquímicas, Facultad de Ciencias, UNED, P°/Senda del Rey 9, 28040 Madrid, Spain
| | - A. Horta
- Departamento CC. y TT. Fisicoquímicas, Facultad de Ciencias, UNED, P°/Senda del Rey 9, 28040 Madrid, Spain
| | - C. S. Renamayor
- Departamento CC. y TT. Fisicoquímicas, Facultad de Ciencias, UNED, P°/Senda del Rey 9, 28040 Madrid, Spain
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243
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Molina MJ, Gómez-Antón MR, Piérola IF. Factors driving the protonation of poly(N-vinylimidazole) hydrogels. ACTA ACUST UNITED AC 2004. [DOI: 10.1002/polb.20104] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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244
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İnam R, Çaykara T, Akkoç S, Kantoğlu Ö. Investigation of ZnO-release behavior of poly(N-isopropylacrylamide-co-maleic acid)/ZnO composite hydrogels by differential pulse polarography. J Appl Polym Sci 2004. [DOI: 10.1002/app.20194] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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245
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Çaykara T. Effect of maleic acid content on network structure and swelling properties of poly(N-isopropylacrylamide-co-maleic acid) polyelectrolyte hydrogels. J Appl Polym Sci 2004. [DOI: 10.1002/app.20032] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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246
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Çaykara T, Kantoğlu Ö. Thermal behavior and network structure of poly(N
-vinyl-2-pyrrolidone-crotonic acid) hydrogels prepared by radiation-induced polymerization. POLYM ADVAN TECHNOL 2004. [DOI: 10.1002/pat.423] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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247
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Atta AM, Arndt KF. Characterization of strong polyelectrolyte hydrogels based on poly(vinyl alcohol). POLYM INT 2004. [DOI: 10.1002/pi.1718] [Citation(s) in RCA: 8] [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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248
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Davies LC, Novais JM, Martins-Dias S. Detoxification of olive mill wastewater using superabsorbent polymers. ENVIRONMENTAL TECHNOLOGY 2004; 25:89-100. [PMID: 15027653 DOI: 10.1080/09593330409355441] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The detoxification of agro-industrial effluents using superabsorbent polymers is a new and innovative process. Olive mill wastewater constitutes a major environmental problem in Mediterranean countries due to the large volumes generated, the seasonality of the industry, and the high content of polyphenols and organic matter. The application of superabsorbent polymers allows olive mill wastewater to be used as a fertilizer, as it is immobilized, increasing the biological activity that decreases its phytotoxicity, thus making its water, organic matter and mineral content usable for plant nutrition. Various parameters that characterise olive mill wastewater were evaluated after absorption in 2 different superabsorbent polymers (SAP1 and SAP2). The organic matter was equally distributed in both phases, while there was a concentration of protein and sodium in solution. The K:Na ratio decreased from 70:1 to 2:1. The polyphenol desorption from the gel into solution was found to follow Fick's law. The mass transfer coefficients were 0.147 min(-1) and 0.0085 min(-1) for SAP1 and SAP2, respectively. Phytotoxicity tests were carried out with SAP2. Olive mill wastewater in SAP2 with polyphenol concentrations up to 200 mg l(-1) revealed no phytotoxicity, and even stimulated Lepidium sativum growth, while olive mill wastewater without superabsorbent polymer revealed growth inhibition for all concentrations tested. Caffeic acid degradation by the immobilised biomass followed zero order kinetics. Degradation constants of 0.087 mg l(-1) min(-1) gSAP2(-1) and 1.156 mg l(-1) min(-1) gSAP2(-1) were found. Fungi that developed in the plant growth medium were identified as Aspergillus sp. and Penicillium sp.
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Affiliation(s)
- L C Davies
- Centre of Biological and Chemical Engineering, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
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249
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Lowman AM, Dziubla TD, Bures P, Peppas NA. STRUCTURAL AND DYNAMIC RESPONSE OF NEUTRAL AND INTELLIGENT NETWORKS IN BIOMEDICAL ENVIRONMENTS. ADVANCES IN CHEMICAL ENGINEERING: MOLECULAR AND CELLULAR FOUNDATIONS OF BIOMATERIALS 2004. [DOI: 10.1016/s0065-2377(03)29004-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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250
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Harabagiu V, Fundueanu G, Pinteala M, Constantin M, Hamaide T. Bioapplication Oriented Polymers. Micro- and Nanoparticles for Drug Delivery Systems. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2004; 553:69-82. [PMID: 15503448 DOI: 10.1007/978-0-306-48584-8_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Valeria Harabagiu
- Petru Poni Institute of Macromolecular Chemistry, 700487 Iasi, Romania
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