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Louf JF, Lu NB, O'Connell MG, Cho HJ, Datta SS. Under pressure: Hydrogel swelling in a granular medium. SCIENCE ADVANCES 2021; 7:7/7/eabd2711. [PMID: 33579709 PMCID: PMC7880600 DOI: 10.1126/sciadv.abd2711] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 12/23/2020] [Indexed: 05/28/2023]
Abstract
Hydrogels hold promise in agriculture as reservoirs of water in dry soil, potentially alleviating the burden of irrigation. However, confinement in soil can markedly reduce the ability of hydrogels to absorb water and swell, limiting their widespread adoption. Unfortunately, the underlying reason remains unknown. By directly visualizing the swelling of hydrogels confined in three-dimensional granular media, we demonstrate that the extent of hydrogel swelling is determined by the competition between the force exerted by the hydrogel due to osmotic swelling and the confining force transmitted by the surrounding grains. Furthermore, the medium can itself be restructured by hydrogel swelling, as set by the balance between the osmotic swelling force, the confining force, and intergrain friction. Together, our results provide quantitative principles to predict how hydrogels behave in confinement, potentially improving their use in agriculture as well as informing other applications such as oil recovery, construction, mechanobiology, and filtration.
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Affiliation(s)
- Jean-François Louf
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Nancy B Lu
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Margaret G O'Connell
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
| | - H Jeremy Cho
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
- Department of Mechanical Engineering, University of Nevada, Las Vegas, NV 89154, USA
| | - Sujit S Datta
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA.
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2
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Cho HJ, Datta SS. Scaling Law for Cracking in Shrinkable Granular Packings. PHYSICAL REVIEW LETTERS 2019; 123:158004. [PMID: 31702300 DOI: 10.1103/physrevlett.123.158004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 05/21/2019] [Indexed: 06/10/2023]
Abstract
Hydrated granular packings often crack into discrete clusters of grains when dried. Despite its ubiquity, an accurate prediction of cracking remains elusive. Here, we elucidate the previously overlooked role of individual grain shrinkage-a feature common to many materials-in determining crack patterning using both experiments and simulations. By extending classical Griffith crack theory, we obtain a scaling law that quantifies how cluster size depends on the interplay between grain shrinkage, stiffness, and size-applicable to a diverse array of shrinkable granular packings.
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Affiliation(s)
- H Jeremy Cho
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - Sujit S Datta
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA
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3
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Cho HJ, Lu NB, Howard MP, Adams RA, Datta SS. Crack formation and self-closing in shrinkable, granular packings. SOFT MATTER 2019; 15:4689-4702. [PMID: 31119245 DOI: 10.1039/c9sm00731h] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Many clays, soils, biological tissues, foods, and coatings are shrinkable, granular materials: they are composed of packed, hydrated grains that shrink when dried. In many cases, these packings crack during drying, critically hindering applications. However, while cracking has been widely studied for bulk gels and packings of non-shrinkable grains, little is known about how packings of shrinkable grains crack. Here, we elucidate how grain shrinkage alters cracking during drying. Using experiments with model shrinkable hydrogel beads, we show that differential shrinkage can dramatically alter crack evolution during drying-in some cases, even causing cracks to spontaneously "self-close". In other cases, packings shrink without cracking or crack irreversibly. We developed both granular and continuum models to quantify the interplay between grain shrinkage, poromechanics, packing size, drying rate, capillarity, and substrate friction on cracking. Guided by the theory, we also found that cracking can be completely altered by varying the spatial profile of drying. Our work elucidates the rich physics underlying cracking in shrinkable, granular packings, and yields new strategies for controlling crack evolution.
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Affiliation(s)
- H Jeremy Cho
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA.
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4
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Abi-Akl R, Ledieu E, Enke TN, Cordero OX, Cohen T. Physics-based prediction of biopolymer degradation. SOFT MATTER 2019; 15:4098-4108. [PMID: 31086866 DOI: 10.1039/c9sm00262f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In the natural environment, insoluble biomatter provides a preeminent source of carbon for bacteria. Its degradation by microbial communities thus plays a major role in the global carbon-cycle. The prediction of degradation processes and their sensitivity to changes in environmental conditions can therefore provide critical insights into globally occurring environmental adaptations. To elucidate and quantify this macro-scale phenomenon, we conduct micro-scale experiments that examine the degradation of isolated biopolymer particles and observe highly nonlinear degradation kinetics. Since conventional scaling arguments fail to explain these observations, it is inferred that the coupled influence of both the physical and biochemical processes must be considered. Hence, we develop a theoretical model that accounts for the bio-chemo-mechanically coupled kinetics of polymer degradation, by considering the production of bio-degraders and their ability to both dissociate the material from its external boundaries and to penetrate it to degrade its internal mechanical properties. This change in mechanical properties combined with the intake of solvent or moisture from the environment leads to chemo-mechanically coupled swelling of the material and, in-turn, influences the degradation kinetics. We show that the model quantitatively captures our experimental results and reveals distinct signatures of different bacteria that are independent of the specific experimental conditions (i.e. particle volume and initial concentrations). Finally, after validating our model against the experimental data we extend our predictions for degradation processes across various length and time scales that are inaccessible in a laboratory setting.
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Affiliation(s)
- Rami Abi-Akl
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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Jafari M, Kaffashi B. Synthesis and characterization of a novel solvent-free dextran-HEMA-PNIPAM thermosensitive nanogel. JOURNAL OF MACROMOLECULAR SCIENCE PART A-PURE AND APPLIED CHEMISTRY 2016. [DOI: 10.1080/10601325.2016.1120173] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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6
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Carvalho J, Moreira S, Maia J, Gama FM. Characterization of dextrin-based hydrogels: rheology, biocompatibility, and degradation. J Biomed Mater Res A 2010; 93:389-99. [PMID: 19569221 DOI: 10.1002/jbm.a.32553] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A new class of degradable dextrin-based hydrogels (dextrin-HEMA) was developed. The hydroxyethyl methacrylate ester (HEMA) hydroxyl groups were activated with N,N'-carbonyldiimidazole (CDI), followed by their coupling to dextrin, yielding a derivatized material that can be polymerized in aqueous solution to form hydrogels. A comparative study of the stability of the dextrin-HEMA hydrogels and dextrin-vinyl acrylate (dextrin-VA, produced in previous work) revealed that only the firsts are effectively hydrolyzed under physiological conditions. A severe mass loss of dextrin-HEMA gels occurs over time, culminating in the complete dissolution of the gels. Rheologic analysis confirmed that physical structuring is less pronounced when dextrin is modified with methacrylate side groups. The biocompatibility results revealed that the dextrin hydrogels have negligible cell toxicity, irrespective of the hydrogel type (HEMA and VA), allowing cell adhesion and proliferation. Gathering the biocompatibility and the ability to tailor the release profiles, we consider dextrin a promising biomaterial for biomedical applications, namely for controlled release.
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Affiliation(s)
- Joana Carvalho
- Department of Biological Engineering, Universidade do Minho, 4710-057 Braga, Portugal
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7
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Lin H, Zhou J, Yingde C, Gunasekaran S. Synthesis and characterization of pH- and salt-responsive hydrogels based on etherificated sodium alginate. J Appl Polym Sci 2010. [DOI: 10.1002/app.30408] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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8
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Van Thienen TG, Raemdonck K, Demeester J, De Smedt SC. Protein release from biodegradable dextran nanogels. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:9794-801. [PMID: 17696367 DOI: 10.1021/la700736v] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The use of drugs with intracellular targets will strongly depend on the availability of delivery systems that are able to deliver them to specific intracellular sites at an optimal rate. Biodegradable dextran nanogels were prepared using liposomes as a nanoscaled reactor.1,2 These nanogels were obtained by UV polymerization of dextran hydroxyethylmethacrylate (dex-HEMA) containing 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine (SOPC) liposomes. We found the encapsulation efficiency of bovine serum albumin (BSA) and lysozyme in the dextran nanogels to be about 50%. Specifically, the release of BSA and lysozyme from the dextran nanogels was clearly governed by the cross-link density of the tiny gels. Depending on the size of the encapsulated protein, the cross-link density of the dextran network, and the presence or absence of a lipid coating, proteins were released from the nanogels over days to weeks. Interestingly, when sufficiently diluted, dextran nanogels did not aggregate in human serum, which is of major importance when one considers intravenous administration of such nanogels. Also, reconstitution of lyophilized dextran nanogels seemed perfectly possible, which is also an important finding since dextran nanogels will have to be stored in dry form. Because dextran nanogels can be taken up by cells, they are promising materials for controlled intracellular release of proteins.
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Affiliation(s)
- T G Van Thienen
- Laboratory of General Biochemistry and Physical Pharmacy, Department of Pharmaceutics, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium
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9
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Van Thienen TG, Horkay F, Braeckmans K, Stubbe BG, Demeester J, De Smedt SC. Influence of free chains on the swelling pressure of PEG-HEMA and dex-HEMA hydrogels. Int J Pharm 2006; 337:31-9. [PMID: 17229536 DOI: 10.1016/j.ijpharm.2006.12.022] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2006] [Revised: 12/17/2006] [Accepted: 12/18/2006] [Indexed: 10/23/2022]
Abstract
Insight in the osmotic behavior of degrading hydrogels is of great importance in the design of biodegradable hydrogels for biomedical applications. This study compares the degradation behavior of PEG-HEMA (hydroxyethylmethacrylated polyethylene glycol) and dex-HEMA (hydroxyethylmethacrylated dextran) hydrogels. The degradation of PEG-HEMA gels takes several months to over a year, while that of dex-HEMA gels takes only days or weeks. The faster degradation kinetics of dex-HEMA networks can be attributed to stabilization of the keto-enol form by hydroxyl groups. Upon degradation of PEG-HEMA and dex-HEMA hydrogels, respectively, free PEG and free dextran chains are produced. We investigated the effect of unattached PEG and dextran chains on the swelling pressure of the degrading gels. It is found that low molecular weight free chains significantly increase the swelling pressure. However, the contribution of higher molecular weight free chains (M(w)>10 kDa) is similar to that of the network chains.
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Affiliation(s)
- T G Van Thienen
- Laboratory of General Biochemistry and Physical Pharmacy, Department of Pharmaceutics, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium
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10
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Spinks GM, Lee CK, Wallace GG, Kim SI, Kim SJ. Swelling behavior of chitosan hydrogels in ionic liquid-water binary systems. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:9375-9. [PMID: 17042556 DOI: 10.1021/la061586r] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The swelling behavior of chitosan hydrogels in ionic liquid-water binary systems was studied using hydrophilic room-temperature ionic liquids (RTILs) to elucidate the swelling mechanism of chitosan hydrogels. No penetration of RTIL into a dry chitosan material was observed. Swelling was achieved by soaking in water-RTIL binary mixtures, with larger swelling observed at higher water contents. In one instance, the binary mixture was acidic and produced larger than expected swelling due to the dissociation of the amine groups in the chitosan. The equilibrium binary system content behavior of the chitosan hydrogels depended upon the amount of free water, which is a measure of the number of water molecules that do not interact with the ionic liquid. After evaporation of water, remnant RTIL remained in the chitosan network and hardness testing indicated a plasticization effect, suggesting that the RTIL molecularly mixed with the chitosan. Chitosan hydrogels containing only RTIL were prepared by dropping pure RTIL onto a fully preswollen hydrogel followed by water evaporation. This method may be a useful means for preparing air-stable swollen chitosan gels.
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Affiliation(s)
- Geoffrey M Spinks
- ARC Centre of Excellence in Electromaterials Science, Intelligent Polymer Research Institute, University of Wollongong, NSW, Australia
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11
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Vlugt-Wensink KDF, Jiang X, Schotman G, Kruijtzer G, Vredenberg A, Chung JT, Zhang Z, Versluis C, Ramos D, Verrijk R, Jiskoot W, Crommelin DJA, Hennink WE. In Vitro Degradation Behavior of Microspheres Based on Cross-Linked Dextran. Biomacromolecules 2006; 7:2983-90. [PMID: 17096522 DOI: 10.1021/bm060385z] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The aim of this study was to investigate the in vitro degradation of hydroxyl ethyl methacrylated dextran (dex-HEMA) microspheres. Dextran microspheres were incubated in phosphate buffer pH 7.4 at 37 degrees C, and the dry mass, mechanical strength, and chemical composition of the microspheres were monitored in time. The amount and nature of the formed degradation products were established for microspheres with different cross-link densities by FT-IR (Fourier transformed infrared spectroscopy), NMR, mass spectrometry, SEC analysis, and XPS (X-ray photoelectron microscopy). The dex-HEMA microspheres DS 12 (degree of HEMA substitution; the number of HEMA groups per 100 glucose units) incubated at pH 7.4 and 37 degrees C showed a continuous mass loss, leaving after 6 months a residue of about 10% (w/w) of water-insoluble products. NMR, mass spectrometry, and SEC showed that the water-soluble degradation products consisted of dextran, low molecular weight pHEMA (M(n) approximately 15 kg/mol), and small amounts of unreacted HEMA and HEMA-DMAP (intermediate reaction product of the Baylis-Hillman reaction of HEMA with DMAP (4-dimethyl aminopyridine)). Microscopy revealed that the water-insoluble residue consisted of particles with shape and size similar to that of nondegraded microspheres. However, these particles had lost their mechanical strength as evidenced from micromanipulation experiments. FT-IR and XPS (X-ray photoelectron microscopy) revealed that these particles consisted of pHEMA, of which a small fraction was soluble in methanol (M(n) ranging between 27 and 82 kg/mol). The insoluble material likely consisted of lightly cross-linked pHEMA. In conclusion, in vitro degradation of dex-HEMA microspheres results in the formation of water-soluble degradation products (mainly dextran), leaving a small water-insoluble residue mainly consisting of pHEMA.
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Affiliation(s)
- Karin D F Vlugt-Wensink
- Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, P. O. Box 80082, 3508 TB Utrecht, The Netherlands.
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12
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Van Tomme SR, van Nostrum CF, de Smedt SC, Hennink WE. Degradation behavior of dextran hydrogels composed of positively and negatively charged microspheres. Biomaterials 2006; 27:4141-8. [PMID: 16600367 DOI: 10.1016/j.biomaterials.2006.03.023] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2006] [Accepted: 03/16/2006] [Indexed: 10/24/2022]
Abstract
This paper reports on the degradation behavior of in situ gelling hydrogel matrices composed of positively and negatively charged dextran microspheres. Rheological analysis showed that, once the individual microspheres started to degrade, the hydrogel changed from a mainly elastic to a viscoelastic network. It was shown with gels composed of equal amounts of cationic and anionic microspheres, that both a higher crosslink density of the particles and a decrease in water content of the hydrogels resulted in a slower degradation, ranging from 65 to 140 days. Dispersions containing cationic, neutral or anionic microspheres completely degraded within 30, 55 or 120 days, respectively. The microspheres were loaded with rhodamine-B-dextran and degradation was studied with confocal microscopy and fluorescence spectroscopy. After a lag time of 3 days rhodamine-B-dextran started to release from the positive microspheres with a 50% release after 16 days. In contrast, release of rhodamine-B-dextran from the negative microspheres started after 10 days with a 50% release after 36 days. The faster degradation of the positively charged microspheres as compared to the negatively charged microspheres is attributed to stabilization of the transition state in the hydrolysis process by the protonated tertiary amine groups present in the cationic microspheres. On the other hand, the presence of negatively charged groups causes repulsion of hydroxyl anions resulting in a slower degradation. Combining the oppositely charged microspheres in different ratios makes it possible to tailor the network properties and the degradation behavior of these hydrogels, making them suitable for various applications in drug delivery and tissue engineering.
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Affiliation(s)
- Sophie R Van Tomme
- Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences (UIPS), University Utrecht, P.O. Box 800082, 3508 TB Utrecht, The Netherlands
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Shingel KI, Faure MP. Structure-property relationships in poly(ethylene glycol)-protein hydrogel systems made from various proteins. Biomacromolecules 2006; 6:1635-41. [PMID: 15877388 DOI: 10.1021/bm0492475] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A series of poly(ethylene glycol)-protein hydrogels were synthesized with different proteins, and the resultant structures were characterized in terms of swelling behavior and mechanical, optical, and drug release properties. Irrespectively of the protein involved in polymerization with poly(ethylene glycol), all studied systems were found to be loosely cross-linked networks, where both polymer and protein are completely solvated, enabling as high as 96% water content. Changes in the apparent transparency of the hydrogels synthesized with different proteins were attributed to the ability of the protein component to self-associate via hydrophobic interactions. The polyelectrolyte nature of the protein component governs the pH responsiveness of the network, which manifested itself in a pH-dependent mechanism of swelling and drug release. It was demonstrated that there is great opportunity to modulate the final characteristics of the hydrogel system to fit the need of specific biomedical application.
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Affiliation(s)
- Kirill I Shingel
- Bioartificial Gel Technologies Inc., 400 Maisonneuve West, Suite 1156, Montreal, H3A 1L4 Quebec, Canada.
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14
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Van Thienen TG, Lucas B, Flesch FM, van Nostrum CF, Demeester J, De Smedt SC. On the Synthesis and Characterization of Biodegradable Dextran Nanogels with Tunable Degradation Properties. Macromolecules 2005. [DOI: 10.1021/ma050822m] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- T. G. Van Thienen
- Laboratory of General Biochemistry and Physical Pharmacy, Department of Pharmaceutics, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium, and Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, University Utrecht, 3508TB Utrecht, The Netherlands
| | - B. Lucas
- Laboratory of General Biochemistry and Physical Pharmacy, Department of Pharmaceutics, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium, and Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, University Utrecht, 3508TB Utrecht, The Netherlands
| | - F. M. Flesch
- Laboratory of General Biochemistry and Physical Pharmacy, Department of Pharmaceutics, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium, and Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, University Utrecht, 3508TB Utrecht, The Netherlands
| | - C. F. van Nostrum
- Laboratory of General Biochemistry and Physical Pharmacy, Department of Pharmaceutics, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium, and Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, University Utrecht, 3508TB Utrecht, The Netherlands
| | - J. Demeester
- Laboratory of General Biochemistry and Physical Pharmacy, Department of Pharmaceutics, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium, and Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, University Utrecht, 3508TB Utrecht, The Netherlands
| | - S. C. De Smedt
- Laboratory of General Biochemistry and Physical Pharmacy, Department of Pharmaceutics, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium, and Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, University Utrecht, 3508TB Utrecht, The Netherlands
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15
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Lecomte F, Siepmann J, Walther M, Macrae RJ, Bodmeier R. pH-Sensitive Polymer Blends used as Coating Materials to Control Drug Release from Spherical Beads: Importance of the Type of Core. Biomacromolecules 2005; 6:2074-83. [PMID: 16004447 DOI: 10.1021/bm0500704] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The aim of this study was to coat theophylline-loaded spherical beads with pH-sensitive polymer blends to control the resulting drug release kinetics. Various mixtures of ethylcellulose (water-insoluble) and Eudragit L (methacrylic-acid-ethyl-acrylate-copolymer; water-insoluble/water-soluble below/above pH 5.5) were used as coating materials. Two types of theophylline cores were studied: pure drug matrixes and theophylline-layered sugar cores. Importantly, the type of core significantly affected the resulting drug release patterns. Interestingly, not only the slope, but also the shape of the release curves was altered, indicating changes in the underlying mass transport mechanisms, despite of the identical composition of the polymeric coatings. The observed differences could be explained based on the physicochemical properties of the film coatings and the swelling behavior of the beads upon exposure to the release media. Using this knowledge the development/optimization of this type of drug delivery system can be facilitated and the safety of the pharmacotherapies be improved.
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Affiliation(s)
- Florence Lecomte
- College of Pharmacy, Freie Universitaet Berlin, Kelchstr. 31, 12169 Berlin, Germany
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16
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Stubbe BG, Hennink WE, De Smedt SC, Demeester J. Swelling Pressure of Hydrogels That Degrade through Different Mechanisms. Macromolecules 2004. [DOI: 10.1021/ma040103s] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- B. G. Stubbe
- Laboratory of General Biochemistry and Physical Pharmacy, Department of Pharmaceutics, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium, and Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, University Utrecht, 3508TB Utrecht, The Netherlands
| | - W. E. Hennink
- Laboratory of General Biochemistry and Physical Pharmacy, Department of Pharmaceutics, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium, and Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, University Utrecht, 3508TB Utrecht, The Netherlands
| | - S. C. De Smedt
- Laboratory of General Biochemistry and Physical Pharmacy, Department of Pharmaceutics, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium, and Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, University Utrecht, 3508TB Utrecht, The Netherlands
| | - J. Demeester
- Laboratory of General Biochemistry and Physical Pharmacy, Department of Pharmaceutics, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium, and Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, University Utrecht, 3508TB Utrecht, The Netherlands
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17
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Stubbe BG, Horkay F, Amsden B, Hennink WE, De Smedt SC, Demeester J. Tailoring the swelling pressure of degrading dextran hydroxyethyl methacrylate hydrogels. Biomacromolecules 2003; 4:691-5. [PMID: 12741786 DOI: 10.1021/bm020129w] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Swelling pressure measurements were performed on degrading dextran hydroxyethyl methacrylate (dex-HEMA) hydrogels. In these networks, the cross-links are hydrolyzable carbonate ester bonds formed between methacrylate groups and dextran molecules. It is demonstrated that dex-HEMA gels made in the presence of a known amount of free dextran chains exhibit osmotic properties similar to those of partially degraded dex-HEMA gels. The swelling pressure, Pi(sw), of degrading dex-HEMA gels is controlled primarily by the cross-linked dex-HEMA polymer and the free dextran molecules, while the contribution of short poly-HEMA fragments (produced in the degradation process) is negligible. It is found that Pi(sw) only slightly changes during the first 15 days of degradation. Close to the end of the degradation process, however, a much faster increase in Pi(sw) is observed. The swelling pressure profile of these gels strongly depends on the concentration of the cross-linked dex-HEMA and its chemical composition (amount of HEMA groups per 100 glucose units).
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Affiliation(s)
- Barbara G Stubbe
- Laboratory of General Biochemistry and Physical Pharmacy, Department of Pharmaceutics, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium
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