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J. Funct. Biomater. 2011, 2(4), 373-390; doi:10.3390/jfb2040373
Article

Ionic and Polyampholyte N-Isopropylacrylamide-Based Hydrogels Prepared in the Presence of Imprinting Ligands: Stimuli-Responsiveness and Adsorption/Release Properties

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Received: 8 November 2011; in revised form: 8 December 2011 / Accepted: 9 December 2011 / Published: 15 December 2011
(This article belongs to the Special Issue Molecularly Imprinted Polymers in Biomedical Applications)
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Abstract: The conformation of the imprinted pockets in stimulus-responsive networks can be notably altered when the stimulus causes a volume phase transition. Such a tunable affinity for the template molecule finds interesting applications in the biomedical and drug delivery fields. Nevertheless, the effect that the binding of the template causes on the stimuli-responsiveness of the network has barely been evaluated. In this work, the effect of two ionic drugs used as templates, namely propranolol hydrochloride and ibuprofen sodium, on the responsiveness of N-isopropylacrylamide-based hydrogels copolymerized with acrylic acid (AAc) and N-(3-aminopropyl) methacrylamide (APMA) and on their ability to rebind and to control the release of the template was evaluated. The degree of swelling and, in some cases, energetics (HS-DSC) of the transitions were monitored as a function of temperature, pH, and concentration of drug. Marked decrease in the transition temperature of the hydrogels, accompanied by notable changes in the transition width, was observed in physiological NaCl solutions and after the binding of the drug molecules, which reveals relevant changes in the domain structure of the hydrogels as the charged groups are shielded. The ability of the hydrogels to rebind propranolol or ibuprofen was quantified at both 4 and 37 °C and at two different drug concentrations, in the range of those that cause major changes in the network structure. Noticeable differences between hydrogels bearing AAc or APMA and between imprinted and non-imprinted networks were also observed during the release tests in NaCl solutions of various concentrations. Overall, the results obtained evidence the remarkable effect of the template molecules on the responsiveness of intelligent imprinted hydrogels.
Keywords: stimulus-responsive network; imprinted hydrogel; ionic and polyampholite hydrogels; propranolol; ibuprofen; controlled release stimulus-responsive network; imprinted hydrogel; ionic and polyampholite hydrogels; propranolol; ibuprofen; controlled release
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Lago, M.A.; Grinberg, V.Y.; Burova, T.V.; Concheiro, A.; Alvarez-Lorenzo, C. Ionic and Polyampholyte N-Isopropylacrylamide-Based Hydrogels Prepared in the Presence of Imprinting Ligands: Stimuli-Responsiveness and Adsorption/Release Properties. J. Funct. Biomater. 2011, 2, 373-390.

AMA Style

Lago MA, Grinberg VY, Burova TV, Concheiro A, Alvarez-Lorenzo C. Ionic and Polyampholyte N-Isopropylacrylamide-Based Hydrogels Prepared in the Presence of Imprinting Ligands: Stimuli-Responsiveness and Adsorption/Release Properties. Journal of Functional Biomaterials. 2011; 2(4):373-390.

Chicago/Turabian Style

Lago, Miguel A.; Grinberg, Valerij Ya.; Burova, Tatiana V.; Concheiro, Angel; Alvarez-Lorenzo, Carmen. 2011. "Ionic and Polyampholyte N-Isopropylacrylamide-Based Hydrogels Prepared in the Presence of Imprinting Ligands: Stimuli-Responsiveness and Adsorption/Release Properties." J. Funct. Biomater. 2, no. 4: 373-390.



J. Funct. Biomater. EISSN 2079-4983 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert