Hydrogels are formed when a three-dimensional polymeric network is loosely crosslinked. They are swollen by water but not dissolved in it. Hydrogels may display reversible sol–gel transitions, induced by changes in the environmental conditions such as temperature, pH, ionic strength, phase separation, wave length of light, crystallinity, etc. Hydrogel is described as smart or intelligent when sharp transition is induced by small change in such conditions. For the shape-memory hydrogels, reversible change in shape may also be induced by such stimuli. The preparation and applications of the molecularly imprinted polymeric hydrogels (MIPs) are illustrated by a few examples. The use of shape sensitive hydrogels in microfluidic is mentioned. Application of hydrogels for chronobiology and chronotherapy is outlined. The conversion of hydrogels into aerogels and their respective properties is discussed. Copyright © 2009 John Wiley & Sons, Ltd.

Polymeric gels and hydrogels for biomedical and pharmaceutical applications

Polymeric hydrogels for novel contact lens-based ophthalmic drug delivery systems: A review

Glaucoma therapy by extended release of timolol from nanoparticle loaded silicone-hydrogel contact lenses

Chlorhexidine-releasing methacrylate dental composite materials.

The field of encapsulation, especially microencapsulation, is a rapidly growing area of research and product development. The Handbook of Encapsulation and Controlled Release covers the entire field, presenting the fundamental processes involved and exploring how to use those processes for different applications in industry. Written at a level comp

Handbook of Encapsulation and Controlled Release

Synthesis and characterization of poly(methacrylic acid) hydrogels for metoclopramide delivery

Timolol maleate release from pH-sensible poly(2-hydroxyethyl methacrylate-co-methacrylic acid) hydrogels

1 HIDROGELES. PRINCIPALES CARACTERISTICAS EN EL DISENO DE SISTEMAS DE LIBERACION CONTROLADA DE FARMACOS J.L. Escobar, D.M. Garcia, D. Zaldivar e Issa Katime 2 1 Centro de Biomateriales, Universidad de la Habana. Avenida Universidad e/ G y Ronda, CP 10600, Caja Postal 6130, Plaza de la Revolucion, Ciudad de la Habana, Cuba. email: jlescobar@biomat.uh.cu 2 Grupo de Nuevos Materiales, Departamento de Quimica Fisica. Facultad de Ciencias. Campus de Leioa. Universidad del Pais Vasco, Bilbao, Espana. email: qfpkaami@lg.ehu.es

Hidrogeles. principales características en el diseño de sistemas de liberación controlada de fármacos

Hydrogels are hydrophilic polymers that swell to an equilibrium volume in the presence of water, preserving their shape. The dynamic swelling behavior of poly(N-isopropylacrylamide-co-N,N-dimethylacrylamide) [poly(NIPA-co-DMA)] copolymers at 37°C was investigated. It was observed that the swelling degree in the copolymers decreases with the N-isopropylacrylamide content. In addition, the liberation mechanism was found to be Fickian. Diffusion coefficients according to Fick′s law as a function of the N-isopropylacrylamide concentration and results of the release process are reported. The kinetics of cephazoline sodium release from poly(NIPA-co-DMA) hydrogels with different compositions was studied. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3433–3437, 2004

Cephazoline sodium release from poly(N‐isopropyl acrylamide‐co‐N,N‐dimethylacrylamide) hydrogels

Los hidrogeles son redes polimericas compatibles con el agua, los cuales pueden aumentar varias veces su volumen sin perder su forma. Las aplicaciones de este tipo de material dependen de su grado de hinchamiento maximo y de las propiedades mecanicas que presentan. 
En el presente trabajo se describe la sintesis de los hidrogeles mediante la copolimerizacion radicalica de N-isopropilacrilamida (NIPA) con N,N-dimetilacrilamida (DMA), en solucion acuosa a 60oC utilizando persulfato de potasio como iniciador y N,N’-metilenbisacrilamida como agente entrecruzante. El objetivo principal de este trabajo es determinar la influencia de la temperatura y la composicion de los copolimeros sobre el proceso de hinchamiento. En este sentido se estudio el comportamiento de hinchamiento de los copolimeros sintetizados en agua destilada a diferentes temperaturas (20, 30, 32, 34, 37 y 40oC) . La difusion del agua se analizo sobre la base del modelo de relajacion de las tensiones de las cadenas polimericas. Los resultados obtenidos se ajustan satisfactoriamente al comportasmiento fickiano para los primeros estadios de hinchamiento excepto para las muestras con un 100% de NIPA a partir de los 30oC y al modelo propuesto por Schott (segundo orden) para estadios superiores.

Influencia de la temperatura y la composición de los copolímeros sobre el proceso de hinchamiento en hidrogeles de poli-(n-isopropilacrilamida-co-n,n,dimetilacrilamida)

J.L. Escobar

Papers

Synthesis and characterization of poly(methacrylic acid) hydrogels for metoclopramide delivery

Timolol maleate release from pH-sensible poly(2-hydroxyethyl methacrylate-co-methacrylic acid) hydrogels

Hidrogeles. principales características en el diseño de sistemas de liberación controlada de fármacos

Cephazoline sodium release from poly(N‐isopropyl acrylamide‐co‐N,N‐dimethylacrylamide) hydrogels

Influencia de la temperatura y la composición de los copolímeros sobre el proceso de hinchamiento en hidrogeles de poli-(n-isopropilacrilamida-co-n,n,dimetilacrilamida)