Smart Hydrogels for Pharmaceutical Applications

Abstract

The latest development in the field of smart hydrogels application as drugs carriers is shown in this chapter. Hydrogels are three-dimensional polymer network consisting of at least one hydrophilic monomer. They are insoluble in water, but in the excess presence of water or physiological fluids, swell to the equilibrium state. The amount of absorbed water depends on the chemical composition and the crosslinking degree of 3D hydrogel network and reaches over 1000% of the xerogel weight. Stimuli-responsive hydrogels exhibit significant change of their properties (swelling, color, transparency, conductivity, shape) due to small changes in the external environment conditions (pH, ionic strength, temperature, light wavelength, magnetic or electric fields, ultrasound, or a combination thereof). This smart hydrogels, with different physical and chemical properties, chemical structure and technology of obtaining, show great potential for application in the pharmaceutical industry. The application of smart hydrogels is very promising and at the beginning of the development and exploitation.

Intelligent Poly(N-Isopropylmethacrylamide) Hydrogels: Synthesis, Structure Characterization, Stimuli-Responsive Swelling Properties, and Their Radiation Decomposition

“…The pore size of the synthesized homopolymer p(NiPMAm) in the swollen state was up to 150 µm. Based on average pore size, the synthesized p(NiPMAm) can be classified as a macroporous hydrogel [2,28]. The three-dimensional structure of p(NiPMAm) hydrogels looked like a pretty settled, semi-uniform cross-linked network.…”

“…The behavior of the poly(N-isopropylmethacrylamide) xerogels that were swollen in distilled water was monitored at 20 • C and in the fluids with pH values 2.0 and 7.4. The swelling ratio, α, was calculated according to Equation (1), and the equilibrium swelling ratio, α e , was calculated according to Equation (2). The mass of the xerogel samples (m 0 ) was measured until equilibrium (m e ) was reached.…”

“…Responsive, or stimuli-sensitive, hydrogels are cross-linked three-dimensional polymeric matrices based on natural or synthetic materials that have the ability to swell while retaining a large amount of surrounding fluid, but they do not dissolve [1]. They are known as "intelligent" or "smart" hydrogels, because when environmental factors change (e.g., pH-value, temperature, light, glucose concentration, pressure, and magnetic or electric fields), they can respond with the changes of some physicochemical property (e.g., swelling capacity) [2]. Their syntheses can be designed to vary swelling ability, porosity, physical structure, etc., in order to provide an adequate response to the external stimuli changes [3].…”

“…All changes that occur in the hydrogels are reversible, and they can return to their original state upon the removal of the stimulus. Thermosensitive hydrogels with an upper critical solution temperature (UCST) swell above and contract below, while polymers with a lower critical solution temperature (LCST) swell below and contract over critical temperature [2,4].…”

Cellulose-g-poly(2-(dimethylamino)ethylmethacrylate) Hydrogels: Synthesis, Characterization, Antibacterial Testing and Polymer Electrolyte Application

“…Moreover, the medium–strong band at 1428 cm −1 is assigned to the in-plane scissoring or bending of CH 2 . The strong band around 1380 cm −1 is assigned to the out-of-plane bending of CH 2 , while the band at 987 cm −1 is assigned to the vibration of CH 2 , respectively [ 41 , 42 ].…”