Hydrogels: A Novel Drug Delivery System

Abstract

Hydrogels are water-swollen networks, which are cross-linked structures consisting of hydrophilic polymers. They are made three-dimensional by the creation of the cross-links by joining them through covalent or ionic bonds. Hydrogels have been used in various areas including industry and medicine due to their excellent characteristics such as high swelling capacity, high content of water, compatibility with other biological molecules, controlled chemical and physical properties, high mechanical integrity and biodegradability. They have been the center of attention of researchers from the past 50 years because of their promising applications in industries and other areas. They are used in different fields, in medicine, in the diagnosis of the diseases, in culturing of cells, in injuries as wound healers, in cosmetics, in skin diseases like pruritis, in environmental pollution reduction and other miscellaneous applications such as in diapers for babies and sanitary products. Extensive literature can be found on the subject of hydrogels. The present review discusses the history, description of hydrogels, basic properties, classification, different techniques or methods of hydrogel synthesis and the areas in which hydrogels find applications.

Superporous Hydrogel: A Novel Approach for Safe Gastroretentive Drug Delivery System

“…When the hydrogel networks are bonded by molecular entanglements and other forces such as hydrogen bonding, ionic bonding, or hydrophobic forces, they are referred to as reversible or physical gels. 5…”

New Composite Materials with Cross-Linked Structures Based on Grafted Copolymers of Acrylates on Cod Collagen

“…However, grafted MMA copolymers on collagen can only be considered only as precursors of biodegradable materials. The creation of special-purpose materials requires the development of composites by introducing additional components with certain characteristics [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]. Thus, the research on the creation of composite materials with the inclusion of modifiers is significant and promising.…”

“…Along with PEG, other modifiers are also used. Natural collagen (gelatin) is characterized by low chemical and mechanical stability, so, when "cross-linked" with various chemical agents or physical exposure, its strength and elasticity are usually increased [23][24][25][26][27][28][29][30][31][32][33][34]. Moreover, "crosslinking" is possible with the formation of covalent [8,20,23,[25][26][27][28][29][30][32][33][34][35] and ionic [8,19,24,26,30] connections.…”

“…In this regard, an important step in the creation of any collagen material is the development of cross-linking conditions that provide mechanical strength and stability for the duration that the material is used. In this case, cross-linking agents were used for collagen fibers of various natures [23][24][25][26][27][28][29][30][31][32][33][34].…”