Hydrogels
In hydrogel nanocomposites, hydrogels form the continuous matrix containing the dispersed nanoparticles. (RDC 5/3/2009) “Hydrogel (also called Aquagel) is a network of polymer chains that are water-insoluble, sometimes found as a colloidal gel in which water is the dispersion medium. Hydrogels are highly absorbent (they can contain over 99% water) natural or synthetic polymers. Hydrogels also possess a degree of flexibility very similar to natural tissue, due to their significant water content.” Wikipedia 5/3/2009)
Recent US Patents
9/13/2011
8,017,139
Blend hydrogels and methods of making
Thomas, Yakimicki and Hudgins of Zimmer Technology, Indiana, developed blends of water-swellable materials and hydrogels for use in biomedical or other applications. The blend water swellable materials and hydrogels have at least one hydrophilic polymer and at least one other polymer or oligomer having both hydrophobic and hydrophilic recurring units where the blend phase separates and is opaque and immiscible in the presence of water. (RDC 9/15/2011)
Recent Journal Articles
(Bio)polymeric Hydrogels as Therapeutic Agents
(994-1003) Journal of Macromolecular Science Part A - Pure and Applied Chemistry 48 #12 (2011)
Abstract
Dhal, Gianolo and Miller of theGenzyme Corporation,, Massachusetts, reviewed the use hydrogels as a a new generation of drugs and medical devices. For example, polymeric hydrogels can be restricted to the gastrointestinal tract, where they can selectively recognize, bind, and remove the targeted disease-causing substances from the body without causing any systemic toxicity that are associated with traditional small molecule drugs. Similarly hydrogels can be implanted at specific locations (such as knee and abdomen) to impart localized therapeutic benefits. The present article provides an overview of certain recent developments in the design and synthesis of functional hydrogels that have led to several polymer derived drugs and biomedical devices. (RDC 11/2/2011)
Preparation and characterization of dual responsive sodium alginate-g-poly(vinyl alcohol) hydrogel
(2244–2249)Journal of Applied Polymer Science 123 #4 (2012)
Xia and Xiao of Huaqiao University, China, first, grafted polyvinyl acetate (PVAc) onto SA via radical copolymerization. Then, the copolymer was subsequently converted into SA-g-poly(vinyl alcohol) (SAPVA) by alcoholysis reaction. The crystallinity of SAPVA hydrogels depended on the PVA content of SAPVA. The swelling test showed that SAPVA hydrogels were pH-responsive, and the swelling was reversible. The pH-sensitivity of SAPVA hydrogels was able to be controlled with the composition of the hydrogels. (RDC 11/2/2011)
The Effect of Mixing on the Mechanical Properties of Hyaluronan-Based Injectable Hydrogels
(944–951)Macromolecular Materials and Engineering 296 #10 (2011)
Piskounov et al of Uppsala University, Sweden, developed a method for determining the correlation between the mixing of two reactive polymers and the structural and mechanical properties of the formed hydrogels. Rheological measurements show that insufficient mixing gives rise to soft and not fully crosslinked hydrogels while excessive mixing beyond gel point results in weaker hydrogels due to potential breakage of their 3D network. Furthermore, the hydrogels swell significantly more in cell culture medium than in phosphate-buffered saline, attributed to interactions with additional molecules such as proteins. Thus, moderate mixing gives rise to the most homogenous and mechanically stable hydrogels and the choice of medium e.g., for release experiments, should be consistent in order to avoid unnecessary variations in the data caused by different swelling profiles. (RDC 10/13/2011)