Purdue Research Foundation

Akina, Inc.

The United States Government As Represented by the Department of Veterans Affairs

Samyang Biopharmaceuticals Corporation

Haesun Park

Kinam Park

Ghanashyam S Acharya

John J Garner

Jun Chen

John Solomon Garner

Yourong Fu

Dukjoon Kim

Hossein Omidian

Shicheng Yang

Clark Tobias Barco

Yong Qiu

Ghanashyam Acharya

Discrete microstructures of predefined size and shape are prepared using sol-gel phase-reversible hydrogel templates. An aqueous solution of hydrogel-forming material is covered onto a microfabricated silicon wafer master template having predefined microfeatures, such as pillars. A hydrogel template is formed, usually by lowering the temperature, and the formed hydrogel template is peeled away from the silicon master template. The wells of predefined size and shape on the hydrogel template are filled with a solution or a paste of a water-insoluble polymer, and the solvent is removed to form solid structures. The formed microstructures are released from the hydrogel template by simply melting the hydrogel template in water. The microstructures are collected by centrifugation. The microstructures fabricated by this method exhibit pre-defined size and shape that exactly correspond to the microwells of the hydrogel template. The method of preparing microstructures based on hydrogel templates is simple and can easily produce large quantities of the microstructures.

Sol-gel phase-reversible hydrogel templates and uses thereof

The present invention provides tissue expanders comprising biodegradable, chemically cross-linked hydrogels which are elastic in the dry state. These biocompatible tissue expanders are self-inflating and membrane-free. They swell slowly and elicit minimal negative tissue responses, while allowing for rapid and easy manipulation by the surgeon at the time of emplacement.

Hydrogel tissue expanders

Hydrogels having improved elasticity and mechanical strength properties are obtained by subjecting a hydrogel formulation containing a strengthening agent to chemical or physical crosslinking conditions subsequent to initial gel formation. Superporous hydrogels having improved elasticity and mechanical strength properties are similarly obtained whenever the hydrogel formulation is provided with a foaming agent. Interpenetrating networks of polymer chains comprised of primary polymer(s) and strengthening polymer(s) are thereby formed. The primary polymer affords capillary-based water sorption properties while the strengthening polymer imparts significantly enhanced mechanical strength and elasticity to the hydrogel or superporous hydrogel. Suitable strengthening agents can be natural or synthetic polymers, polyelectrolytes, or neutral, hydrophilic polymers.

Hydrogels having enhanced elasticity and mechanical strength properties

A superporous hydrogel composite is formed by polymerizing one or more ethylenically-unsaturated monomers, and a multiolefinic crosslinking agent, in the presence of particles of a disintegrant and a blowing agent. The disintegrant, which rapidly absorbs water, serves to greatly increase the mechanical strength of the superporous hydrogel and significantly shorten the time required to absorb water and swell. Superporous hydrogel composites prepared by this method have an average pore size in the range of 10 &mgr;m to 3,000 &mgr;m. Preferred particles of disintegrant include natural and synthetic charged polymers, such as crosslinked sodium carboxymethylcellulose, crosslinked sodium starch glycolate, and crosslinked polyvinylpyrrolidone. The blowing agent is preferably a compound that releases gas bubbles upon acidification, such as NaHCO,. Improved hydrogel composites formed without a blowing agent are also provided.

Hydrogel composites and superporous hydrogel composites having fast swelling, high mechanical strength, and superabsorbent properties

A water swellable foam matrix formed as a macroporous solid comprising a foam stabilizing agent and a polymer or copolymer of a free radical polymerizable hydrophilic olefin monomer crosslinked with about 0.1 to about 10% by weight of a multiolefin-functional crosslinking agent is described. The foam matrix is characterized by rapid swelling and high water swelling ratios.

Super absorbent hydrogel foams

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West Lafayette, IN, United States of America

Haesun Park