Abstract: There is disclosed aqueous solutions of polyelectrolytes that can be neutralized by increasing temperature, under suitable polyelectrolyte charge state conditions, in order to obtain a homogeneous gel. This can be achieved by adding an appropriate weak electrolyte to the polyelectrolyte so that an increase of temperature will lead to a spatially homogeneous neutralization of the polyelectrolyte via proton transfer between the polyelectrolyte and the weak electrolyte. The ability of such a system to be thermally sensitive and to gel upon heating relies on the temperature dependence of the ionization equilibrium for the two components. This thermally induced neutralization reduces electrostatic repulsion between polyelectrolyte molecules allowing the manifestation of attractive polyelectrolyte-polyelectrolyte hydrophobic interactions and hydrogen bonding that result in gel formation. These new kinds of thermo sensitive gels can be used for biomedical applications.

Abstract: The present invention relates a biopolymeric liquid aqueous composition for producing self-gelling systems and gels, which comprises: an acidic water-based medium, 0.1 to 10% by weight of a pH-gelling acid-soluble biopolymer; and 0.1 to 10% by weight of a water-soluble molecule having a basic character and a pKa between 6.0 and 8.4, or a water-soluble residue or sequence of the molecule having a basic character and a pKa between 6.0 and 8.4. The liquid composition has a final pH ranging from 5.8 and 7.4, and forms a stable solid and homogeneous gel within a temperature range from 10 to 70° C. The present invention also relates to a method for preparing the composition and uses thereof.

Abstract: The present invention provides compositions and methods for tissue repair using a cytocompatible self-gelling cross-linked hydrogel. The composition comprises a biocompatible mixture of chitosan, bifunctional dialdehyde, and hydroxylated polymer, which can be used to immobilize or encapsulate viable cells, or bioactive substances. The method includes the process of mixing bioactive substances, live cells, and/or extracellular matrix components with a cross-linking solution comprising a bifunctional aldehyde-treated hydroxylated polymer such as hydroxyethyl cellulose. The cross-linking solution is then mixed homogenously with a neutral isotonic chitosan solution. The chitosan becomes cross-linked by the bifunctional aldehyde, while the cells are protected from potentially nocive effects of the aldehyde cross-linker by the hydroxylated polymer. The injectable solution retains cell viability and bioactivity, and immobilizes cells at the site of injection or delivery.

Abstract: There is disclosed aqueous solutions of polyelectrolytes that can be neutralized by increasing temperature, under suitable polyelectrolyte charge state conditions, in order to obtain a homogeneous gel. This can be achieved by adding an appropriate weak electrolyte to the polyelectrolyte so that an increase of temperature will lead to a spatially homogeneous neutralization of the polyelectrolyte via proton transfer between the polyelectrolyte and the weak electrolyte. The ability of such a system to be thermally sensitive and to gel upon heating relies on the temperature dependence of the ionization equilibrium for the two components. This thermally induced neutralization reduces electrostatic repulsion between polyelectrolyte molecules allowing the manifestation of attractive polyelectrolyte-polyelectrolyte hydrophobic interactions and hydrogen bonding that result in gel formation. These new kinds of thermo sensitive gels can be used for biomedical applications.

Abstract: There is disclosed a composition and a method for the efficient non-viral delivery of nucleic acids to cells using chitosan. In order to achieve high efficiency of transfection, the composition contains a nucleic acid and a chitosan that has the following physico-chemical properties: a combination of a number-average molecular weight between 8 kDa and 185 kDa and a degree of deacetylation between 72% and 92%. The chitosan molecule can also present additional physiochemical properties such as a block distribution of acetyl groups obtained by a heterogeneous treatment of chitin, and/or a polydispersity index between 1.4 and 7.0. By correctly controlling these parameters, efficient delivery systems may be produced that are effective when optimized for different conditions such as the pH of transfection media and amine-to-phosphate ratio.

Abstract: The present invention relates to a minimally-invasive method for restoring a damaged or degenerated intervertebral disc at an early stage. The method comprises the step of administering an injectable in situ setting formulation in the nucleus pulposus of the damaged or degenerated disc of the patient. The formulation once injected combines with nucleus matters and host cells, and becomes viscous or gels in situ within the annulus fibrosus of the disc for increasing the thickness and volume of the damaged or degenerated disc. The formulation is retained within the disc for providing restoration of the damaged or degenerated disc.

Abstract: The present invention relates to a method for treating damaged or degenerated fat pads in a foot of a host in need thereof. The method comprises the step of injecting into the fat pad of the host a biocompatiable solution having physico-chemical and mechanical properties substantially similar to a fatty acid mixture normally present in a healthy fat pad.

Abstract: A universal material testing device which includes a frame; an actuator mounted on the frame for controlling a displacement of a sample to be tested; a load cell movably mounted on the frame and adapted to abut against the sample for detecting a force applied thereon by the actuator, the load cell producing a signal corresponding to the force detected; a signal conditioning unit for reducing input noise and for processing of the signal and executing specific tests by coordination of displacement control and load signals received for processing from the load cell; and a detachable chamber with humidifying media for humidification of the sample environment confined within the chamber and separated frm the sample so as to avoid potential damaging effects of humidity on the sample or on the device. The device is useful for determining certain material properties of a sample.