Water‐borne, in situ crosslinked biomaterials from phase‐segregated precursors

Abstract

A novel process for the preparation of water-borne biomaterials for hard tissue repair from injectable precursors is described, where the precursors form crosslinked materials in situ under physiological conditions. The precursors react by means of a Michael-type addition reaction that makes use of addition donors such as pentaerythritol tetrakis 3'-mercaptopropionate (QT) and addition acceptors such as poly(ethylene glycol) diacrylate 570 MW (PEGDA), pentaerythritol triacrylate (TA), and poly(propylene glycol) diacrylate 900 MW (PPODA). These crosslinked materials (at 75 wt% solid), prepared from water dispersions or reverse emulsions, showed ultimate strengths in compression of 1.8 +/- 0.2 and 6.7 +/- 0.5 MPa and ultimate deformations of 35 +/- 2+/- and 37 +/- 2%, respectively. Scanning electron microscopy (SEM) shows that the morphology of the precursors templated the morphology of the final materials. The current study indicates that it is possible to obtain injectable high-modulus materials that have appropriate mechanical properties and gelation kinetics for tissue augmentation and stabilization applications such as mechanical stabilization of the intervertebral disc annulus.

Corticosterone modulation of reproductive and immune systems trade-offs in female tree lizards: long-term corticosterone manipulationsviainjectable gelling material

“…In situ studies demonstrate that steroid hormones are released from the gelled material in a controlled, zero-order manner (Vernon et al, 2003;Vernon et al, 2004). Furthermore, pilot studies in our laboratory found that the implants achieve constant, sustained concentrations of plasma corticosterone for 2 weeks post-injection.…”

Conducting polymer-hydrogels for medical electrode applications

“…One of these methods that is particularly useful in generating crosslinked networks is Michael and Michael-type addition reactions [91,98]. These reactions generally have good specificity and rate, and can be carried out in mild conditions.…”

“…These reactions generally have good specificity and rate, and can be carried out in mild conditions. The most common Michael-type polymerizations are thiol-ene reactions [98,99]. While Michael-type addition does result in a controlled network architecture, it suffers from problems with side reactions and incomplete conversion of the functional groups.…”

In vivo embolization of lateral wall aneurysms in canines using the liquid-to-solid gelling PPODA-QT polymer system: 6-month pilot study

“…In the presence of a basic (high pH) initiating solution, PPODA and QT undergo a chemical reaction called Michael-type addition to form a solid, cross-linked network. 49 Radiopacity was incorporated into the PPODA-QT system by using a liquid contrast agent as the basic initiating solution, adjusted appropriately with 5 N sodium hydroxide to meet the pH conditions required for the chemical reaction to occur. For this study, the liquid contrast agent Conray (60% w/v iothalamate meglumine, Mallinckrodt, Inc.) was adjusted to pH 11.0 and then incorporated into the PPODA-QT system.…”

“…This PPODA-QT material is composed of liquid monomer precursors, poly(propylene glycol) diacrylate and pentaerythritol tetra kis (3-mercaptopropionate), which undergo chemical cross-linking after being mixed with a water-based initiating solution. 49 When the precursors are mixed with this initiator, they form a cross-linked gel in a predictable and controllable manner. 39 This water-based system can be endovascularly delivered as a liquid rather than being mixed with angiotoxic organic solvents.…”