Formulation and characterization of radio-opaque conjugated in situ gelling materials

X-ray visibility is an integral design component of in situ gelling embolization systems for neurovascular treatment. The goals of this project included the synthesis and characterization of a unique intrinsically radio-opaque in situ gelling material for neurovascular embolization. The gels formed using Michael-Type Addition between pentaerythritol tetrakis 3-mercaptopropionate (QT) thiols and poly(propylene glycol) diacrylate (PPODA) with the addition of the new material Iodobenzoyl poly(ethylene glycol) acrylate (IPEGA), a radio-opaque agent, synthesized successfully as confirmed with ¹H NMR. The PPODA and IPEGA were mixed using a syringe coupler with QT and buffer at pH 11 for 90 seconds. Gel mixes were weighed to provide equal molar thiols and acrylate groups, changing the present acrylate-bearing compounds wt % ratios from 100 PPODA: 0 IPEGA, 90:10, 80:20, 70:30, 60:40, 50:50, and 0:100. Formulations with 10% and above of IPEGA were X-ray visible. Rheology showed that increasing the amount of IPEGA decreased the storage. Kinetic FT-IR studies indicate that the amphiphilic nature of the PEG backbone increased the reaction rate of the phase segregated reactants. Second order reaction constant modeling showed a change in initial reaction rate from 0.0029 to 0.0187 (M sec)^-1 from the 10% to 50% IPEGA formulations respectively.