| Endovascular interventional therapy of intracranial aneurysms is a new type of aneurysm treatment,but the common problem for embolic agents currently used is recanalization.In this work,a polymeric adhesive(PAN-PEGDA)based on dipole interaction was first prepared via simple one-step copolymerization of dipole monomer acrylonitrile(AN),crosslinker polyethylene glycol diacrylate(PEGDA),and a monomer-soluble redox initiation system that initiated room-temperature polymerization.The special initiation system allowed the adhesive to work at a lower curing temperature.One compelling feature was that liquid AN was exactly the solvent of PEGDA,so no solvent was required.Due to the dipole-dipole interaction between the cyano groups and the chemical cross-linking of PEGDA,the copolymerized product could be solidified and exhibit excellent mechanical properties.The cyano groups could form strong dipole-dipole interactions with diverse material surface,affording high bonding strength.In addition,the water absorption capacity of the copolymer could be reduced by adjusting the molecular weight of PEGDA,resulting in an adhesive with outstanding water-resistant adhesion performance.Although the PAN-PEGDA adhesive possessed the basic performance as a liquid embolic agent,its viscosity was too low and may flow into the aorta with blood during deployment.Therefore,polyethylene oxide(PEO)with high molecular weight was introduced to thicken the adhesive system.And the thickened adhesive was further doped with barium sulfate particles to endow the adhesive with radiopacity under Xrays.The viscosity of the adhesive introduced with PEO and barium sulfate was significantly increased,which reduced the possibility of embolizing the aorta.The curing speed was slower than that of cyanoacrylate liquid embolization,thus avoiding microcatheter entrapment during embolization treatment.Further,a kind of p H and temperature dual responsive hydrogel(PPH)enhanced by dipole-dipole interaction was fabricated by copolymerizing AN,N-acryloyl 2-glycine(ACG)and crosslinker PEGDA in solvent dimethyl sulfoxide(DMSO)at 25 ℃ through a redox initiation system.The initial shape of PPH can be fixed to a complex coil by phase conversion method.The dipole-dipole interaction formed between cyano groups endowed PPH with high strengths,while the carboxyl groups in ACG afforded PPH p H responsiveness.The hydrogel network equilibrated in acidic buffer met the criteria for the formation of upper critical dissolution temperature(UCST)-type temperature sensitive polymers,indicating that PPH exhibited temperature-sensitive shape memory capabilities and could be used as a solid coil embolic agent to treat aneurysms.The excellent mechanical properties of PPH allowed it to pass through the microcatheter smoothly when it was temporarily straightened.After reaching the aneurysm cavity,the straight hydrogel could be stimulated by warm blood and return to the original coil shape,preventing PPH from shedding off from aneurysm and embolizing the aorta.The PPH gradually swelled in the blood to a new equilibrium,which could significantly increase the filling rate and thus prevent recanalization.The ability of X-ray radiopacity could be obtained by depositing barium sulfate in the hydrogel network,which had little effect on the properties of PPH.In vivo animal experiment showed that the aneurysm was isolated from the parent vessel,indicating that complete embolization within 4months.The designed embolic agents will be able to solve the problems of recanalization associated with traditional embolic materials,offering a promising approach to fabricate a novel permanent embolic agent for treating different aneurysms. |
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