Preparation Of Water Soluble Two-photon Polymerization Initiators And Microfabrication Of3D Hydrogels

Two-photon polymerization occurrs in small volume of the light focus becausetwo-photon absorption is a third-order nonlinear process. Two-photon polymerizationmicrofabrication (TPPM) can fabricate arbitrary3D microstructure because thewavelength of laser source used in TPP is infrared laser which can penetratea large depth with a little loss. TPPM is an advanced3D print technologyand can fabricate3D microstructure with high resolution beyond the opticaldiffraction limit. TPPM has been applied in the fabricationof photonic crystals,waveguides and others optics.3D hydrogels fabricated by TPPM was particularlyfavored because3D hydrogels are useful for tissue engineering and drug delivery.However, most of high efficiency TPPM initiators are hydrophobic and TPPM has tobe fulfilled in organic solvent, resulting in residue of organic solvent in3D hydrogelswith obvious cytotoxicity that hinder the application of3D hydrogels. Therefore, thekey to solve this problem is to develop water soluble TPPM initiators with highefficiency. In this case, we prepared water soluble TPP initiator through host-guestchemical interaction and hydrophilic-hydrophobic interaction. The properties of theiroptical and initiating polymerization were investigated.Firstly, we designed and synthetized a novel hydrophobic TPP initiator,7-bis(2-(4-pentaneoxy-phenyl)-vinyl)anthraquinone with C2vsymmetrical structure.We prepared a water soluble TPP initiator (WI) by combining it with2-hydroxypropyl-?-cyclodextrins (2-Hp-?-CDs) through host-guest chemicalinteraction. In aqueous medium, WI showed a two-photon absorption cross-section ofaround200GM at the wavelength of780nm which was much higher compared withthat of commercial initiators. The threshold energy of TPP for the resin withpoly(ethylene glycol) diacrylate (PEGda) as monomer and WI as photoinitiator (themolar ratio of N in resin is0.03%) was8.6mW.3D hydrogels with woodpilemicrostructure similar to cell scaffold were further fabricated by using an averagepower of9.7mW and a scanning speed of30?m s-1.Secondly, we prepared water soluble TPP initiators by combining2,7-bis(2-(4-pentaneoxy-phenyl)-vinyl)anthraquinone and2,7-Bis-[2-(4-dimethylamino-phenyl)-vinyl]-anthraquinone previous reported in ourlab with PF127through hydrophilic-hydrophobic interaction, respectively. In aqueousmedium, the inclusion complexes formed by PF127and2,7-bis(2-(4-pentaneoxy-phenyl)-vinyl)anthraquinone showed a two-photon absorption cross-section of around160GM at the wavelength of780nm. The threshold energyof TPP for the resin with that complexes as photoinitiator (the molar ratio of N inresin is0.03%) was11.2mW. The threshold energy of TPP for the resin withpoly(ethylene glycol) diacrylate (PEGda) as monomer and the inclusion complexesformed by PF127and2,7-Bis-[2-(4-dimethylamino-phenyl)-vinyl]-anthraquinone asphotoinitiator (the molar ratio of N in resin is0.03%) was only6.9mW. Different3Dhydrogels microstructures were further fabricated by using an average power of10.5mW and a scanning speed of30?m/s. The school badges of Tianjin Univeristy werefabricated by using average power of11.4mW and scanning speed of60?m/s and100?m/s, respectively.