3D Hydrogels With High Resolution Fabricated By Two-Photon Polymerization In Aqueous

Two-photon absorption(Two-photon absorption,TPA)is a kind of third order nonlinear optical process.Which refers to under strong light excitation,molecule could absorb and combine both low energy photons simultaneously(The energy can be the same or different),then molecular is induced to the excited electronic state.This process has many advantages,such as high three-dimensional spatial selectivity,emitting shorter wavelength light with absorbing longer wavelength light with lower energy and high penetration depth.Two-photon polymerization occurs only in the laser focus.TPPM is an advanced 3D print technology and can fabricate arbitrary 3D microstructure,because the wavelength of laser source used in TPP is infrared laser which can penetrate a large depth with a little loss.The resolution of 3D microstructure fabricated by TPPM has beyond the optical diffraction limit.In recent years,TPPM technology has been widely used in 3D information storage,photonic crystals and waveguides fabrication.Recently,the researchers pay close attention to 3D hydrogels(Hydrogels are commonly referred to as polymeric materials with water contents similar to those of soft tissues)fabricated by TPPM,which are important for tissue engineering and drug delivery.However,a large proportion of high efficiency TPPM initiators are hydrophobic and TPPM has to be reacted in organic solvent,giving rise to residue of organic solvent in 3D hydrogels with serious cytotoxicity which hinders the biomedical application of 3D hydrogels.At present,we obtain water soluble TPPM initiator with high efficiency is the important questions in the field.In this study,a water soluble two-photon polymerization(TPP)initiator(WTPPI)with high initiating efficiency was prepared by using a poloxamer(PF127)to encapsulate 2,7-bis(2-(4-pentaneoxy-phenyl)-vinyl)anthraquinone via a hydrophilic-hydrophobic assembly.The properties of their optical and fabrication were investigated.Finally,two-photon polymerization could occur in aqueous phase.Firstly,we prepared a water soluble TPP initiator(WTTPI)by using a poloxamer(PF127)to encapsulate 2,7-bis(2-(4-pentaneoxy-phenyl)-vinyl)anthraquinone which is an efficient initiator has been reported by our group via a hydrophilic-hydrophobic assembly.The water solubility of new compound increase and biocompatibility monomer could be polymerized in aqueous.In aqueous medium,the ?TPA value of WI is around 200 GM at 780 nm which is much larger compared with those of commercial initiators and most of the water soluble TPA materials reported with a low ?TPA less than 100 GM.The threshold energy of TPP for the resin with poly(ethylene glycol)diacrylate(PEGda)as monomer and WTPPI as photoinitiator(the molar ratio of N in resin is 0.03%)was 6.29 mW.Which was much lower than those reported previously 8.6 mW.A lateral spatial resolution of 92 nm was achieved as the resolution breakthrough of 3D hydrogels under 100 nm.In the study,we fixed the scanning speed and research the laser power effect on the line width.We fabricated perfectively school badges of Tianjin University by using an average of 9 mW and a scanning speed of 10 ?m/s.On the other hand,we studied the laser power effect on the resolution of 3D microstructure.The adenovirus were fabricated by using scanning speed of 110 ?m/s and average power of 7.27 m W,9.46 mW and 11.27 m W,respectively.The studies lay important foundation for 3D hydrogels applied in biomedical fields.