Synthesis Of Upconversion Nanoparticles And Its Application In Photopolymerization

In recent years,lanthanide-doped upconvertion nanoparticles(UCNPs)receive extensive attention,which have unique anti-Stokes and are more suitable for biological applications compared with other fluorescent materials(fluorescent proteins,metal complexes,organic dyes,semiconductor quantum dots and carbon dots).The researchers have carried out detailed studies on UCNPs,mainly for the synthesis process,emission band,fluorescence intensity,and the applications.Particularly,the UCNPs can be used to induce photopolymerization under the action of near infrared lasers.Particularly,UCNPs can produce ultraviolet or visible light under the action of near infrared light.The photosensitizers/photoinitiators absorb ultraviolet or visible light derived from UCNPs,thereby generating free radicals to initiate photopolymerization of reactive monomers in the system.This process is defined as UCNPs-assisted photopolymerization,which can achieve the 3D printing of biological tissue structure.The field is still in preliminary exploration and hence needs to be further explored and summarized.In this paper,we discusse the effects of the preparation on the morphology,size,and heterogeneous shell coating of UCNPs.And then we adjust the doping amount of Ln³⁺to prepare Na Yb F₄,Er,Na Er F₄,Na YF₄,Yb,Er and explore the effect of energy injection on the fluorescence intensity.By epitaxial shell coating and Yb³⁺doping,the fluorescence intensity of Na Er F₄ is optimized,balancing the relationship of energy injection,transmission,and leakage.Meanwhile,we use the amphiphilic polymer poloxamer to improve the hydrophilicity of UCNPs.In order to explore the potential of UCNPs to achieve 3D printing in the biological field,we use the green light,emission from ligand-free upconversion nanoparticles Na YF₄,Yb,Er(spherical)and Na YF₄,Yb,Er,Tm@Na Nd F₄,Yb(dumbbell),to induces the photopolymerization of polyethylene glycol diacrylate(PEGDA)in the eosin/triethanolamine(EY/TEOA)co-initiator system.And compared with the photopolymerization induced by the 532 nm laser,the experiments show that the spherical upconversion nanoparticles have an advantage in precise light-controlled polymerization.