Preparation And Study Of Up-conversion Composite O-nitorbenzyl Esters Nanoparticles As Photosensitive Nano-drug Delivery

As a stimulus source,light has the advantages of cleanliness,controllability,and non-contact.The photo-responsive polymer is made into a drug carrier.By changing the release method of the existing drug,the efficacy of the drug can be improved and the toxic side effects can be reduced.O-nitrobenzyl is a photocleavage response unit and can be used to prepare two different types of photo-responding polymers.By means of distillation precipitation,the photoresponsive polymer and upconversion nanoparticles were combined to prepare functional particles with stable structure,and the drug release was controlled by remote NIR.The details are as follows1.Using the chlorides of three elements of Yb,Y and Tm as raw materials,up-conversion nanoparticles（UCNPs）with regular morphology,uniform size and good particle dispersion are prepared by two solvothermal methods.The surface of UCNPs was coated with a layer of silica by reverse microemulsion method to modify the surface.In the process,kh-570 was added to introduce unsaturated carbon-carbon double bonds,which created conditions for subsequent photoresponsive polymer coating.2.The upconversion/side-chain o-nitrobenzyl ester functional particles（UCNPs@Si O₂@PNBMA/MAA）were prepared by distillation precipitation method.The middle silicon dioxide layer was etched with HF to obtain UCNPs@PNBMA/MAA particles.Adriamycin hydrochloride was selected as the drug model for drug loading,and the drug loading rate reached 7.23%.The UV spectrophotometer was used to investigate the drug release behavior of drug-loaded particles under different conditions..Under the synergistic conditions of p H=4.5 and near-infrared irradiation,drug release could be promoted to the maximum extent,with the cumulative release amount reaching 59.55%.3.Up-conversion/main-chain o-nitrobenzyl ester functional particles（UCNPs@Si O₂@PONB/MAA）were prepared by distillation precipitation method.By changing the amount of monomer and crosslinking agent to control the dispersion of composite nanoparticles and the thickness of the PONB/MAA layer,the thickness of the outermost coating layer is about 7 nm.The middle silicon dioxide layer was etched with HF to obtain UCNPs@PONB/MAA particles.Through dynamic light scattering and transmission electron microscopy to explore its light responsiveness,under near-infrared light irradiation,the outermost shell disappears,and the particle size decreases from 110 nm to 67 nm.