Development Of Hydrophobic Hydrationshell Structure Coated Rare-earth Upconversion Nanomaterials With Restricted Dissolution

Rare-earth upconversion nanoparticles(UCNPs)show particular promising in biosening,bioimaging and upconversion luminescence triggered cancer therapies,depending on their unique optical properties.However,the dissolution of UCNPs in destructive media leads to bio-safety challenges.We noted an interesting hydrophobic hydration phenomenon that is strengthened water-to-water hydrogen bonds(w HB)will form in the vicinity of small purely hydrophobic solutes(alkanes),yielding ice phase configurational hydrophobic hydration-shell structure.Inspired by this phenomenon,we present a unique hydrophobic hydration-shell structure by codoping a hydrophobic functional molecular pair of Chlorin e6(Ce6)/perfluorocarbons(PFC)into confinement of m SiO₂ to serve anti-dissolution coating for UCNPs via providing hydrophobicity/strong w HB based restricted molecular mobolity.Instead of suffering poor structure/colloid stability in no or single-doped case,hydrophobic hydration-shell structure coated UCNPs show ultra-stability in both destructive media and lysosomes.Based on this,detailed characteristics and formation mechanisms of the proposed hydrophobic hydration-shell structure,as well as their preliminary photodynamic therapy efficiency at cellular level were performed.The main research contents are as follows:(1)Design,preparation and mechanism research of hydrophobic hydration-shell structure coated rare-earth upconversion nanomaterials with restricted dissolution.The Ce6/PFC codoped mesoporous silicon modified UCNPs were prepared by a sol-gel templating method,and their structure was characterized by means of transmission electron microscopy,elemental mapping,fourier transform infrared spectrometer,and X-ray photoelectric spectrometer.The formation of hydrophobic hydration-shell structure was confirmed by fourier transform infrared spectrometer,¹H NMR and Raman spectrum.Then,the upconversion luminescence,colloid and structural stability of hydrophobic hydration-shell structure coated UCNPs in destructive media were studied;at the same time,the upconversion luminescence lifetime and quantum yield were measured.It is confirmed that special ambient ice phase is formed in the designed hydrophobic hydration-shell structure,which ensures that the hydrophobic hydration-shell structure has simultaneous strong hydrophobicity and good water-friendliness.The formation mechanism of the hydrophobic hydration-shell structure was studied by ultraviolet spectroscopy,small-angle X-ray powder diffraction,Brunauer-Emmett-Teller,transmission electron microscopy with appropriate magnification.Results showed that PFC with right chain length play a bridging role to render stable bacteriochlorophyll aggregates-mimetic Ce6 face-to-face?-?stacking and a templating role to afford special ordered silica channels coinciding with the nano confinement characteristics of carbon nanotubes via hydrophobic-electrostatic forces,leading to confinement contain not only weak hydrogen-bonded dangling OH but also completely tetrahedrally coordinated H₂O,yielding ambient efficient/stable hydrophobic hydration-shell structure with interior ice phase.(2)Photodynamic therapy application of hydrophobic hydration-shell structure coated rare-earth upconversion nanomaterials.On the basis of the research in the previous chapter,we evaluated the oxygen-carrying properties of hydrophobic hydration-shell structure coated UCNPs by dissolved oxygen meter and Zeta potential analysis.Then,1,3-Diphenylisobenzofuran was used as a probe to detect efficiency of different materials to produce ¹O₂,and finally the potential of the material's biological application was evaluated at the cellular level,including dark toxicity,and near-infrared light(980 nm)-driven stimulated photodynamic therapy efficiency.The results show that the herein designed hydrophobic hydration-shell structure coated UCNPs not only have high O₂-carrying capacity,cell dark toxicity,but also high photodynamic therapy efficiency.Therefore,the structure we designed has great potential in the field of biological applications.The mechanistic picture of herein hydrophobic hydration-shell structure opens up a new efficient nanoparticle functionalization concept and also sheds light on the practical use of the hydrophobic hydration and water/ice science of extensive research interests.