Study On Application Of Nanodiamonds Modified By Rare Earth Upconversion Nanoparticles For Dual-Mode Imaging And Drug Delivery

With the development of nanomaterials and nanotechnology,the integration of nanotechnology and biomedicine has become closer and closer.Multifunctional nanomaterials have played a significant role of biomedicine such as the prevention,diagnosis and treatment of disease,which showed a broad application prospect in the development.Nanodiamonds（NDs）,which have the characteristics of both diamond and nanomaterial,are nano inert material with high biocompatibility,low toxicity,fluorescence effect and other characteristics.NDs are excellent nanocarrier for drug delivery due to the high specific surface area（200-420 m²/g）and strong surface activity.Therefore,NDs have been widely used in biomedical fields such as drug delivery,fluorescent cell labeling and Raman imaging.Ln³⁺（lanthanide ion）-based upconversion nanoparticles,is a kind of functional materials which convert low energy photons into high-energy photons,which emitting higher-energy visible light as excited by low-energy NIR light.Upconversion nanoparticles have great potential value in biological applications owing to the excitation wavelength at biological window area,the deep biological tissue penetration,the biomarkers,cell imaging,disease detection and biological sensing.Among lanthanide ions,Gd³⁺possesses the advantages of superior paramagnetic properties owing to 7 unpaired 4f layer electrons,which are shielded by the outer layer 5s²5p⁶without being affected by the crystal field.Therefore,doping Gd³⁺nanoparticles used in magnetic resonance imaging and CT imaging in medical diagnosis,and Gd³⁺-based upconversion nanoparticles were used to dual-mode imaging of fluorescence imaging and magnetic resonance imaging.Considered the advantages of high drug loading rate of NDs,NDs were conjugated with magnetic upconversion nanoparticles（UCMPs）Na Gd F₄:Yb,Er by amide reaction to form magnetic nanocomposite materials（UCMP-NDs）.Spectral tests and cell fluorescence imaging in vitro showed that the nanocomposite had good upconversion fluorescence properties.T₁-weighted magnetic resonance imaging in aqueous solution in vitro showed that the composite had good magnetic resonance imaging properties.Therefore,the application of the composite in multimodal imaging could improve the accuracy of cancer diagnosis.The nanocomposite loading with adriamycin has the same killing effect to cancer cells as adriamycin monomer.Therefore,the nanocomposite has the function of dual-mode imaging and drug delivery,which provides a promising solution for accurate diagnosis of cancer and improving therapeutic effect.