Basic Research On Applications Of Near Infrared Nanoplatform In Biomedicine

Photodynamic therapy?PDT?is a new method with high selectivity and broad applicability in development for early treatment of tumors.The photosensitizer molecules,the oxygen molecules in tissue and the excitation light are the three elements in clinical PDT.The interactions between the oxygen in tissue and photosensitizer,upon excitation of near infrared light from ultraviolet to visible light,make the triplet oxygen molecule in the ground state reaches the excited state into the singlet state?¹O₂??one of the active oxygen species?.The ¹O₂ has a very strong oxidative killing effect on cells or biomolecules,which is the basis of the PDT applied in the clinical medicine.However,many problems including the poor depth of tissue penetration of the light from UV to visible light generally used for excitation of the photosensitizers,nonspecific targeting of photosensitizers,the anti-oxidative stress induced by PDT,seriously restrict PDT efficacy and its development.In addition,the occurrence of lung cancer and its treatment by chemotherapy,radiotherapy,biological targeted therapy and PDT,etc.will lead to varying degrees of blood glucose changes in patients.Obviously,the evaluation of cancer status by blood glucose-related information and the evaluation of pre-and post-operative treatment have important scientific research value and clinical diagnostic significance.However,there is still few of techniques and methods for obtaining sensitive and accurate information on glucose sensitivity,especially for trace blood glucose.The combination of nanophotonic technology with biomedicine makes it possible to solve many of the above-mentioned problems that have not been solved.The researches of the near infrared light conversion photosensitive nanoplatform with multifunction of photodynamic diagnosis and therapy have become a hot research topic in the field of nano-biotechnology in recent years to solve many problems mentioned above in the present clinic.Although there were lot of reports on the imaging of UCNP fluorescence probes,the multifunctional up-conversion photosensitive nanoplatform with imaging-guided photodynamic therapy,the researches of the kinetics of the interaction between the nanophotosensitizer and the cancer cell,in particular,the studies of the cell kinetics of release of the anti-oxidative stress inhibitor associated with the kinetics of cancer cells has not yet been reported.Obviously,these fundamental scientific issues are critical to the development of the methods and technologies integrated by photodynamic diagnosis and photodynamic therapy without anti-oxidative stress for highly efficient cancer treatment.More importantly,PDT for cancer,like drug treatment,also has a similar anti-drug problem,that is,the problem of anti-oxidative stress which will ultimately lead to the invalidation of cancer PDT,and which is also one of the key bottlenecks in the development of the new methods of cancer PDT based on the near-infrared conversion of the photosensitive nanoplatforms.It is particularly noteworthy that although there have been many convenient methods for the analysis and detection of blood glucose in medical clinic,and a variety of blood glucose analysis and detection methods and new technologies in researching and developing.The sensitivity of these methods and techniques is almost at the concentration range of mM M,which is far from being adapted to the needs of the highly sensitive analysis of the small change in blood glucose,especially trace glucose.In the thesis,to aim at the problems with the poor efficiency of PDT of cancer,photosensitizer non-specific biological targeting,and the poor penetration depth of tissue of the excitation light used in clinic,and with the existing methods for blood glucose detection,in view of the advantages of the deep tissue penetration of near infrared light which does not excite biological self-fluorescence,and is not scattered by cells or biomolecules due to its location in the biological spectrum window region,the near-infrared up-conversion nanoparticles?UCNPs?and photosensitizer?ZnPc?be covalently assembled into the novel photosensitive nanoplatform,and then,the nanoplatform was assembled with ABT737 inhibitor of the anti-oxidative stress factor Bcl-2,and the polymer molecule sensitive to pH of the microenvironment of cancer cell,which can be used for researches of the high definition cell imaging for early photodynamic diagnosis and therapy of lung cancer.In addition,the novel approach of the SERS-based nanoplatform for the ultrasensitive glucose detection was developed to analyze sensitively the very small change in the concentration of glucose,especially the trace glucose.The innovative results obtained are as follows:1.The time-and-space controlled co-release of the inhibitor ABT 737 and the¹O₂ generated from the UCNP-based photosensitive nanoplatform in the cancer site,for the first time,was realized by innovatively assembling up-conversion nanophotosensitizer with pH-sensitive polymer molecules and the inhibitor ABT 737of anti-oxidative stress Bcl-2 protein.The stability of the UCNP-based photosensitive nanoplatform with the function inhibiting anti-oxidative stress Bcl-2 protein in different physiological solutions,the loading capacity of the inhibitor molecule ABT737 and the release rate in different pH solutions are systematically investigated.The dynamic distribution of the UCNP-based photosensitive nanoplatform ABT 737@ZnPc-UCNPs in LLC cells,for the first time,was studied in detail by combining ABT737@ZnPc-UCNPs a fluorescent tracer probe and co-localization technique.The results showed that the ABT 737/ZnPc-UCNPs with the function inhibiting antioxidant stress of Bcl-2 was internalized and were first enriched on lysosomes,and then escapes from lysosome,and gradually accumulated on mitochondria as the evolution of incubation time.Accurately oxidative killing of lung cancer cells is achieved by the nanoplatform with function inhibiting anti-apoptotic protein Bcl-2was achieved under near infrared irradiation and guide of mitochondrial fluorescence imaging.The efficiency of PDT for lung cancer cells was improved because ABT737effectively inhibited the anti-apoptotic protein Bcl-2.2.The effect and mechanism of PDT were studied at the level of the cells and the level of the mouse model of lung cancer by the constructed ABT 737@ZnPc-UCNPs.The research results that the pyknosis of nucleus,the decrease of mitochondrial membrane potential,and the change of mitochondrial outer membrane permeability lead to the release of cytochrome c and the irreversible division of mitochondrial morphology are obtained.It is,for the first time,observed that PDT of ABT 737@ZnPc-UCNPs with the function inhibiting the anti-oxidative stress Bcl-2protein led to the programmed death of the lung cells and effectively improved the efficiency of the lung cancer PDT due to combing the UCNP-based PDT and inhibiting the expression of the anti-apoptotic protein Bcl-2.In addition,it is also observed that the UCNP-based PDT mediated by the ABT 737@ZnPc-UCNPs can effectively improve the microenvironment of the tumor and inhibit the generation and regeneration of the tumor blood vessel.For ultrasensitive glucose detection,the SERS-based homogeneous nanoplatform?HSNPF?consisting of glucose oxidase and SERS tags are designed and constructed,by combining the advantages of the high Raman activity of p-ATP,the strong local surface plasmon resonance?LSPR?at the tip of the silver nano-triangle?SNTs?,the hydrogen peroxide?H₂O₂?generated by the catalytic reaction of glucose oxidase to the blood glucose,especially the sensitive etching of H₂O₂ to the tips of the SNTs,and the three-dimensional diffusion of the H₂O₂ molecules to SERS tags in the aqueous solution?rather than the two-dimensional diffusion process of the SERS substrate or the chip which is generally reported?.The sensitively sensing behavior of the HSNPF on the low concentration of glucose was studied.The obtained results show that the nonlinear relationship between the SERS intensity and the glucose concentration can be well fitted by a number of linear relationships corresponding to different concentration ranges of glucose.For the first time,it is proposed to apply the obtained different linear relationship to the range of different concentration of glucose for the high sensitivity and high accuracy of glucose detection.The detection limitation of400pM of the glucose analysis is achieved.In the thesis,based on the advantages of the near-infrared light located in the window region of biological spectrum,not exciting biological self-fluorescence and no light scattering from biomolecules or cells,the UCNP-based photosensitive nanoplatform was constructed and studied without anti-oxidation stress mediated by Bcl-2.The researched results showed that the dynamic process of the interaction between theUCNP-based nanoplatform and lung cells provided the basis for developing the novel methods of the early diagnosis and précised PDT for lung cancer.In addition,to develop a highly sensitive and accurate method for the evaluation and detection of small changes in blood glucose associated with lung cancer,highly sensitive SERS-based HSNPF was developed and demonstrated.The application potential of the novel HSNPF for high sensitivity and high precision analysis is shown.However,although the some very basic exploratory researches have been done,there is still a need for many interdisciplinary works to be carried out,and demonstrated the potential and prospect of near-infrared nanoplatform used in biomedical field.