Construction Of Fluorescence Nanomaterials And Exploration Of Their Applications For Diagnosis And Therapy In Protein Aggregation Disease

The misfolding and aggregation of amyloidgenic proteins are closely correlated with the onset and progression of multiple severe neurodegenerative and metabolic diseases.In the process of amyloid aggregation,the protein monomers could gradually aggregate to form theβ-sheet-rich protein aggregates,which are both reported as the significant pathological hallmarks of some protein aggregation diseases.Besides,a series of accompanying toxic effects such as oxidative stress and metal ion dyshomeostasis during the amyloid aggregation could further exacerbate the progression of diseases.Therefore,on the one hand,in order to deeply investigate the pathogenic mechanism as well as realize early diagnosis of protein aggregation diseases,it is urgent to develop efficient detection methods targeting amyloidgenic proteins,protein aggregates,related metal ions and drug molecules.On the other hand,construction of novel potential therapeutic agent targeting the alleviation of specific pathological damage could further promote the drug development of protein aggregation diseases.To reach above goals,a series of efficient fluorescence nanoprobes as well as some of which with the therapeutic potential were constructed in this thesis.The results are summarized as follows:（1）In order to overcome the problem of high cost of conventional detection method,a low-cost fluorescence sensor array was successfully constructed for the rapid and sensitive identification of multiple amyloidgenic proteins.Using the citric acid,Congo red and oxidant（ammonium persulfate or hydrogen peroxide）as raw materials,the fluorescent carbon dots（CDs）with selective response performance to proteins were prepared through a simple and convenient one-pot method for the first time.Due to the electrostatic and hydrophobic interactions,the fluorescence intensity of CDs could be quenched by multiple proteins to different degrees.Therefore,a dual-element fluorescence sensor array was successfully constructed for the discrimination of four amyloidgenic proteins and two common serum proteins at low concentration.Besides,the sensor array showed good applicability for protein quantitation,discrimination of protein mixtures and identification of target proteins in complex matrix.Furthermore,it could monitor the aggregation process ofα-synuclein,a significant pathological marker of Parkinson’s disease（PD）,indicating the potential of the sensor array to investigate the pathology of protein aggregation in PD.At last,the sensor array could discriminate liver cancer and breast cancer patients from healthy people by measuring serum samples,indicating its potential of preliminary cancers screening in clinical trials.（2）To break through the limits of CDs in the application area of red fluorescence response and treatment targeting amyloid aggregation,a relative applicable preparation strategy of the bifunctional CDs was developed.Firstly,the influences of reducibility of carbon sources,the amounts of Congo red and types of oxidants on the application performance of the prepared CDs were detailly investigated.Congo red was herein adopted for its properties of recognition and fluorescence response for protein aggregates.The proposed three multifunctional CDs could realize“turn-on”red fluorescence imaging of proteins aggregates,effective inhibition of amyloid aggregation as well as scavenging of reactive oxygen species（ROS）.Furthermore,they all exhibited good protective effects onβ-amyloid 1-42(Aβ₄₂)induced cytotoxicity,indicating their treatment potential for Alzheimer’s disease（AD）.（3）Targeting the metal ion dyshomeostasis,novel bifunctional nanomaterials of selective chelation and fluorescence detection of Cu²⁺were successfully proposed.Silicon dots and mesoporous silica nanoparticles hybrids（mSiO₂@SiDs）were constructed as Cu²⁺chelator.mSiO₂@SiDs could regulate the enzymatic activities of free Cu²⁺and Aβ₄₂-Cu²⁺complex,thus effectively reducing the generation of ROS.Besides,mSiO₂@SiDs showed slight inhibition effect towards Cu²⁺mediated Aβ₄₂ aggregation,which could further alleviate Aβ₄₂-Cu²⁺induced cytotoxicity,indicating its potential therapeutic value for AD.Furthermore,to achieve rapid and sensitive detection of Cu²⁺,using mSiO₂@SiDs as blue fluorescence supporter,a convenient in situ reduction method for loading red fluorescence gold nanoclusters was herein developed.The constructed ratiometric fluorescence nanoprobe could effectively detect Cu²⁺in artificial cerebrospinal fluid,which provided an effective analytical tool to investigate the role of Cu²⁺in neurodegenerative diseases.（4）To achieve the fast and sensitive detection of the potential drug molecule of AD（i.e.curcuminoids）,a novel fluorescence probe,i.e.fluorescence silicon nanoparticles（Si NPs）,was prepared by using 3-glycidyloxypropyltrimethoxysilane as the silicon source and through a simple one-pot hydrothermal method for the first time.The Si NPs could simultaneously achieve the fluorescence"turn-off"quantification and fluorescence colorimetric semi-quantification of curcuminoids.Based on the good selectivity and anti-interference ability,curcuminoids could be accurately detected by Si NPs in actual food samples and biological samples.Moreover,with the merit of low cytotoxicity,Si NPs was successfully used in cell imaging and intracellular curcuminoids visual monitoring.Our proposed highly effective detection method had great potential for monitoring the therapeutic application and exploring the therapeutic mechanism of curcuminoids in neurodegenerative diseases.