Design And Application Of Single-Component Fluorescence Sensor Array Based On Carbon Dots

As people’s life and social production standards continue to rise,there is an increasing demand for environmental analysis and medical testing.The health of people is closely linked to many components in biological fluids,so it is particularly important to distinguish harmful substances or disease markers in complex environments.Fluorescent sensors have gained a great deal of attention of scientific researchers due to their low detection limits,simple technology and fast response times.Carbon dots（CDs）have many unique superiorities,including low cost,mild preparation process,excellent biocompatibility,good water solubility and modifiable photoluminescence,which are playing an important role in the fields of analytical detection and bioimaging.Conventional fluorescent sensors urgently require receptors with high specificity for the analyte,namely"lock and key"sensing model,making it almost impossible to recognize different analytes simultaneously.For this,a“chemical nose/tongue”strategy based on sensor arrays needs to be introduced.Fluorescent sensor arrays enable high throughput measurement and pattern recognition of multiple targets,as well as the identification of subtle differences of analytes with similar chemical structures.So,they have shown their great potential in a variety of fields.However,current sensor arrays still suffer from drawbacks such as complex synthesis of materials,complicated preparation of multiple sensing units and lack of application in biological fluids.Therefore,the design of simple and efficient single component fluorescent sensor arrays based on CDs is of great importance.This thesis focuses on a single-component multifunctional fluorescence sensor array based on CDs,combining the fluorescence properties of the CDs and porphyrin to address the problem of multiple materials required for sensor array and the complexity of sensing elements.Firstly,multiple emission peaks of CDs supraparticles（SPs）were selected as sensing elements to form a fluorescent sensor array for pattern recognition of multiple metal ions in biological fluids;and then the CDs SPs were combined with Cu²⁺to form another sensor array to achieve the analytical identification of multiple thiols.In addition,the fluorescence quenching effect of Cu²⁺to carbonized polymer dots（CPDs）was used to design a sensor array for the differentiation of glycosaminoglycans in biological fluids.Chapter 1 IntroductionThis chapter begins with an introduction of CDs,mainly covering synthesis methods,optical properties and their applications in analytical sensing,bioimaging and anti-counterfeiting.It then describes the theory related to fluorescent sensor arrays,focusing on their principles,data processing methods and applications in analytical detection.Finally,the research significance and main content of this thesis are analyzed.Chapter 2 Design of fluorescent sensor arrays based on CDs SPs and their recognition of metal ions in biological fluidsSPs,such as assemblies of inorganic and organic components,have achieved widespread interest in biochemical analysis.In this chapter,we develop a multifunctional fluorescence sensor array of SPs for the high-throughput determination of heavy metal ions in biofluids,which is a hybrid inorganic/organic SPs composed of CDs and TCPP.Under 380 nm excitation,the formed CDs/TCPP SPs have two independent and clearly separated fluorescence emission peaks(F₄₇₀,F₆₆₈).With the company of metal ions,the three sensor elements can generate different fluorescence response signals,which apply to further pattern identification of multiple heavy metal ions by principal component analysis（PCA）.In addition,thiols readily trap Cu²⁺and can cause CDs/TCPP fluorescence that was initially altered by Cu²⁺to change again.Thus,CDs/TCPP-Cu²⁺were further designed as a sensor array for pattern recognition of seven kind of thiols and even chiral recognition of cysteine enantiomers.This new strategy avoids the complex synthesis of multiple sensing probes and provides an innovative approach to build“chemical nose/tongue”sensor arrays,which will hopefully generate more homologous hypotheses to expand their application in biosensing areas.Chapter 3 A novel single-component fluorescence sensor array based on CPDs for the detection of glycosaminoglycansCPDs are a novel fluorescent nanomaterial consisting of organic polymer chains and carbon cores,which are widely used in fields of drug delivery,photocatalysis and bioimaging due to their unique structure and excellent properties.In this chapter,we develop a single-component fluorescent sensor array composed of CPDs and Cu²⁺for high-throughput detection of glycosaminoglycans（GAGs）in biological fluids.CPDs were synthesized by a one-step hydrothermal method.Cu²⁺was aggregated with CPDs by electrostatic interaction to form a unique CPDs-Cu²⁺sensor array.With the addition of GAGs,the three sensor elements can generate different fluorescence response signals,which are further differentiated by PCA method.The CPDs-Cu²⁺sensor array,not only allows the identification of four similarly structured GAGs,but also realizes the detection of different concentrations of the same GAGs and mixed samples of different GAGs.Remarkably,the identification of GAGs in biological fluids can also be achieved using our proposed single component sensor array,validating its application potential.This new strategy avoids the complex synthesis of multiple sensing probes,broadens the application of“chemical nose/tongue”sensor arrays and provides a viable idea for the development of single-component sensing platforms.