| As a fluorescent nanomaterial,silicon nanoparticles(Si NPs),have not only excellent optoelectronic properties,but also good biocompatibility and non-toxic advantages,which make it widely used in the fields of biosensor,photochemistry and biological imaging.Si NPs with excellent luminescent properties,together with special materials,molecules or ions,can be used as fluorescence probes to establish fluorescence methods for specific target analysis through internal filtration effect(IFE),fluorescence resonance energy transfer(FRET)or photoinduced electron transfer(PET).Catecholamine drugs such as dopamine(DA)and isoproterenol(ISO)all play important physiological roles in human body,and a new convenient and fast method needs to be established to monitor DA and ISO.Based on the characteristics that DA could be oxidized and self polymerized to form polydopamine(p DA)in alkaline condition(p H>7.5)and adsorbed on the surface of the material,as well as the properties of ISO that can be oxidized to ortho-quinone under the action of some specific enzymes,Si NPs is used as fluorescence probe to detect DA,ISO and tyrosinase.The main contents of this thesis are divided into the following three parts:Chapter 1: Preparation and properties of luminescent stable silicon quantum dotsIn this chapter,Si NPs were prepared by hydrothermal method.Three Si NPs with different luminescent properties were synthesized by changing silicon source or reducing agent.The results showed that the quantum yield of Si NPs prepared with3-aminopropyltrimethoxysilane(APTMS)as silicon source and sodium ascorbate as reducing agent was low and its long-term stability was poor;The Si NPs with N-[3-(trimethoxysilyl)propyl] ethylenediamine(DAMO)as silicon source and trans-aconitic acid as reducing agent had good quantum yield and high stability;Si NPs with DAMO as silicon source and pyrimidine as reducing agent had high quantum yield but poor stability.Furthermore,the response of Si NPs prepared with DAMO as silicon source and trans-aconitic acid as reducing agent to other environmental factors and its properties were investigated.It was found that it had good optical properties and excellent stability,as well as great potential in the application of biosensor and bio imaging,which provides a way for the determination of catecholamines.Chapter 2: Determination of dopamine by fluorescence sensor based on Si NPs and the study on its mechanismIn this chapter,we used Si NPs with stable luminescent properties as probe to realize the quantitative detection of dopamine.The polydopamine formed by self polymerization of dopamine under alkaline conditions and had IFE effect with Si NPs,and the fluorescence of Si NPs was absorbed by polydopamine,which leads to its fluorescence quenching.The fluorescence quenching efficiency of Si NPs was linearly related to the concentration of dopamine in a certain range.By optimizing reaction conditions such as time,temperature,p H,the linear range of dopamine detection was0.5-40 ?M,the detection limit was 0.06 ?M.This method was sensitivity specific and had been successfully applied to the accurate determination of dopamine in human serum samples and dopamine injection,which shows that it has a good prospect in clinical and biomedical fields.Chapter 3: Construction of fluorescence biosensor for detection of isoproterenol and tyrosinase based on enzyme catalysisIn this chapter,Si NPs that synthesized in chapter 1 were used as fluorescence probe.Tyrosinase(TYR)was used to oxidize catecholamine isoprenaline to ortho-quinone by diphenolase activity.Then isoprenaline(ISO)was quantitatively detected based on the interaction between ortho-quinone and Si NPs and the quenching behavior.The strategy showed a good linear range for isoprenaline of 2.5-30 ?M,and detection limit of 0.992 ?M,suggesting the sensor had good selectivity.The method had been successfully applied to the determination of isoprenaline in practical samples with good recovery.Subsequently,the activity of TYR was further evaluated by the fluorescence sensing platform.The fluorescence quenching efficiency was related to the activity of TYR under the range of 0.05-2.0 U/m L,and the detection limit of 0.041U/m L.This study shows that the Si NPs probe has potential applications in monitoring ISO,TYR and related diseases. |
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