Study On The Preparation Of Novel Fluorescent Copper Nanoclusters And Carbon Nanoparticles And Their Applications

Over the past decades,fluorescent copper nanoclusters（Cu NCs）and carbon nanoparticles（CNPs）,as newcomers to the nanomaterials family,have received much attention in sensor,bioimaging,catalysis and optical electronics fields due to their good water solubility,photostability,tunable fluorescence emission,cheap raw materials.However,there are still some issues needing to be solved,such as the difficulty on the preparation of Cu NCs,the instability of the obtained Cu NCs,the complicated process of preparation of CNPs,etc.Therefore,the development of facile method for preparation of stable fluorescent Cu NCs and CNPs and expansion of practical application will find its unique significance.Based on the previous works,the following major innovative researches were carried out in order to develop new methods for preparation of stable fluorescent Cu NCs and CNPs,as well as expand their practical application.（1）A facile method was developed for synthesis of BPEI-Cu NCs under room temperature,in which branched polyethyleneimine（BPEI）served as scaffold.The BPEI-Cu NCs displayed excellent stability and were successfully applied for Fe³⁺sensing.（2）A novel,label-free"turn-on"fluorescence biosensor for detection of adenosine triphosphate（ATP）was developed,in which ds DNA-Cu NPs acted as fluorescence probe and graphene oxide（GO）as a superquencher.The method was successfully applied for detection of ATP in human lung adenocarcinoma cell.（3）A p H-dependent synthesis of Cu NCs with blue and yellow fluorescent emission was developed using trypsin as template and hydrazine hydrate as reducing agent.Effect of p H on the fluorescence of the Cu NCs was investigated.By using yellow-emitting Cu NCs as fluorescent probe,a new approach for detection of Hg²⁺was established.The method was applied for the determination of Hg²⁺in real samples with satisfactory results.（4）A low-temperature method for synthesis of fluorescent CNPs was developed with trypsin and dopamine as precursors.The CNPs exhibited excellent water-solubility and photostability.The CNPs were explored as fluorescence probe for fast and sensitive detection of Fe³⁺.The method was successfully applied for determination of Fe³⁺in biological samples.This dissertation consists of six chapters.Chapter 1:The development of fluorescent Cu NCs and CNPs in recent years was summarized.The aspects of synthetic approaches,physicochemical property and present applications,especially in sensors and bioimaging were reviewed.Chapter 2:A facile method for synthesis of fluorescent Cu NCs at room temperature was established,in which BPEI served as capping scaffold and ascorbic acid as reducing agent.The prepared BPEI-Cu NCs exhibited excellent water-solubility and high stability toward high ionic strength.Based on the electron transfer induced fluorescence quenching mechanism,this fluorescence probe was used for detection of Fe³⁺in aqueous solution.Under the optimal conditions,a good linear relationship was obtained from 0.5 to 100μM,and the limit of detection was340 n M.The method was simple,sensitive and selective for detection of Fe³⁺.The method was successfully applied for detection of Fe³⁺in the water samples.It is expected to replace the traditional detection methods for monitoring the environmental pollutants.Chapter 3:DNA was used as templated for synthesis of fluorescent Cu NCs.A novel label-free"turn-on"fluorescence biosensor for detection of ATP was established,in which ds DNA-Cu NCs acted as fluorescence marker and GO as a superquencher.The proposed method was simple and low cost.It exhibited good selectivity for ATP sensing and was successfully applied for the detection of ATP in human serum and cancer cells samples.The method expanded the application of Cu NCs in bio-analytical chemistry.Chapter 4:A simple method to prepare fluorescent Cu NCs by using trypsin as stabilizer and hydrazine hydrate as reducing agent.By changing the p H of reaction,Cu NCs with blue and yellow emission were obtained,respectively.Results indicated that the fluorescence of the Cu NCs related to the secondary structure of protein and particle size.Based on aggregation induced quenching mechanism,the yellow emitting Cu NCs was used for detection of Hg²⁺.The method was applied for the determination of Hg²⁺in human serum and urine samples.Chapter 5:A facile low-temperature method for synthesis of fluorescent CNPs was established with trypsin and dopamine as precursors.The synthesis process avoided any heating operation and organic solvent.The CNPs exhibited excellent water-solubility,salt-tolerance and photostability.Based on the synergistic action of the inner filter effect（IFE）and static quenching mechanism,a sensitive and selective method for determination of Fe³⁺was developed.Under optimal conditions,a good relationship was obtained from 0.1 to 500μM,and the limit of detection was 30 n M.The method was successfully applied for detection of Fe³⁺in biological samples.It expanded the route for synthesis of CNPs under low temperature.Chapter 6:Conclusion.