Synthesis Of New Functional Carbon Quantum Dots And Its Fluorescence Analysis Application

Carbon dots?Cdots?as the luminous carbon nanomaterials with good biocompatibility and low toxicity have attracted increasing interest in recent years.In the present thesis,two functional carbon quantum dots were synthesized newly through the"neutralization heat"reaction simply by a single step.Three kinds of fluorimetric detection technologies have thereby been developed for the separate analysis of total iron ions,copper ions,and tyrosine?Tyr?in urine or blood samples.The contents are mainly presented as follows:?1?The fluorimetric and colorimetric analysis strategies have been developed for simultaneously probing Fe³⁺and Fe²⁺ions in blood or tap water using nitrogen-doped carbon dots?N-Cdots??Chapter II?.Herein,the N-Cdots were prepared using melamine by the one-step synthesis route of the neutralization heat reaction showing high aqueous solubility and environmental stability.Importantly,unlike the common Cdots that generally display one emission of blue fluorescence,they can display the excitation-dependent tunable emissions.Moreover,the bright blue-green fluorescence of N-Cdots could be specifically quenched by Fe³⁺or Fe²⁺ions simultaneously showing a color change.Herein,the fluorescent quenching of N-Cdots is thought to result from the aggregation of N-Cdots triggered by the unique coordination interactions between Fe³⁺or Fe²⁺ions and amine and amide groups of N-Cdots.The so developed analysis strategies were employed for the evaluation of the total iron levels in blood or tap water,with a detection limit down to about 5.0 nM exemplified for Fe³⁺ions,promising the practical applications for the clinical diagnosis of iron-relative diseases?i.e.,anemia and cancers?and environmental monitoring of iron pollutions.?2?A Cdots material was prepared with the fluorescence upconversion property to be used as a fluorescent probe for the fluorescence analysis of iron and copper ions in blood?Chapter 3?.Curcumin-yeast Cdo-dots?CY-Cdots?were synthesized in one step by a"neutralizing heat"reaction by using the bio-carbon sources of yeasts cultivated with curcumin.It was found that the yielded CY-Cdots could have the up-conversion fluorescence properties by the excitation of near-infrared light.More importantly,the up-conversion fluorescence of CY-Cdots could be specifically quenched by iron ions or copper ions.A CY-Cdots-based fluorimetric analysis method has thereby developed for sensing iron ions or copper ions in blood,showing the detection limit of 4.0 nM and 3.5 nM,respectively.In addition,by the introduction of the agent of EDTA for chelating copper ions,the separate detection of iron and copper ions could be expected.In particular,CY-Cdots probes with the up-conversion fluorescence can posssess some advantages such as deep light penetration,low interference of biological background,and no tissue damage,due to the use of near-infrared light as an excitation source.It may also allow for the detection and imaging applications for the sensing analysis and in-vivo imaging of iron or copper ions.?3?A fluorimetric analysis strategy has been developed for probing Tyr in urine by using CY-Cdots with strong yellow fluorescence?Chapter 4?.CY-Cdots materials were synthesized by the one-pot"neutralizing heat"reaction.The sensing performance of the developed CY-Cdots-based fluorimetric method was systematically investigated for analyzing tyrosine.The results indicate that,unlike the common Cdots emitting blue fluorescence in general,the prepared CY-Cdots could display the strong yellow fluorescence that could be specifically quenched by Tyr.The CY-Cdots-based fluorometric method can facilitate the detection of tyrosine in the linear range of 0.050 to 10.0?M for Tyr in urine,with a detection limit of 3.0 nM.It may promise the wide applications for the practical detection of Tyr in the clinical laboratories for the auxiliary diagnosis and monitoring of the early-stage cancers.