Research On The Synthesis And Application Of Functionalized Carbon Dots

Carbon dots?CDs?are carbon-based zero-dimensional materials with the sizes of less than 10 nm.Notably,CDs possess excellent properties including low toxicity,wide source of raw materials,outstanding biocompatibility,photostability and easy functionalization.The research in this paper is mainly to functionalize the CDs surface based on different chemical reactions through one-or two-step synthesis.By studying the optical properties of CDs,they are applied to the fields of analyte detection and optical devices,respectively.The main contents of the paper include the following parts:1. Multicolor fluorescent carbon dots?M-CDs?were synthesized by solvothermal method using anhydrous citric acid and 1-?2-pyridylazo?-2-naphthol as raw materials.M-CDs have concentration-adjustable fluorescence emission wavelengths and solvent-affected aggregation states.By adjusting the concentration of M-CDs,the fluorescence emission spectra of M-CDs can range from 350 nm to 750 nm;In addition,M-CDs possess different aggregation states in water and organic solvents,accompanied by different fluorescence emission,which is attributed to the different surface states of various component CDs in M-CDs.By combining M-CDs with solid substrates,self-quenching-resistant solid fluorescent composite materials were obtained.Furthermore,white light-emitting diodes were successfully fabricated by adjusting the concentration of M-CDs and using epoxy resin as the encapsulant.2.4-aminoantipyrine?AAP?modified CDs?CDs-AAP?was synthesized by amide coupling reaction.CDs-AAP exhibited an emission peak at 484 nm when the excitation wavelength was 370 nm,accompanying 36 nm red shift compare with the pristine CDs.Due to the targeting of AAP towards OCl^-,CDs-AAP has specific recognition ability for OCl^-.Besides,he optimal conditions for detecting OCl^-were p H=7.0,temperature 30°C and incubation time 20 min.Under optimal conditions,the fluorescent intensity of CDs-AAP linearly responded to the OCl-concentration from 3?M to 36?M and the limit of detection was 40 n M.Furthermore,CDs-AAP can also be used for the detection of OCl-in real water samples and labeling E.coli and VMSCs cells.3. In this chapter,thiazole derivatives?AP?were synthesized from acetophenone and thiourea.AP-functionalized carboxyl CDs?CDs-AP?are completed by EDC-activated amidation coupling reaction.Compared with the optimal emission peak of the original CDs at 448 nm,the fluorescence emission peak of CDs-AP is at475 nm.Because the emission peak overlaps with the UV absorption peak of tetracycline?TC?in a large area,CDs-AP can be used to detect tetracycline through the inner filter effect?IFE?mechanism.The linear range of detection of TC is 0-18?M,the detection limit is 0.7 n M,and CDs-AP has been successfully applied to the detection of TC in fish feed.4. In this paper,functionalized CDs-BT were obtained by modifying benzothiazine derivatives?BT?on the surface of carboxyl CDs through amide reaction.Compared with the original CDs,the fluorescence emission intensity of CDs-BT decreased with the increase of the amount of quercetin?QCT?and eventually reached quenching.The optimal conditions such as p H,incubation time,and temperature for the detection of QCT was studied by CCD and RSM.Under the optimal detection conditions,the QCT concentration in the range of 10-19?M has a good linear response to CDs-BT fluorescence intensity?F₀-F?,and the detection limit is 0.717?M.This method can be used to determine QCT in Ginkgo biloba tea,and the recovery were in the range of 98.89%-103.2%.