Synthesis And Detection Of Amphiphilic Fluorescent Carbon Dots

Fluorescent probe sensing technology has attracted widespread attention due to its advantages compared to traditional detection technologies,such as simple operation,low detection limit,fast response,strong portability,and strong real-time on-site performance.Carbon Quantum Dots（CQDs）,also known as carbon dots or carbon nanodots,are a type of zero dimensional carbon nanomaterials with significant fluorescence properties.They are composed of ultrafine,dispersed,quasi spherical,and carbon nanoparticles with a size less than 10 nm.They have high fluorescence intensity and good photostability,and are often used as fluorescent probes for the analysis and detection of target substances.The synthetic raw materials of carbon dots are cheap and abundant,and the preparation routes are simple and diverse.However,most carbon dots can only be used for the determination of hydrophilic substances,and the detection of hydrophobic substances is limited.Therefore,this study used a one-step solvent thermal synthesis method to synthesize amphiphilic carbon dots through high-temperature carbonization condensation in organic solvents,and based on this,three fluorescent probes were designed for analysis and detection ofβ-carotene,Hg²⁺,and benzo[a]pyrene.The main research content is as follows:1.Synthesis of DTSA-MA-CDs and detection the presence ofβ-carotene in spirulina samplesThis study synthesized DTSA-MA-CDs using melamine and dithiosalicylic acid as precursors,and acetic acid,ethanol,and DMF as solvents.The effects of organic solvents on the properties of amphiphilic carbon dots were compared and analyzed.Single blue fluorescence emission,fluorescence quantum yield is 7.185%.The electron transfer betweenβ-carotene as a target substance and DTSA-MA-CDs resulted in a significant decrease in the characteristic peak of carbon dots at 410 nm,which is fluorescence quenching caused by fluorescence resonance energy transfer.The linear response range ofβ-carotene is 0.025-4.5μg/mL,with a detection limit as low as 2.5ng/mL.2.Synthesis of CA-TCPP-EDA-CDs fluorescence probes and detection of Hg²⁺content in water samplesIn this study,CA-TCPP-EDA-CDs were synthesized from citric acid,ethylenediamine and TCPP in ethanol.The carbon dots produced double emission signals at 450 nm and 650 nm,and the fluorescence quantum yield was 31.8%.The conjugated complexation between Hg²⁺and carbon dots,based on the principle of static quenching,alters the fluorescence intensity of the carbon dots at 450 nm.Its linear response range is 5-500μmol/L,with a detection limit as low as 7.26 nmol/L.3.The synthesis of CA-TCPP-HE-CDs and the detection of benzo[a]pyrene content in food.In this study,CA-TCPP-HE-CDs were synthesized with citric acid and TCPP as precursors in ethanol solvent,and the carbon dots were modified with hydrophobic long-chain alkanes,which had dual emission signals and fluorescence quantum yield of 3.42%.Benzo[a]pyrene is used as the detection target,and the carbon dots have strongπ-πconjugation ability of TCPP and conjugation complexation between benzo[a]pyrene polyaromatic rings,resulting in no change in the fluorescence signal of the carbon dots at 650 nm and a significant change in fluorescence at 440 nm.Its I₄₄₀/I₆₅₀ratio fluorescence linear response range is 0.0025-0.5μg/mL,with a detection limit as low as 1.75 ng/mL.