Preparation Of Red Dual-emissive Fluorescent Carbon Dots For Detection Application

Carbon-based nanomaterials play a pivotal role in the development of materials science.From the traditional industrialized carbon such as activated carbon and carbon black to the emerging industrial uses of carbon such as carbon fiber,graphite,and to carbon nanomaterials such as graphene,carbon nanotubes,etc.,a large amount of research attention including interdisciplinary pour into these environmentally friendly carbon materials.As a new type of carbon-based nanomaterials,carbon dots have also attracted great interest from researchers in these years owing to a variety of excellent physical and chemical properties,gratifying biocompatibility,unique optical properties,low cost,environmentally friendly,rich in a large number of easy-to-modify functional groups（such as amino,carboxyl,hydroxyl,aldehyde group）,good stability,flexible electron transfer and strong redox ability.In recent years,they have been widely used in plenty of realms,for example,in optical fields（sensing,information encryption,light-emitting diodes）,catalysis,photovoltaics,supercapacitors,rechargeable por Tab.batteries and other energy fields,as well as potential biomedicine fields.As a common analysis and detection method,the use of carbon dots-based fluorescence sensors to achieve specific fluorescence detection of toxic substances in organisms or water bodies,has its unique characteristics and advantages such as low biological toxicity,high analytical sensitivity,fast detection speed,good selectivity and so on,compared with liquid chromatography and traditional semiconductor quantum dots-based fluorescence sensing detection.Red-dual-emissive carbon dots（CDs）were prepared by a novel and facial solvent-free carbonization method using OPD and Al（NO₃）₃·9H₂O as precursor.CDs manifesting intriguing dual-emission behavior at 600 nm and 650 nm demonstrate good fluorescence quenching rate（99%）on Cu²⁺turn-off sensing identification and excellent GSH fluorescence turn-on detection（F/F₀=580%）accompanied with a red-shift to 650 nm and 700 nm.The linear range of Cu²⁺sensing was 6.67μM-33.3μM and the detection limit was 0.145 m M.The fluorescence quenching selectivity of carbon dots to copper ions was tested at room temperature and exhibit a unique fluorescence quenching ability to copper ions.The detection of copper ions by carbon dots can be applied to actual water samples such as sea water and tap water.Fluorescence lifetime and cyclic voltammetry show that the quenching mechanism is static quenching and dynamic quenching.Cytotoxicity measurements and cell imaging tests displayed good biocompatibility of CDs and cell viability was higher than 83%even under the highest concentration of CDs（50μg/ml）.In addition,by surface modification of the prepared red carbon dots,we obtaine the deep infrared carbon dots with emission wavelength redshifted to about 620 nm/670 nm,and the above two kinds carbon dots are used to achieve ratio fluorescence quenching and internal filtration effect fluorescence quenching detection Malachite green.