Research And Application Of Photoluminescence Carbon Nanodots Materials In Detection

Photoluminescent carbon nanodots?CNs?materials are a new type of fluorescent nanomaterials that have emerged in recent years.Compared with traditional semiconductor quantum dots materials,The CNs not only has excellent optical properties and nano-small size characteristics,but also has good biocompatibility,low toxicity and environmental protection.Therefore,this carbon nanodots material is widely used in the fields of biological imaging,ion detection,electrochemical sensing,and fluorescent inks.In the paper,a series of new photoluminescent carbon nanodots materials were synthesized by a one-pot hydrothermal method for the first time.These prepared carbon nanodots were carried out various characterizations,and were applied in fluorescent inks,fluorescent polymer films,ions detection and anti-counterfeiting technology.The details were described as follows:1.Highly efficient water-soluble fluorescent carbon nanodots materials for visual detection of Fe???ions and fluorescent inks applicationsIn this study,using m-phenylenediamine?mPD?and methacrylic acid?MAA?as raw materials,a novel carbon nanodots?CNs?was synthesized by one-pot method.The prepared CNs aqueous solutions exhibited bright and long-lasting green fluorescence under ultraviolet?UV?light?365 nm?.Fluorescent inks manufactured with aqueous solutions of the CNs can be used for writing,painting and dyeing.The fluorescent inks showed yellow ink and clear green fluorescence under daylight and UV light?365 nm?.Meanwhile,the CNs aqueous solutions were also manufactured test strips for detecting ions.In addition,the CNs was also used to specifically detection of Fe³⁺in naked eye.By comparing the fluorescence quenching effect of various metal ions to CNs,other metal ions have little effect to CNs in fluorescence intensity,while Fe³⁺has strong responsiveness to CNs.The limit of detection?LOD?of Fe³⁺in visual was 50?M in the range of 50-1000?M.The CNs was also used to detect Fe³⁺using molecular fluorescence spectrometer.The maximum fluorescence intensity of the CNs demonstrated a linear relationship with concentration of Fe³⁺in the range of 1-100?M with an LOD of 0.6?M?S/N=3?.The CNs also has pH responsiveness,which fluorescence of CNs can be quench in strong alkaline environment.The result showed that the CNs possessed good optical properties and could be used for applications in fields of the visual detection of Fe³⁺,pH sensors and fluorescent inks.2.Multicolor photoluminescent carbon nanodots for multicolor patterning,invisible inks and detection of metal ionsA strategy for preparing multicolor photoluminescent carbon nanodots?CNs?has been proposed.Using three types of phenylenediamine and methacrylic acid as raw materials,a series of novel CNs were synthesized by one-pot method.Prepared CNs showed bright green,yellow and indigo blue fluorescence under ultraviolet?UV?light,respectively.The optical properties of CNs were characterized using ultraviolet visible?UV?spectra and fluorescence spectra,the microscopic morphology was characterized by transmission electron microscopy?TEM?and dynamic light scattering?DLS?,and the elemental composition was characterized by Fourier transform-infrared spectroscopy?FT-IR?and X-ray photoelectron spectra?XPS?.We preliminarily proposed that the different fluorescence emission of CNs might be attributed to the surface oxygen content of the CNs.In addition,these CNs could also be applied for multicolor patterning and polymer films,invisible inks and detection of metal ions.3.UV Light-tunable fluorescent inks and polymer hydrogels films based on carbon nanodots and lanthanide for enhancing anti-counterfeitingWater-soluble green fluorescent carbon nanodots?CNs?were synthesized?CNs in experiment one?.Red fluorescent lanthanide complexes were prepared using lanthanide ion Eu³⁺and pyridine-2,6-dicarboxylic acid.A simple strategy was developed to prepare UV light-tunable fluorescent inks and polymer hydrogels films based on CNs and lanthanide complexes.The fluorescent inks and polymer hydrogels films can be repeatedly switched between green and red fluorescence.The change of color depended on luminescence of the CNs and the lanthanide complexes under 254 and 365 nm UV light,respectively.The result showed that the UV light-tunable fluorescent inks and polymer hydrogels films could enhance the anti-counterfeiting function for data and information.