Abstract: A method for preparing a ratiometric fluorescent sensor for paracetamol based on a copper nanoclusters-carbon dots-arginine composite is provided. Copper nanoclusters CuNCs with red fluorescence are bonded to carbon dots (CDs) with blue fluorescence by electrostatic adsorption and hydrogen bonding, and then arginine is added to form the CuNCs-CDs-arginine composite. The addition of arginine leads to a significant decrease in the blue fluorescence of the CDs, while after the paracetamol is added, the blue fluorescence of the CDs gradually recovered as a result of the specific binding of arginine to paracetamol. The ratiometric fluorescent sensor for paracetamol is constructed by taking the fluorescence of the CuNCs as a reference signal, and the fluorescence of the CDs as a response signal, and fitting the linear relationship between the ratios ICDs/ICuNCs of fluorescence emission peak intensities of CDs and CuNCs and the molar concentrations of paracetamol.

Abstract: A method for preparing a ratiometric fluorescent probe for melamine based on a DNA-stable silver nanocluster-rhodamine 6G complex, wherein the electrostatic self-assembly technology is adopted to construct a silver nanocluster-rhodamine 6G complex. The melamine forms a strong hydrogen bond with thymine in the DNA of the surface of the silver nanocluster, causing rhodamine 6G to dissociate from the surface of the silver nanocluster, destroying the fluorescence resonance energy transfer, so as to restore the fluorescence of the silver nanocluster. This process has little effect on Rhodamine 6G fluorescence which can be used as a reference signal, while silver nanocluster fluorescence can be used as a response signal. By fitting the linear relationship between the ratio of fluorescence emission peak intensities of the silver nanocluster to rhodamine 6G and the molar concentration of the melamine, the ratiometric fluorescent probe for melamine can be constructed.

Abstract: A method for preparing a ratiometric fluorescent probe for melamine based on a DNA-stable silver nanocluster-rhodamine 6G complex, wherein the electrostatic self-assembly technology is adopted to construct a silver nanocluster-rhodamine 6G complex. The melamine forms a strong hydrogen bond with thymine in the DNA of the surface of the silver nanocluster, causing rhodamine 6G to dissociate from the surface of the silver nanocluster, destroying the fluorescence resonance energy transfer, so as to restore the fluorescence of the silver nanocluster. This process has little effect on Rhodamine 6G fluorescence which can be used as a reference signal, while silver nanocluster fluorescence can be used as a response signal. By fitting the linear relationship between the ratio of fluorescence emission peak intensities of the silver nanocluster to rhodamine 6G and the molar concentration of the melamine, the ratiometric fluorescent probe for melamine can be constructed.

Abstract: A method for preparing a ratiometric fluorescent sensor for phycoerythrin based on a magnetic molecularly imprinted core-shell polymer is provided. With Fe3O4 magnetic nanoparticles as the core, blue fluorescence-emitting carbon quantum dots (B-CDs) are coupled on the surfaces of Fe3O4 magnetic nanoparticles, and SiO2 shells carrying template molecules (phycoerythrin) are grown on the surfaces of Fe3O4/B-CDs. Then, the molecularly imprinted polymer SiO2-MIPs are obtained by eluting the template molecules, that is, Fe3O4/B-CDs/SiO2-MIPs are obtained. Fluorescence emission spectra of the dispersion of Fe3O4/B-CDs/SiO2-MIPs in the presence of different concentrations of phycoerythrin are measured. By fitting the linear relationship between the ratios Iphycoerythrin/IB-CDs of fluorescence emission peak intensities of phycoerythrin and B-CDs and the molar concentrations of phycoerythrin, the ratiometric fluorescent sensor for phycoerythrin is constructed.

Abstract: A method for preparing a ratiometric fluorescent sensor for paracetamol based on a copper nanoclusters-carbon dots-arginine composite is provided. Copper nanoclusters CuNCs with red fluorescence are bonded to carbon dots (CDs) with blue fluorescence by electrostatic adsorption and hydrogen bonding, and then arginine is added to form the CuNCs-CDs-arginine composite. The addition of arginine leads to a significant decrease in the blue fluorescence of the CDs, while after the paracetamol is added, the blue fluorescence of the CDs gradually recovered as a result of the specific binding of arginine to paracetamol. The ratiometric fluorescent sensor for paracetamol is constructed by taking the fluorescence of the CuNCs as a reference signal, and the fluorescence of the CDs as a response signal, and fitting the linear relationship between the ratios ICDs/ICuNCs of fluorescence emission peak intensities of CDs and CuNCs and the molar concentrations of paracetamol.

Abstract: A method for preparing a ratiometric fluorescent sensor for phycoerythrin based on a magnetic molecularly imprinted core-shell polymer is provided. With Fe3O4 magnetic nanoparticles as the core, blue fluorescence-emitting carbon quantum dots (B-CDs) are coupled on the surfaces of Fe3O4 magnetic nanoparticles, and SiO2 shells carrying template molecules (phycoerythrin) are grown on the surfaces of Fe3O4/B-CDs. Then, the molecularly imprinted polymer SiO2-MIPs are obtained by eluting the template molecules, that is, Fe3O4/B-CDs/SiO2-MIPs are obtained. Fluorescence emission spectra of the dispersion of Fe3O4/B-CDs/SiO2-MIPs in the presence of different concentrations of phycoerythrin are measured. By fitting the linear relationship between the ratios Iphycoerythrin/IB-CDs of fluorescence emission peak intensities of phycoerythrin and B-CDs and the molar concentrations of phycoerythrin, the ratiometric fluorescent sensor for phycoerythrin is constructed.