Yabang Pharmaceutical Group Co Ltd

Carbon quantum dots (CQDs) are powerful signal transducers in dual-mode assays while still being challenged by their poor peroxidase-mimicking activity and photoluminescence property. Herein, bimetallic copper-iron-doped CQDs (CuFe-CQDs) as a multifunctional nanozyme were proposed for dual-mode colorimetric and ratiometric fluorescence assays of alendronate sodium (ALDS). Notably, CuFe-CQDs were identified to show enhanced and tunable photoluminescence and peroxidase-mimicking activities with bimetallic doping, ascribed to the boosting activation ability of H₂O₂ into HO• and ¹O₂, and the improving carrier mobility in the π-conjugated structure of CuFe-CQDs. Based on the inhibition of ALDS on the peroxidase-mimicking activity of CuFe-CQDs, which further disturbed the inner filter effect (IFE) between CuFe-CQDs and the chromatic product, a dual-mode colorimetric and ratiometric fluorescence assay for the differentiation and determination of ALDS and its analogues was developed with better quantification and high identification, reaching a limit of detection of 0.019 μM in colorimetric mode and 0.146 μM in ratiometric fluorescence mode. The developed dual-mode assay also demonstrated accurate analysis of ALDS in diluted tablets and human urine with recoveries of 92-110%. Our work provides a new approach for the development of functional nanozymes and holds great prospects in multi-mode/signal sensing in complex matrix.

2-(N-Propyl) 4-methyl-6-methoxycarbonylbenzimidazole (I) is an important intermediate of telmisartan pharmaceutical.3-Methyl-4-butylamino-5-aminobenzoate was efficiently converted into I in fluorous biphasic system (FBS) without acetic acid.It was found that Yb(OPf)₃ and C₁₀F₁₈ were the best catalyst and fluorous solvent resp. for the reaction.Yield of I could be up to 94% at 80° for 2 h with x [Yb(OPf)₃] = 0.3%.By simple phase separation, the fluorous phase containing only the catalyst could be directly reused next time.Based on ¹⁹F NMR and UV-Vis and GC-MS data, no loss of catalyst or fluorous solvent to the organic phase could be detected, and no organic compounds could be found in the fluorous phase.There was no significant difference between the UV-Vis spectra of the initial and recovered fluorous phases, indicating that Yb(OPf)₃ was recovered unaltered after the condensation reaction.The catalyst was completely (> 99%) recovered as determined by at. emission spectrometry.The fluorous phase containing only catalyst could be reused up to ten times with only a slight decrease in yields from 94% to 90%.

A method for the determination of main degradation products including mono-POM PMEA, adefovir and other impurities in adefovir dipivoxil was established.The Welch Materials XB-C₈ column (250 mm × 4.6 mm, 5 μm) was adopted with the mobile phase consisting of buffer solution-acetonitrile (65:35), the buffer solution contained 50 mmol · L^-1 potassium phosphate dibasic and 10 mmol · L^-1 tetrabutylammonium hydrogen sulfate, and was adjusted to pH 3.0 with phosphate acid.The detection wavelength was 260 nm, and the flow rate was 1.0 mL · min^-1.The baseline separation was achieved between the main peak of adefovir dipivoxil and the near peak of impurities, and the resolutions among the main degradation products (i.e., adefovir, mono-POM PMEA and 9-[2-(diethyl-phosphonomethoxy)ethyl]adenine) were above 2.0.The good linearity was obtained over the range of 0.109-21.8 μg · mL^-1 for adefovir, 0.111-22.2 μg · mL^-1 for mono-POM PMEA, and 0.105-21.0 μg · mL^-1 for adefovir dipivoxil.The average recoveries were 98.8% for adefovir and 99.7% for mono-POM PMEA, resp.This method is simple, accurate, with well specificity, and can be applied to determination of the relative substances in adefovir dipivoxil and quality control.