Adsorption and detection of baicalin by ZrO2 carbon microspheres modifying with boronic acid carbon dots

• Fluorescent boronic acid-containing carbon dots (BA-CDs) was fabricated by 3-aminophenylboronic acid and adipic acid as precursor. • Zr layer coated microspheres was synthesized by sonochemical method, forming ZrO 2 carbon microspheres after carbonation. • BA-CDs were introduced into ZrO 2 carbon microspheres to form BA-CDs/ZrO 2 composite microspheres. • BA-CDs/ZrO 2 had the specific boron affinity and Zr affinity towards cis -diol-containing baicalin . • BA-CDs/ZrO 2 showed high-capacity and high-sensitivity of adsorption and fluorescence response to baicalin . The selectivity of material is crucial for adsorption and detection of target compounds from complex samples. Herein, boronic acid-containing carbon dots (BA-CDs) integration of ZrO 2 carbon microspheres (named BA-CDs/ZrO 2 ) was devised by combining the specific boron and Zr affinity towards cis -diol-containing baicalin (BAI). BA-CDs was prepared by 3-aminophenylboronic acid and adipic acid , and meanwhile Zr layer coated microspheres was synthesized by sonochemical method using poly (glycidyl methacrylate- co -ethylene glycol dimethacrylate) microspheres as hard template and deep eutectic solvents (DESs) as cross-linking agent, after carbonation, they were formed ZrO 2 carbon microspheres. Then, BA-CDs were introduced into ZrO 2 carbon microspheres by addition reaction. Characterization of BA-CDs/ZrO 2 demonstrated that zirconium and boronic acid were successfully decorated into microspheres. The isothermal adsorption experiments determined the maximum adsorption capacity of BAI to be 49.9 mg g −1 , which correlated well with the Langmuir adsorption model. The kinetic adsorption experiments further revealed that adsorption equilibrium was attained within 60 min, conforming to the pseudo-second-order adsorption model. Fluorescence experiments indicated the quenching efficiency of BAI by BA-CDs/ZrO 2 , and the superior fluorescence selectivity to BAI by comparing to quenching intensity of metal ions, amino acids and BAI structure like-drugs. The fluorescence detection method was established with a broader linearity in range of 0.40–300 μmol L -1 BAI concentration, 0.03 μmol L -1 of limit of detection and good reproducibility. The detection ability of BAI by BA-CDs/ZrO 2 in Goji berry and Yinhuang oral liquid was verified the applicability, the measurement of BAI content was checked by HPLC method, the almost same qualitative results confirmed BA-CDs/ZrO 2 practical application values.