Investigation of in vivo and in vitro behaviors of quercetin nanocrystals tracked by ACQ probe
Objective Fluorescently labeled quercetin-hydroxyapatite nanocrystals(QUE-HNC)was prepared by incorporating the aggregation-induced quenching(ACQ)probe P2 into the crystal lattice of quercetin nanocrystals,and investigated the in vitro dissolution behavior and in vivo pharmacokinetics of QUE-HNC.Methods The QUE-HNC was prepared by precipitation-anti-solvent ultrasonic method,and single factor analysis was used to investigate the effects of dropping speed,probe immersion position,ultrasonic power,and PVP K30 addition method on the preparation process.The preparation process was optimized to produce QUE-HNC with three different sizes of 170,250,and 310 nm.The content of QUE was determined by HPLC,the size and polymer dispersion index(PDI)were determined by Nano ZS90 laser particle size analyzer,the Zeta potential was determined by Zeta potential analyzer,the microstructure was observed by scanning electron microscopy,the in vitro dissolution behavior of QUE raw material and different sizes of QUE-HNC was compared using dialysis bags,and the in vivo distribution behavior and particle kinetics of QUE-HNC with three different sizes were investigated in male Kunming mice by iv injection of 126 mg·kg-1 and in Wister rats by iv injection of 100 mg·kg-1.The pharmacokinetics of QUE-HNC with three different sizes were investigated in Wister rats by iv injection of 100 mg·kg-1.Results As a result of the single factor investigation,the final formulation was determined to be:A 1∶10 ratio of organic phase to water,with PVP K30 added to the aqueous phase,and a drop rate of 0.01 mL·s-1 for the organic phase.By adjusting the ultrasonic power and grinding time,we successfully prepared QUE-HNC particles with three different sizes of 170,250,and 310 nm,within the desired range,with PDI all less than 0.3,microscopic morphology in the form of rods,relatively uniform size,and QUE concentration all around 0.40 mg·mL-1.Compared with the raw drug,the dissolution rate and extent were significantly improved.The in vivo distribution behavior of the three sizes of QUE-HNC was basically the same,with the fluorescence signal mainly accumulating in the liver area in the first 4 h,gradually shifting to the lower abdomen and spleen area after 11 h,and the fluorescence signal intensity in the liver area and the total fluorescence signal intensity gradually decreasing over time.The pharmacokinetic experiment results reflected the phenomenon of rapid elimination of particles,but the particle dynamics results showed that QUE-HNC would not dissolve rapidly in the blood,with some QUE-HNC remaining in particle form.All three sizes of QUE-HNC had a relatively long average residence time in the body.Conclusion Fluorescent hybridized nanocrystals with three particle sizes were successfully prepared,and the nanocrystals significantly improved the dissolution compared to quercetin API,but they still had a slow release effect.
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