Objective To prepare cationic Vancomycin hydrochloride multivesicular liposome (MVL) and to inspect its quality. Methods Cationic Vancomycin hydrochloride MVLs were prepared by double emulsion method, and the storing solution of Vancomycin was prepared. The analysis method of Vancomycin in vitro was established; the specificity, precision, and resorption rate were estimated. Reverse phase high performance liquid chromatography (RP-HPLC) was used to determine the concentration of Vancomycin, encapsulation efficiency, and release characteristics in vitro. The formulation and pharmaceutical process were optimized by single factor experiments and orthogonal experimental design with the factor of encapsulation efficiency as the criteria. The liposome morphology was observed by optical microscopy and transmission electron microscopy. The particle size and Zeta potential were determined by Malvern instrument. The stability was analyzed by dynamic analysis. Results An RP-HPLC method was established for the assay of Vancomycin. The analysis method was precise, simple, and reliable for the quality control of Vancomycin. Vancomycin hydrochloride MVLs were round and well-distributed. The average particle size and the encapsulation efficiency were 3.3 μm and 24.9%, respectively. Zeta potential was 24.53 mV, and 90.5% of Vancomycin hydrochloride was released after 264 hours in normal saline under 37℃. Cationic Vancomycin MVLs were stored for 1 month at 4 ℃, which mantained good stability. Conclusion Cationic Vancomycin hydrochloride MVLs have good appearance, high encapsulation efficiency, good stability, and significant sustained release properties.
ObjectiveTo optimize the extracting process of Zipu gouty mixture by orthogonal experiment, and to provide theoretical basis for its preparation procedure and quality control. MethodsThe water drawn extract yield and the total content of the chlorogenic acid were considered as research indexes. The orthogonal test was conducted to evaluate the effects of three factors including the amount of material/solvent ratio, extraction times, and duration of sample extraction of Zipu gouty mixture extracting process. ResultsThe extracting process was optimized with the material/solvent ratio of 1:8, extract time of 30 minutes for 3 cycles. ConclusionThe Zipu gouty mixture extracting process optimized by orthogonal test is simple, reliable and easy to repeat, which provides a theoretical basis for large-scale production.
The locking mechanism between bracket and shape memory alloy (SMA) archwire in the newly developed domestic orthodontic device is the key to controlling the precise alignment of the teeth. To meet the demand of locking force in clinical treatment, the tightening torque angle of the locking bolt and the required torque magnitude need to be precisely designed. For this purpose, a design study of the locking mechanism is carried out to analyze the correspondence between the tightening torque angle and the locking force and to determine the effective torque value, which involves complex coupling of contact, material and geometric nonlinear characteristics. Firstly, a simulation analysis based on parametric orthogonal experimental design is carried out to determine the SMA hyperelastic material parameters for the experimental data of SMA archwire with three-point bending. Secondly, a two-stage fine finite-element simulation model for bolt tightening and archwire pulling is established, and the nonlinear analysis is converged through the optimization of key contact parameters. Finally, multiple sets of calibration experiments are carried out for three tightening torsion angles. The comparison results between the design analysis and the calibration experiments show that the deviation between the design analysis and the calibration mean value of the locking force in each case is within 10%, and the design analysis method is valid and reliable. The final tightening torque angle for clinical application is determined to be 10° and the rated torque is 2.8 N∙mm. The key data obtained can be used in the design of clinical protocols and subsequent mechanical optimization of novel orthodontic devices, and the research methodology can provide a valuable reference for force analysis of medical devices containing SMA materials.