Determination of Encapsulation Efficiency of Aptamer-Modified Cantharidin Liposomes Targeting Nano-system by Small Column Centrifugation Combined with HPLC Method and Pharmaceutical Characteristics
OBJECTIVE To establish a small column centrifugation combined with HPLC method for the determination of encap-sulation efficiency for aptamer-modified cantharidin(CTD)liposomes targeting nano-system carrier system(Apt-CTD-NLP),and investigate the pharmaceutical characteristics.METHODS The surface of CTD-Lip was modified by chemical self-assembly tech-nology by aptamer to construct Apt-CTD-NLP,and its pharmaceutical properties were characterized.CTD-Lip was made by the thin film dispersion method.Using the recovery rate of blank liposomes column and the elution rate of free CTD as indexes,the optimum centrifugation conditions of small column were investigated by single factor,and the encapsulation rate of Apt-CTD-NLP was quantita-tively determined by HPLC.RESULTS Apt-CTD-NLP was regularly round and spherical,and the mean particle size,PDI and Zeta potential were(101.0±1.058)nm,(0.208±0.012)and(-1.9±0.397)mV,and had a sustained release effect.The optimal conditions for separation of free CTD by dextran gel column were as follows:400 μL loading volume,standing adsorption for 25 min,centrifugation for 5 min at 1 000 r·min-1,and elution with deionized water for 3 times(500 μL,1 000 r·min-1 ×5 min).The average encapsulation rate of three batches of Apt-CTD-NLP was(94.56±0.80)％.CONCLUSION For lipophilic small molecule drug liposomes,column centrifugation combined with HPLC can quickly and effectively separate liposomes from free drugs,and deter-mine the encapsulation rate of Apt-CTD-NLP.
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