Studies On The Interaction Of Liposomal Doxorubicin With Pore-Forming Peptide

Objective:Doxorubicin(DOX)is anthracycline antibiotics.In the early 1960 s,it was for the first time separated from a kind of Streptomyces.DOX is widely used to treat blood system cancer,solid tumors and sarcoma.In the late 1960 s,DOX shows it's antitumor efficacy in clinical trials,but it is toxic to normal cells.Improving the selective delivery of drugs and reducing the toxicity of drugs is the key to the clinical application.Liposomes are microspheres by phospholipid bilayer orientation,with favorable targeting effect.Liposomes,as drug delivery systems,have the advantage of improving the pharmacokinetics,in vivo distribution and reducing toxicity of drugs.In recent years,concerned studies have shown that the anti-tumor efficacy of liposomes loading DOX is not only similar or slightly stronger than the free DOX,but also it can significantly reduce cardiotoxicity and expand the scope of treatment.Pore-forming peptide is a linear peptide with an ?-helical conformation.It can induce the penetration of lipid membrane,forming holes by the surface self-assembly of the membrane,thus make inner small molecules outflow.The incorporation of pore-forming peptide into liposome carrier results that the drug molecules quickly release into the extracellular region,enhancing drug accumulation in tumor.In the research,DOX liposomes are prepared by ammonium sulfate gradient method.Investigating the morphology,particle size and encapsulation efficiency,the prescription of excellent physical and chemical properties is screened.Investigating the interaction between liposome carrier and pore-forming peptide,we investigate the fluorescence leakage of liposome carriers.Methods:Based on the literature and experimental research,we have identified the DOX liposome preparation methods.Blank liposome is prepared by thin film dispersion and ammonium sulfate gradient method is adopted to loading drug.The carrier is characterized by measuring the particle size,potential and encapsulation efficiency of the drug-loaded liposomes.To choose the best formulation,the physical and chemical stability(particle size,polydispersity index,encapsulation efficiency as indicators)and drug loading stability(the release degree as an indicator)was studied.Experiment is conducted by high throughput real time fluorescence analysis system,detecting the fluorescent leakage of liposomal DOX,evaluating the interaction of liposomes with pore-forming peptide.Results:According to the different formulation and procedure,seven kinds of DOX-loaded liposome were prepared.The particle size of liposome carrier were between 110 nm and 150 nm,with PDI less than 0.3,and zeta potential negative.The encapsulation efficiency of liposomal DOX is in the range of83% ~ 99%.Following 30-day standing,POPC-DOX suffered from obvious change in particle size,PDI and encapsulation efficiency formulations maintained favorable stability.The rest after 60 days,with no significant changes in physicochemical property.In three release medium,the cumulative release rate of liposomal DOX is relatively low showing good stability.The determination method of the interaction between the liposome and pore-forming peptide is established.By testing liposomal DOX leakage,we evaluate interaction of liposomes carrier and pore-forming peptide.Conclusions:Preparation method is simple and the preparation time is short.This preparation method has good reproducibility.The encapsulation of DOX is simple.By determination of liposomal DOX leakage,we establish the methodof studying the interaction between the liposome carrier and the pore-forming peptide.