The Influence Of Particle Size On Nano Liposome Distribution In Vivo And In Vitro

Tumor targeted therapy is an ideal way to reduce the side effects of chemotherapy drugs and improve the therapeutic effect of malignant tumors.Although the current research about tumor targeted therapy,very few of them can be successfully transformed into a clinical application.The passive targeting which is the prerequisite for physical targeting and active targeting taking place is ignored.Therefore,improving the passive targeting is the key to improve the targeting efficiency.Factors which can affect passive targeting are surface charge,carrier traits,and particle size.Particle size is an important factor which cannot be neglected in many factors that affect passive targeting efficiency.The size of the particle affects the passive targeting from the distribution of the nano-carriers.However,there are few studies of the effect about the particle size influenced its distribution in vivo and in vivo.Therefore,in this study two particle sizes of long circulating drug loaded?fluorescent?liposomes are designed to study the effects of particle size on the distribution both in vivo and in vitor through a series of experiments.The liposome was prepared by two different methods,and the preparation method was screened to obtain the liposome with suitable particle size.Finally,the particles with the diameter of 30 nm blank liposome were prepared by reverse evaporation method and the particle with the diameter of 100 nm blank liposome was prepared by film dispersion method.Vincristine sulfate?VCR?as a model drug was loaded on the blank liposomes by pH gradient method.The drug loading of 30 nm vinblastine sulfate loaded liposome?VCR-lip?was 1.59±0.46 mg/ml and the encapsulation efficiency was 94.73±5.26%.The drug loading of 100 nm VCR-lip was 1.70±0.12 mg/ml and the encapsulation efficiency was 96.28±2.38%.The particle size and morphology of the VCR-lip was characterized by laser dynamic light nanoparticle and transmission electron microscopy?TEM?.The free VCR,30 nm VCR-lip and 100 nm VCR-lip with different dilution way were used to observe the relationship between particle size and diffusion ability for 48 h in vitro by scanning the transmission light scanning.The results showed that the free VCR can diffuse and quickly diffusion uniformity in a short time.With the increase of VCR-lip particle size,the time of diffusion uniform was increased.In the other word,the increase of particle size is not conducive to distribution uniform in vitro.IC₅₀ tested by MTT was used to determine the relationship between particle size and cytotoxicity in each group.The VCR-lip and free VCR was added in the inside and outside of the cell culture chamber with 400 nm membrane hole at the bottom,while adding mixed drugs to compare the size of the liposome and the ability of diffuse through the pore structure in the vertical direction.The results show that increasing the particle size is not conducive to the drug carrier diffusion through the membrane pore,while the free drugs can be quickly diffusion balance in the cell culture chamber in a short time.The diffusion ability of different particle size VCR-lip and free VCR in the cross-linking three-dimensional network structure in the horizontal direction was investigated by agar plate diffusion experiment.The results showed that the free drug was stronger and easier to the diffusion and distribute in the agar plate,and the increase of particle size of VCR-lip was hinder it diffusion uniform in the crosslinked structure.The diffusion ability of free VCR and different particle size VCR-lip influence the degree of apoptosis was investigated by different methods of drugs administration and cell placement ways.The results showed that change the drugs administration and cell placement of free VCR did not affect the drug distribution and had little effect on the apoptosis.With the increase of VCR-lip particle size,the effect of drug distribution increased the drug concentration which affected the apoptosis.The effect of particle size on the cell uptake in the horizontal direction was studied by changing the administration position of the fluorescent dye.The results showed that the increase of the particle size was not conducive to the diffusion balance in the horizontal direction and will effect on the uptake of the cells.The tumor ball penetration test was investigated the size of the relationship between particle size and penetration ability.The result showed that small particle size liposomes had stronger penetration ability.The body distribution and pharmacodynamics was studied by the HpeG-2 tumor-bearing mice.Small-size liposomes had obvious advantages both in tissue distribution and pharmacodynamics.In this subject,a series of diffusion and distribution studied in vivo and in vitor showed that reducing the particle size can increase the ability of carrier diffusion.Decreasing the particle size of liposome can help the liposome diffusion close to tumor cells and play a curative effect,while preserving the characteristics of liposomes such as Retention effect,good cell affinity,and increased drug solubility and so on.