Research On The Correlation Between The Intestinal Absorption Capacity And Basic Properties Of The Polymer Nanoparticles As Oral Delivery Drug Carrier

Improving the oral bioavailability of drugs that are hard to oral absorb is a problem that has long plagued pharmacists.The related theories and concepts of nano-preparation are intuitively compatible with promoting oral absorption,and oral nano-preparation may break through this bottleneck.This study will explore the impact of the size,surface charge and surface pro-hydrophobics of polymer nanoparticles(NPs)on oral delivery systems.The impact of the basic properties including size,surface charge and surface pro-hydrophobics to overcome the physiological barrier of intestinal absorption after oral administration for drug-loaded polymer nanoparticles have been systematically and comprehensively investigated.The results,characteristics and reasons of the impact are learned.The main research contents and conclusions are as follows:1.Construction and characterization of model polymer nanoparticlesPolystyrene NPs(PSNPs),water-soluble chitosan NPs and(PEG-)PLGA NPs were used to construct model NPs with different particle sizes,types and degrees of surface charges,and hydrophobicity respectively.For each group of model NPs,following characterization were selectively performed:(1)Observation through scanning electron microscope(SEM)or transmission electron microscope(TEM).(2)Dynamic light scattering Were used to measure particle size and zeta potential.(3)The contact angle with pure water and the fat-water distribution in the water-n-octanol system were measured to evaluate the hydrophilic and hydrophobic properties of the NPs.(4)The fluorescence stability of the model NPs were evaluated in three dispersion media: deionized water,PBS and artificial intestinal fluid.The each group of model NPs were characterized correspondly and the results were obtained following:(1)The diameters of the six groups of polystyrene NPs were about 70,100,150,200,300,and 500 nm,respectively.(2)The particle sizes of the three groups of carboxymethyl chitosan NPs(CMCNPs)and the three groups of chitosan hydrochloride NPs(CHNPs)are all within the range of 155±15 nm,and the zeta potential values are-20,-30,-40,+20,+30,and +40.(3)The particle diameters of the three groups of PLGA NPs(PNPs)and the three groups of PEG-PLGA NPs(PPNPs)are all within the range of195±10 nm,the zeta potential does not exceed 5 m V,and they exhibit a nearly spherical shape and gradient differences in hydrophilic or hydrophobic.(4)All model NPs can maintain stable fluorescence in three dispersion media after fluorescent labeling.The above results indicate that the model NPs were successfully constructed in this study.2.Evaluation of the intestinal absorption capacity of model NPsThe absorption and penetration ability of nanoparticles in the small intestine tissue was evaluated in the experimental model constructed from the small intestine of rats in vitro or in vivo.It can be found that:(1)The permeability of NPs in the isolated small intestine tissue is size-dependent.NPs with a smaller particle size have better permeability.(2)If NPs with similar charge levels are compared with each other,all the penetration results of NPs in the negative group were higher than those in the positive group.(3)PPNPs with a hydrophilic surface have a higher intestinal permeability than PNPs without PEG.Besides,the longer the PEG chain used in the scope of this study,the stronger the penetration ability of PPNPs.3.Study on the interaction between model NPs and intestinal mucusIn vitro and in vivo,the penetration and retention of model NPs of the potential group and the hydrophobic group in the intestinal mucus,and the interaction with the intestinal mucus were studied.The results of the above studies show that the factors of larger particle size,surface positive charge,higher level of surface charge,surface hydrophilicity will make the NPs more likely to stay in the intestinal mucus.At the same time,the factors of smaller particle size,low level of surface negative charge and hydrophilic properties make the NPs have a higher level of intestinal mucus penetration.4.Research on the cell endocytosis process of model NPsIn the co-culture system of Caco-2 and HT29-MTX cells,the cell uptake and endocytosis mechanism of each group of model NPs were studied and analyzed.NPs and concluded as follow.(1)The group with a particle size of 100 nm obtained the highest uptake among all PSNPs.(2)Clathrin-mediated endocytosis of NPs tends to be 100～150nm in particle size,while caveolin-mediated endocytosis tends to be NPs with a particle size of about 300 nm.(3)The overall cellular uptake of CHNPs is slightly higher than that of CMCNPs.Under the same degree of charge,the positively charged NPs have higher absorption than the negatively charged NPs.(4)The clathrin-mediated endocytosis is biased towards NPs with positive zeta potential.(5)The PEG component will reduce the cellular uptake of the NPs.(6)Clathrin-mediated endocytosis may have slight choice in hydrophilic NPs.The modification of PEG will also make the giant pinocytosis play a more important role in the pinocytosis of NPs.5.Study on the intracellular transport and exocytosis process of model NPsThe mechanism of intracellular transport and exocytosis of NPs was studied by the method of specific inhibition and co-localization of organelles.Finally,the monolayer cell model was used to evaluate the monolayer cell transport ability of each group of NPs.The results show that:(1)The activation of retransportation after entering the cell is more likely to occur on NPs with a particle size of more than 100 nm,while subsequent transport from the endoplasmic reticulum to the Golgi complex is more likely to occur on NPs with a particle size of less than 300 nm.(2)NPs with a lower level of positive charge may have a more positive tendency to exocytosis after entering the cell.(3)The trans-cell transport capacity of positively charged NPs is generally higher.The lower the charged level of the NPs will also result in more monolayer cell transport value.(4)The transport volume of PPNPs containing PEG components is slightly lower than that of PNPs,and in each group of PPNPs,there is a trend that the transport value increases as the PEG chain becomes longer.