Interactions Of Nanoparticles With Live Cytoplasm,Biological Membrane And Protein Molecules

For the better application of nanoparticles into biomedical engineering area,it is a fundamental task to systematically and deeply understand the various interactions between nanoparticles and biological systems.In this paper,we used fluorescent nanoparticle,quantum dots(QDs),as a model.Three key issues of the interaction between nanoparticles and biological systems have been studied with the excellent fluorescence properties of quantum dots.First,the biological transport process of single quantum dots in live cell cytoplasm was studied.A kind of quantum dots delivery technique based on Streptolysin O(SLO)membrane perforation was developed and successfully delivered single quantum dots into a variety of live cells,including a variety of common cancer cell lines and a type of stem cell.Furthermore,it was found for the first time that,the single QDs which existed in live cell cytoplasm,after several hours,the vast majority of QDs were captured by dynein molecules,transported along the microtubule directionally,and finally accumulated in the microtubule-organizing center(MTOC),outside the nucleus.This phenomenon occurs in all types of cells tested in this paper.Therefore it is a common phenomenon for the live cell cytoplasm,which is a biological system,reacted to foreign substances such as quantum dots.Then we tracked the the movement of motor protein molecules(dynein)in live cells used SLO delivered single quantum dots.Second,the effect of simple operation--adding a small proportion of organic solvent(cosolvent)in water on the delivery performance of water-soluble quantum dots conjugated with cell-penetrating peptide(QDs-Tat)at the subcellular level was investigated.The results showed that cosolvent(such as 1%DMSO)could significantly enhanced the ability of water-soluble quantum dots conjugated with cell-penetrating peptide(QDs-Tat)to cross cell membrane and escaped from intracellular vesicles.Vesicle escape with particular importance is a common bottleneck barrier for the nano-structure biological delivery.Therefore,in addition to the conventional fluorescence co-localization study on vesicle escape,a new biophysical quantitative analysis method(pair-correlation function analysis)was used to study the crossing process of this barrier.Our work was the first to report that a small proportion of organic solvent could significantly improve vesicle escape and presented a simple method to enhance intracellular targeting delivery.Third,the technique,the interfacial instability process,has been introduced to fabricate protein nanoparticle co-assembly supraparticles(PNCAS).PNCAS are a new kind of emerging nanoparticles in recent years.This work focused on the PNCAS preparation process.For the first time,the interface instability process has been introduced into the preparation of such nanoparticles,and realized(1)Hydrophobic nanoparticles can be directly used as raw materials to simplify the preparation process;(2)Combining the interface instability process with the electrostatic spray process,semi-continuous and large-scale production could be carried out;(3)Solved the problems of poor packaging control of nanoparticles and difficult control of assembly size in the traditional interfacial instability process.