Effect Of Colloidal Particles’ Shape And Photo-responsiveness On Their Interactions With Cells

Due to the quick development of technology,diverse materials with novel structure and excellent properties have been fabricated.Among them,colloidal particles with size ranging from nanometers to micrometers have gained much attention,and widely used in various fields including bio-medical area.During the interactions with cells,physicochemical properties of colloidal particles have significant influence.As the introduction of responsiveness,the physicochemical properties of colloidal particles can be regulated under different stimulations,providing possibility for complex applications.The influence of microcapsules’ shape during the interaction between microcapsules and cells was first studied.Then,colloidal particles with photo-responsiveness were chosen.Photo-responsive polyethyleneimine(PEI)microcapsules cross-linked by ortho-nitrobenzyl derivatives were fabricated.The physicochemical structure before and after UV irradiation was systematically characterized.Also based on ortho-nitrobenzyl derivatives,photo-responsive poly(ethylene glycol)(PEG)microparticles which can responsed inside cells were fabricated.The effect of their intracellular responsiveness on cell behaviors was studied.Finally,diazo-resin(DZR)was also used to prepare photo-responsive microparticles.Due to the decomposition of diazo group,the particles could release N2 upon UV irradiation,which was used to kill cancer cells.Colloidal particles’ shape may strongly affect their interactions with cells.Bowl-like microcapsules with the size about 2μm were prepared by an osmotic pressure method.The uptake behaviors of the bowl-like and spherical microcapsules by human vascular smooth muscle cells(SMCs)and typical macrophage cells RAW 264.7 are compared.Results showed that,bowl-like capsules can be internalized faster than their spherical counterparts.After co-incubation for 12 h,the number of bowl-like capsules per cell was 3.8-fold larger than their spherical counterparts.The mechanism for different uptake behaviors was discussed.During the application of colloidal particles as carriers for delivery of bioactive molecules including drugs,proteins and DNAs,researchers mainly focus on the effect of the released bioactive molecules,while the change of the materials themselves are usually ignored.Here,ortho-nitrobenzyl derivative was selected as a typical photo-responsive moietie.By a templating method,after being reacted with PEI-doped CaCO3 particles and core removal,photo-responsive polyethyleneimine(PEI)microcapsules were obtained.In acidic condition,the cross-linking points were cleaved gradually after irradiation,and the capsules were expanded and their shell became looser,which may increase the permeability of the capsules.The cleaved PEI molecules could diffuse out.Expansion of capsules and release of component also result a thinner shell(54.6±4.6 nm to 12.3 ± 0.8 nm).At last,the microcapsules decomposed completely.Using rhodamine B isothiocyanate-labeled dextran(RBITC-dextran)as a model,the photo-controlled release was demonstrated.Photo-responsive cross-linker with active ester group was synthesized.After reacted with PEG-doped CaCO3 particles,photo-responsive PEG microparticles were obtained.Such particles could swell and decompose after UV irradiation as the cross-linker cleaved.The effect of intracellular response on cell behaviors was investigated.After irradiation,the relative viability of cells which internalized PEG particles decreased obviously compared with cells only treated with particles or irradiation,and cells tended to demonstrate non-spreading morphology.To realize killing cancer cell without drug,diazo-resin which could release N2 upon UV irradiation was used for fabrication of photo-responsive microparticles via polyamine-salt aggregate method.After modification of hyaluronic acid(HA),the particles can selectively internalized by cancer cells.After internalization,the particles resided in lysosome and released N2 upon irradiation.Which cause damage to lysosome membrane and finally resulted in the cancer cell death.