Loading And Release Behavior Of Polymeric Nanoparticles Based On Natural Macromolecular Derivatives

In recent years,the application of core-shell polymeric nanoparticles in the filed of drug delivery has attracted more and more interest.Core-shell polymeric nanoparticles can encapsulate a large number of materials ranging from organic molecules to biological macromolecules.Various methods,such as microemulsion polymerization,the deposition of polyelectrolytes on a core template,and the self-assembly of block copolymer in a selective solvent,have been developed to prepare the core-shell polymeric nanoparticles.The traditional self-assembly route to prepare nanoparticles is multi-step, difficult and of low efficiency.Combining self-assembly and flee-radical polymerization,we developed an easy method to fabricate core-shell nanoparticles at high concentration in water,that is,template polymerization.Using this method,we have obtained two kinds of core-shell nanoparticles,i.e.,poly(methacrylic acid)/hydroxyethyl cellulose(PMAA/HEC) nanoparticles and poly(acrylic acid)/gelatin(PAA/Gelatin) nanoparticles.In this paper,three different dyes were chosen as model molecules to investigate the loading and release behavior of these two core-shell nanoparticles.Specifically,the following work was carried out:(1)The loading capacity and in vitro release behavior of core-shell PMAA/HEC polymeric nanoparticles against methylene blue(MB) were studied using UV absorption spectroscopy.The nanoparticles before and after loading MB were also characterized by DLS,TEM,IR,DSC and TGA.It was found that,the MB-loading capacity of PMAA/HEC nanoparticles mainly depended on the mass of PMAA,and it increased with the increase of pH value in the pH range between 2.0 and 5.0.In the media of pH2.0,3.0,4.0 and 5.0,the cumulative MB release of MB-loaded PMAA/HEC nanoparticles(pH5.0) were 94%,87%,51%and 8%,respectively. Release rate and total MB release increased with the rise of the temperature and ion strength of release medium.The controlled release of MB-loaded nanoparticles was realized via alternative release in two media of different pH value.(2) The loading capacity and in vitro release behavior of core-shell PMAA/HEC polymeric nanoparticles against acid red 14(AR14) were studied using UV-vis absorption spectroscopy.The nanoparticles before and after loading AR14 were also characterized by DLS,IR and TGA.It was found that,the AR14-loading capacity of PMAA/HEC nanoparticles mainly depended on the aggregation state of AR14 and the density of the nanoparticles.The cumulative AR14 release of AR14-loaded nanoparticles(pH1.0) in the release media of pH1.0,3.0 and 5.0 were 73.2%,97.5% and 97.8%,respectively.With the rise of temperature,release rate of AR14-loaded nanoparticles increased,the total AR14 release remained constant.Release rate and total MB release decreased with the increasing of the ion-strength of release medium.(3) Disperse Blue 79(DB79) was chosen as the model molecule to investigate the loading ability of PMAA/HEC core-shell nanoparticles against hydrophobic substances.It was found that the loading capacity of the nanoparticles to DB79 was only 0.058mg/g.(4) The cavitation process of PAA/Gelatin core-shell nanoparticles was traced by DLS.It was found that,the intensity of dynamic light scattering decreased with the dialysis time.After cavitation,the size of nanoparticles was twice of its original size.(5) The loading capacity and release behavior of core-shell PAA/Gelatin nanoparticles and hollow PAA/Gelatin nanoparticles against MB were investigated.It was found that,at the same loading conditions,the loading rate of hollow nanoparticles against MB was faster than that of core-shell nanoparticles.At the time of loading equilibrium,the loading content of hollow nanoparticles and core-shell nanoparticles to MB were 0.59mg/mg and 0.48mg/mg,respectively.