The Preparation Of Liposomes/Au Nanoshells And The Controllable Release Of Drugs By Light

Currently,in order to reduce the direct damage of drug molecules to normal cells and increase the accumulation of drugs to tumor cells,it is extremely important to seek nano-carriers that can achieve effective loading,controlled release and convenient metabolism of drug molecules.The liposomes as conventional drug nano-carriers have been widely researched for loading drug molecules,but the controlled release of the drug molecules still requires surface modification by other ligands.Gold nanoparticles have a unique tunable optical property-local surface plasmon resonance(LSPR),with the help of LSPR property to achieve the purpose of remote controlled release.At the same time,gold nanoparticles are less biologically toxic and can be used to protect liposomes effectively,which makes the complex of liposomes and gold nanoparticles more popular in the field of biological treatment.The enhanced permeability and retention effect of tumor cells(EPR effect)can improve the accumulation of the size-appropriate compounds.In addition,the photo-thermal effect of gold nanoshells and the special pH around the cancer cells can contribute to the release of drug molecules.After the drug molecules are released from the nanoshells,the overall size reduction of the gold nanoshells is advantageous for the degradation and metabolism of the nanomaterial.Based on the above view,the specific research contents are as follows:(1)The orthogonal experimental method was utilized to find the optimum conditions for preparation of liposomes.Liposomes with appropriate size distribution were synthesized.The stability of liposomes during storage was studied.After the gold clusters were coated on the liposomes,the stability of liposomes was improved.The positions of absorption peaks were adjusted by changing the molar ratio of chlorine acid and ascorbic acid.The theoretical analysis of the position change was performed.Based on the temperature change(ΔT)and power density(Io),the photo-thermal conversion parameters of absorption peaks at different locations had been calculated after the liposomes/Au nanoshells irradiated by the 808 nm laser.From the perspective of the particle size,the overall size of the nanoparticles after laser irradiation was studied.Finally,the biocompatibility of liposomes/Au nanoshells was investigated.(2)The liposomes/Au nanoshells were used as nano-carriers for drug molecules.In order to determine whether the DOX·HCl was loaded into liposomes/Au nanoshells or not,they were tested with TEM,size distributions,zeta potential,UV-vis absorption spectra and fluorescence emission spectra.Next,the loading efficiencies of DOX·HCl at different concentrations were tested.As the liposomes/Au nanoshells had a significant photo-thermal effect,the release efficiencies of DOX·HCl from liposomes/Au nanoshells were calculated.The release efficiencywas significantly higher than that without laser irradiation.At the same time,the release of DOX·HCl was demonstrated at the level of cytotoxicity.In addition,the release efficiencies of DOX·HCl from liposomes/Au nanoshells were tested under acid and neutral conditions.The release efficiency was increased at pH=5.6 than that under pH=6.8.