Preparation And Application Of Aptamer Functionalized Nanodrug Delivery System

In conventional cancer therapy,nanomaterials that fail to distinguish between tumor cells and normal cells often lead to adverse side effects and higher systemic toxicity.Therefore,more and more attention has been paid to the development of multi-functional nano-platform for a variety of biomedical applications.Aptamers are a single-stranded oligonucleotide that can specifically recognize their substrates,such as metal ions,small molecule,proteins,and even cells.Owing to their high specificity,aptamers can endow the delivery system with robust targeting ability and enhance the enrichment of drugs and imaging agents in tumor tissues,holding great promise in molecular diagnosis and cancer therapy.Here,we constructed a multifunctional aptamer-modified nano-platform for tumor cell-targeted upconversion luminescence imaging and photodynamical effects to promote NO release.The specific research results are summarized as follows:1.Aptamer functionalized liposome delivery platform based on UCNPs@Apt-Lip for tumor cells-targeted upconversion luminescence imagingHere,we designed a NIR-activated optical imaging and target-recognition multifunctional nanoplatforms by the capsulation of poly?acrylic acid??PAA?coated NaYF₄:Yb/Er/Nd@NaYF₄:Nd upconversion nanoparticles?UCNPs-PAA?within aptamer-guided liposome?Apt-Lip?to form UCNPs@Apt-Lip.Transmission electron microscopy?TEM?images showed that the composite nanomaterials had a uniform spherical structure,and the UCNPs nanoparticles were successfully loaded into the liposome modified by AS1411 aptamer,and the monodispersity of nanoparticles was good.Dynamic light scattering?DLS?detected further confirmed that the AS1411 aptamer was successfully connected to the surface of UCNPs@lip.In addition,UCNPs@Apt-Lip was able to maintain its stability after 48 h by measuring the hydrodynamic diameter of UCNPs@Apt-Lip within 48 h and the release ratio of the loading in 5%FBS and DPBS solutions,respectively.Flow cytometry and targeted cell fluorescence imaging experiments show that UCNPs@Apt-Lip nanostructure has strong ability of target recognition and fluorescence imaging to MCF-7 cells.With the unique properties of movable cores,interstitial hollow spaces,and the functionality of shells,we believe that multifunctional nanoplatforms will have great potential for application in various fields,such as photocatalysis,nanoreactors,drug delivery and tumor treatment.2.Aptamer functionalized liposome delivery platform based on L-Arg/ICG@Apt-Lip for tumor cells-targeted photodynamic effects to promote NO releaseWe prepared the aptamer-functionalized liposome drug delivery system based on L-Arg/ICG@Apt-Lip,and utilized the strong ox idant singlet oxygen generated by photodynamical effects to enhance NO release in tumor cells.TEM images confirmed that the liposomes have the spherical structure and a uniform size with an average size of 206.3±40.8 nm.In addition,we also synthesized micro-sized L-Arg/ICG@Apt-Lip and then confirmed the successful modification of Apt-Lip by flow cytometry and laser confocal fluorescence co-localization imaging.Finally,to verify whether L-Arg/ICG@Apt-Lip can enhance the NO release under 808 nm laser excitation,H₂O₂ was used to simulate the oxidative environment in the tumor microenvironment,the absorption peak of NO at 54 0 nm was detected by Griess reagent method.The result shows that the absorption peak increases with L-Arg/ICG@Apt-Lip under 808 nm irradiation,indicating that Singlet oxygen generation by the photodynamic effects can promote NO release.