Study On Transmembrane Dynamic Process Of Dendrimers PAMAM-loaded Drug Complexes Based On Force Tracing Technique

Among many nanodrug carriers,polyamidoamine(PAMAM)dendrimers have more superior performance.Unlike traditional drug delivery systems,the structure of the polyamideamine dendrimers compound is iteratively formed by dendritic branching units,thus resulting in a unique core-shell structure,whichmakes polyamideamine dendrimers many cavities inside.Through electrostatic attraction,hydrogen bonding,and physical action,polyamideamine dendrimers compounds can trap drug molecules into the cavity of the molecule to form nanodrug complexes.In addition,there are many terminal functional groups on the surface of the polyamideamine dendrimers compound.After chemical modification,the surface functional groups of polyamideamine dendrimers compounds can be conjugated with more drug molecules to form nano drug complexes.Due to its excellent performance,more and more researchers have focused their attention on the research and application of polyamide-amine dendrimer compounds as drug carriers.However,because of limitations in the spatiotemporal resolution of research methods,the first important step in the delivery of drugs into cells as drug carriers—the dynamic transmembrane process—is not yet particularly clear.Thus,in the study,the eighth-generation polyamideamine dendrimers(G8-PAMAM)and MTX(target drug)were used to prepare G8-PAMAM-MTX nano drug complexes by physical encapsulation.G4-PAMAM-MTX nanodrug complexes were prepared by chemical conjugated bondingwith the fourth-generation polyamideamine dendrimers(G4-PAMAM)as the raw material.Afterwards,we studied the dynamics parameters of G8-PAMAM-MTX nanocomposites and G4-PAMAM-MTX nanocomposites getinto and acrossthe cellular membranes based on the atomic force microscopy(AFM)single molecule "force-tracing technique".The dynamic process of single G8-PAMAM-MTX nano drug complexes and G4-PAMAM-MTX nano drug complexes getinto living cells were recorded in real time.The time and force required for the transmembrane process of the two nanodrug complexes were measured,the rate of the two nano-drugs enterinto the cell was calculated,and the mechanism of its endocytosis into the cell was further investigated.This study will provide a richer theoretical basis for the application of polyamideamine dendrimers compounds as drug carriers,and it will have important implications on the biomedical and pharmaceutical fields.The main contents include the following sections:1.Two nanomedicines,G8-PAMAM-MTX and G4-PAMAM-MTX,were prepared by physical encapsulation and chemical bonding,respectively,and then characterized.2.Record the dynamic process of the single G8-PAMAM-MTX nano drug molecule prepared by physical coating into living cells and measure the transmembrane force and the time and rate of entry into the cell,using AFM "force tracing" at the single molecule level.;study the endocytosis mechanism of G8-PAMAM-MTX nanomedicine into living cells.3.Record the dynamic process of G4-PAMAM-MTX nano drug molecules prepared by conjugated bonding into living cells,measure the transmembrane process force and the time and rate required for entering the cells by AFM "force tracing technology" at the single-molecule level.