Synthesis and characterization of fourth generation polyester-based dendrimers with cationic amino acids-modified crown as promising water soluble biomedical devices

Dendrimers are nanostructured architectural motifs which fascinate researchers for their several potentiality due to well-tailored structure, symmetric tree-like shape, and abilities in entrapping or binding hydrophilic or hydrophobic entities such as genetic materials, drugs, and target molecules. Nowadays dendrimers inhabit the top places among the materials suitable for biomedical applications as drug delivery, gene transfection, and imaging. In this work, we report the design and realization of two versatile successful procedures to decorate a fourth generation polyester-based dendrimer matrix with a mixture of four different amino acids. The hydrochloride dendrimers achieved after removal of protecting groups were characterized by a core-shell structure. They harmonized a not charged hydrolysable inner matrix potentially able to accommodate hydrophobic molecules and a cationic highly hydrophilic crown conferred by biocompatible amino acids that provided very satisfactory buffer capacity and will allow easy host/guest electrostatic interactions. Their structures and peripheral composition were confirmed by NMR analysis and experimental molecular weight computed by volumetric titration, while their buffer capacity was obtained by potentiometric titrations. Because in the inner matrix, the achieved hetero dendrimers do not present the high density of positive charges typical of PAMAM, they ensure a lower level of toxicity. But thanks to the cationic periphery, as preliminary investigations still in progress have already put in evidence, they were able to entrap not water soluble molecules by electrostatic interactions, with the result to increase their water solubility in a very satisfactory or amazing way. They therefore represent two new very promising devices for biomedical applications.