Polyamidoamines: Versatile Bioactive Polymers with Potential for Biotechnological Applications

Abstract

Polyamidoamines (PAAs) are multifunctional polymers prepared from prim-or sec-amines by Michael-type polyaddition with bisacrylamides. The reaction is preferably carried out at room temperature in water and without added catalysts or organic solvents. The reaction is specific. The presence in the starting monomers of additional functions, leaving apart amine, thiol and phosphine groups, does not interfere with the polymerization process. Consequently, PAAs are a polymer class endowed with unusual structural versatility. Moreover, at pH > 7 they are hydrolytically degradable in aqueous media to harmless products mostly consisting of β-amino-propionic acids. Many PAAs are remarkably biocompatible notwithstanding their polycationic nature. These properties allow to prepare multifunctional polymeric structures suitable for many diversified applications in biotechnology, such as drug carriers, transfection promoters, antiviral and antimalarial agents, hydrogels scaffolds for tissue engineering. The objective of this paper is to fully report the PAA chemistry and the studied biotechnological applications of a vast PAA library.

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“…Synthetic and natural polymers, organic surfactants, inorganic compounds and bioactive molecules have been extensively used as a surface coating for nanoparticle functionalization, improving its stability, pharmacokinetics, biodistribution and biocompatibility [4,6]. Aminodextran (AMD) is one of the most promising nontoxic polymers used for coating a wide variety of theranostic agents due to their excellent physico-chemical properties and physiological acceptance.…”

Highlight on the Mechanism of Linear Polyamidoamine Degradation in Water

“…Linear polyamidoamines (PAAs) are the aza-Michael polyaddition products of prim-monoamines or bis-sec-amines with bisacrylamides [ 1 , 2 , 3 ]. A recent development of PAA chemistry consisting of employing natural α-amino acids as monomers has led to polyamidoamino acids (PAACs), a novel class of polymers deriving from natural α-amino acids, which maintain the α-amino acid chirality and amphoteric properties [ 4 , 5 , 6 , 7 , 8 , 9 ].…”

“…Tuning PAA degradation and identifying the nature of PAA degradation products is of paramount importance for predicting their behavior in different model environments, as for instance biological fluids, aquifers and wet soil. The degradation mechanism of PAAs has long been considered hydrolytic and internally catalyzed by the chain tert-amine groups located in the γ-position to the chain amide groups [ 1 , 2 ]. This hypothesis was apparently supported by the fact that the degradation occurred at pH > 7 where the PAA chain tert-amine groups were mostly unprotonated and, therefore, capable of exerting their catalytic activity.…”