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Controlled Synthesis of Linear Polyamidoamino Acids.

ABSTRACT: Polyamidoamino acids (PAACs) are synthetic polymers prepared by the polyaddition of bisacrylamides with natural ?-amino acids, which in the process maintain both their chirality and their amphoteric nature. This polymerization process is slow, but has the merits of taking place in water and of neither involving protection/de-protection steps nor releasing by-products. However, it leads to polydisperse polymers and, using ?-amino acids mixtures, random copolymers. This paper presents a step-by-step polyaddition process leading to homo- and copolymeric PAACs with controlled sequences and controlled molecular weights. It exploits the much different rates of the two Michael addition steps of NH₂ of ?-amino acids with acrylamides, and the low solubility in organic solvents of the ?-amino acid addition products. As a proof of principle, the controlled synthesis of the PAAC from l-arginine and N,N'-methylenebisacrylamide was performed up to a monodisperse product with 11 monomeric units and molecular weight 1840. This synthetic procedure was also tested with l-alanine. All intermediates were isolated and characterized. Noticeably, all of them were ?,?-difunctionalized with either acrylamides or sec-amines and were, in fact, building blocks with potential for preparing complex macromolecular architectures. In a first instance, copolymers with controlled sequences of amidoamine- and amidoamino acid units were prepared.

SUBMITTER: Ferruti F

PROVIDER: S-EPMC6722684 | biostudies-literature | 2019 Aug

REPOSITORIES: biostudies-literature

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Controlled Synthesis of Linear Polyamidoamino Acids.

Ferruti Federica F Alongi Jenny J Manfredi Amedea A Ranucci Elisabetta E Ferruti Paolo P

Polymers 20190808 8

Polyamidoamino acids (PAACs) are synthetic polymers prepared by the polyaddition of bisacrylamides with natural α-amino acids, which in the process maintain both their chirality and their amphoteric nature. This polymerization process is slow, but has the merits of taking place in water and of neither involving protection/de-protection steps nor releasing by-products. However, it leads to polydisperse polymers and, using α-amino acids mixtures, random copolymers. This paper presents a step-by-st ...[more]

PMID: 31398875

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Project description:ObjectivesThis work aimed to design, synthesize and characterize replacement natural moisturizing factor (NMF) composed of modified hygroscopic linear amino acids to pre-empt or repair skin barrier dysfunction.MethodsFollowing synthesis and characterization, thermo-gravimetric analysis and quantum mechanics molecular modelling quantified and depicted water binding to the new compounds. Deliquescence relative humidity demonstrated the water-scavenging ability of the compounds, whereas snake skin moisturizing studies showed they increased water uptake into snake skin.ResultsFrom thermal analysis, N-hydroxyglycine showed greatest water-holding capacity followed by N-hydroxyserine, l-homoserine and ?-hydroxyglycine; coupled with quantum mechanics molecular modelling, between 8 and 12 molecules of water could associate with each molecule of either N-hydroxyglycine, N-hydroxyserine or l-homoserine. All of our modified amino acids were efficacious and induced similar or greater water uptake compared with the established moisturizing compounds hyaluronic acid, glycerine and urea in snake skin. Incorporated at 10% in Oilatum, N-hydroxyserine induced >200% greater moisture uptake into dry snake skin compared to treatment with water alone, with efficacy related to the molecule structure and ability to bind to 12 water molecules. Oilatum cream spiked with all our unnatural amino acid hydrotropes increased water uptake into snake skin compared with Oilatum alone. The compound series was designed to elucidate some structure - efficacy relationships. Amino acid chirality did not affect the water-holding capacity but did affect uptake into skin. Compounds with high melting points and bond energies tended to decrease water-holding capacity. With isosteric replacement, the more electronegative atoms gave greater water-holding capacities.ConclusionsThis work demonstrates the potential of unnatural amino acid hydrotropes as skin moisturizers and has developed some predictive 'rules' for further design and refinement of chemical structures.

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Controlled Synthesis of Linear Polyamidoamino Acids.

Publications

Controlled Synthesis of Linear Polyamidoamino Acids.

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