Data di Pubblicazione:
2017
Citazione:
Amino acid-deriving chiral polymers with potential for biotechnological applications / F. Lazzari, A. Manfredi, J. Alongi, E. Ranucci, P. Ferruti, N. Mauro, A. Terenzi. ((Intervento presentato al 11. convegno Materia 2020 tenutosi a Ischia nel 2017.
Abstract:
Introduction
Polyamidoamines (PAAs) represent a well-known family of soluble synthetic functional polymers with a recognized potential for biotechnological applications. PAAs are obtained by stepwise Michael-type polyaddition of prim-monoamines or sec-diamines with bisacrylamides. The reaction occurs at pH = 8-9 aqueous solution and at room temperature, with the involved amine groups preserving their amine character. By using α-amino acids as monomers, poly(amidoaminoacid)s (PAACs) are obtained.
PAACs maintain the chirality and the amphoteric properties of the starting monomers.
Material and Methods
(D)-,(L)- and (D,L)-Arginine were added to a suspension of N,N’-methylenebisacrylamide and lithium hydroxide in water under vigorous stirring. The reaction mixture was heated to 50°C for 5 days then acidified to pH = 4. To evaluate acid-base properties, 0.1 M NaCl solutions of ARGO7 isomers were titrated with 0.1 M NaOH and then back-titrated with 0.1 M HCl at 25°C under inert atmosphere.
Their secondary structure was investigated in aqueous solution by circular dichroism (CD) spectroscopy at 25°C and pH ranging from 3.0 to 10.0.
Results
Amphoteric polyamidoaminoacids isomers were obtained with 58% yield, Mn = 8500 and PDI = 1.08.
Their β corrected pKa1 (COOH) and pKa2 (main chain tert-amine) values were evaluated exploiting the modified Henderson-Hasselbach equation.
L-ARGO7 speciation curves show an isolectric point of ≈10 and +0.25 positive net average charges per repeating unit at pH 7.4, resulting in a highly citycompatible polymer with an IC50 ≥ 8 mg/mL.
Cell internalization in Balb/3T3 cells, also highlight its preferential localization in the perinuclear region.
Circular dichroism spectra show broad signals in the 250-340 nm region, but none at pH = 5.
Discussion
(D)-,(L)- and (D,L)-ARGO7 were obtained with yield and Mn comparable to previous Ca2+ catalyzed synthesis. Their pKa1 values resembled that of arginine, whereas pKa2 decreased by two units due to the acrylamide electron withdrawing effect. Both β constants exhibit deviations from ideal behaviour, more pronounced for the carboxyl group.
D- and L-ARGO7 gave mirror imaging CD spectra consistent with pH-dependent conformation transitions. These properties, together with the high cytocompatibility and a possible stereochemical-governed intracellular localization, may affect their interactions with biological structures as proteins and living cells.
Tipologia IRIS:
14 - Intervento a convegno non pubblicato
Elenco autori:
F. Lazzari, A. Manfredi, J. Alongi, E. Ranucci, P. Ferruti, N. Mauro, A. Terenzi
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