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Self‐Assembly of Lipoaminoacids‐DNA Based on Thermodynamic and Aggregation Properties
Author(s) -
Faustino Célia,
Martins Tiago,
Duarte Noélia,
Ribeiro Maria H.
Publication year - 2020
Publication title -
journal of surfactants and detergents
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.349
H-Index - 48
eISSN - 1558-9293
pISSN - 1097-3958
DOI - 10.1002/jsde.12391
Subject(s) - chemistry , critical micelle concentration , gibbs free energy , micelle , ethidium bromide , alkyl , organic chemistry , dna , biochemistry , aqueous solution , physics , quantum mechanics
Abstract Lipoamino acids (LAA) are biocompatible and biodegradable biosurfactants, a promising alternative to viral vectors in gene delivery. LAA are constituted by a polar head, the amino acid, and a hydrocarbon (alkyl) chain usually from a fatty acid or fatty acid derivative, such as a fatty amine or a fatty alcohol. In this work, dodecyl LAA was produced from dodecylamine and natural l ‐amino acids cystine (Cys), lysine (Lys), and phenylalanine (Phe) using an enzyme‐based approach with porcine pancreatic lipase. The self‐assembly behavior of LAA solutions, in the absence or presence of DNA, was studied by conductivity and fluorescence regarding the application as transfection agents. Conductivity measurements yielded important system parameters, including critical micelle concentration (CMC) and standard Gibbs energy of micellization (Δ G ° mic ) for pure LAA systems, and apparent critical aggregation concentration (CAC app ) and apparent standard Gibbs energy of aggregation (Δ G ° agg ) for the mixed LAA‐DNA systems. The CMC increased in the order of decreasing lipophilicity: (C 12 Cys) 2 < C 12 Phe < C 12 Lys, CMC values were higher in the presence of DNA, suggesting the formation of a LAA‐DNA complex responsible for hindering the micellization process. Binding of the LAA with DNA was confirmed from fluorescence measurements for the ethidium bromide exclusion assay. Results suggest a weak interaction of the LAA with DNA which can be attributed to their relatively short dodecyl chains and/or the ionic strength of the buffer solution, supporting the role of hydrophobic interactions in complex formation between DNA and the oppositely charged surfactant in combination with electrostatic interactions. The CAC app values decreased with increasing LAA hydrophobicity, reflecting the relevance of hydrophobic interactions in complex coacervation.