Four cationic chiral amino acid-based surfactants, cis- and trans-1 and cis- and trans-2, have been studied as DNA-condensing agents with enhanced properties and the absence of cell toxicity. The polar head of the surfactant is made of a cyclobutane β-amino acid in which the amino group is a hydrochloride salt and the carboxyl group is involved in an amide bond, allowing the link with hydrophobic C₁₂ (surfactant 1) or C₁₆ (surfactant 2) chains. The ability of these surfactants to condense DNA was investigated using a dye exclusion assay, gel electrophoresis, and circular dichroism and compared with the well-studied dodecyltrimethylammonium bromide (DTAB) and cetyltrimethylammonium bromide (CTAB). The surfactant with the longest chain length and the trans stereochemistry (trans-2) was found to be the most efficient in condensing the DNA, including CTAB. Surfactant cis-2 was found to be less efficient, probably due to its poorer solubility. The β-amino acid surfactants with the shorter chain length behaved similarly, such that the cis/trans stereochemistry does not seem to play a role in this case. Interestingly, these were also found to induce DNA condensation for the same concentration as trans-2 and CTAB but showed a lower binding cooperativity. Therefore, a longer alkyl chain only slightly improved the effectiveness of these surfactants. Further, atomic force microscopy revealed that they compact DNA into small complexes of about 55–110 nm in diameter.

中文翻译：

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手性 β-氨基酸基阳离子表面活性剂诱导的高效 DNA 缩合

四种基于阳离子手性氨基酸的表面活性剂，顺式和反式- 1和顺式- 和反式- 2，已作为 DNA 缩合剂进行了研究，具有增强的特性和无细胞毒性。表面活性剂的极性头由环丁烷β-氨基酸组成，其中氨基为盐酸盐，羧基参与酰胺键，可与疏水性C ₁₂（表面活性剂1）或C ₁₆（表面活性剂2) 链。使用染料排除测定、凝胶电泳和圆二色性研究了这些表面活性剂凝聚 DNA 的能力，并与经过充分研究的十二烷基三甲基溴化铵 (DTAB) 和十六烷基三甲基溴化铵 (CTAB) 进行了比较。发现具有最长链长和反式立体化学 ( trans - 2 ) 的表面活性剂在缩合 DNA 方面最有效，包括 CTAB。发现表面活性剂cis - 2的效率较低，可能是由于其溶解度较差。具有较短链长的β-氨基酸表面活性剂表现相似，因此顺式/反式在这种情况下，立体化学似乎不起作用。有趣的是，还发现它们在与trans - 2和 CTAB相同浓度下诱导 DNA 凝聚，但显示出较低的结合协同性。因此，较长的烷基链仅略微提高了这些表面活性剂的有效性。此外，原子力显微镜显示它们将 DNA 压缩成直径约 55-110 nm 的小复合物。