On the interaction of the lipopolysaccharide-specific LA27 aptamer and asymmetric lipid bilayers mimicking the external bacterial membrane.

Aptamers are single-stranded nucleic acid molecules that bind target molecules with a high affinity and specificity, favoring their detection. Different aptamers are used in the detection of lipopolysaccharides (LPS). The most widely used is the B2 aptamer, while various truncated forms of different length were analyzed. The LA27 variant showed a doubled binding affinity with respect to the parent aptamer, thus offering an LBA ultrasensitive and selective detection of LPS endotoxin. The portion of LPS molecule interacting with LA27 was not understood yet. Any clear information on the affinity of the LA27 aptamer with respect to LPS molecules deriving from different kind of Gram(-) bacteria was investigated yet. In this context, we are interested in understanding the interaction between LA27 and LPS-containing asymmetric lipid bilayers as mimics of the external bacterial membrane.