Surfactant-Assisted Lipopolysaccharide Conjugation Employing a Cyanopyridinium Agent and Its Application to a Competitive Assay

DIEGO PALLAROLA; FERNANDO BATTAGLINI

ANALYTICAL CHEMISTRY

American Chemical Society

Lugar: Washington, USA; Año: 2009

0003-2700

The activation of a lipopolysaccharide (LPS) with 1-cyano-4-dimethylaminopyridinium tetrafluoroborate (CDAP) inthe presence of a surfactant allows an efficient conjugationwith dansyl hydrazine or horseradish peroxidase (HRP)in an aqueous medium maintaining its biological activity.In order to promote the reaction a series of amphiphiliccompounds were tested, sodium deoxycholate being themost suitable. The method presents several advantages:it is carried out in a mild environment, good conjugationratios are obtained, it is suitable for any label bearingamino, hydrazine, or hydrazide groups, and the LPSendotoxic and HRP enzymatic activities are preserved.The HRP conjugate is applied in an amperometric competitiveassay for the detection of lipopolysaccharides inan electrode array combined with a multipotentiostat ableto carry out simultaneous determinations. The system isable to detect samples in concentrations as low as 100pg mL-1 of LPS.