Lipopolysaccharides properties and potentiometric detection method

Abstract

The main component forming the outer membrane of gramnegative bacteria is lipopolysaccharide (LPS). LPS is endotoxin which causes sepsis in animal cells. Lipopolysaccharide molecule has three main components: lipid A, core oligosaccharide and O antigen. Hydrophobic part responsible for the immune response and the hydrophilic part is responsible for the micelle formation process. Lipopolysaccharide molecules associate on the membrane surface forming LPS-LPS complex which is stabilized by divalent cations such as Ca+2 or Mg+2. Potentiometric analysis with ion-selective electrodes is fast, accurate, real-time method selectively detect the desired ion. Membrane (sensor) synthesis is very important electrode production phase; inadequate membrane means poor or non-response to the desired ion. There is no references about potentiometric detection of amphiphilic ranging negatively charged anion. The scientific literature abound evidence that not a single LPS molecule induces an immune response in animal cells but associated molecules units- micelles. There is data that in 10 pg/ml LPS solution molecules are aggregated, therefore forming micelles. The aim of this study is to determine the concentration of released LPS from E. coli KMY using potentiometric analysis. This method is based on direct potentiometry. According to the linear response, using linear trendline, different concentrations of bacterial suspension were analysed. Bacteria were affected with Polymyxin E antibiotic which selectively binds to LPS.