Specificity and sensitivity comparative study between phage PVP-S1 and monoclonal antibody as receptor in polydiacetylene vesicles for Salmonella colorimetric detection

Abstract

Polydiacetylene polymer (PDA) has been intensively studied because of its properties as colour change from blue to red and change from non-fluorescent to fluorescent form due to an external stimulus that lead to a reorientation of the PDA within the organized structure. External stimulus could be temperature, pH, solvent influence, bacteria presence, mechanical stresses and others (Oliveira et al., 2012). Pires et al. (2010) support the hypothesis that such phenomena occurred due to conformational changes associated with the functional group rotation around the simple carbon-carbon bond present in PDA chains. When the backbones of PDA conjugated polymer chains are perturbed, the delocalized π-network induces changes in electronic absorption and emission properties (Huo et al., 1999). For a particular colour change, it is possible to incorporate a compound in the polydiacetylene carboxyl groups that will work as a specific receptor for the bacteria detection. This technology can be used for the detection of pathogens and thus is important to avoid food contamination once the standard technology demands long time and people trained. The selection of the receptor used in the PDA is the first critical step to develop a biosensor with improved selectivity, selectivity and stability. For this reason, the aim of this study was to make a comparative study between two recognition molecules: phage PVP-S1 (Santos et al., 2011) and a monoclonal antibody in the PDA sensor for the detection of Salmonella. Antibodies lack specificity, poor separation efficiency and sensitivity. Phages are extremely specific, withstand harsh environments, are economically and easily produced, show high stability during storage and thus present potential for bacterial detection. Overall the selection of the recognition molecule that show the best features is important to develop a simple and rapid sensor for the industry and consumer’s life. The specificity of the sensor was proven by using Staphylococus aures and Escherichia coli as gram-positive and gram-negative controls, respectively.