Development of PDA/Phospholipids/Lysine vesicles to detect pathogenic bacteria

• Published in: Sensors and actuators. B, Chemical Chemical, 2013-11, Vol.188, p.385-392
• Main Authors: de Oliveira, Taíla V., Soares, Nilda de F.F., Silva, Deusanilde J., de Andrade, Nélio J., Medeiros, Eber Antônio A., Badaró, Amanda T.
• Format: Article
• Language: English
• Subjects: bacteria; biosensors; color; colorimetry; Detection of S. Choleraesuis; Escherichia coli; food industry; food pathogens; light scattering; Lysine; particle size; phospholipids; Polydiacetylene vesicle; Salmonella choleraesuis; sphingomyelins; Staphylococcus aureus
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2013.06.022

Colorimetric response of PCDA/DMPC and PCDA/SPH/CO vesicles in the presence of S. Choleraesuis, E. coli and S. aureus. The behavior of blue polydiacetylene vesicles was studied in the presence of pathogens to evaluate their application as sensors for the food industry. In this study, lysine-containing vesicles of 10,12-pentacosadyinoic acid (PCDA)/dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC) and PCDA/Sphingomyelin (SPH)/Cholesterol (CHO) were tested to determine the colorimetric response induced by pathogenic bacteria (Staphylococcus aureus, Salmonella Choleraesuis and Escherichia coli). The structures were characterized using the dynamic light scattering technique in which the intensity correlation functions of dilute solutions were fitted using cumulant analysis. The PCDA/DMPC vesicles exhibited improved molecular packing compared to the PCDA/SPH/CHO vesicles, with a particle size of approximately 150nm for the PCDA/DMPC vesicles compared to 200nm for the PCDA/SPH/CHO vesicles. Subsequent to the vesicle assembly, their colorimetric response was evaluated. Importantly, the colorimetric response was more pronounced for the PCDA/SPH/CHO/Lysine vesicles than for the PCDA/DMPC/Lysine vesicles, indicating that the SPH/CHO decreased the activation barrier, thus improving the bacterial colorimetric response. The PCDA concentration influenced the vesicle selectivity, with 1mM PCDA exhibiting a slightly greater sensitivity to S. Choleraesuis than the other bacteria, while 2mM and 3mM PCDA exhibited greater selectivity for E. coli and S. aureus. Likewise, 1mM PCDA and the phospholipids SPH/CHO favored the detection of S. Choleraesuis, and due to the complexity of the bacteria behavior, additional studies were conducted. The colorimetric response was evaluated at various lysine concentrations (6.7μgml−1; 35.0μgml−1 and 63.0μgml−1) and pH values (5.0, 6.0 and 7.0) to improve the PCDA/SPH/CHO/Lysine vesicle specificity. At a lysine concentration of 6.70μgml−1, no color change in the PCDA/SPH/CHO/Lysine vesicles was observed in the absence of S. Choleraesuis, indicating that they were suitable for use in the food industry. In terms of pH, the expression of the lysine-dependent system was verified in PCDA/SPH/CO/Lysine vesicles at pH 5.0, although an increase in the pH value to approximately 6.5 provided the highest colorimetric response. Therefore, the PCDA/SPH/CHO/Lysine vesicles demonstrated great potential for use as a biosensor to detect food pathogens in ro