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

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 150 nm for the PCDA/DMPC vesicles compared to 200 nm 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 1 mM PCDA exhibiting a slightly greater sensitivity to S.Choleraesuis than the other bacteria, while 2 mM and 3 mM PCDA exhibited greater selectivity for E. coli and S. aureus. Likewise, 1 mM 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 (6.7 μg ml−1; 35.0 μg ml−1 and 63.0 μg ml−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 6.70 μg ml−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 routine analyses.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 150 nm for the PCDA/DMPC vesicles compared to 200 nm 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 1 mM PCDA exhibiting a slightly greater sensitivity to S.Choleraesuis than the other bacteria, while 2 mM and 3 mM PCDA exhibited greater selectivity for E. coli and S. aureus. Likewise, 1 mM 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 (6.7 μg ml−1; 35.0 μg ml−1 and 63.0 μg ml−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 6.70 μg ml−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 CDA/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 routine analyses