Title: Colorimetric Indicators based on polydiacetylene and Tween 80: A Fast and Simple Alternative for detecting microbiological contaminants

The food industry has been facing numerous critical challenges associated with microbiological contamination, directly linked to the early detection of contaminants and the preservation of food quality. Therefore, this study aimed to propose an efficient, simple, practical, and affordable solution to indicate the presence of contaminating microorganisms in food to prevent deterioration caused by them. In this regard, polydiacetylene (PDA) vesicles were synthesized from 10,12-pentacosadiynoic acid (PCDA) diacetylene monomers, conjugated with Tween 80, and polymerized under ultraviolet light for 10 minutes (patent BR1020140044850). Sensitivity tests were conducted to assess the colorimetric transition capacity of PDA vesicles in the presence of bacterial suspensions peviously activated in culture medium broth (37°C, 24 h), at 106 CFU.mL-1. The bacteria tested were Pseudomonas aeruginosa ATCC 15442, Escherichia coli ATCC 11229, Staphylococcus aureus ATCC 6538, Listeria monocytogenes ATCC 15313, and Salmonella enterica serovar Choleraesuis ATCC 10708. After 15 minutes of interaction between 1 mL of PDA vesicles and 1 mL of each aforementioned microbial suspension, a color change from blue to translucent light green occurred. The results suggest that PDA vesicles can be an interesting option to detect and control the microbiological quality of food since, they can change their color in the presence of important foodborne pathogens, spending less time than conventional methods and at a more affordable cost. Therefore, the developed system has the potential to be applied as a rapid-response diagnostic test for indicating and controlling the microbiological quality of food matrices.