Anais da IX Conferência Internacional de Proteínas e Coloides Alimentares

Bilayer-structured polydiacetylene vesicles in physiological environments can be easily obtained from the assembly of amphiphilic diacetylene monomers with phospholipids incorporated, which resemble the cellular membrane structure, making them ideal for biosensing purposes and for studying protein-membrane interactions. The main lipids used as membrane compounds responsible to compress the vesicles are dimyristoyl-phosphocholine, sphingomyelin, and cholesterol. However, these lipids can increase significantly the price of the system. Therefore, other substances, such as polysorbate, commercially known by Tween 80, can be used as a cheaper membrane compound of the nanovesicles. Tween 80 is an ethoxylated sorbitan ester with amphiphilic properties, which are ideal for being used as a compound of nanovesicles. After the system formation, it has to be exposed to ultra-violet light to self-polymerize and assume the non-fluorescent blue form. Polydiacetylene nanovesicles can change their color when exposed to an external stimulus to a fluorescent red form, which is influenced by the composition of the nanovesicles. In this context, this study proposes to manufacture polydiacetylene (1 mM) and Tween 80 (1 mM) nanovesicles and study the color change under ammonia vapor exposure. Moreover, the potency (250 W and 500 W) and time of ultrasound (5 min and 15 min), and the time of ultra-violet light exposure (5 min and 10 min) were analyzed to understand the effect of these factors on the size, polydispersity index, and the color transition under ammonia vapor exposure (10 min). Systems around 170-300 nm were obtained after the polymerization. Conversely the expected, lower potency of the ultrasound tips (Modelo DES500, Unique Group, Brasil), combined with the highest time of ultrasound and ultra-violet exposure, resulted in the lowest size of the nanovesicles (168±10 nm) and polydispersity index (1.33±0.5), and more intense blue color (0.038±0.5 AU, at 640 nm). According to some authors, high-intensity turbulence generates by the sonochemical energy of ultrasound systems, induces droplets collision, regrouping, and leading to an increase in the size of the vesicles. The higher time of polymerization at ultraviolet light enabled more diacetylene monomers to polymerize, influencing in the visual color and the compatibilization of the nanovesicles. After ammonia exposure for 10 min, this system also exhibited an intense pink color (0.041±0.5 au, at 540 nm), and the nanovesicles' properties were 220±20 nm and 1.50±0.5 polydispersity index. The color transition induced by the vapor probably occurred due to the ionic interaction between the ammonia with the carboxyl’s polydiacetylene groups, changing the planarity of the hole structure. Volatile biogenic amines are the degradation products of enzymatic and microbiological metabolism of protein-rich foods, such as trimethylamine and ammonia, and these compounds can alter the pH of the food environment, generating unpleasant odors and flavors that may not be accepted by consumers. Therefore, through simple synthesis, the sensitive chromatic response of the polydiacetylene and Tween 80 nanovesicles demonstrated the feasibility of visual early detection of food spoilage in a broad temperature range furnishes significant practical advantages compared to existing food monitoring technologies.