Time temperature indicators made with sublimating azulene derivatives as the functional dye for use of fast reaction rate

Abstract

Time temperature indicators (TTIs) based on a dye sublimation process have been developed for full time monitoring of heat sensitive vaccines with shorter shelf-life during cold chain transportation and storage. The structure of TTI and the methods to make the TTI are introduced. TTI 1 and TTI 2 introduced in the article were made with methyl azulene-1-carboxylate and methyl 3-methylazulene-1-carboxylate as the functional dyes, respectively. The kinetic parameters of TTI 1 and TTI 2 were studied.

Principle, development and application of time–temperature indicators for packaging

“…95 Therefore, exploration of novel TTIs for monitoring vaccine transportation and storage is still in strong demand. 96 Shi and coworker 97,98 Reproduced with permission from ref. 100 Copyright 2021 American Chemical Society.…”

“…Shi and coworker 97,98 developed a simple structured TTI consisting of a substrate layer, an isolation layer and an absorption layer (Figure 6A) taking advantage of the sublimation property of guaiazulene derivatives, which could be utilized to monitor the temperature regarding vaccines. For example, methyl 5‐isopropyl‐3,8‐dimethyl‐azulene‐1‐carboxylate (MIDAC) could present a colour change from colourless to violet and finally to purple over time when tested at 37°C (Figure 6A).…”