Abstract

A novel time-temperature indicator (TTI) with instantaneous color change was developed by applying cysteine-loaded pH-responsive liposome/gold nanoparticles (Cys-pRL/AuNP) as a pH indicator to the glucose oxidase/glucose (GOx/Glu) TTI. It was hypothesized that the pH change caused by gluconic acid production causes cysteine release from the Cys-pRL, resulting in the AuNP aggregation (red→blue) at the pRL critical pH. The Cys-pRL with a lipid bilayer (phosphatidylcholine/dioleoylphosphatidylethanolamine/cholesterol/oleic acid in molar ratio of 24/24/40/12) was prepared by the freeze-drying method. The spherical morphology of the Cys-pRL was confirmed from TEM micrographs. FTIR analysis revealed that the cysteine was captured in the Cys-pRL. The critical pH of the pRL was found to be 4.0–4.7 by using [Cys-pRL/AuNP]/HCl. [Cys-pRL/AuNP]/[GOx/Glu] TTI showed the instantaneous color change in a narrow transition zone (pH 4.0–4.6), whereas a conventional TTI with regular pH indicator bromocresol green/[GOx/Glu] showed the gradual color change in a wide transition zone (pH 3.9–6.1).

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.