Cysteine-loaded pH-responsive liposome/gold nanoparticles as a time-temperature indicator with instantaneous color change. (October 2021)

• Record Type: Journal Article
• Authors: Lee, Ji Hyun; Koo, Yong Keun; Cho, Hye Won; Cha, Hee Jin; Shin, Dong Un; Oh, Tae Gyu; Lee, Seung Ju
• Is Part Of: Innovative food science & emerging technologies. Volume 73(2021)
• Publication Date: 2021-10
• Subjects: Instantaneous color-changing TTI -- pH-responsive liposome -- Gold nanoparticle/cysteine aggregation -- pH change by glucose oxidase; Food -- Biotechnology -- Periodicals; Food industry and trade -- Technological innovations -- Periodicals; Aliments -- Biotechnologie -- Périodiques; Food -- Biotechnology; Periodicals; Electronic journals; 664.005
• DOI: 10.1016/j.ifset.2021.102794
• Languages: English
• ISSNs: 1466-8564

Abstract

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). Highlights: A new time-temperature indicator was developed with liposome system. The time-temperature indicator was based on enzymatic pH change. The liposome system consisted of pH-responsive lipid, cysteine, and gold nanoparticle. The cysteine entrapped in the liposome was released at its critical pH. The reaction of cysteine and free gold nanoparticles caused an instantaneous color change.