title: Biopolymer/gold nanoparticles composite plasmonic thermal history indicator to monitor quality and safety of perishable bioproducts.
abstract: Quality and safety of perishable products such as foods, pharmaceutics, and biologicals is a constant concern. We have developed a plasmonic thermal history indicator (THI) taking advantage of the localized surface plasmon resonance of gold nanoparticles (AuNPs) synthesized in situ in alginate, a natural polysaccharide. The color of the THIs becomes more intense with increased storage temperature and/or duration, with the color changing from grey to red with time of exposure at high temperature (40°C). The results suggest that decreasing viscosity with increasing number of AuNPs being synthesized in the system, along with aggregation of newly synthesized AuNPs onto larger ones and their settling are potentially responsible for the distinct color change observed. The use of alginate in the THIs also facilitates fabricating them as solid hydrogel matrices by adding divalent calcium ions. This alginate-AuNPs THI system is tunable by altering its composition to suit different time-temperature monitoring scenarios and the color-change reaction is irreversible. The THI provides a convenient, reliable, safe, and inexpensive means for tracking the thermal history of perishable products without the need for a read-out device.
authors.affiliation: Department of Biological Systems Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA.
authors.forename: Yi-Cheng
authors.initials: YC
authors.lastname: Wang
authors.affiliation: Department of Biological Systems Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA.
authors.forename: Lin
authors.initials: L
authors.lastname: Lu
authors.affiliation: Department of Biological Systems Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA. Electronic address: guna@wisc.edu.
authors.forename: Sundaram
authors.initials: S
authors.lastname: Gunasekaran
mesh_terms: D000464:Alginates / Q000737:chemistry*; D003116:Color; D003124:Colorimetry / Q000379:methods*; D020723:Glucuronic Acid / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D064088:Hazard Analysis and Critical Control Points / Q000379:methods*; D006603:Hexuronic Acids / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D020349:Surface Plasmon Resonance / Q000379:methods*; D013696:Temperature; D014783:Viscosity
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D006046:Gold; D020723:Glucuronic Acid
keywords: Colorimetric sensors; Food safety; Hydrogel; Intelligent packaging; Localized surface plasmon resonance (LSPR); Time temperature indicator