Gelatin-templated gold nanoparticles as novel time-temperature indicator.
Gold nanoparticles (AuNPs) were generated by mixing of gelatin solution and gold precursor (HAuCl(4,) 1 mM) under isothermal condition (80 °C). The effects of gelatin concentration (1% to 6%) and pH (3, 5, and 9) on the color signal of gelatin-templated AuNPs were examined. The λ(max) of AuNPs shifted from 535 to 552 nm at 1% gelatin, and the color intensity of the AuNPs was a maximum at 2% gelatin. The speed of color development was accelerated at pH 3, and the AuNPs prepared at pH 3 were bigger (45 to 162 nm) and more irregular in shape than those prepared at pH 5 or 9. When the performance of gelatin nanoreactor as time-temperature indicator (2%, pH 5) was evaluated in a simulated frozen storage, clear color signals developed as little as 6 h of exposure at 30 °C and the intensity of the color signal was proportional to duration of exposure.


CONCLUSIONS
Gelatin-gold precursor mixture acted as a "nanoreactor" for gold nanoparticle synthesis without need for any additional reactants. When the gelatin-templated AuNPs were exposed to 30 °C, color signals developed with intensities that depended on the duration of exposure. The reaction was irreversible and colors were easily discerned by the naked eye.
Dept of Biological System Engineering, Univ of Wisconsin-Madison, USA.
Seokwon
S
Lim
Sundaram
S
Gunasekaran
Jee-Young
JY
Imm
D015374:Biosensing Techniques / Q000379:methods*; D003116:Color; D005780:Gelatin / Q000737:chemistry*; D006046:Gold / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D053768:Metal Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D013696:Temperature
D006046:Gold; D005780:Gelatin