Gelatin-templated gold nanoparticles as novel time-temperature indicator

Area of Science:

• Nanotechnology
• Materials Science
• Chemical Engineering

Background:

• Gold nanoparticles (AuNPs) have diverse applications.
• Developing simple methods for AuNP synthesis is crucial.
• Gelatin can act as a template and stabilizing agent.

Purpose of the Study:

• To synthesize gelatin-templated gold nanoparticles (AuNPs).
• To investigate the effects of gelatin concentration and pH on AuNP characteristics.
• To evaluate the potential of these AuNPs as a time-temperature indicator.

Main Methods:

• AuNPs were synthesized by mixing gelatin solution with a gold precursor (HAuCl4) at 80 °C.
• Varying gelatin concentrations (1-6%) and pH levels (3, 5, 9) were tested.
• The optical properties (λmax, color intensity) and particle morphology were analyzed.
• Performance as a time-temperature indicator was assessed under simulated frozen storage conditions.

Main Results:

• Gelatin concentration influenced AuNP color intensity, peaking at 2%.
• pH 3 accelerated color development but resulted in larger, irregular AuNPs.
• The optimal formulation (2% gelatin, pH 5) produced a visual color signal upon exposure to 30 °C.
• Color signal intensity correlated with the duration of temperature exposure.

Conclusions:

• The gelatin-gold precursor mixture functions as a nanoreactor for AuNP synthesis.
• Gelatin-templated AuNPs provide an irreversible, visually discernible color signal proportional to temperature exposure time.
• This system offers a promising approach for simple time-temperature monitoring.