Preparation and Stability of Nano-gold Cold Melt Indicators Based on Different Stabilizers

In order to study the effect of different kinds of stabilizers on the properties of nano-gold sols prepared,nano-gold sols were prepared by using chloroauric acid as raw material and three kinds of stabilizers of trisodium citrate,sodium alginate and chitosan. The change of sol color before and after freezing,the change of sol plasma absorption peak and its peak value and the aggregation between particles were taken as indicators to study the stability of nano-gold cold-melt indicator prepared by different stabilizers before and after freezing. The results showed that:The color of the nano-gold sol prepared by using trisodium citrate as a stabilizer changed from wine red to transparent and colorless after one freezing. Nano-gold sol prepared by using chitosan as a stabilizer,the particles would accumulate after freezing,but the color would not change significantly. None of the above phenomena met the requirements for indicators. The nano-gold sol prepared by 2.0% sodium alginate and 10 mL of 1.0 mmol/L chloroauric acid solution was the most effective:After repeated freezing of the sol,the color changes from positive red to purple,and the color deepened with the increase of freezing time. The aggregation between the particles will change from a single dispersion to a cluster. All the above phenomena were in accordance with the requirements of nano-gold cold melt indicator. Therefore,the nano-gold sol prepared by using sodium alginate as a stabilizer is a good nano-gold cold-melt indicator.