Organic antifreeze discrimination by pattern recognition using nanoparticle array

We report a colorimetric nanoparticle array for discrimination of five organic antifreezes containing ethylene glycol (EG), formamide (FA), ethanol (EtOH), glycerin (Gly), and polyethylene glycol (PEG). Silver nanopartciles, gold nanoparticles, and Prussian blue nanoparticles are employed to be three sensing elements due to their unique optical absorption properties. The organic antifreezes can alleviate the aggregation of three nanoparticles after a freeze-thawing cycle. Based on the different freezing resistances of various antifreezes, the sensor array shows a unique colorimetric pattern of absorbance variations for each antifreeze, which is further analyzed by principal component analysis (PCA). The present sensor array has the capacity to differentiate antifreezes and their mixtures at a concentration as low as 50 mM. Moreover, the sensor array can also discriminate organic antifreezes in real water sample. Additionally, a high accuracy (100%) examination of 30 unknown samples is achieved.