Colorimetric sensing of lactose through formation of gold nano-particles

Abstract

The lactose is sugar of the animal milk and a major source of carbohydrate. Either it is cow milk or buffalo milk or goat milk, lactose is found in all of the above mentioned sources of animal milk. One of the adulterations in the animal milk is playing with lactose concentration by either diluting it or completely replacing it with synthetic chemicals. Hence lactose sensing in the milk becomes very important. The present work reports colorimetric sensing of lactose using gold nano-particles (GNP). The GNPs have been synthesized and verified by UV–vis spectroscopy (UVS), Transmission electron microscopy (TEM) and Selected area electron diffraction pattern (SAED). The different amount of synthetic lactose (0.5 to 100 mM) was sensed by the color change of the GNP seed solutions (colorimetric sensing) and the absorbance (absorption coefficients) in UVS. Based on absorbance of the seed solutions, kinetic and time dependent studies are also performed. Though this work focuses on synthetic lactose sensing, the real milk samples will be tested for lactose concentration in the next phase of this work.