Fluorescence-based sensing matrices for heavy metal detection in water, spoilage monitoring and urea detection in milk

Abstract

The first objective of this study is the detection of heavy metal ions in water using fluorescent Carbon Quantum Dots. Carbon Quantum Dots are carbon nanoparticles (size around or less than 10nm) that show fluorescence upon excitation with a light of a particular wavelength. Heavy metal ions behave as quenchers when they come in contact with Carbon Quantum Dots. The degree of quenching is directly proportional to the heavy metal concentration in the sample (in the concentration range of 0- 100µM). Using this phenomenon, the presence or concentration of heavy metals can be determined. Heavy metals like Mn, Pb, Ni, Co, Hg and Cr showed a linear relationship between the heavy metal ion concentration in the solution phase and the fluorescence intensity of Carbon Quantum Dots. Same beavious is observed in Carbon Quantum Dot embedded thin film also. The study reports the developmental a fluorescence based thin that cat detect heavy metal ion ceoncemtration in water. The second objective of this study is the detection of mil spoilage and urea adulteration using recombinant mTFP. mTFP is a fluorescent protein that shows pH sensitivity. The change in pH leads to a change in the fluorescence intensity of the protein. This property is used to detect milk spoilage. When mixed with the urease enzyme, urea adultered milk shows a rapid pH change. This pH change causes a change in the fluorescence intensity of mTFP and is detected by the fluorescence reader. This study reports urea detection in milk in the range of 0-100mM.