Arsenic is one of the most significant ground water contaminants, and the detection kits that have been used in the field up to this point have been unreliable and dangerous to use. In this project we set out to develop a novel colorimetric arsenic sensor based on the surface plasmon resonance of L-cysteine functionalized gold nanoparticles. The gold nanoparticles were synthesized using the Turkevich method, and they were then analyzed by via TEM, DLS and ICP-AES. The particles were then functionalized by the additions of small concentrations of L-cysteine. The functionalized particles were then tested for detection of three concentrations of arsenic (V) using UV-Vis Spectroscopy. The resulting optical spectra showed that lower maxima of absorbance was correlated with higher concentrations of arsenic. The results indicated a potential method of detection and quantification down to 5 ppb of arsenic in water by adding gold nanoparticles and then analyzing the absorbance peak of the optical spectra. It was concluded that L-cysteine functionalized gold nanoparticles have much potential to be used as a field sensor for mass arsenic detection, with some work still having to be done on selectivity, robustness, reproducibility and speed.This is how I came up with the idea for this project:
Knowing that I wanted to do something regarding nanotechnology and water, I decided to contact the KTH Materials and Nanophysics department. After having been given access to university literature, I slowly developed the aim of detecting arsenic in water with L-Cysteine functionalized gold nanoparticles.