What do colloids do?

Hello, everyone! I don’t know if you remember but this summer I’m working in Professor Kristin Wustholz’s lab using Surface-Enhanced Raman Scattering (SERS) to identify dyes in paintings created by Charles Willson Peale. When I came in this summer I had an official list of things I wanted to get done and learn. They were: [Read more…]

Have you ever watched colloids dry?

At the beginning of the summer I developed a series of steps that I need to complete in order to have a successful summer researching auto paints. The first step was stabilizing the colloidal silver nanoparticles that my lab uses; we call them colloids for simplicity. Colloids are a suspension of silver nanoparticles in a sodium citrate and water solution. Stable colloids can be applied to auto paint samples, amongst other substances, for surface-enhanced Raman spectroscopy analysis. The trick is getting them to remain stabilized. Over the past semester, our colloids were only stable for a max of two days. The lifespan of colloids should be upwards of two weeks. After reviewing the procedure that we had been using all semester, we found some flaws. We discovered that our sodium citrate was expired by three years and that we were not boiling the silver nitrate enough before adding the sodium citrate. We corrected these two details and now we have colloids that last for three weeks! With stabilized colloids, I am able to move on to step two, reproducibility of auto paint standards.

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