Gold NP separations with SiN-NP
Karl and attempted to pass 10, 20, 40 and 50 nm Au NPs through samples from the center of wafer # 1019 (avg por dia 50-60 nm, porosity ~27%). The bottles of stock Au from BBI solutions do not have the concentrations marked, but according to BBI’s website, they only sell the concentrations provided in the jpg I attached below:
We diluted the Au NPs using 3 parts filtered water + 1 part Au solution. The final concentrations should be as listed below. (We ran the samples through the Malvern as well and that data is included in the parentheses.)
10 nm – 1.9 E12 particles/mL (Z-ave ~22 nm, peak 1 15 nm, peak 2 ~350 nm)
20 nm – 2.3 E12 particles/mL (Z-ave ~ 28 nm)
40 nm – 3 E12 particles/mL (Z-ave ~ 41 nm)
50 nm – 1.5 E12 particles/mL (Z-ave ~ 54 nm)
We started out spinning the SEPCONs at 3krpm for 10-15 minutes in order to get ~100 uL of filtrate from a starting volume of 400 uL. Once we used 40 nm particles, we saw pelleting along the side of the tube on both the filtrate and retentate side. We redid the 40 nm and then the 50 nm using the pressure cell at ~2 psi for 10-15 minutes using the same volumes. We measured the absorbance using the quartz cuvette with 60 uL of solution in the TECAN. We typically flushed the filter after each gold passage with a centrifuge run with water. We tested both the retentate and filtrate of the water run to make sure there was no residual gold. (I forgot to do this in between the 40 and 50 nm runs, but I included a lower “placeholder” bar in the plot below)
The plot shows that 10, 20, and 40 nm Au passed through the pores, while the 50 nm NPs did not.
