- Calculate the amount of AgNO3 to add to LB media solutions for desired final [Ag+].
- Remove PLA films, made on 2013/02/19, from glass molds.
- Soak PLA films in pure H2O to test for Ag+ leaching with a silver ion selective electrode.
- Run X-ray on 100Ag-LMT.
- Harvest DH5α-T1 cells for Ag+ cell growth inhibition studies.
DH5α-T1 Cell Harvesting
- Five cell starter cultures, made on 2013/02/19 were obtained and their absorbance at 600 nm was recorded.
- Please refer to Keyun Wang's entry for the absorbance data and the protocol to pellet the cells.
X-Ray Diffraction on 100Ag-LMT
- Peaks at values of 2θ were observed as follows: 19°, 21°, and 35°. These peaks correspond to d-spacing values of 4.491 Å, 4.277 Å, and 2.547 Å. When compared to the XRD spectrum of Laponite, there was a decrease in the d-spacing from 4.544 nm in Laponite to 4.491 nm in 100AgLMT. According to [literature], this decrease in d-spacing indicates that Ag+ was successfully exchanged into the clay galleries, as the structure of the clay has changed. Note that the peak at 21° may be attributed to background noise.
- The peak at around 35° represents a d-spacing of 2.547, similar to the same peak in the Laponite XRD spectrum that displays a d-spacing of 2.550. The similarities between these peaks indicate that the peak at 35° is due to the structure of Laponite.
- Two sample calculations are given as examples. The final [Ag+] in 50-mL solutions of LB media was calculated as follows:
1 μM Ag+ in 50 mL of LB media
(0.0105 M Ag+) × V1 = (1×10-6 M) × (50 mL)
V1 = 0.00476 mL of 0.0105 M AgNO3
10 μM Ag+ in 50 mL of LB media
(0.1 M Ag+) × V1 = (10×10-6 M) × (50 mL)
V1 = 0.005 mL of 0.1 M AgNO3
- AgNO3 solutions made on 2013/02/05 and 2013/02/13 will be added to the LB media solutions in the following amounts:
||Volume of AgNO3 Solution Added
| 1 μM||4.76 μL of 0.0105 M
| 10 μM||5.00 μL of 0.1 M
| 100 μM||50.0 μL of 0.1 M
| 1 mM||500 μL of 0.1 M
| 10 mM||5000 μL of 0.1 M
- Note that for each volume of AgNO3 added to the LB media, the same volume of LB media will first be removed from the flask to maintain the final concentration of Ag+.
ISE Study of PLA2002D + 5 wt% 100Ag-LMT
- To determine maximum [Ag+] possible, assume that all Ag+ leaches out of solution.
- The solution contained 50 mL pure H2O and 1 mL ionic strength adjuster. The recommended ratio of solution to ionic strength adjuster is 50 mL to 1 mL. Then, 0.50 g of film was added to the solution.
(4.47 × 10-8 mol Ag+) ÷ 0.051 L = 8.76 × 10-7 M or 0.876 μM
- Pour 50 mL pure H2O into a clean, dry 250-mL Erlenmeyer flask and add 1 mL of 5 M KNO3.
- Measure the conductivity of the solution with the ISE.
- Place a single 0.5 g piece of film into the flask, swirl, and measure the conductivity.
- Wait 30 min, then measure the conductivity again.
- Repeat the above step 5 more times.
||mol Ag+ [μmol]