1. Obtain bacterial culture with pre-transformed bacteria (with gene that synthesizes CdS)
2. Prepare subculture of bacteria cells into 200 mL of LB broth, OD600 = .6 at 37C
3. Prepare 6 samples: no bacteria control, no IPTG control, 3hr CdCl2, 2hr CdCl2, 1hr CdCl2 and a 3hr CdCl2 with no Na2S
4. The below procedure is based off of the summer iGEM procedure
5. Induce culture with .5 mM IPTG for 4 hours
6. Take 10 mL of LB medium with kanamycin
7. Add CdCl2 (approximately .00183g) until the final concentration is 1 mM
8. Incubate the sample for 3 hours (check progress each hour)
9. Add freshly prepared Na2S 9H20 (approximately .024018g) to final concentration 1 mM
10. Incubate samples at room temperature with end-over-end rotation for 1.5 hours
11. Wash final sample with water 3 times, place resulting sample under UV-vis and fluorescence spectrometry

1. Set negative control of experiment
   • Repeat steps 1-9 without the initial bacteria
   • This procedure ensures that the bacteria is synthesizing CdS (quantum dot)
2. Adjust the times of incubation
   • Adjust the the total times of incubation (suggested by steps 6 and 8)
   • Adjust by plus/minus 1 or 2 hours
   • Adjustment to see if incubation time affects the productivity in synthesis of CdS

Material Safety Data Sheet

Note: Protocol is based off experiment conducted by Mi et al.
Article source: Biosynthesis and characterization of CdS quantum dots in genetically engineered E. Coli from Journal of Biotechnology

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