This is intended to be a subpart of a BosLab competent cells protocol currently in development that is based on the Chung, Niemella, and Miller, 1989 protocol. Protocol verified to work and produce transformed E. coli at BosLab Novice Nights Dec 16th and 30th, 2021.
Materials:
100 mM CaCl2 aqueous solution
E.g. the 500 mL bottle of sterile 100 mM CaCl2 in 18 MΩ H2O in the BosLab 4°C fridge
Food grade CaCl2 powder is available for sale online (e.g. in the United States, try Amazon, Walmart) for homebrewing, winemaking, pickling, and cheesemaking. It may work for making TSS but as of Dec. 3, 2021, we have not tried this. You'll also have to guess at how many waters of hydration is with each molecule.
PEG 3350 powder
We have lab grade PEG 3350 at BosLab but it may be possible to use Miralax laxative powder from the drugstore. Miralax is 100% USP grade PEG 3350.
DMSO
E.g. we have 99% DMSO at BosLab which we used, but the BosLab teen class succeeded with their transformations without using any DMSO in their TSS.
60 mL syringe with compatible 0.22 µm (or smaller pore size) syringe filter to sterile filter the solution.
Use a Buchner funnel and a vacuum pump if you need to make more than 50 mL TSS.
LB media.
We use LB (Miller) media, which has 10 g/L NaCl, but it's likely that LB (Lennox) with 5 g/L NaCl will also work.
BosLab PCR workstation, laminar flow workstation, biological safety cabinet, or if DIY, work on a sanitized surface within 50 cm of a Bunsen burner flame