Background

According to our large-scale worldwide survey and the field event, many people regard it as a shame to take medicine related to drugs. When designing our administration route, we took both convenience and privacy into consideration. Finally, we reached the ideal version of our Cannabis “Vaccine”.

Freeze-dried Powder

After our extensive literature research, we finally chose the vacuum freeze-drying method as our living bacteria preparation form and found the formulation of a protective agent for our chassis in the project of SZU-China 2021（Team:SZU-China/Drug Form - 2021.igem.org）.The lyophilized protectant formula is 3% sucrose concentration, 14.25% skim milk concentration, and 3% L-ascorbate sodium.According to SZU-China, the highest enzyme activity per unit resuscitation was 5.2686x108 CFU/ mL, suggesting that the protectant could reduce cell damage caused by freeze-drying to a large extent.

Moreover, during our experiment, we surprisingly found that the C-phycocyanin might be oxidized to brown but not remain blue in the air.^[1]This may cause interference for visualization. Therefore, we tried to find some feasible methods to ensure the stability of C-phycocyanin. Finally, the whey protein came into our sights, which was proved to result in blue color maintenance.^[2]Thus, we designed to pack the whey protein powder along with the freeze-dried powder of our engineering bacteria in a suitable capsule, so as to release them together and let the whey protein to protect the C-phycocyanin.

Capsules

After searching for a lot of information, we finally chose to use the capsule to coat the freeze-dried powder with hydroxypropyl methylcellulose as container .The seemingly common capsule is actually cryptic, giving consideration to both privacy and convenience.In our design, our capsule is divided into two parts, namely the freeze-dried powder module and the whey protein powder module, separated by the same material as its shell. When it comes to the capsule material, we specially chose the hydroxypropyl methylcellulose^[3], helping the capsule resist gastric acid and specifically be digested in the intestines.

Fig 1.Capsule divided into two parts (freeze-dried powder part and the whey protein powder part)

After being taken, our capsule will safely enter the intestines and break down soon. Apart from the freeze-dried powder of our Nissle 1917, the whey protein will also be released into the intestinal environment to prevent the oxidation of the C-phycocyanin.