One of our biosensor is detecting the level of lactate. In order to achieve this purpose, we constructed a lactate detection system (BBa_K2292005) in E. coli.
To test our lactate detection system worked or not, we added different concentrations of lactate into the liquid culture of E. coli DH5α which contains the lactate detection system.
a. The fluorescent density of each lactate concentration depends on time.
b. The fluorescent denity of different time point depends on lactate level.
c. Three-dimension diagram of fluorescence, time and lactate concentration
The difference of fluorescent intensity between adding each lactate concentration can be distinguished after 90 minutes. The experiment result demonstrates that the function of lactate detection system is work.
CSP detection system
PCR result：Prove that we successfully transformed our plasmid into E.coli, DH5α
The identical length of DNA is 2563 bp, hence from the electrophoresis gel photos above, we can prove that the plasmid DNA in well number 1, 3, 4, 8, 9, 10, 11, 13, 16, 19, 21, 24, 25, 27, 28 were successfully transformed, and the corresponding colonies are those colonies that we want.
The identical length of DNA is 1344 bp, hence from the electrophoresis gel photos above, we can prove that the plasmid DNA in all wells, except well number 5, 17,18 ,31 were successfully transformed, and the corresponding patches are those colonies that we want.
Functional test result
According to the measurement of absorbance of wavelength 595 nm, we can confirm that CSP isn’t toxic to Bacillus subtilis.
And after a series of experiment for measuring the fluorescent plate reader (excitation: 485 nm, emission: 520 nm), we found out that the optimally bacterial density for measuring the CSP conc. is at the value of OD600 = 0.2.
The intensity of fluorescence slowly drops after a sharp rise in a short amount of time, hence we can tell that the function starts working as soon as CSP is added.
Video demo - transparent version
Here is a prototype showing how to use Carindex.
In the second video we made the shell transparent so that you can see how it work clearly.
First of all, open the app and connect to device (through bluetooth).
Set the timer so that device can help you germinate the bacteria on the test paper while you are asleep.
When finish spitting your saliva into the container, press "detect". Our device will move the sample elevator to let the consumptive materials (the test paper) dipped onto the sample.
After the device finished doing its job, click "show risk of cavity". The detected data will be sent to the server, calculated through machine learning; then be sent back to the app, showing the risk and level of dental caries (% and # value). The pH test paper color displayed on the lower right corner can be used to read the corresponded pH value.