One of our biosensor is to detect the level of lactate. In order to achieve this purpose, we constructed a lactate detection system (BBa_K2292005) in E. coli.
In order to test our lactate detection system work or not, we add different concentrations of lactic acid into the liquid culture of E. coli DH5α which contain lactate detection system.
a. The fluorescence of each lactate concentration depends on time.
b. The fluorescence of different time point depends on lactate level.
c. Three-dimension diagram of fluorescence, time and lactate concentration
The fluorescence difference between each concentration of lactate is more obvious after 90 minutes. The experiment result demonstrates that the function of lactate detection is work.
CSP detection system
PCR result：Prove that we successfully transformed our plasmid into E.coli, DH5α
The DNA size we expect to show up is 2563 bp, hence from the electrophoresis gel photos above, we can say that the plasmid DNA in well number 1, 3, 4, 8, 9, 10, 11, 13, 16, 19, 21, 24, 25, 27, 28 are those we want, and the corresponding patch are those that are successfully transformed.
The DNA size we expect to show up is 1344 bp, hence from the electrophoresis gel photos above, we can say that the plasmid DNA in all wells, except well number 5,17, 18 ,31, are the ones we want, and the corresponding patch are those bacteria that has been successfully transformed.
Functional test result
According to the measurement of absorbance of wavelength 595 nm, we can confirm that CSP isn’t toxin to Bacillus Subtilis.
And for the measurement of the fluorescent plate reader (excitation: 485 nm, emission: 520 nm), we found out that the best amount of bacteria for measuring, the CSP conc. is at the value of OD600 = 0.2 after a series of experiment.
The intensity of fluorescence slowly drops after a sharp rise in a small amount of time, hence we can tell that the reaction starts right away as soon as CSP is added.
Here is a prototype showing how to use Carindex.
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 you awake, 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 it's job, click "show risk of cavity". The detected data will be sent to the server, calculated through machine learning; then, it will be sent back to the app, showing the risk and level dental caries (% and # value). The pH test paper color displayed on the bottom right corner can be used to read the corresponded pH value.