Team:Hong Kong UCCKE/Implementation

Proposed Implementation

What is the application?

Our tool can be used to develop a multi-disease detection kit. Since Our cell uses an antibody on the cell membrane to detect different disease antigens, the type of disease for detection by this method can be highly diverse Therefore, we hope that with help with antibody engineering, scientists using our tool can develop a convenient and affordable detection kit for detecting multiple antigens at the same time and method. Furthermore, our aim is to help people to have detection of disease in a more convenient way and cheaper than other methods. At the same time, we hope we can detect disease using non-invasive samples, for example, saliva. Other than that, it detects different diseases at the same time using the same technology in order to provide more solutions for biology researchers.

How do developers and users use our tool?

Who are the developers and users?

In this application, our target developers for our toolkit are antibody engineers while our target users of the developed detection kit are nurses and doctors since the kit will mostly be used in medical areas for example to detect the antigen of different diseases.

What do developers do?

Our kit allows the developers to customize their own VHH antibody to detect different disease antigens. Antibodies can be designed to target against disease antigens one desires to detect. After designing and synthesizing the antibody DNA sequence, it can be cloned into the coding region of Modular Receptor Platform (MRP) by using the restriction enzyme KasI (Toolkit Component 2). The cloning of fluorescence protein genes into the multiple cloning site allows the expression of a colored protein upon positive detection. This is a demonstrative part where the user can flexibly change the antibody VHH region to detected desired antigen while expressing GFP when the said antigen is detected.

What is the detection kit like?

It is a kit with E. coli that is customizable for both the VHH and the expression genes. Our cell uses an antibody on the cell membrane to detect different disease antigens. It is a part of the MRP(Modular Receptor Platform). After the detection of antigen with the customized MRP, the CadC DBD will be activated to express other downstream genes. Taking the circuit below as an example, When the antigen is detected by MRP, GFP will be produced by the CadBA operator. Therefore, green fluorescence protein will be expressed in order to give out visual signals. Besides GFP, the circuit also expresses iclR and arcA genes, which we hope to restore the cell growth back to normal visual signal is amplified by restoring the cell proliferation rate back to normal, which could also lower the rate of false positive.

We picture something like this below, one kit can possibly screen for multiple diseases using GM bacteria by using different MRP properties. Users will load the samples in the sample compartment and the colorimetric result will be compared against the negative control.

What do users do when using the detection kit?

They are going to take samples from the patients and they will put the E. coli into different spaces or categories in the kit. After a few hours, the result will be shown including the developer’s desire expression genes.

What are some challenges faced by developers?

This system requires a pair of split single domain antibody which will dimerize upon binding of antigen. Although antibody engineering technology is very advanced nowadays, it may be difficult for the developers to design a split antibody homodimer to fit the system requirement. It may take a long time to test the functionality of these antibodies. This may hinder the potentially rapid development of the flexible system. In hope of more technological advances, we believe this problem will soon be improved.

What are some safety issues?

The kit given has E.coli inside it. Users need to deal with the living cells. Although the E.coli in the testing kit is not pathogenic, it is still our obligation to prevent the leakage of GM bacteria as they may cause unknown harm to the environment and human bodies. Therefore they need to prevent the bacteria from leaking out.

The device will be separated into two compartments, the sample compartment and the storage compartment. Before detection, dry E. coli is stored in the storage compartment in sealed condition. Only after the sample is loaded into the sample compartment, where there are no bacteria when the separation between the two compartments is broken. The sample can then be in contact with the bacteria, while the user will not contact the bacteria at any point.

We imagine the design of the detection compartments to be like this.