“Dr. Hanger provided suggestions for the design of our cartridges.<p style="display:inline;background-color:#FFFF00;font-weight: 600;">According to our needs, he proposed that we should design the interior of the capsule into the shape of funnel and he also pointed out the design requirements for some important details of the shape. We applied his suggestions to the design of our third generation device.</p>”
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“Dr. Gul provided suggestions for the design of our cartridges.<p style="display:inline;background-color:#FFFF00;font-weight: 600;">According to our needs, he proposed that we should design the interior of the capsule into the shape of funnel and he also pointed out the design requirements for some important details of the shape. We applied his suggestions to the design of our third generation device.</p>”
In the process of many iGEM teams carrying out projects, it is often impossible to develop projects that can be applied to life given the cost and schedule.In order to avoid this situation, we draw on the waterfall model in software engineering as a development model, which is divided into feasibility analysis, requirements analysis, project design and project realization. Human practice is an indispensable tool for us throughout our entire process.We also hope that more iGEM teams can use such models to develop projects.
Feasibility Analysis
Overview
After we have the idea of degrading antibiotics, the first step is the feasibility analysis. If we don't think about whether we can do it, we will blindly carry out the project, then our project will ultimately lack practical significance.In order to determine whether the project is feasible, we organized and participated in the 5th Southwest China iGEM Exchange Conference to determine the technical feasibility and visited the 7th Water Supply Plant in Chengdu to determine the application feasibility and discussed the feasibility of policy. Through this series of activities, we decided to pay more attention to expired drugs.
Technical feasibility
In our brainstorming process we have proposed the idea of degrading ciprofloxacin. In order to determine the technical feasibility, we held the 5th Southwestern iGEM exchange meeting with UESTC-Software at the University of Electronic Science and Technology. We invited Ms. Zhang Nan, Ambassador of Asia, to explain the concept of human practices to us, and invited BM-AMU, SCU-China, SICAU-iGEM, XJTU-China and SCU-China to exchange ideas.
RESULT:
“During the process of project demonstration, students from SCU-China and Ms. Zhang Nan made suggestions: Pay great attention to safety issues, because if genetic escape occurs, it will cause great impact on the environment.
So according to their suggestions, we designed the kill switch and decided to use the semantic inclusion method to further control our E.coli.
”
Application feasibility
After we had the idea of degrading antibiotics, in order to determine the feasibility of the application scenario, we went to the fourth water purification plant in Chengdu to understand the source of antibiotic pollution.
We learned that the dirt is first filtered through the pretreatment system and the membrane grid station. In the MP-MBR system, activated sludge is used, and microorganisms in the activated sludge are used for degradation, and the MP-MBR membrane system filters out pollutants larger than 0.1 μm and most bacteria. The UV is then sterilized again to prevent damage to the machine that actually runs the diaphragm.
RESULT:
“The technicians told us that the main sources of antibiotics in the sewage flew into sewage plants are veterinary antibiotics used in farming irrigation water and medical antibiotics used in pharmaceutical plants, hospitals and families.
We decided to learn more about how to treat these three sources of antibiotics.
”
Policy feasibility
In our subsequent investigations, it was found that antibiotic contamination in expired drugs has not received widespread attention. Among the 663 cities in China, Most cities treat expired drugs as domestic waste. Only Shanghai that implements waste sorting has a clear treatment for expired drugs, and expired drugs in Shanghai are classified as hazardous waste. The main treatment process is the rotary kiln incineration process which has a variety of pollution pathways. So in the process of our local government collecting the draft garbage classification, we proposed to the government to set up a specific point of recycling drugs.
RESULT:
“We found that 99% of cities in China do not have regulations on the treatment of family expired drugs, and there are also many types of pollution in the treatment process prescribed by Shanghai.
We recommend that the government should set up some specific expired drug collection point.
”
Conclusion
Combined with the above investigations and analysis, from the aspects of the economy, implementation, policy, we want to make a project to recycle and degrade expired drug which is closest to our lives.
Demand Analysis
Overview
Demand analysis has a major impact on the entire project development phase and is the basis for project development. Insufficient demand analysis can lead to a series of problems, such as cost and budget out of control, project design can not meet user needs, etc. In order to accurately analyze user needs, we distributed more than 200 questionnaires for analysis which helps us decide to design the expired drugs recycling bin---drug avenger, and visited a number of chain pharmacies to determine the function and performance of the recycling bin.
User needs analysis
In order to determine whether people have special request for recycling device, we have released a questionnaire on the status of expired drugs, and a total of 240 valid questionnaires were collected.
“ 78.33% of respondents confirmed or inclined to think that there were expired drugs in their homes. It can be seen that the phenomenon of expired drugs in the family is still very common. What's more, most respondents didn't pay enough attention to their use of drugs and prefer nearer recycling position.People prefer to have an expired drug recycling bin near their home.
So we decided to make an expired drug recycling bin and use mathematical modeling to determine where the bins are placed.
”
Moreover, according to our analysis, the elderly are the group that takes the most expired drugs. These allow us to decide to regard elderly people as the project audience and pay attention to families with elderly people, improve the living habits and knowledge level of the elderly, and verify the practicality. In order to be more helpful to the elderly, we have also carried out educational activities on the elderly.
In order to determine that our recycling bins whether require some special functions or not, we visited several pharmacies and exchanged our projects with the staff of the store manager, pharmacist, salesperson and other staff around the treatment of expired drugs. They questioned our bins, is it safe to use E.coli degradation chambers? Will it harm people's bodies? Where is this recycling bin placed? Is it possible to establish some incentives to encourage people to throw expired drugs into the recycling bin?
RESULT:
“
We need to be more cautious about security issues. In addition to suicide switches and semantic inclusion, we design UV lamp sterilization zones in the recycling bin. We need to use the mathematical modeling of the recycling bins to determine how our recycling bins are set up in the city. We also think about what can be used as rewards to encourage people to use our projects.
”
Project design
Overview
In the process of project design, using modular design principles, it is divided into three modules: synthetic biology design, hardware process design, and mathematical modeling urban layout design. In this process, we exchange ideas with five teachers and constantly improve our project.
Synthetic biology design
In order to quickly produce a large number of degrading enzymes after antibiotic is detected, our PI suggests us to design quorum sensing system.
RESULT:
“
In order to increase the degradation rate, we have designed quorum sensing system. When ciprofloxacin is detected, the detected bacteria can start degrading bacteria and degrade when detected.
”
Hardware process design
We planned to use microfluidic technology to encapsulate E.coli with alginate solution, CaCl2 solution and water. The gel beads formed can allow certain enzymes produced by E.coli to be released to the outside world, while E.coli can not be produced. Microorganisms in the environment also do not enter the gel. And E.coli can live for several days. It doesn't matter if other chemicals in the outside world can go in, as long as you can isolate most of the damage. However, we still have doubts about hardware fabrication, microfluidic chip fabrication, embedding and cross-linking methods, gene influx release, and E.coli survival. Just as we thought about the harmful substances entering the microbeads, the risk of cell escape, and so on, it coincided with Professor Yin Huabing from the University of Glasgow's biomedical engineering program, and we asked her about these problems.
RESULT:
“1. In terms of light source made by hardware, Professor Yin believes that it is feasible to use laser, but the teacher recommends using a light source: X-Cite LED fluorescence microscope to excite the light source.
However, due to funding constraints, we decided to use laser light sources after repeated consideration.
2. The design of microfluidic chips is the most important and the most difficult step. The design process is too specialized, and the microfluidic chips currently applied to cell encapsulation are less, and the technology is less mature. Even if the chip is designed, it may take dozens of adjustments to achieve the function, and the cost is too high.
Taking the comprehensive consideration into account , we decided to abandon the use of microfluidic technology.
”
Recycling bin position design
In order to make the processing device in the project can be placed reasonably in the cell, we apply mathematical methods to solve this problem. Whether the device is properly placed in the cell depends on the structural characteristics of the cell, the population of the community, and throwing drugs. When residents can accept the longest distance to walk, etc., the lack of consideration of these factors will cause the irrational position of the device, so we have established a mathematical model to scientifically place the processing device.
After we made the second-generation device, we used the data detected by it to analyze the resolution of the acquisition card together with the teacher, and finally selected the appropriate 24-bit data acquisition development board.
RESULT:
“
The teacher also provided suggestions for the design of the device and the circuit design to solve the problem of centralized power supply for pumps, lasers, development boards and other equipment.
”
Hardware device selection
We and professor Ke Chen learned about the type and working principle of the detector, analyzed the advantages and disadvantages of common photoresistor, avalanche diode and photomultiplier tube in terms of cost, function, size and difficulty of use, and discussed the self-made filter and amplifier circuit. Difficulty and time cost.
RESULT:
“
Finally, the plan to purchase an avalanche detector with its own amplifier circuit was decided.
”
3D printing
In order to complete our hardware, we and professor Xiangyu Mao learned the basic operation and precautions of 3D printing. With the help of Mr.Mao, we analyzed the advantages and disadvantages of fused deposition rapid prototyping (FDM) technology and photocuring technology. After taking these advantages and disadvantages into account,we finally decided to use ABS for photocuring 3D printing.
RESULT:
“
Considering the accuracy and cost of 3D printing, we improved the optical path and detail design of the device, and used 3D printers in Mao’s laboratory to print 3D printing of the second generation device to verify the design flaws of device in actual use. It greatly helped us to further improve the device.
”
Bacterial box design
RESULT:
“Dr. Gul provided suggestions for the design of our cartridges.
According to our needs, he proposed that we should design the interior of the capsule into the shape of funnel and he also pointed out the design requirements for some important details of the shape. We applied his suggestions to the design of our third generation device.