Dominic

Hi, I'm Dom, and I'm from Walpole, Massachusetts. I'm here because I've had a lifelong love of all things science, which is inspired by my parents. My mom is a microbiologist/geneticist, and my dad is an engineer. Both of them have inspired me to pursue my goals, and reach for the stars, and all of those cliche encouraging things. When I grow up, I think I want to become some sort of doctor, as I enjoy anatomy and physiology. I took biology in school this year, and have done other science camps before this one, although few have been as interesting. I run cross country and track, and in my free time, I like to read, play drums, and play video games. And something interesting about myself....I don't know what to say here....Well, in 7th grade, I broke both bones in my left forearm, and had to go to the hospital. While I was there, I was given morphine as a painkiller. I stayed overnight at the hospital, but when i came home, I was very sick, and couldn't keep down any food for about 5 days. It was awful, and looking back on it now, I realize that I was going through withdrawal. So, I overcame morphine addiction at age 13. Please don't tell the cops :o

Sooooo..........yeah, that's about it.


 * Biosensors: **

The technology of biosensors is relatively simple to explain: utilizing organisms or parts of organisms to detect something. They are designed to alert the user to the presence of a substance in the environment. Typically, these devices are used to check for harmful substances such as heavy metals, chemicals, or pathogens in food, water, living space, or the human body itself. For example, these sensors allow for quick and easy testing determining whether or not water may be safe to drink. Or, they might be used to show a diabetes patient their levels of blood glucose.

A pioneer of biosensor technology is Anthony P. F. Turner. A British professor, he led a team which developed the hand-held mediated amperometric glucose sensor, which monitors the levels of glucose in the blood. He founded the World Congress on Biosensors in 1990 and has been chairman ever since.

There are numerous different forms of biosensors. Electrochemical biosensors can utilize amperometry; detection of ions in a solution based on electric current or changes in electric current. Electric biosensors utilize conductivity to gather information. Optical sensors, however, use fluorescence or the absorption and reflection of light. Mass sensitive sensors use piezoelectric crystals, which accumulate electric charge when acted upon by a force. And thermal sensors can measure the heat of a reaction or adsorption. Each can be utilized to detect differe nt materials, and more types of sensors may later be discovered.


 * Project: **

Purpose:

 Every year, approx. 140 million people develop dysentery, and 600,000 people die from it. Passed through contaminated water, food, and feces, it is caused by either the Shigella bacterium or by an amoeba called //Entamoeba histolytica//. Dysentery often causes fever, abdominal cramps, rectal pain, and occasionally bloody stool. It is usually accompanied by dehydration caused by diarrhea, and is occasionally fatal. Obviously, contracting this illness would be extremely unpleasant, and there is no vaccine, although there are multiple treatments. However, in undeveloped nations, treatment can be hard to come by, and for this reason, I have designed a mass sensitive biosensor to test for the presence of Shigella bacteria in water.

Competing Technologies:

 There are a multitude of different technologies for detecting the Shigella bacteria. Conventional bacterial cultures are always an option, but there is a noted lack of appropriate selective media. Immunological methods have been researched, but only one is currently commercially available. Molecular microbiological methods have also been developed for the detection and identification of Shigella; however, the speed, complexity, and availability of these products vary. Hopefully, my design will be able to solve some of these problems.

The Design:

 So, here’s the important part: the actual design. Of all of these different biosensors, I chose to look at the mass-sensitive sensor. Through extensive research, I discovered that it is possible to attach DNA to a piezoelectric quartz crystal. The crystal outputs a certain electrical frequency b ased on how much mass it has. The crystal is incredibly sensitive, and can detect minute changes in mass. The device functions by attaching single strands of DNA to the crystal which is complimentary to DNA from the Shigella bacterium. This is the DNA probe. Next, a questionable water sample is put through the process of isolating and denaturing the DNA, so that if any Shigella were in the water, their DNA is now is single strands. The DNA is either put immediately in the water, or is put through PCR, to increase the amount of DNA. Whichever the choice, the DNA is then pipetted into a beaker full of clean water, which also contains the quartz crystal. At approximately 50 degrees Celsius, DNA strands will anneal. With enough DNA, some strands will bind to the probes on the crystal. The crystal’s mass is changed by the addition of more DNA, and the frequency emitted changes. Using special equipment, it is possible to measure the frequency, and how it changes due to the mass increase. Therefore, by knowing the starting frequency of the crystal, it’s possible to detect change, and therefore the presence of Shigella bacteria in the water source in question. To make this device, a manufacturer would need complimentary DNA to Shigella DNA, a piezoelectric quartz crystal, pure water to perform the test in, and a machine to measure the electric frequencies emitted by the crystal.

Expected Results:

 If there is no Shigella in the water, then the frequency will not change and the water source will be safe to drink from. However, if there are bacteria in the water, then the frequency will change. This will identify  the water as unsafe, and the persons in the area will know not to drink from it, preventing the spread of dysentery.

<span style="font-family: Verdana,sans-serif;">Advantages:

<span style="font-family: Verdana,sans-serif;"> The design has many advantages over competing technologies. There is no lack of supplies needed for the product, unlike with bacterial cultures. The design is also a lot faster than growing a bacterial culture, especially if PCR is not run on the samples. In addition, piezoelectric crystals are pretty cheap, and it would definitely be possible to create this biosensor on a large scale.

<span style="font-family: Verdana,sans-serif;">Potential Problems:

<span style="font-family: Verdana,sans-serif;"> There are, of course, some problems that come along with the design. The assembly of this device would be relatively difficult to do on a large scale, depending on the level of technology and the skill of the workers available. In addition, the speed of the device would be drastically increased if PCR had to be run on the sample. And it may not be feasible to make a handheld or battery powered system, which is important in rural areas, as power may not be available. Finally, the crystals degrade over time, meaning that either they or the entire machine would have to be replaced.

<span style="font-family: Verdana,sans-serif;">Testing:

<span style="font-family: Verdana,sans-serif;"> Tests could be done on the effectiveness of the device in a controlled environment with different solutions, some of which contained Shigella bacteria and some of which did not. In addition, the crystals and the equipment could be put to different environmental tests to determine what the crystals can withstand before they start to degrade. If the tests go successfully, not only will the device be effective and efficient, but it can provide a foundation for other pathogen-sensing biosensors by just changing out the DNA probe.

<span style="font-family: Verdana,sans-serif;">And this concludes my report.

<span style="font-family: Verdana,sans-serif;">Sorry there are no pictures, they make my page go berserk when I try to add them.

<span style="font-family: Verdana,sans-serif;">Too many links:

[]

[]

[]

[]

[]

[]

[]

[]

[]

[]

[]

[]

[]

[]

[]

[]

[]

[]

[]



[]

[]

[]

[]