LOS ANGELES, Calif. — Everybody has blood, but we all don’t have the same type. So one donated pint of it may help — or do harm — depending on the recipe your genes had used to make your own blood. That’s why hospitals must collect a sample of blood and test it to know which donated blood to safely transfuse into patients who have suffered catastrophic blood loss. But that may change, a Kuwaiti teen now reports.
She’s just shown that it’s possible to discriminate between different types of blood using infrared light. In future, she says, this may mean nurses or lab workers could simply shine a light into your skin — and analyze the light that reflects back — to know which blood donation would be right for you. The good news: For this low-cost method, no needles would be required!
Blood is a complicated soup of particles and proteins. These include white blood cells, which help fight infection, and platelets, which help blood clot after an injury. But red blood cells are the most common. They deliver oxygen to tissues throughout the body and transport carbon dioxide back to the lungs. Red blood cells are important for another reason, too, notes Zainab Alnakkas. This 17-year-old at the Bayan High School for Girls in Kuwait points out that certain proteins or other substances on the surface of red blood cells help someone’s immune system react and fight foreign substances. These substances are known collectively as antigens.
There are four major blood types: A, B, AB, and O. A, B, and AB all have antigens (known by those letter names). Blood having none of these is known as O type. Particular proteins on red blood cells determines whether a person’s blood type hosts another type of antigen, known as Rh. Those that don’t are known as “Rh-negative” and those that do are considered “Rh-positive.” If the immune system encounters an antigen its host shouldn’t have, antibodies will form and attempt to fight the source of that antigen. That’s why it’s very important that a person receiving donated blood is given a type that is compatible with theirs (both in terms of the letter type and Rh factor), the teen explains.
Today, most labs identify a person’s blood type by testing a sample of the red stuff. Lab workers will check to see whether the blood’s cells contain various antigens. (They do this by adding various antibodies that can recognize those antigens, then looking for any reactions.)
But scientists also have shown that red blood cells of different blood types reflect light slightly differently. That’s especially true at certain wavelengths of infrared light, Zainab notes. So she wondered if she could use light to identify blood types.
She shone infrared light of three different wavelengths through the samples of blood from 30 people. Then she used sensors to measure the light reflecting from the samples at wavelengths between 10 meters and 30 centimeters. (All of these correspond to radio waves.) She also measured how much of an incoming wavelength of light was absorbed as it passed through blood. With yet another test, she measured the angle at which light was scattered by red blood cells.
In general, Zainab found, the fewer antigens there were, the less light that red blood cells absorbed. Also, blood with fewer antigens scattered less light. For example, the teen discovered that blood type O, which has no A or B antigens, scattered light less than other types. Blood type AB, which has both antigens A and B, scattered light the most.
Zainab showcased her research last week, here, at the Intel International Science and Engineering Fair. ISEF was created by Society for Science & the Public and is sponsored by Intel. The competition lets students from around the world show off their winning science fair projects. (The Society also publishes Science News for Students.) This year, nearly 1,800 high school students from more than 75 countries competed for big prizes and the ability to display their research.
Right now, Zainab’s technique still needs a blood sample to work. That means needles. (Ouch!) But in the future, engineers could make a device that shines the proper wavelength of light into a person’s skin. That light should be able to pass through the skin, bounce off of blood and then reemerge. Such a test could be done on blood still inside a person’s body, the teen explains.
The light scanner and analyzer used for this testing also could be portable, she notes. So, for example, emergency medical technicians could use it at the scene of an accident. Then, if someone needed blood for surgery, it could be waiting for them before they ever got to the hospital.
angle The space (usually measured in degrees) between two intersecting lines or surfaces at or close to the point where they meet.
antigen A substance capable of causing an immune reaction.
carbon dioxide (or CO2) A colorless, odorless gas produced by all animals when the oxygen they inhale reacts with the carbon-rich foods that they’ve eaten. Carbon dioxide also is released when organic matter burns (including fossil fuels like oil or gas). Carbon dioxide acts as a greenhouse gas, trapping heat in Earth’s atmosphere. Plants convert carbon dioxide into oxygen during photosynthesis, the process they use to make their own food.
cell The smallest structural and functional unit of an organism. Typically too small to see with the unaided eye, it consists of a watery fluid surrounded by a membrane or wall. Depending on their size, animals are made of anywhere from thousands to trillions of cells. Most organisms, such as yeasts, molds, bacteria and some algae, are composed of only one cell.
clot (in medicine) A collection of blood cells (platelets) and chemicals that collect in a small region, stopping the flow of blood.
discriminate (n. discrimination) The detection or recognition of a difference between two or more versions of something.
emergency medical technician (abbr. EMT) A heath care provider who serves in times of emergency. They are not doctors or nurses. They are trained to respond quickly to emergency situations to aid a patient until a doctor or nurse can see them. They often work in ambulances and are sometimes called paramedics.
engineering The field of research that uses math and science to solve practical problems.
gene (adj. genetic) A segment of DNA that codes, or holds instructions, for a cell’s production of a protein. Offspring inherit genes from their parents. Genes influence how an organism looks and behaves.
immune system The collection of cells and their responses that help the body fight off infections and deal with foreign substances that may provoke allergies.
infection A disease that can spread from one organism to another. It’s usually caused by some type of germ.
infrared light A type of electromagnetic radiation invisible to the human eye. The name incorporates a Latin term and means “below red.” Infrared light has wavelengths longer than those visible to humans. Other invisible wavelengths include X-rays, radio waves and microwaves. Infrared light tends to record the heat signature of an object or environment.
Intel International Science and Engineering Fair (Intel ISEF) Initially launched in 1950, this competition is one of three created (and still run) by the Society for Science & the Public. Each year now, approximately 1,800 high school students from more than 75 countries, regions, and territories are awarded the opportunity to showcase their independent research at Intel ISEF and compete for an average of $4 million in prizes.
oxygen A gas that makes up about 21 percent of Earth's atmosphere. All animals and many microorganisms need oxygen to fuel their growth (and metabolism).
platelets The smallest of blood cells, their role is to hunt for signs that a blood vessel has been damaged. Then the platelets congregate at the site of damage and transform themselves, growing long tentacles. There, they link together, creating a clot to plug any hole. This should help stem the potential loss of blood.
protein A compound made from one or more long chains of amino acids. Proteins are an essential part of all living organisms. They form the basis of living cells, muscle and tissues; they also do the work inside of cells. Among the better-known, stand-alone proteins are the hemoglobin (in blood) and the antibodies (also in blood) that attempt to fight infections. Medicines frequently work by latching onto proteins.
radio waves Waves in a part of the electromagnetic spectrum. They are a type that people now use for long-distance communication. Longer than the waves of visible light, radio waves are used to transmit radio and television signals. They also are used in radar.
red blood cell A type colored red by hemoglobin. These cells move oxygen from the lungs to all tissues of the body. Red blood cells are too small to be seen by the unaided eye.
Rh An antigen on the surface of red blood cells in most people. People whose blood cells have it are said to have an “Rh-positive” type. The others are “Rh-negative.” The Rh stands for rhesus, the type of monkey in which this antigen was first observed. Before someone can safely receive a blood transfusion, the general type of blood — A, B, AB or O — must match, as well as this Rh factor.
sensor A device that picks up information on physical or chemical conditions — such as temperature, barometric pressure, salinity, humidity, pH, light intensity or radiation — and stores or broadcasts that information. Scientists and engineers often rely on sensors to inform them of conditions that may change over time or that exist far from where a researcher can measure them directly.
tissue Made of cells, any of the distinct types of materials that make up animals, plants or fungi. Cells within a tissue work as a unit to perform a particular function in living organisms. Different organs of the human body, for instance, often are made from many different types of tissues.
wavelength The distance between one peak and the next in a series of waves, or the distance between one trough and the next. Radiation with wavelengths longer than visible light includes infrared light, microwaves and radio waves.
white blood cells Blood cells that help the body fight off infection.
Meeting: Z. Alnakkas. Blood types identification using photons. Intel International Science and Engineering Fair. May 15, 2017. Los Angeles, Calif.