Alzheimer´s is a brain disease which impacts the memory and is the main reason for dementia in the elderly, and which now is possible to identify in its early stages thanks to a sensor which detects the agglomeration of beta-amyloid fibers.
These are like types of protein trash which begin to deposit in the brain towards the age of 28, much before the first symptoms of the disease.
The device developed helps to detect the amyloid protein predisposition to agglomerate and produce a barrier which hinders neurons to function correctly. “It is the same as taking a blood sample,” said Universidad Nacional de Colombia (UNal) in Medellín, Department of Materials and Minerals Professor Juan Pablo Hernández Ortiz, who worked on this platform with an interdisciplinary group from the Universities of Wisconsin-Madison in Chicago.
The sensor is a simple diagnostic tool which turns into a biological marker, making early detection of neurodegenerative diseases easier.
According to Clinical Neurologist Francisco Lopera, the current manner to detect Alzheimer’s disease is examining the cerebrospinal fluid extracted from the spinal cord or by taking a positron-emission tomography (PET) which consists of injecting a radioactive substance which later combines with amyloid proteins and diagnosed with help of imagery.
The developed device uses liquid crystals which essentially act like a liquid, with viscosity and fluid features and solid like features which produce optic behaviors such as deviating white light and changing colors.
In its solid form, the base material can continually deform, as a fluid, therefore it can get organized and directed, making it easy to charge form by hand or with electromagnetic fields.
Professor Hernández says that changes in orientation are used to measure and become cognizant when there are different molecules in the system. “For instance, if the liquid crystal is organized, light passes through it and it is white, but if it has a drop of oil, the liquid crystal changes direction and the drop may be seen,” he added.
The sensor is made of a polymer known as polydimethylsiloxane and form 283x285x20 micron containers. This is approximately like a vase half the size of a needle and the thickness of half a human hair. The liquid crystal molecules form a grid of approximately 1,200 “buckets” in a square centimeter.
The liquid crystal “buckets” get in contact with a thin layer of lipids. The proteins which need to be researched are then introduced between the bucket and the lipid layer according to the disease of interest.
The proteins interact between themselves and according to the behavior, the liquid crystals help detect if the molecules agglomerate or not, using an optical microscope. The proteins are in charge of disturbing the liquid crystal molecules and according to what is observed researchers may make an early diagnosis.
“One checks each liquid crystal bucket to see which bucket has a fibrous sign, which looks like a tree branch. If nothing is going on, everything appears white or black because there are dispersed proteins. When the abnormal fiber is formed it is seen as a structure or pattern which may be darker or clearer,” said Hernández.
Before manufacturing the device they carried out a theoretical study and a computer-guided design to mimic the sensor and help understand molecule behavior. In this step the chose the liquid crystal, the lipids and the geometry of the buckets.
Tests were first performed with non-agglomerating proteins: mouse islet amyloid polypeptide, ovispirin and bovine serum albumin (BSA). Because these proteins do not agglomerate when the researcher observes structures and they are not similar to tree branches, it means that the patient is not prone to the disease.
Later they research agglomerating fiber-forming proteins: human islet amyloid polypeptide (linked to Alzheimer’s and Type II diabetes) and polyglutamine chains (linked to Huntington’s disease). The device is capable of detecting when this happens.
The sensor seems futuristic or sophisticated, but according to the researcher, it is not. In medical physics, there are objects limited by the short, medium and long-term. Almost all of them are focused on early diagnosis, the discovery of biomarkers and customized precision medicine reduce secondary effects and diagnosis costs and treatments.
According to the World Health Organization statistics (2016), there are 47 million people in the world with dementia (Alzheimer’s disease) and there are approximately 10 million new cases each year. These figures encourage researchers to work on a solution which will allow them to become cognizant at an early stage if a person is prone or not to this or other diseases and prevent greater issues due to late diagnosis.
According to professor Hernández that is his main contribution, avoiding complications of “complex pathologies which can disturb the quality of life of people such as Alzheimer’s and Type II diabetes which are statistically growing and which not only impact the lives of patients and their families but society as a whole because they are high-cost diseases.”
On the long-term. the next step is to market the sensor, which needs to be tested by the Food and Drug Administration.
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