A team of scientists from Indian Institute of Technology Jodhpur and other national research institutes has developed an efficient fluorescent molecular probe that can be used in the diagnosis of Alzheimer’s disease. The findings of the research have been recently published in ACS Chemical Neuroscience journal
Alzheimer’s disease is believed to be caused by the abnormal build-up of plaques in and around brain cells. Plaques are aggregates of a type of small protein (peptide) called amyloid-beta (Aβ). According to the Dementia India Report 2010 by the Alzheimer’s and Related Disorders Society of India (ARDSI), there will be around 7.6 million Indians with Alzheimer’s by 2030 in India.
According to health experts, the diagnosis of Alzheimer’s disease involves assessment of cognitive functions, the observation of brain size and structure through SPECT, PET and MRI scans, and the detection of amyloid plaques. Amyloid plaques are detected by extracting the brain fluid (cerebro-spinal fluid) through a spinal tap, or by PET Scans. Although both methods are reliable, they are invasive and expensive, the scientists revealed.
“Optical imaging systems that use fluorescent or colour-based chemicals to target tissues and molecules of interest are considered better diagnostic techniques in the biomedical area,” He added that fluorescence probes can enable rapid and safe analytical sensing due to the absence of radioactive chemicals or expensive equipment. Fluorescent probe diagnosis involves injecting a fluorescent chemical that specifically attaches itself to the amyloid plaque and assessing the change in fluorescent properties using an appropriate detector,” Dr. Surajit Ghosh, Professor, Department of Bioscience & Bioengineering and Dean, Research and Development, IIT Jodhpur and lead author said in a statement.
Dr. Ghosh also said that the fluorescent chemical, in addition to being able to specifically and selectively attach to Aβ aggregates, must also be able to cross the blood-brain barrier to reach the brain. There must also be a change in its fluorescent properties – colour and intensity – when it attaches to Aβ aggregates.
According to a press statement from the institute, the researchers have successfully designed and developed a series of benzothiazole based fluorescent molecules that can selectively bind to Aβ aggregates.
All these molecules were seen to emit fluorescence in one colour when unbound, and the emission colour shifted towards red in the visible light (rainbow – violet indigo blue green yellow orange red) spectrum with a concomitant increase in fluorescence intensity, the scientists revealed.
“This molecule was stable in biological fluids and could easily traverse the blood-brain barrier. It was also selective to Aβ aggregates in the presence of competing biomolecules. Hence, the probe found by the research team will provide a non-invasive and inexpensive reliable alternative to a spinal tap or PET Scan methods Alzheimer’s diagnosis,” they said.