Alzheimer’s disease is a form of dementia that is steadily growing as the life expectancy of human populations grows. A marker for Alzheimer’s disease is the formation of plaques of folded protein. Many of the treatments for Alzheimer’s being considered (and there is currently no effective treatment) will be geared towards early detection. A secondary part of Alzheimer’s treatment is concerned with picking up clues about the disease as early as possible.
Early detection is the focus of Swinburne University of Technology researchers. As a step towards this, the research group has developed surfaces with features that mimic the textured surface of insect wings, like dragonflies.
Dragonflies have an ability to respond to light in special ways and it is the property of their wings as sensors that the research group aims to emulate.
The outcome of the research is a special nanotextured surface technology. The surface uses a developed form of aluminium, which is 40 percent denser than the metal in its normal form. This surface was formed using an extremely short laser pulse. The laser created a high concentration of energy via crystal composed of aluminium oxide.
The process reproduces the pattern found on dragonfly wings onto the surface. A dragonfly’s wing is covered with spikes a couple of hundred nanometers tall and tens of nanometers in diameter. Despite this, because the surface scatters light effectively the wing appears black to the human eye. When light is shined onto the surface, within the tiny nanoscale spaces the light is concentrated to a very high intensity (some one thousand times greater). Due to the effect of being concentrated, light ‘floats’ across the material surface almost as though it was a liquid droplet.
Speaking with Controlled Environments about the technological feat, lead scientist Professor Saulius Juodkazis said: “Using this focused laser technique, we may now be able to create a range of superdense metals that have extraordinary properties.”
He added: “The creation of superdense silver or gold, for example, could lead to many new possibilities for bio-sensing and plasmonics.”
The technology could be harnessed to look for the biological markers of disease. A biomarker, or biological marker, generally refers to a measurable indicator of some biological state or condition. Biomarkers are often measured to examine normal biological processes, pathogenic processes, or pharmacologic responses to a drug product.
Here it is hoped the created surface can one day be used look for the biological markers associated with Alzheimer’s disease. This is based on the premise that once a molecule crosses into one of the light hot spots, the energy of the light scatters forming a pattern. These patterns will differ depending upon the type of molecule present. It is theoretically possible for a sensor to read the patterns and to identify the presence of a biological marker.
In initial trials the molecular pattern effect has been used to test for the presence of beta amyloid. Beta amyloid is a biomarker of Alzheimer’s disease. Here plaques form when protein pieces called beta-amyloid clump together. These plaques are sticky and as small clumps may block cell-to-cell signaling at synapses. In addition, the plaques could activate immune system cells that trigger inflammation and devour disabled cells. These biochemical activities are probably, according to most medical thinking, the basis of Alzheimer’s disease.
The trials used beta amyloid is very low concentrations, as part of the assessment to see if Alzheimer’s disease could be detected at an early stage. This inquiry found that the nanotextured surface, made with sapphire, was capable of detecting the molecule at very low concentrations. The level of concentration mirrored the levels that might be found in the spinal fluid of individuals with early-stage Alzheimer’s disease.
In addition to sapphire, nanotextured silicon surfaces also make for effective sensors. A form of black silicon is inexpensive to manufacture and it can be produced in a straightforward manner using plasma etching. Plasma etching involves covering the surface of a material and then applying a stream of plasma to etch a pattern onto the area not covered by the mask.
As well as medical applications, a nanotextured surface could be used for military purposes, helping certain surfaces appear invisible. The findings are published in the journal Research Impact. The article is titled “Pattern of Discovery.”
This article is part of Digital Journal’s regular Essential Science columns. Each week we explore a topical and important scientific issue. Last week we considered gene extinction’ technology (or ‘gene drives’) could impact upon species loss. The previous week we looked at how a new Parkinson’s protein test could lead to earlier diagnosis of the disease.
