Bioanalysis Zone

Analyzing ascorbic acid levels to determine the extent of eye injuries

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A team comprising a bioengineer and an ophthalmologist are working together to develop a first of its kind portable sensor that can inexpensively and rapidly determine the severity of an eye injury.

The development of such a sensor is important as there is currently no way to determine the extent of an eye injury at the site of an accident, in rural areas lacking ophthalmology specialists or on the battlefield. The device, known as OcuCheck, operates by measuring levels of vitamin C in the fluids that coat or leak from the eye. The teams findings where recently published in Scientific Reports.

The OcuCheck sensor capitalizes on the fact that the viscous fluid that coats the eyeball – the ocular tear film – contains low levels of ascorbic acid (vitamin C) compared with the interior of the eye.

“So the concept is if there is severe damage to the eye that penetrates deeply, the ascorbic acid will leak out in high concentration,” commented Dipanjan Pan, professor of bioengineering at the University of Illinois (IL, USA), who is creating the device with Leanne Labriola from Carle Foundation Hospital (IL, USA).

At the current time, individuals with an eye injury must have their injury assed at a hospital – a process that is often complicated, time-consuming and imprecise. “The new device will change the standard of care for evaluating eye traumas,” Labriola noted.

The sensor utilizes graphene platelets that are layered, 1 nm thick, on filter paper to detect ascorbic acid. The upper layer contains a unique polymer that interacts with graphene, gold electrodes and ascorbate oxidase – an enzyme that binds to ascorbic acid. The device is the first of its kind to measure ascorbic acid for the assessment of eye injuries.

The sensor is designed so that when ascorbic acid is present it binds to the ascorbate oxidase, disturbing the interaction of the polymer with the graphene, which leads to a change in the sensors electrical properties.

When tested with clinical samples from 16 individuals undergoing eye surgery, the sensor detected ascorbic acid concentrations with an accuracy above 80%, sensitivity above 88% and specificity above 71%, when compared with the gold-standard colorimetric assay.

OcuCheck has not yet been tested on actual samples from trauma patients. However, as Pan noted, “…we have mixed the samples with blood, and the sensor’s sensitivity to ascorbic acid is retained even in the presence of blood. The filter paper will filter out the blood.”

The team is building a housing unit for the sensor, with the help of an industrial design professor at the University of Illinois, which will allow the sensor to be portable and easy to use. Pan and Labriola have also founded a new company, InnSight Technology, to help them bring the device to market. Their company has had a great start, obtaining a phase I Small Business Innovation Research grant from the National Science Foundation (VA, USA).

Sources: Portable device can quickly determine the extent of an eye injury; Gartia MR, Misra SK, Ye M et al. Point-of-service, quantitative analysis of ascorbic acid in aqueous humor for evaluating anterior globe integrity. Sci Rep DOI: 10.1038/srep16011 (2015)

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