Lateral Flow Immuno Assay for Point-of-care Screening of Retinopathy of Prematurity

Abstract

Purpose : Retinopathy of Prematurity (ROP), a retinal disorder in preterm babies may lead to blindness, if left untreated. The current clinical gold standard for screening of ROP involves oculur examination, which is not only expensive and time consuming, but also stressful for infants and families. A simple and low-cost screening method that circumvents ocular examination would greatly benefit at-risk population. We have identified 8-hydroxy deoxyguanosine (8-OHdG) as a valid urinary biomarker for ROP, and designed a simple “dip-stick” ROP screening method based on Gold Nanoparticles (AuNPs) integrated Lateral Flow Immuno Assay (LFIA) for 8-OHdG detection. We performed a prospective study to employ the LFIA sensor to quantitatively detect 8-OHdG levels in premature infants, in order to evaluate if the sensor facilitates point-of-care screening of ROP, as an alternative to ocular examinations.

Methods : A total of 18 premature infants who were at risk for ROP were enrolled. Urine was collected at 24 hours, 72 hours and weekly until discharge from the NICU. The LFIA strips were custom fabricated by assembling different components (Figure 1). Urinary 8-OHdG levels were quantified using LFIA, based on the color intensity of test line, as captured by a smartphone. The 8-OHdG levels were correlated with the different stages of ROP as determined by screening ocular examinations.

Results : Urine samples were tested using LFIA and results were correlated with ocular examination. Out of 18 infants enrolled, (total of 144 urine samples), ocular examinations diagnosed 7 infants with ROP, and 11 with no apparent ROP. Average 8-OHdG levels measured by LFIA for infants without ROP was 25 ng/ml; for stage 1 ROP was 47 ng/ml, for stage 3 ROP was 52ng/ml. (Figure 2).

Conclusions : Increasing concentrations of 8-OHdG levels in the urine of infants with advancing stages of ROP indicate 8-OHdG to be a promising screening biomarker for ROP. The results obtained by LFIA correlated well with ocular examination, suggesting that, LFIA based quantification of urinary 8-OHdG is impending to serve as a cost effective, and point of service technique that could circumvent the discomfort of ocular examination for ROP screening.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

 

Schematic Illustration of several components of a LFIA strip

 

Average 8-OHdG values calculated from LFIA for different stages of ROP (the numbers provided in parenthesis correspond to urine samples under each category)