Clinical validation of fiberoptic immunobiosensor for point-of-care analysis of plasma nerve growth factor

BackgroundUpregulation of plasma nerve growth factor (NGF) is indicative of cardiac nerve sprouting that is underlying the mechanisms for cardiac arrhythmias. A conventional assay method (e.g., enzyme-linked immunosorbent assay [ELISA]) is usually time consuming and technically complicated for NGF analysis for potential arrhythmia prognosis.ObjectiveThis study is to develop a rapid and and reliable assay method for point-of-care (POC) testing of plasma NGF.MethodsWe recently developed a fiberoptic immunobiosensor for point-of-care testing of human plasma NGF. Physiological concentrations of NGF (1 to 200 ng/ml) could be quantified in both buffer and human blood plasma samples (100 μl) within 5 min. The intra-assay coefficient of variation was 5%, and the interassay coefficient of variation was 8%. The clinical utility of the NGF biosensor was evaluated using clinical blood samples from atrial fibrillation patients (n = 21). Peripheral venous blood was sampled before and immediately after radiofrequency ablation and again at postoperative day 1.ResultsThe NGF level did not change significantly between before (15.73 ± 16.67 ng/ml) and immediately after radiofrequency ablation (13.58 ± 11.45 ng/ml, P = NS); however, there was a significant elevation to 28.41 ± 19.52 ng/ml in postoperative day 1 (P <.01). In a follow-up study (11 ± 1 months), the increased magnitude in patients with atrial fibrillation recurrence (4.1-fold ± 1.96-fold) was significantly higher than those without (1.72-fold ± 0.53-fold; P <.001). The results were highly comparable to those of the ELISA analysis.ConclusionBecause of the comparable data accuracy and much faster assay time as compared with ELISA, the fiberoptic biosensor is promising as a clinical POC assay method for plasma NGF analysis at patient bedsides for potential cardiac disease diagnosis and prognosis.