Theoretical and experimental analysis of analyte transport in a fiber-optic, protein C immuno-biosensor

• Published in: Biotechnology and bioengineering 2004-12, Vol.88 (7), p.869-879
• Main Authors: Tang, Liang, Kwon, Hyun J., Kang, Kyung A.
• Format: Article
• Language: English
• Subjects: Anticoagulants; Biological and medical sciences; Biosensing Techniques - instrumentation; Biosensing Techniques - methods; Biosensors; Biotechnology; Blood; Blood Chemical Analysis - instrumentation; Blood Chemical Analysis - methods; Computer Simulation; Computer-Aided Design; Convection; convective mass transport; Diffusion; Disease; disease diagnosis; Equipment Design; Equipment Failure Analysis; Fiber Optic Technology - instrumentation; Fiber optics; fiber-optic biosensor; Flow Injection Analysis - instrumentation; Flow Injection Analysis - methods; Fluorescence Polarization Immunoassay - instrumentation; Fluorescence Polarization Immunoassay - methods; Fundamental and applied biological sciences. Psychology; immunoreaction kinetics; immunosensors; Media (transport); Medical diagnosis; Models, Chemical; Motion; Optical Fibers; protein C; Protein C - analysis; protein C deficiency; Proteins; Q1; Reaction time task; sample viscosity; Velocity; Viscosity
• ISSN: 0006-3592; 1097-0290
• DOI: 10.1002/bit.20310

Protein C (PC) is an important anticoagulant in human blood plasma, and early diagnosis of PC deficiency is critical for preventing dangerous thromboembolic complications. A fiber‐optic PC immuno‐biosensor has been under development in our research group for real‐time PC‐deficiency diagnosis. The sensor has demonstrated a good sensitivity and specificity for quantifying PC in buffered solutions. However, for plasma samples, with a limited sample reaction time, the sensor produced only 30% of the signal intensity of PC in buffer. The high plasma viscosity (1.9 cP) was speculated as the major reason for signal intensity reduction. In this investigation, the sensing performance of the fiber‐optic PC biosensor is systematically characterized in terms of physical and chemical properties of the sample media. Theoretical and experimental analyses indicate that the reduced diffusion rate of PC molecules in viscous samples caused the sensing system to be more mass‐transfer‐limited. Convective flow of sample/reagent solutions during immunoreactions can increase the rate of the analyte mass transport from the bulk solution to the sensor surface, with reaction kinetics changing from mass‐transfer‐limited to reaction‐limited as flow velocity increases. It was shown that PC sensor performance was significantly improved for plasma samples with convection. The effect of the flow velocity and incubation times for samples and reagents on the sensor performance was also systematically analyzed to optimize the assay protocol for PC sensing. Currently, a 6‐cm‐long immuno‐biosensor is capable of quantifying PC in plasma (1 mL) in the heterozygous PC deficiency range (0.5 to 2.5 μg/mL) within 5 minutes, at an average signal‐to‐noise ratio of 50. © 2004 Wiley Periodicals, Inc.