Permantently oriented antibody immobilization for digoxin determination with a flow-through fluoroimmunosensor

摘要

This paper reports a new flow-through fluoroimmunosensor, the function of which is based on antibodies immobilized on an inmunoreactor of controlled-pore glass (CPG), for determination of digoxin, used in the treatment of congestive heart failure and artery disease. The immunosensor has a detection limit of 1.20 μg L~(-1) and provides high reproducibility (RSD = 4.5% for a concentration of 0.0025 mg L~(-1), and RSD = 6.7% for 0.01 mg L~(-1)). The optimum working concentration range was found to be 1.2 * 10~(-3) - 4.0 * 10~(-2) mg L~(-1). The lifetime of the immunosensor was about 50 immunoassays; if stored unused its life-time can be extended to three months. A sample speed of about 10-12 samples per hour can be attained. Possible interference from substances with structures similar to digoxin (morphine, heroin, tebaine, codeine, pentazocine and narcotine) was investigated. No cross-reactivity was seen at the highest digoxin: interferent ratio studied (1:100). The proposal fluoroimmunosensor was successfully used to determine digoxin concentrations in human serum samples.