title: Microfluidic capillary system for immunoaffinity separations of C-reactive protein in human serum and cerebrospinal fluid.
abstract: A miniaturized system based on microfluidic capillaries is presented for point-of-care testing and clinical assessment. The approach relies on microsyringe pump-generated flow to deliver reagents and immunoaffinity chromatography to isolate the antigen from biological matrixes. Capillary sandwich immunoassays for C-reactive protein (CRP) were demonstrated in human serum and cerebrospinal fluid (CSF), which are relevant matrixes for cardiovascular disease risk and meningitis research, respectively. Capillaries packed with antibody-coated silica beads were used to capture CRP from the matrix and a second, dye-labeled antibody was introduced to form a sandwich complex. An acidic elution buffer dissociated the antibody-antigen complexes, and the labeled antibody was detected with diode laser-induced fluorescence. Four parameter logistic functions and % relative error plots were used to model and assess the data. The calibration ranges for CRP were 0.05-3.0 microg/mL in 1:10 diluted serum and 0.01-30 microg/mL in undiluted CSF. The microfluidic apparatus employed a flow rate of 2 microL/min and a sample injection volume of 250 nL. Since it was not necessary to reach antibody-antigen reaction equilibrium and the assay platform dimensions were minimal, run times were as short as 10 min.
authors.affiliation: Department of Pharmaceutics, Virginia Commonwealth University Medical Center, P.O. Box 980533, Richmond, Virginia 23298-0533, USA.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Peoples
authors.forename: H Thomas
authors.initials: HT
authors.lastname: Karnes
mesh_terms: D002097:C-Reactive Protein / Q000134:cerebrospinal fluid / Q000302:isolation & purification*; D002846:Chromatography, Affinity / Q000379:methods*; D006801:Humans; D044085:Microfluidics / Q000295:instrumentation*
chemical_list: D002097:C-Reactive Protein