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Automation and Analytical Techniques |
1 Department of Laboratory Medicine, 2
Laboratory Center of Urology, and 3
Endocrinology Department, Southwest Hospital, The Third Military Medical University, Chongqing, Peoples Republic of China.
4 The 26th Research Institute, Chinese Electronic Scientific and Technical Group Company, Chongqing, Peoples Republic of China.
aAddress correspondence to this author at: Department of Laboratory Medicine, Southwest Hospital, Third Military Medical University, Chongqing 400038, Peoples Republic of China. Fax 86-23-65460909; e-mail weilingfu{at}yahoo.com.
Background: Urinary proteins are predictive and prognostic markers for diabetes nephropathy. Conventional methods for the quantification of urinary proteins, however, are time-consuming, and most require radioactive labeling. We designed a label-free piezoelectric quartz crystal microbalance (QCM) immunosensor array to simultaneously quantify 4 urinary proteins.
Methods: We constructed a 2 x 5 model piezoelectric immunosensor array fabricated with disposable quartz crystals for quantification of microalbumin,
1-microglobulin, ß2-microglobulin, and IgG in urine. We made calibration curves after immobilization of antibodies at an optimal concentration and then evaluated the performance characteristics of the immunosensor with a series of tests. In addition, we measured 124 urine samples with both QCM immunosensor array and immunonephelometry to assess the correlation between the 2 methods.
Results: With the QCM immunosensor array, we were able to quantify 4 urinary proteins within 15 min. This method had an analytical interval of 0.0160 mg/L. The intraassay and interassay imprecisions (CVs) were <10%, and the relative recovery rates were 90.3%109.1%. Nonspecificity of the immunosensor was insignificant (frequency shifts <20 Hz). ROC analyses indicated sensitivities were
95.8% and, specificities were
76.3%. BlandAltman difference plots showed the immunosensor array to be highly comparable to immunonephelometry.
Conclusions: The QCM system we designed has the advantages of being rapid, label free, and highly sensitive and thus can be a useful supplement to commercial assay methods in clinical chemistry.
The following articles in journals at HighWire Press have cited this article:
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A. A. Ellington, I. J. Kullo, K. R. Bailey, and G. G. Klee Antibody-Based Protein Multiplex Platforms: Technical and Operational Challenges Clin. Chem., February 1, 2010; 56(2): 186 - 193. [Abstract] [Full Text] [PDF] |
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