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Copper nanowires immobilized on the boards of microfluidic chips for the rapid and simultaneous diagnosis of galactosemia diseases in newborn urine samples Miguel García, José Ramón Alonso-Fernández, and Alberto Escarpa Anal. Chem., Just Accepted Manuscript • DOI: 10.1021/ac402331v • Publication Date (Web): 02 Sep 2013 Downloaded from http://pubs.acs.org on September 17, 2013
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Analytical Chemistry
Copper nanowires immobilized on the boards of microfluidic chips for the rapid and simultaneous diagnosis of galactosemia diseases in newborn urine samples Miguel García1, José Ramón Alonso-Fernández2, and Alberto Escarpa1* 1
Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering, University of Alcalá, E-28871. Alcalá de Henares, Madrid, Spain. 2
Laboratorio de Metabolopatías. Departamento de Pediatría. Hospital Clínico (CHUS) and Universidade de Santiago de Compostela. Santiago de Compostela, Galicia, Spain
*E-mail:
[email protected] FAX number: (+34) 91 885 49 71
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Analytical Chemistry
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ABSTRACT Galactosemia is a rare disease which is diagnosed towards the identification of different metabolite profiles. Therefore, the specific detection of galactose 1-phosphate (Gal 1-P), galactose (Gal) and uridyl diphosphate galactose (UDP-Gal) confirms types I, II and III galactosemia diseases. Due to the low prevalence of galactosemia, sample availability is very scarce and screening methods to diagnose the illness are not commonly employed around the world. This work describes the coupling of microfluidic chips (MC) to copper nanowires (CuNWs) as electrochemical detectors for the fast diagnosis of galactosemia in precious newborn urine samples. Conceptually speaking, we hypothesize that the inherent selectivity and sensitivity of CuNWs, towards galactosemia metabolites detection in connection with MC selectivity could allow the fast and simultaneous detection of the three galactosemia biomarkers which implies the fast diagnosis of any galactosemia type in just one single analysis. using extremely low sample using electrokinetic injection protocols. Electrosynthesized CuNWs were homogeneously dispersed in water showed ing a well-defined shape with an average length of 6 µm and a width of 300 nm. Field emission scanning electron microscopy (FESEM) revealed randomly distributed CuNWs over the screen-printed electrode background. This The modified electrodes exhibited an enhanced electroactive surface area twice higher than the nonmodified ones. Very good intra-electrode repeatability with RSDs 1.4 mM). Excellent reproducible recoveries (93-107%, RSDs 0.4 mM and/or Gal > 1.4mM), indicating that a galactosemia diagnosis may be achieved using the analysis results from the MC-Cu ACS Paragon Plus Environment
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Analytical Chemistry
NW devices with reliability. Also, since ill urine samples were previously diagnosed with a specific type of galactosemia, these results reveal the suitability of the approach and the real analytical potency of the MC-CuNWs as novel analytical screening tool for galactosemia diagnosis. Finally and in comparison with previous literature, the commonly employed methods are listed in Table 4, most of them employing blood samples (more invasive) and involving longer analysis times derived from the necessity of extraction, incubation or derivatization steps during the sample pretreatment. Also, detection of only one biomarker was commonly carried out. The approach presented here is an alternative to enzyme based assays being even more sensitive than other nanowires-enzyme based galactose sensors with the additional advantages of the simultaneous detection of the three target biomarkers involved in galactosemia diseases allowing the specific diagnosis of each type of galactosemia. Another clear advantage of our proposal is that microfluidic technology allows introducing minute amounts of samples using electrokinetic injection protocols allowing the representativeness. CONCLUSION The inherent sensitivity and selectivity of CuNWs toward galactosemia metabolites in the context of MCs selectivity enables a novel and creative approach to the rapid, reliable and simultaneous diagnosis of the three types of galactosemia disease from an analysis of newborn urine samples. Types I, II, and III galactosemia profiles were identified through the detection of the specific biomarkers Gal 1-P, Gal, and UDP-Gal, with LOD’s of 16, 15 and 120 µM respectively. The analysis results were obtained in less than 350 s with negligible sample consumption as well as with good signal-to-noise characteristics (>15, noise levels under 0.15 nA). Excellent accuracy (recoveries 93–107%) and stability of the electrochemical detector (intra-electrode repeatability with RSDs
