title: Calling Biomarkers in Milk Using a Protein Microarray on Your Smartphone.
abstract: Here we present the concept of a protein microarray-based fluorescence immunoassay for multiple biomarker detection in milk extracts by an ordinary smartphone. A multiplex immunoassay was designed on a microarray chip, having built-in positive and negative quality controls. After the immunoassay procedure, the 48 microspots were labelled with Quantum Dots (QD) depending on the protein biomarker levels in the sample. QD-fluorescence was subsequently detected by the smartphone camera under UV light excitation from LEDs embedded in a simple 3D-printed opto-mechanical smartphone attachment. The somewhat aberrant images obtained under such conditions, were corrected by newly developed Android-based software on the same smartphone, and protein biomarker profiles were calculated. The indirect detection of recombinant bovine somatotropin (rbST) in milk extracts based on altered biomarker profile of anti-rbST antibodies was selected as a real-life challenge. RbST-treated and untreated cows clearly showed reproducible treatment-dependent biomarker profiles in milk, in excellent agreement with results from a flow cytometer reference method. In a pilot experiment, anti-rbST antibody detection was multiplexed with the detection of another rbST-dependent biomarker, insulin-like growth factor 1 (IGF-1). Milk extract IGF-1 levels were found to be increased after rbST treatment and correlated with the results obtained from the reference method. These data clearly demonstrate the potential of the portable protein microarray concept towards simultaneous detection of multiple biomarkers. We envisage broad application of this 'protein microarray on a smartphone'-concept for on-site testing, e.g., in food safety, environment and health monitoring.
authors: RIKILT Wageningen UR, Wageningen, The Netherlands.
authors: Susann K J
authors: SK
authors: Ludwig
authors: Biologisch-Pharmazeutische Fakultät, Friedrich-Schiller-Universität Jena, Jena, Germany.
authors: Christian
authors: C
authors: Tokarski
authors: Biologisch-Pharmazeutische Fakultät, Friedrich-Schiller-Universität Jena, Jena, Germany.
authors: Stefan N
authors: SN
authors: Lang
authors: RIKILT Wageningen UR, Wageningen, The Netherlands.
authors: Leendert A
authors: LA
authors: van Ginkel
authors: Electrical Engineering Department, University of California Los Angeles, Los Angeles, California, United States of America.
authors: Hongying
authors: H
authors: Zhu
authors: Electrical Engineering Department, University of California Los Angeles, Los Angeles, California, United States of America; Bioengineering Department, University of California Los Angeles, Los Angeles, California, United States America; California NanoSystems Institute (CNSI), University of California Los Angeles, Los Angeles, California, United States of America.
authors: Aydogan
authors: A
authors: Ozcan
authors: RIKILT Wageningen UR, Wageningen, The Netherlands; Laboratory of Organic Chemistry, Wageningen University, Wageningen, The Netherlands.
authors: Michel W F
authors: MW
authors: Nielen
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis; D002417:Cattle; D013006:Growth Hormone / Q000032:analysis*; D007118:Immunoassay; D008892:Milk / Q000737:chemistry*; D040081:Protein Array Analysis / Q000379:methods*; D000068997:Smartphone
chemical_list: D015415:Biomarkers; D013006:Growth Hormone