A miniaturized optoelectronic biosensor for real-time point-of-care total protein analysis
Ophir Vermesh,
Fariah Mahzabeen,
Jelena Levi,
Marilyn Tan,
Israt S. Alam,
Carmel T. Chan,
Sanjiv S. Gambhir,
James S. Harris
Affiliations
Ophir Vermesh
Department of Radiology, Stanford University, Stanford, CA, 94305, USA; Molecular Imaging Program at Stanford, Stanford University, Stanford, CA 94305, USA; Corresponding authors.
Fariah Mahzabeen
Department of Electrical Engineering, Stanford University, Stanford, CA, 94305, USA
Jelena Levi
Department of Radiology, Stanford University, Stanford, CA, 94305, USA; Molecular Imaging Program at Stanford, Stanford University, Stanford, CA 94305, USA
Marilyn Tan
Department of Medicine, Stanford University, Stanford, CA 94305, USA
Israt S. Alam
Department of Radiology, Stanford University, Stanford, CA, 94305, USA; Molecular Imaging Program at Stanford, Stanford University, Stanford, CA 94305, USA
Carmel T. Chan
Department of Radiology, Stanford University, Stanford, CA, 94305, USA; Molecular Imaging Program at Stanford, Stanford University, Stanford, CA 94305, USA
Sanjiv S. Gambhir
Department of Radiology, Stanford University, Stanford, CA, 94305, USA; Molecular Imaging Program at Stanford, Stanford University, Stanford, CA 94305, USA; Department of Bioengineering, Stanford University, Stanford, CA 94305, USA; Stanford Bio-X, Stanford University, Stanford, CA 94305, USA
James S. Harris
Department of Electrical Engineering, Stanford University, Stanford, CA, 94305, USA; Corresponding authors.
A miniaturized optoelectronic sensor is demonstrated that measures total protein concentration in serum and urine with sensitivity and accuracy comparable to gold-standard methods. The sensor is comprised of a vertical cavity surface emitting laser (VCSEL), photodetector and other custom optical components and electronics that can be hybrid packaged into a portable, handheld form factor. In conjunction, a custom fluorescence assay has been developed based on the protein-induced fluorescence enhancement (PIFE) phenomenon, enabling real-time sensor response to changes in protein concentration. Methods are described for the following: • Standard curves: Used to determine the sensitivity, dynamic range, and linearity of the VCSEL biosensor/PIFE assay system in buffer as well as in human blood and urine samples. • Comparison of VCSEL biosensor performance with a benchtop fluorimetric microplate reader. • Accuracy of the VCSEL biosensor/PIFE assay system: Evaluated by comparing sensor measurements with gold-standard clinical laboratory measurements of total protein in serum and urine samples from patients with diabetes.
