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

doi:10.1016/j.mex.2021.101414

A miniaturized optoelectronic biosensor for real-time point-of-care total protein analysis

MethodsX. 2021 Jun 17:8:101414. doi: 10.1016/j.mex.2021.101414. eCollection 2021.

Authors

Ophir Vermesh^{1

2}, Fariah Mahzabeen³, Jelena Levi^{1

2}, Marilyn Tan⁴, Israt S Alam^{1

2}, Carmel T Chan^{1

2}, Sanjiv S Gambhir^{1

2

5

6}, James S Harris³

Affiliations

¹ Department of Radiology, Stanford University, Stanford, CA, 94305, USA.
² Molecular Imaging Program at Stanford, Stanford University, Stanford, CA 94305, USA.
³ Department of Electrical Engineering, Stanford University, Stanford, CA, 94305, USA.
⁴ Department of Medicine, Stanford University, Stanford, CA 94305, USA.
⁵ Department of Bioengineering, Stanford University, Stanford, CA 94305, USA.
⁶ Stanford Bio-X, Stanford University, Stanford, CA 94305, USA.

Abstract

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.

Keywords: Diabetes; Nephropathy; PIFE; Sensor; Total protein; Urine; VCSEL.