Method for Measuring Bioactive Molecules in Blood by a Smartphone Using Bioluminescent Ratiometric Indicators.

Bioluminescent indicators facilitate determination of bioactive molecules in blood samples with high sensitivity. Using a bright luciferase, its bioluminescence (BL) can be easily detected by conventional light sensing devices. In this chapter, we describe a protocol to measure bioactive molecules in blood by taking the BL images with a smartphone camera. We exemplify the measurement of unconjugated bilirubin (UCBR) concentration in the blood of mice using a ratiometric bioluminescent UCBR indicator, BABI (bilirubin assessment with a bioluminescent indicator), and a smartphone camera. We show the UCBR concentration is easily determined through measuring the variance in the BL color with a smartphone camera. This method provides a practical method to lead to future point-of-care diagnosis with quick and simple procedures.