A fluorescence sandwich immunoassay for the real-time continuous detection of glucose and insulin in live animals

Real-time biosensors that can continuously measure circulating biomolecules in vivo would provide valuable insights into a patient’s health status and their response to therapeutics, even when there is considerable variability in pharmacokinetics and pharmacodynamics across patient populations. Unfortunately, current real-time biosensors are limited to a handful of analytes (e.g. glucose and blood oxygen) and are limited in sensitivity (high nanomolar). In this work, we describe a general approach for continuously and simultaneously measuring multiple analytes with picomolar sensitivity and sub-second temporal resolution in a device with an incubation time of 30 s. As exemplars, we report the simultaneous detection of glucose and insulin in live diabetic rats. Using our system, we demonstrate the capacity to resolve inter-individual differences in the pharmacokinetic response to insulin, and discriminate profiles from different insulin formulations at high temporal resolution. Critically, our approach is general and could be readily modified to continuously and simultaneously measure other circulating analytes in vivo, thus making it a versatile tool for biomedical research.