Biosensor for Rapid Measurement of Lactate in Exhaled Breath Condensate
Authors: Zhang Shulin , O'Hare Danny 
Published: February 2024

Lactate concentration plays an important role in disease diagnostics. Higher lactate concentrations are associated with sepsis and septic shock [2], trauma [3], tissue hypoxia due to acute lung injury [4], and respiratory diseases [5]. Lactate level is also widely used in monitoring athletes’ training and fitness as long-term exhausting exercise leads to a rapid increase in lactate level and result in muscle weakening and fatigue [6]. Compared with the traditional blood sample media which is invasive and capillary blood monitoring is not suitable for routine clinical use, the exhaled breath condensate (EBC) is simple and non-invasive method with no potential for adverse effects for lactate analysis.
In this presentation, a point-of-care electrochemical biosensor is introduced for the EBC lactate analysis. This disposable and low-cost sensor is aimed to be inserted in an EBC collection device developed by our team that enables real-time monitoring and rapid measurements of EBC lactate level. The sensor measurement is done directly after EBC sample collection, that minimizes the risk of sample degradation and is cheaper than the traditional laboratory techniques such as fluorometry or mass spectrometry.
The sensor is modified with poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), Prussian blue (PB) and lactate oxidase (LOD) enzyme. Lactate concentration is measured from amperometric current response generated by the redox reactions on sensor surface. The enzyme gel formulation is optimized based on rotating disk electrode (RDE) experiments and kinetics analysis, investigating the effect of LOD concentration and gel thickness, and was then applied to disposable sensors.
Finally, human EBC analysis is conducted on healthy subjects at rest and after 30 min of intense aerobic cycling exercise. Sensor’s results in real EBC lactate measurements demonstrate a good correlation with fluorometry and mass spectrometry calibrations and exhibit high stability and sensitivity in both short-term and long-term use. Mass production of the sensor is done by robotic gel dispensing using a Biodot aspirate dispensing machine.
Note: This presentation is based on the corresponding author's recent publication ‘Rapid Measurement of Lactate in the Exhaled Breath Condensate: Biosensor Optimization and In-Human Proof of Concept’ in ACS Sensors (doi.10.1021/acssensors.2c01739) [1]
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2022.

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Figure 1