Covalent and Site-Specific Immobilization of a Fluorogenic Sensor Protein on Cellulose-Based Paper for Detection of Lactate in Cell Culture Media

TL;DR

This paper presents a paper-based sensor using fluorescent proteins to detect lactate in cell culture media, offering a new method for monitoring metabolic states.

Contribution

The study introduces a novel covalent and site-specific immobilization method for fluorogenic sensor proteins on cellulose-based paper.

Findings

Immobilizing the proteins on paper does not hinder their lactate binding ability.

The sensor successfully detects lactate in cell culture supernatant under various conditions.

The fluorescent readout provides a reliable and visual method for lactate detection.

Abstract

Lactate is a key metabolite with applications ranging from monitoring training efficiency to early sepsis detection and monitoring the metabolic state of cell cultures. In this study, a paper-based lactate sensor utilizing a fluorescent readout was developed. Unlike common lactate dehydrogenase (LDH)-based methods, these sensors use a green fluorescent protein (GFP) or mApple-coupled lactate binding domain, which provides a fluorescent readout upon lactate binding. We demonstrate that immobilizing these proteins on paper does not affect their ability to bind lactate and produce a fluorescent readout, by monitoring lactate levels in the cell culture supernatant applying different cell culture conditions.

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