# Universal Platform Based on Carbon Nanotubes Functionalised with Carboxylic Acid Groups for Multi-Analyte Enzymatic Biosensing

## TL;DR

Researchers developed a versatile biosensing platform using carbon nanotubes to detect multiple biomolecules in blood plasma, showing promise for health and food applications.

## Contribution

A novel oxygen-sensitive electrochemical platform using CNT-COOH for multi-analyte biosensing with extended detection range via catalase.

## Key findings

- CNT-COOH nanotubes attached end-on with horizontal orientation on gold electrodes.
- Catalase significantly improved the linear detection range by reducing hydrogen peroxide accumulation.
- The biosensor successfully measured glucose, lactate, glutamate, and dopamine simultaneously in blood plasma.

## Abstract

This work presents the development of carbon nanotubes functionalised with carboxylic acid groups (CNT-COOH) as an oxygen-sensitive electrochemical platform for parallel multi-analyte enzymatic biosensing. The platform was constructed by depositing carboxylic-acid-functionalised single-walled carbon nanotubes covalently onto nanostructured gold electrodes modified with a self-assembled monolayer of 4-aminothiophenol. Atomic force microscopy characterization revealed that the nanotubes attached via their ends to the surface and had a predominantly horizontal orientation. Glucose oxidase, lactate oxidase, glutamate oxidase, and tyrosinase were immobilised onto the electrodes to create selective biosensor for lactate, glucose, glutamate, and dopamine, respectively. A key finding is that incorporating catalase significantly extends the linear detection range for analytes by mitigating the accumulation of hydrogen peroxide. The resulting multifunctional biosensor demonstrated its capability for the simultaneous and independent measurement of glucose, lactate as the key bioanalytes under uniform conditions in blood plasma samples, highlighting its potential for applications in health and food technologies.