# Serine-Grafted Cu2O Electrode Enabling Specific β‑Hydroxybutyrate Detection by Surface Sensitization-Promoted Electrolysis in Amperometry

## TL;DR

A new electrochemical sensor using serine-grafted copper oxide nanoparticles can detect β-hydroxybutyrate, a marker for diabetic ketoacidosis, with high sensitivity and specificity.

## Contribution

A novel electrochemical method using serine-grafted Cu2O nanoparticles for specific and sensitive detection of β-hydroxybutyrate is introduced.

## Key findings

- The sensor shows a linear response to β-hydroxybutyrate concentrations from 0–20 mM.
- The detection limit is as low as 0.1 mM.
- Surface sensitization via esterification and amide bond formation enhances electrolysis for accurate detection.

## Abstract

As the global prevalence of diabetes continues to rise,
the home health testing market has experienced rapid growth. Although
blood glucose monitoring is widespread among diabetic patients, there
remains a significant lack of testing methods for diabetic ketoacidosis.
The present study developed a feasible electrochemical technique for
ketoacid detection using serine-immobilized copper­(I) oxide nanoparticles
(Cu2O NPs) as the primary electrode material. Given that
the serine on the nanoparticle surface enables conjugation with β-hydroxybutyrate
(β-HBA) through an esterification reaction between the hydroxyl
group of serine and carboxylic acid of β-HBA and another intramolecular
nucleophilic acyl substitution between amine and ester groups to form
irreversible amide bonding, thus resulting in the β-HBA deposition
on the surface of the Cu2O NP-coated electrode. The quantification
of β-HBA can be determined through current variations in amperometry
measurement. The results showed a highly linear relationship between
reductive current and β-HBA concentration at 0–20 mM,
with a reasonable detection limit of 0.1 mM. Moreover, a reasonable
mechanism involving the NP surface covering-mediated electrolysis
enhancement was proposed. The present method reveals a promising direction
in developing sensors for small molecule detection with high specificity
and sensitivity.