Ion sensors with crown ether-functionalized nanodiamonds

TL;DR

This paper presents a novel approach to detecting specific alkali metal ions using nanodiamonds functionalized with crown ethers, enabling selective biosensing through changes in NV center charge states.

Contribution

The study introduces crown ether-functionalized nanodiamonds as selective sensors for alkali ions, leveraging NV centers' optical properties for bioimaging and diagnostics.

Findings

Crown ether grafting enables selective sodium ion detection.

Ion presence alters NV center charge states detectable via photoluminescence.

Method demonstrates potential for highly sensitive biosensors.

Abstract

Alkali metal ions such as sodium and potassium cations play fundamental roles in biology. Developing highly sensitive and selective methods to both detect and quantify these ions is of considerable importance for medical diagnostics and bioimaging. Fluorescent nanoparticles have emerged as powerful tools for nanoscale imaging, but their optical properties need to be supplemented with specificity to particular chemical and biological signals in order to provide further information about biological processes. Nitrogen-vacancy (NV) centers in diamond are particularly attractive as fluorescence markers, thanks to their optical stability, biocompatibility and further ability to serve as highly sensitive quantum sensors of temperature, magnetic and electric fields in ambient conditions. In this work, by covalently grafting crown ether structures on the surface of nanodiamonds (NDs), we build sensors that are capable of detecting specific alkali ions such as sodium cations. We will show that the presence of these metal ions modifies the charge state of NV centers inside the ND, which can then be read out by measuring their photoluminescence spectrum. Our work paves the way for designing selective biosensors based on NV centers in diamond.