# Selective Addressing of Versatile Nanodiamonds via Physically-Enabled Classifier in Complex Biosystems

## TL;DR

This paper introduces a new optical method to enhance nanodiamond imaging in complex biological systems by reducing background noise.

## Contribution

A novel all-optical modulated imaging method using a physically enabled classifier to isolate nanodiamond fluorescence.

## Key findings

- Signal-to-background ratio improved from 1.92 to 60.39 dB in neural protein imaging.
- Fourfold contrast improvement in magnetic resonance measurements inside stained cells.

## Abstract

Nitrogen-vacancy (NV) centers show
great potential for
nanoscale
biosensing and bioimaging. Nevertheless, their envisioned bioapplications
suffer from intrinsic background noise due to unavoidable light scattering
and autofluorescence in cells and tissues. Herein, we develop a unique
all-optical modulated imaging method via a physically enabled classifier,
for on-demand and direct access to NV fluorescence at pixel resolution
while effectively filtering out background noise. Specifically, NV
fluorescence can be modulated optically to exhibit sinusoid-like variations,
providing a basis for classification. We validate our method in various
complex biological scenarios with fluorescence interference, ranging
from cells to organisms. Notably, our classification-based approach
achieves an enhancement of signal-to-background ratio from 1.92 to
60.39 dB for fluorescent nanodiamonds in neural protein imaging. We
also demonstrate a 4-fold contrast improvement in optically detected
magnetic resonance measurements inside stained cells. Our technique
offers a generic, explainable, and robust solution, applicable for
realistic high-fidelity imaging and sensing in challenging noise-laden
scenarios.