Revolutionizing Nanofluidics: Breakthrough Discovery Using Boron Nitride’s Fluorescent Properties

In a remarkable advancement in nanofluidics, scientists have developed a method to observe individual molecules in tiny spaces. This achievement is made possible by exploiting the newly discovered fluorescent attributes of boron nitride. The image above illustrates the research breakthrough in understanding molecular movement in nano-confined areas. Credit: Titouan Veuillet / EPFL

A collaborative team from EPFL and the University of Manchester has made significant strides in the field of nanofluidics by employing a two-dimensional, graphene-like material, and light.

This innovation in nanofluidics is poised to transform our understanding of molecular behavior at extremely small scales. Researchers from EPFL and the University of Manchester have tapped into a hidden realm by utilizing the fluorescent qualities of boron nitride, a two-dimensional material similar to graphene. This method allows for the tracking of individual molecules in nanofluidic environments, shedding light on their behavior in previously unachievable ways. The research, recently featured in Nature Materials, highlights this breakthrough.

Nanofluidics, the study of fluid behavior in tiny spaces, aims to provide insight into liquid dynamics at a nanoscale. However, tracking individual molecule movements in such confined spaces has been a challenge due to the limitations in traditional microscopy methods. This hindered real-time imaging and sensing, leaving a significant knowledge gap in understanding molecular behaviors in confined environments.

Overcoming the Challenges of Traditional Microscopy

EPFL scientists have overcome these barriers thanks to a surprising characteristic of boron nitride. This two-dimensional material exhibits unique light-emitting properties when in contact with liquids. Utilizing this feature, researchers at EPFL’s Laboratory of Nanoscale Biology have been able to directly monitor and map the trajectories of individual molecules in nanofluidic structures. This breakthrough has opened doors to a more profound understanding of ion and molecule behaviors in conditions resembling biological systems.

Professor Aleksandra Radenovic, leading the LBEN, states, “Advancements in material science and fabrication techniques have enabled us to manipulate fluidic and ionic transport at a nanoscale. Yet, our comprehension of nanofluidic systems was limited, as conventional light microscopy couldn’t explore structures smaller than the diffraction limit. Our research now illuminates the field of nanofluidics, revealing aspects of it that were mostly unexplored until now.”

Potential Applications and Future Directions

This new understanding of molecular properties holds exciting prospects, including direct imaging of emerging nanofluidic systems where liquids behave unusually under various stimuli such as pressure or voltage. The study’s core lies in the fluorescence emanating from single-photon emitters on the surface of hexagonal boron nitride. “This fluorescence activation was unexpected since neither hBN nor the liquid normally exhibit fluorescence in the visible range. It likely results from molecules interacting with surface defects on the crystal, but the exact mechanism remains unclear,” comments Nathan Ronceray, a doctoral student from LBEN.

These surface defects, often missing atoms in the crystal structure, possess properties distinct from the original material, allowing them to emit light upon interaction with specific molecules. The researchers observed that when one defect stops emitting light, a neighboring one starts, indicating a molecule’s movement from the first site to the second. This process helps in reconstructing entire molecular trajectories.

By employing a mix of microscopy methods, the team was able to observe color changes, demonstrating that these light emitters release photons individually, providing precise information about their immediate environment within approximately one nanometer. This advancement enables the use of these emitters as nanoscale probes, offering insights into molecular arrangements in confined nanometer spaces.

Collaborative Efforts and Visualization Techniques

Professor Radha Boya’s team from the University of Manchester’s Physics department developed the nanochannels from two-dimensional materials, confining liquids just nanometers away from the hBN surface. This collaboration facilitated optical probing of these systems, revealing hints of liquid ordering due to confinement. “Seeing is believing, but visualizing confinement effects at this scale is challenging. We create extremely thin slit-like channels, and this study provides an elegant method to visualize them through super-resolution microscopy,” says Radha Boya.

The discovery’s potential is extensive. Nathan Ronceray foresees applications beyond passive sensing. “So far, we have observed molecule behaviors with hBN without active interaction. However, we believe it can be used to visualize nanoscale flows triggered by pressure or electric fields.” This could lead to more dynamic future applications in optical imaging and sensing, offering unparalleled insights into the complex behaviors of molecules in confined spaces.

Reference: “Liquid-activated quantum emission from pristine hexagonal boron nitride for nanofluidic sensing” by Nathan Ronceray, Yi You, Evgenii Glushkov, Martina Lihter, Benjamin Rehl, Tzu-Heng Chen, Gwang-Hyeon Nam, Fanny Borza, Kenji Watanabe

Frequently Asked Questions (FAQs) about Nanofluidics

More about Nanofluidics

• Nature Materials Article
• EPFL Laboratory of Nanoscale Biology
• University of Manchester Physics Department
• Nanofluidics Research Overview
• Fluorescent Properties of Boron Nitride
• Advances in Optical Imaging and Sensing Techniques
• Super-Resolution Microscopy in Nanofluidics
• Molecular Dynamics in Confined Spaces