Fluorescent Carbon Dots for Super-Resolution Microscopy

Abstract

Conventional fluorescence microscopy is limited by the optical diffraction of light, which results in a spatial resolution of about half of the light’s wavelength, approximately to 250–300 nm. The spatial resolution restricts the utilization of microscopes for studying subcellular structures. In order to improve the resolution and to shatter the diffraction limit, two general approaches were developed: a spatially patterned excitation method and a single-molecule localization strategy. The success of super-resolution imaging relies on bright and easily accessible fluorescent probes with special properties. Carbon dots, due to their unique properties, have been used for super-resolution imaging. Considering the importance and fast development of this field, this work focuses on the recent progress and applications of fluorescent carbon dots as probes for super-resolution imaging. The properties of carbon dots for super-resolution microscopy (SRM) are analyzed and discussed. The conclusions and outlook on this topic are also presented.

Recent advances in red-emissive carbon dots and their biomedical applications

“…They can give off fluorescence in the red or NIR spectral range, which makes them particularly useful in different imaging applications like Super Resolution Microscopy (SRM). 95 R-CDs as a fluorescent probe can be functionalized with fluorescent labels to identify specific biological structures or molecules, thus improving imaging contrast and reducing background noise. They can also be engineered to emit light at different wavelengths, enabling multi-color imaging for a more comprehensive understanding of complex biological systems.…”

Intrinsic Burst-Blinking Nanographenes for Super-Resolution Bioimaging

“…Moreover, CDots display buffer-independent fluorescence properties, enabling SRM imaging under a wide range of conditions, such as imaging of materials in air, live-cell imaging under physiological conditions, − and potentially correlative light-electron microscopy (CLEM) in vacuum and hydrophobic environments . Precise control of the chemical structures of CDots, which are typically heterogeneous and mostly undefined at the molecular level, however, remains challenging and constitutes a hurdle for the unambiguous elucidation of their structure–property relationship and fluorescence mechanism, ,, thus prohibiting an accurate control of their optical properties. Furthermore, conjugation of CDots to biomolecules remains challenging at the single-molecule level, ,, restricting their applicability in bioimaging and biosensing of specific targets.…”

“…In addition to organic fluorophores and fluorescent proteins, different types of fluorescent nanoparticles, such as semiconductor quantum dots (QDots), carbon-based nanodots (CDots), polymer dots (PDots), and fluorescent nanodiamonds (FNDs), have been extensively investigated as blinking fluorophores with higher brightness and stability. , Among them, CDots have emerged as one of the most promising candidates with unique optical properties that are advantageous for SMLM imaging. − CDots can be very small (∼2 and 5 nm) and demonstrate the so-called burst-blinking with a long and complete off state, which are crucial to achieving SRM imaging of high-density labeling samples. Moreover, CDots display buffer-independent fluorescence properties, enabling SRM imaging under a wide range of conditions, such as imaging of materials in air, live-cell imaging under physiological conditions, − and potentially correlative light-electron microscopy (CLEM) in vacuum and hydrophobic environments . Precise control of the chemical structures of CDots, which are typically heterogeneous and mostly undefined at the molecular level, however, remains challenging and constitutes a hurdle for the unambiguous elucidation of their structure–property relationship and fluorescence mechanism, ,, thus prohibiting an accurate control of their optical properties.…”

Microwave-synthesized narrow emitting carbon dots and their tunable fluorescence for sensing applications

“…[1][2][3][4] Although great progress has been made in the preparation of CDs, most of the reported CDs have wider emission bands scaled by the full width at half maximum (FWHM, usually larger than 80 nm). [5][6][7][8] A large FWHM means that the optical purity of CDs is low, which reduces the imaging resolution, weakens the fluorescence effect, and thus diminishes application performances of the fluorescent material. Practically, a narrow-bandwidth emission with the FWHM smaller than 60 nm is necessary in bioimaging, sensing, and photoelectric displays.…”