Structure Rigidification Promoted Ultrabright Solvatochromic Fluorescent Probes for Super-Resolution Imaging of Cytosolic and Nuclear Lipid Droplets

Abstract

Lipid droplets (LDs) containing cytosolic and nuclear LDs have recently received increasing attention because of their diverse biological roles in living systems. However, developing fluorescent probes for super-resolution visualization of these subcellular LDs still remains challenging due to insufficient fluorescence brightness and poor nuclear membrane permeability. Herein, we rationally synthesized a series of ultrabright solvatochromic fluorescent probes based on benzoboranils (BBAs) for LD-specific super-resolution imaging using structured illumination microscopy (SIM). The rigidly structured probes exhibit ultrahigh fluorescence quantum yields of up to 99.9% in low-polar solvents. They also show more significant fluorescence enhancements in lipid environments than commercial LD probes. Owing to these excellent merits, our lipophilic fluorescent probes can specifically light up subcellular LDs at ultralow concentrations down to 10 nM. Further use of BBA-CF 3 for super-resolution SIM imaging of cytosolic and nuclear LDs and their fusion process was successfully achieved. The unprecedented spatial resolution for nuclear LDs with an FWHM value of 142 nm was also acquired. Collectively, our ultrabright fluorescent probes hold tremendous potential to unveil the mysterious roles of cytosolic and nuclear LDs in biological research using SIM.

Donor–Acceptor–Acceptor-Conjugated Dual-State Emissive Acrylonitriles: Investigating the Effect of Acceptor Unit Order and Biological Imaging

“…Remarkably, the emission signals of TPA-AN-PhBT and TPA-BT-ANPh overlapped with the black spots in the bright field. This shows that these dyes possibly stain lipid droplets, as per our experience and previous reports. − …”

Reversible Near-Infrared Fluorescent Probe for Rapid Sensing Sulfur Dioxide and Formaldehyde: Recognition and Photoactivation Mechanism and Applications in Bioimaging and Encryption Ink

“…In the meantime, the near-infrared emission also disappears correspondingly at λ ex = 550 nm. Therefore, probe 1 probe belongs to the type of intramolecular charge transfer (ICT) probes. , The recognition and color-changing mechanism of HSO 3 – originates from the great changes in molecular structure between 1 and 1-SO 3 H , which leads to the destruction of the conjugate system and the migration of molecular orbitals. These results provide strong support for the experimental phenomena.…”

A new organic molecular probe as a powerful tool for fluorescence imaging and biological study of lipid droplets

“…Under the STED laser intensity of 5 MW cm −2 , the STED imaging with gate delay times (tg) of 1 ns, 3 ns or 6 ns provided FWHM resolutions of 93 ± 9 nm, 60 ± 7 nm, or even up to 37 ± 4 nm (Figure 3D and Figure S17B). The resolution of 37 ± 4 nm is substantially broken the diffraction limit of light (~250 nm) and represents the highest resolution of fluorescence imaging of LDs up to date (Table S3) [11][12][13][14][15][16]. This is also a state-of-the-art resolution of living cell STED super-resolution imaging (Table S4) [33][34][35][36][37][38][39][40][41][42][43][44][45].…”

“…To visualize LDs and reveal their versatile functions, the confocal and wide-field fluorescence microscopies have been widely employed with sub-micrometer resolution (~250 nm) [6][7][8][9][10]. The emerging super-resolution fluorescence microscopies, such as stimulated emission depletion microscopy (STED) and photoactivated localization microscopy (PALM), successfully broke the resolution limit of light diffraction and make it possible to further visualize the small/nascent LDs with nanoscale resolution [11][12][13][14][15][16]. For example, our group developed a super-photostable LDs fluorescent probe Lipi-DSB for STED super-resolution imaging, successfully visualizing the nanoscale fusion process of nascent LDs [12].…”