A lysosome-specific near-infrared fluorescent probe for in vitro cancer cell detection and non-invasive in vivo imaging

Fluorescent naphthalimide boronates as theranostics: structural investigations, confocal fluorescence and multiphoton fluorescence lifetime imaging microscopy in living cells

New design and synthetic strategies were developed to generate functional phenyl boronic acid (BA)-based fluorescent probes incorporating the 1,8-naphthalimide (NI) tag. This fluorescent core was anchored onto the BA unit through small organic linkers consisting of nitrogen groups which can arrest, and internally stabilise the phenyl-boronate units. The newly synthesised fluorophores were characterised spectroscopically by NMR spectroscopy and mass spectrometry and evaluated for their ability to bind to a naturally occurring polysaccharide, β-d-glucan in DMSO and simultaneously as act as in vitro cell imaging reagents. The uptake of these new NI-boronic acid derivatives was studied living cancer cells (HeLa, PC-3) in the presence, and absence, of β-d-glucan. Time-correlated single-photon counting (TCSPC) of DMSO solutions and two-photon fluorescence-lifetime imaging microscopy (FLIM) techniques allowed an insight into the probes' interaction with their environment. Their cellular uptake and distributions were imaged using laser scanning confocal fluorescence microscopy under single- and two-photon excitation regimes (λmax 910 nm). FLIM facilitated the estimation of the impact of the probe's cellular surroundings using the fluorophore lifetime. The extent to which this was mediated by the β-d-glucan was visualised by 2-photon FLIM in living cells. The fluorescence lifetime observed under a range of temperatures varied appreciably, indicating that changes in the environment can be sensed by these probes. In all cases, the cellular membrane penetration of these new probes was remarkable even under variable temperature conditions and localisation was widely concentrated in the cellular cytoplasm, without specific organelle trapping: we conclude that these new probes show promise for cellular imaging in living cancer cells.

Recent Advances in Applications of Fluorescent Perylenediimide and Perylenemonoimide Dyes in Bioimaging, Photothermal and Photodynamic Therapy

The emblematic perylenediimide (PDI) motif which was initially used as a simple dye has undergone incredible development in recent decades. The increasing power of synthetic organic chemistry has allowed it to decorate PDIs to achieve highly functional dyes. As these PDI derivatives combine thermal, chemical and photostability, with an additional high absorption coefficient and near-unity fluorescence quantum yield, they have been widely studied for applications in materials science, particularly in photovoltaics. Although PDIs have always been in the spotlight, their asymmetric counterparts, perylenemonoimide (PMI) analogues, are now experiencing a resurgence of interest with new efforts to create architectures with equally exciting properties. Namely, their exceptional fluorescence properties have recently been used to develop novel systems for applications in bioimaging, biosensing and photodynamic therapy. This review covers the state of the art in the synthesis, photophysical characterizations and recently reported applications demonstrating the versatility of these two sister PDI and PMI compounds. The objective is to show that after well-known applications in materials science, the emerging trends in the use of PDI- and PMI-based derivatives concern very specific biomedicinal applications including drug delivery, diagnostics and theranostics.

Perylenemonoimide-Based Colorimetric Probe with High Contrast for Naked-Eye Detection of Fluoride Ions

Excessive fluoride ions (F^-) in drinking water are harmful to the environment and human health. However, most reported probes of F^- can only detect fluorocarbons rather than aqueous F^-. Herein, a colorimetric and fluorescent probe (PMI-OH) based on perylenemonoimide is designed and synthesized for the detection of aqueous F^-, with high sensitivity, good selectivity, and reversibility. The F^- causes deprotonation of PMI-OH, leading to a significant red shift of 222 nm (from 520 to 742 nm) of the absorption band. Upon the addition of fluorocarbons, the fluorescence intensities of PMI-OH show good linearity against the concentrations of F^-, realizing the quantitative detection of fluorocarbons with a limit of detection as low as 0.495 μM. Finally, PMI-OH is applied to detect F^- in drinking water. The color of PMI-OH solution shows remarkable response from pink to green when the concentrations of F^- exceed the upper limit set by the World Health Organization (WHO), realizing rapid and naked-eye detection of aqueous F^-.

One- and Two-Photon Uncaging of Carbon Monoxide (CO) with Real-Time Monitoring: On-Demand Carbazole-Based Dual CO-Releasing Platform to Test over Single and Combinatorial Approaches for the Efficient Regression of Orthotopic Murine Melanoma In Vivo

Herein, we report three new metal-free, photochemically active single, dual, and combinatorial CORMs (photoCORMs) based on a carbazole-fused 1,3-dioxol-2-one moiety which released one equivalent of CO, two equivalent of CO, and a combination of one equivalent of each CO and anticancer drug upon one- and two-photon excitation, respectively. The photoCORMs exhibited good cellular uptake and real-time monitoring ability of CO uncaging by a color change approach in cancerous B16F10 cells. Interestingly, the cytotoxicity assay on B16F10 cells indicated that the dual photoCORM has increased anticancer activity over the single and combinatorial photoCORMs upon irradiation. Our results also showed that CO could accelerate the effectiveness of the well-known anticancer drug (chlorambucil). Finally, the in vivo evaluation of the dual photoCORM on an established murine melanoma tumor (C57BL/6J mouse model) manifested a significant regression of tumor volume and led to significant improvement (>50%) in the overall survivability.

Soft salts based on platinum(II) complexes with high emission quantum efficiencies in the near infrared region for in vivo imaging

Two soft salts (S1 and S2) based on platinum(ii) complexes with a near-infrared emission have been designed and synthesized. It has been demonstrated that S2 has a high photostability and a low cytotoxicity, and it has been successfully applied to in vivo imaging for the first time.