Clearly fluorescent delineating ER+ breast tumor incisal edge and identifying tiny metastatic tumor foci at high resolution

Fluorescence-image guided surgery (FGS) can intraoperatively provide real-time visualization of a tumor incisal edge and high-resolution identification of tumor foci to improve treatment outcomes. In this contribution, we report a fluorescent probe NB-TAM based on intramolecularly folded photoinduced electron transfer (PET), which displayed a prominent turn-on response in the near-infrared (NIR) window upon specific interaction with the estrogen receptor (ER). Significantly, NB-TAM could delineate a clear tumor incisal edge (tumor-to-normal tissue ratio > 5) in a 70-min time window, and was successfully used to guide the facile and precise resection of ER+ breast tumors in mice. To our surprise, NB-TAM was found to be capable of identifying very tiny lung metastatic ER+ breast tumor foci (0.4 × 0.3 mm), and this ultrahigh resolution was essential to effectively promote tumor resection precision and early diagnosis of tiny tumors. These results clearly elucidate the promising application of NB-TAM as a diagnostic agent for intraoperative fluorescence imaging of ER+ breast cancer.

New Highly Fluorescent Water Soluble Imidazolium-Perylenediimides: Synthesis and Cellular Response

The synthesis and characterization of two new water soluble 2,6-bis(imidazolylmethyl)-4-methylphenoxy-containing perylenediimides, PDI-1 and PDI-2, are described. These compounds demonstrate a high fluorescence quantum yield in water and were investigated as potential photosensitizers for generating reactive oxygen species with applications in anticancer activities. The HeLa cell line (VPH18) was used to evaluate their efficacy. Fluorescence microscopy was employed to confirm the successful internalization of PDI-1 and PDI-2, while confocal microscopy revealed the specific locations of both PDIs within the lysosomes and mitochondria. In vitro studies were conducted to evaluate the anticancer activity of PDI-1 and PDI-2. Remarkably, these photosensitizers demonstrated a significant ability to selectively eliminate cancer cells when exposed to a specific light wavelength. The water solubility, high fluorescence quantum yield, and selective cytotoxicity of these PDIs toward cancer cells highlight their potential as effective agents for targeted photodynamic therapy. In conclusion, the findings presented here provide a strong foundation for the future exploration and optimization of PDI-1 and PDI-2 as effective photosensitizers in photodynamic therapy, potentially leading to improved treatment strategies for cancer patients.

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.

Synthesis of Dipyridylaminoperylenediimide-Metal Complexes and Their Cytotoxicity Studies

A new family of perylenediimide (PDI) silver and copper complexes has been successfully synthesized by reacting ortho- and bay-substituted (dipyrid-2',2″-ylamino)perylenediimide ligands with metal phosphine fragments. The coordination of the metal center did not reveal a significant effect on the photophysical properties, which are mainly due to the PDI ligands, and in some cases quenching of the luminescence was observed. The antiproliferative effect of the free perylenediimide ligands and the metalloPDI complexes against the cervix cancer cell line HeLa was determined by MTT assay. The free perylenediimide ligands exhibited a moderate cytotoxic activity, but the coordination of silver or copper to the dypyridylamino fragment greatly enhanced the activity, suggesting a synergistic effect between the two fragments. In attempts to elucidate the cellular biodistribution of the PDIs and the complexes, a colocalization experiment using specific dyes for the lysosomes or mitochondria as internal standards revealed a major internalization inside the cell for the metal complexes, as well as a partial mitochondrial localization.

Intersystem Crossing and Triplet-State Property of Anthryl- and Carbazole-[1,12]fused Perylenebisimide Derivatives with a Twisted π-Conjugation Framework

Heavy atom-free triplet photosensitizers (PSs) are particularly of interest concerning both fundamental photochemistry study and practical applications. However, achieving efficient intersystem crossing (ISC) in planar heavy atom-free aromatic organic compounds is challenging. Herein, we demonstrate that two perylenebisimide (PBI) derivatives with anthryl and carbazole moieties fused at the bay position, showing twisted π-conjugation frameworks and red-shifted UV-vis absorption as compared to the native PBI chromophore (by 75-1610 cm^-1), possess efficient ISC (singlet oxygen quantum yield: Φ_Δ = 85%) and a long-lived triplet excited state (τ_T = 382 μs in fluid solution and τ_T = 4.28 ms in solid polymer film). Femtosecond transient absorption revealed ultrafast intramolecular charge-transfer (ICT) process in the twisted PBI derivatives (0.9 ps), and the ISC takes 3.7 ns. Pulsed laser excited time-resolved electron paramagnetic resonance (TREPR) spectra indicate that the triplet-state wave function of the twisted PBIs is mainly confined on the PBI core, demonstrated by the zero-field-splitting D parameter. Accordingly, the twisted derivatives have higher T₁ energy (E_T1 = 1.48-1.56 eV) as compared to the native PBI chromophore (1.20 eV), which is an advantage for the application of the derivatives as triplet PSs. Theoretical computation of the Franck-Condon density of states, based on excited-state dynamics methods, shows that the efficient ISC in the twisted PBI derivatives is due to the increased spin-orbit coupling matrix elements for the S₁-T₁ and S₁-T₂ states [spin-orbit coupling matrix element (SOCME): 0.11-0.44 cm^-1. SOCME is zero for native PBI], as well as the Herzberg-Teller vibronic coupling. For the planar benzoPBI, the moderate ISC is due to S₁ → T₂ transition (SOCME: 0.03 cm^-1. The two states share a similar energy, ca. 2.5 eV).

Cu(I)-Catalyzed Click Chemistry in Glycoscience and Their Diverse Applications

Copper(I)-catalyzed 1,3-dipolar cycloaddition between organic azides and terminal alkynes, commonly known as CuAAC or click chemistry, has been identified as one of the most successful, versatile, reliable, and modular strategies for the rapid and regioselective construction of 1,4-disubstituted 1,2,3-triazoles as diversely functionalized molecules. Carbohydrates, an integral part of living cells, have several fascinating features, including their structural diversity, biocompatibility, bioavailability, hydrophilicity, and superior ADME properties with minimal toxicity, which support increased demand to explore them as versatile scaffolds for easy access to diverse glycohybrids and well-defined glycoconjugates for complete chemical, biochemical, and pharmacological investigations. This review highlights the successful development of CuAAC or click chemistry in emerging areas of glycoscience, including the synthesis of triazole appended carbohydrate-containing molecular architectures (mainly glycohybrids, glycoconjugates, glycopolymers, glycopeptides, glycoproteins, glycolipids, glycoclusters, and glycodendrimers through regioselective triazole forming modular and bio-orthogonal coupling protocols). It discusses the widespread applications of these glycoproducts as enzyme inhibitors in drug discovery and development, sensing, gelation, chelation, glycosylation, and catalysis. This review also covers the impact of click chemistry and provides future perspectives on its role in various emerging disciplines of science and technology.

Near infrared absorption/emission perylenebisimide fluorophores with geometry relaxation-induced large Stokes shift

The dyes (P-1 and P-2) of perylenebisimide (PBI) conjugated with 2-(2-hydroxyphenyl)benzothiazole (HBT) were prepared by Sonogashira coupling reaction. The new compounds have special photophysical properties, such as near infrared absorption/emission and large Stokes shift. The UV-vis absorption (range from 651 nm to 690 nm) and emission wavelength (range from 732 nm to 756 nm) of P-1 and P-2 extend to near infrared range. Importantly, they have much larger Stokes shifts (range from 73 nm to 105 nm) compared with the conventional PBI derivatives, such as 7 (from 19 nm to 65 nm) and 9 (from 81 nm to 86 nm). TD-DFT calculation was used to rationalize UV-vis absorption, emission and especially large Stokes shift from the theoretical point of view. We found geometry relaxation of P-1 and P-2 in the excited state is an important reason for the origin of large Stokes shift besides intramolecular electron transfer (ICT).

The dyes with near infrared absorption/emission and large stokes shifts induced by geometry relaxation were prepared.

Establishment of evaluation criteria for the development of high quality ERα-targeted fluorescent probes

ERα-targeted fluorescent probes are important tools for ERα study. In order to develop high quality ERα-targeted probes, a sound and complete evaluation system is essential but has not been established yet. Herein, we set up a series of evaluation criteria for ERα-targeted fluorescent probes including ERα binding affinity, fluorescence quantum yield, cytotoxicity, ERα tracking capacity, ERα selectivity and ERα labeling ability. To verify the practicability of the evaluation criteria, we designed and synthesized two ERα-targeted fluorescent probes and fully characterized their properties based on the proposed evaluation criteria. It showed that the probes exhibited better performance. Moreover, we applied the probes in MCF-7 cells to study the ERα motion characteristics for the first time. We hope that our evaluation criteria could be helpful for the establishment of a complete evaluation system for ERα-targeted fluorescent probes.

Tubular Perylene Bisimide Macrocycles for the Recognition of Geometrical Isomers of Azobenzenes

Perylene bisimide-based materials are good candidates for photosensitive applications. Herein, we report synthesis, characterization, and complexation studies of perylene bisimide macrocycles obtained through bayside coupling. The isomeric macrocycles incorporated with interesting optical properties and tubular-shaped cavities are able to recognize geometric isomers of azobenzenes and aromatic amines. Such selective recognition is useful toward developing potential sensors for interesting isomeric pairs in the future.

The role of CT excitations in PDI aggregates

Energies and couplings of local excitations and charge transfer states control the nature of singlets and triplets in PDI aggregates.

Fluorescent glycoconjugates and their applications

Fluorescent glycoconjugates are discussed for their applications in biology in vitro, in cell assays and in animal models. Advantages and limitations are presented for each design using a fluorescent core conjugated with glycosides, or vice versa.

Perylene-Grafted Silicas: Mechanistic Study and Applications in Heterogeneous Photoredox Catalysis

A mechanistic study is herein presented for the use of heterogeneous photocatalysts based on perylene moieties. First, the successful immobilization of perylene diimides (PDI) on silica matrices is demonstrated, including their full characterization by means of electronic microscopy, surface area measurements, powder XRD, thermogravimetric analysis, and FTIR, ²⁹ Si and ¹³ C solid-state NMR, fluorescence, and diffuse reflectance spectroscopies. Then, the photoredox activity of the material was tested by using two model reactions, alkene oxidation and 4-nitrobenzylbromide reduction, and mechanistic studies were performed. The mechanistic insights into their photoredox activity show they have promising dual photocatalytic activity for both organic oxidations and reductions.

Review of fluorescent steroidal ligands for the estrogen receptor 1995-2018

The development of fluorescent ligands for the estrogen receptor (ER) continues to be of interest. Over the past 20 years, most efforts have focused on appending an expanding variety of fluorophores to the B-, C- and D-rings of the steroidal scaffold. This review highlights the synthesis and evaluation of derivatives substituted primarily at the 6-, 7α- and 17α-positions, culminating with our recent work on 11β-substituted estradiols, and proposes an approach to new fluorescent imaging agents that retain high ER affinity.

Diels–Alder reaction on perylenediimides: synthesis and theoretical study of core-expanded diimides

(Un)substituted perylenediimides react with (un)functionalized benzynes yielding core-expanded diimides.

Direct amination and N-heteroarylation of perylenediimides

A mild, fluoride-mediated reaction for the direct introduction of amines and N-heterocycles.

Intramolecular electron transfer of light harvesting perylene-pyrene supramolecular conjugate

Electronic interactions between the cationic N,N'-bis(2(trimethylammonium iodide) ethylene)perylene-3,4,9,10-tetracarboxyldiimide (TAIPDI) with two electron donors, namely, pyrene (Py) and 1-pyrenesulfonic acid sodium salt (PySA), have been investigated. The spectroscopic studies showed the formation of the supramolecular conjugate between TAIPDI and PySA via ionic interaction, but not with Py. Density functional theory (DFT) combined with a natural energy decomposition analysis (NEDA) technique showed an S-like structure of the supramolecular conjugate TAIPDI-PySA via an ionic interaction. The formation constant of the TAIPDI-PySA supramolecular conjugate was determined to be 3.0 × 104 M-1, suggesting a fairly stable complex formation. The excited state events were monitored by both steady state and time-resolved emission techniques. Upon excitation, the quenching pathways via the singlet-excited states of TAIPDI and PySA involved the intramolecular electron transfer from the electron donating PySA to the electron accepting TAIPDI with a rate constant of 1.10 × 1011 s-1 and a quantum yield of 0.99. The thermodynamic parameters of the supramolecular TAIPDI-PySA conjugate have been determined using the stopped-flow technique.

A high-affinity subtype-selective fluorescent probe for estrogen receptor β imaging in living cells

Estrogen receptor β (ERβ) has recently been identified as a pharmaceutical target in hormone replacement therapy for breast cancers. However, the biological function of ERβ in disease progression remains unclear. A highly ERβ-selective fluorescent probe (FPNM) was discovered exhibiting nanomolar affinity for ERβ with an ERβ/ERα selectivity as high as 80, which allowed specific labeling of intracellular ERβ. Moreover, distinct ERβ dynamics in various cellular bio-settings such as prostate cancer (DU-145) or triple-negative breast cancer (MDA-MB-231) cells were directly observed for the first time viaFPNM staining.

Fluoride-mediated alkoxylation and alkylthio-functionalization of halogenated perylenediimides

The presence of fluoride ions in the reaction of chloro- or bromo-PDIs with alcohols and thiols leads to a spectacular increase in the yields of substituted compounds.

Perylenediimide-based glycoclusters as high affinity ligands of bacterial lectins: synthesis, binding studies and anti-adhesive properties

Rapid access to perylenediimide-based glycoclusters allowed their evaluation as high affinity ligands of bacterial lectins and their potential as anti-adhesive antibacterials.

Novel derivatives of 1,6,7,12-tetrachloroperylene-3,4,9,10-tetracarboxylic acid: synthesis, electrochemical and optical properties

Facile synthesis and opto-electrochemical properties of various unsymmetrically “peri”-substituted perylene derivatives, with four chloro-atoms at the bay-positions, have been reported.

Direct alkylthio-functionalization of unsubstituted perylenediimides

A simple fluoride-mediated reaction allows the synthesis of 1,6-dialkylthioperylenediimides from unsubstituted perylenediimides under very mild conditions.

Facile synthesis of pure 1,6,7,12-tetrachloroperylene-3,4,9,10-tetracarboxy bisanhydride and bisimide

A robust and scalable procedure to obtain pure 1,6,7,12-tetrachloroperylene-3,4,9,10-tetracarboxy bisanhydride, a highly valuable synthon, has been developed via synthesis of a novel intermediate compound 1,6,7,12-perylene-3,4,9,10-tetracarboxy tetrabutylester.

Study on the solution and solid-state fluorescence of novel BF2 complexes with (Z)-2-[phenanthridin-6(5H)-ylidene]-1-phenylethanone and its derivatives as ligands

A family of novel N,O-chelated BF₂ complexes with intense solution and solid-state emission were synthesized and their photophysical properties were studied.

A target-induced three-way G-quadruplex junction for 17β-estradiol monitoring with a naked-eye readout

A three-way G-quadruplex junction for 17β-estradiol monitoring has been constructed based on split G-quadruplex DNAzyme and toehold-mediated strand displacement.

The evolving small-molecule fluorescent-conjugate toolbox for Class A GPCRs

The past decade has witnessed fluorescently tagged drug molecules gaining significant attraction in their use as pharmacological tools with which to visualize and interrogate receptor targets at the single-cell level. Additionally, one can generate detailed pharmacological information, such as affinity measurements, down to almost single-molecule detection limits. The now accepted utilization of fluorescence-based readouts in high-throughput/high-content screening provides further evidence that fluorescent molecules offer a safer and more adaptable substitute to radioligands in molecular pharmacology and drug discovery. One such drug-target family that has received considerable attention are the GPCRs; this review therefore summarizes the most recent developments in the area of fluorescent ligand design for this important drug target. We assess recently reported fluorescent conjugates by adopting a receptor-family-based approach, highlighting some of the strengths and weaknesses of the individual molecules and their subsequent use. This review adds further strength to the arguments that fluorescent ligand design and synthesis requires careful planning and execution; providing examples illustrating that selection of the correct fluorescent dye, linker length/composition and geographic attachment point to the drug scaffold can all influence the ultimate selectivity and potency of the final conjugate when compared with its unlabelled precursor. When optimized appropriately, the resultant fluorescent conjugates have been successfully employed in an array of assay formats, including flow cytometry, fluorescence microscopy, FRET and scanning confocal microscopy. It is clear that fluorescently labelled GPCR ligands remain a developing and dynamic research arena.

Submillisecond-lived photoinduced charge separation in a fully conjugated phthalocyanine–perylenebenzimidazole dyad

A fully electronically conjugated phthalocyanine–perylenemonoimidebenzimidazole system has been synthesized, in which the conjugation goes through the imide position of the perylene.