Galactose functionalized diketopyrrolopyrrole as NIR fluorescent probes for lectin detection and HepG2 cell targeting based on aggregation-induced emission mechanism

Recent advances in sugar-based AIE luminogens and their applications in sensing and imaging

Most fluorogens with aggregation-induced emission (AIE) characteristics are hydrophobic and most common sugars are hydrophilic and naturally nontoxic. The combination of AIEgens and sugars can construct glycosyl AIEgens with the advantages of good water-solubility, low fluorescent background and satisfactory biocompatibility. Based on the specific reaction or binding with analytes to change the conjugate system or restrict intramolecular motions, glycosyl AIEgens can be used as powerful tools for detecting bioactive molecules or imaging living cells. In this feature article, we summarize recent advances in sugar-based AIE luminogens and their applications in biosensing and imaging. The sugar units could significantly increase the solubility, biocompatibility, target activity, and chemical modifying capacity and often decrease the background fluorescence of the AIE probes. Corresponding studies not only expand the application fields of AIEgens but also provide effective tools for broad carbohydrate research.

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.

A ratiometric fluorescent probe based on quinoline for monitoring and imaging of Leucine aminopeptidase in liver tumor cells

Leucine aminopeptidase (LAP) is known as an important potential biomarker for liver malignancy and it is urgent to develop an intuitive and effective method to monitor the activity of LAP in liver cancer. Although, numerous LAP fluorescent probes had been developed, it is still a challenge to detect LAP activity in liver cancer. Herein, combained with the DFT, we reported a novel galactose-appended hepatoma-specific ratiometric fluorescent probe (Gal-QL-Leu) based on quinoline group for imaging and tracing LAP in liver tumor cells. Probe Gal-QL-Leu demonstrated a obvious ratiometric characteristics, better selectivity, good biocompatibility and high sensitivity. Moreover, the selective imaging of LAP in HepG2, HCT116, A549 and HeLa cells had been achieved with probe Gal-QL-Leu, demonstrating good application prospect in the detection of LAP activity in liver tumor cells.

Developments of Diketopyrrolopyrrole-Dye-Based Organic Semiconductors for a Wide Range of Applications in Electronics

In recent times, fused aromatic diketopyrrolopyrrole (DPP)-based functional semiconductors have attracted considerable attention in the developing field of organic electronics. Over the past few years, DPP-based semiconductors have demonstrated remarkable improvements in the performance of both organic field-effect transistor (OFET) and organic photovoltaic (OPV) devices due to the favorable features of the DPP unit, such as excellent planarity and better electron-withdrawing ability. Driven by this success, DPP-based materials are now being exploited in various other electronic devices including complementary circuits, memory devices, chemical sensors, photodetectors, perovskite solar cells, organic light-emitting diodes, and more. Recent developments in the use of DPP-based materials for a wide range of electronic devices are summarized, focusing on OFET, OPV, and newly developed devices with a discussion of device performance in terms of molecular engineering. Useful guidance for the design of future DPP-based materials and the exploration of more advanced applications is provided.

Hexaphenyl-1,3-butadiene derivative: a novel “turn-on” rapid fluorescent probe for intraoperative pathological diagnosis of hepatocellular carcinoma

The staining method based on AIE-active ZZ-HPB-NC can simple distinguish the hepatocellular carcinoma from liver noncancerous tissue, which overcomes the drawbacks of the poor anti-interference ability of the authoritative clinical H&E technique.

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.

Targeted photoswitchable imaging of intracellular glutathione by a photochromic glycosheet sensor

The development of photochromic fluorescence sensors with dynamic and multiple-signaling is beneficial to the improvement of biosensing/imaging precision. However, elaborate designs with complicated molecular structures are always required to integrate these functions into one molecule. By taking advantages of both redox-active/high loading features of two-dimensional (2D) manganese dioxide (MnO₂) and dynamic fluorescence photoswitching of photochromic sensors, we here design a hybrid photochromic MnO₂ glycosheet (Glyco-DTE@MnO₂) to achieve the photoswitchable imaging of intracellular glutathione (GSH). The photochromic glycosheet manifests significantly turn-on fluorescence and dynamic ON/OFF fluorescence signals in response to GSH, which makes it favorable for intracellular GSH double-check in targeted human hepatoma cell line (HepG2) through the recognition between β-D-galactoside and asialoglycoprotein receptor (ASGPr) on cell membranes. The dynamic fluorescence signals and excellent selectivity for detection and imaging of GSH ensure the precise determination of cell states, promoting its potential applications in future disease diagnosis and therapy.

Biomacromolecule-Functionalized AIEgens for Advanced Biomedical Studies

The advances in bioinformatics and biomedicine have promoted the development of biomedical imaging and theranostic systems to respectively extend the endogenous biomarker imaging with high contrast and enhance the therapeutic effect with high efficiency. The emergence of biomacromolecule-functionalized aggregation-induced emitters (AIEgens), utilizing AIEgens, and biomacromolecules (nucleic acids, peptides, glycans, and lipids), displays specific targeting ability to cancer cell, improved biocompatibility, reduced toxicity, enhanced therapeutic effect, and so forth. This review summarizes the rational design of biomacromolecule-functionalized AIEgens and their biomedical applications in recent ten years, including high-resolution optical imaging of cell, tissue, and small animal model with low background; the biomarker detection for early diagnosis and prognosis; the delivery and monitoring of prodrugs; image-guide photodynamic therapy and its combination with chemotherapy. Through illustrating their functional mechanisms and application, it is hoped that this review would open up a completely new train of research thought for attracted researchers in various fields.

Excited State Intramolecular Proton Transfer Plus Aggregation-Induced Emission-Based Diketopyrrolopyrrole Luminogen: Photophysical Properties and Simultaneously Discriminative Detection of Trace Water in Three Organic Solvents

Developing solid state near-IR (NIR) emitters and simultaneously discriminative detection of trace water in organic solvents has long been a significant challenge. In this work, a novel diketopyrrolopyrrole-based luminogen (DPP1) with excited state intramolecular proton transfer (ESIPT) and aggregation-induced emission (AIE) characteristics has been designed and synthesized. Its amorphous and crystal solids show red and NIR-emissive fluorescence at 625 and 675 nm, respectively. When DPP1 reacts with fluoride anion, the resulting system (DPP1·F) can discriminatively detect the water content in aprotic solvents with colorimetric and fluorescent dual modes. Distinct fluorescent responses of "turn-on", "ratiometric turn-off", and "ratiometric turn-on" and low limits of detection of 0.0064, 0.042, and 0. The water-induced sensitive and fast change in THF was applied to the determination of water in foodstuffs in practical solid state indicator paper strips.