Recent progress in two-photon small molecule fluorescent probes for enzymes

This review aims to provide a summary of the progress in TP small molecule fluorescent probes for enzymes in recent years and displays the main fluorescent mechanisms that have been applied to design probes.     

Recent progress in small molecule fluorescent probes for nitroreductase

This review aims to provide a summary of the progress in fluorescent probes for nitroreductase (NTR) in recent years and displays the main fluorescent mechanisms that have been applied to design probes.     

Recent advances in molecular fluorescent probes for organic phosphate biomolecules recognition

Organic phosphate biomolecules (OPBs) are indispensable components of eukaryotes and prokaryotes, such as acting as the fundamental components of cell membranes and important substrates for nucleic acids. They play pivotal roles in various biological processes, such as energy conservation, metabolism, and signal modulation. Due to the difficulty of detection caused by variety OPBs, investigation of their respective physiological effects in organisms has been restrained by the lack of efficient tools. Many small fluorescent probes have been employed for selective detection and monitoring of OPBs in vitro or in vivo due to the advantages of tailored properties, biodegradability and in situ high temporal and spatial resolution imaging. In this review, we summarize the recent advances in fluorescent probes for OPBs, such as nucleotides, NAD(P)H, FAD/FMN and PS. Importantly, we describe their identification mechanisms in detail and discuss the general strategies for these OPBs probe designs, which provide new insights and ideas for the future probe designs.     

Recent advances in mitochondria-and lysosomes-targeted small-molecule two-photon fluorescent probes

This review summarized the recent advances in small-molecule two-photon fl uorescent probes for monitoring a wide variety of biomolecules and changes inside micro-environment in mitochondria and lysosomes, or served as mitotracker and lysotracker with the assistance of two-photon microscopy.     

Recent progress in Michael addition-based fluorescent probes for sulfur dioxide and its derivatives

In this review, we have summarized the recent progress of Michael addition-based fluorescent probes for SO₂ and its derivatives in the design strategies, sensing performances, detection mechanisms and applications.     

Recent advances in formaldehyde-responsive fluorescent probes

Formaldehyde is one of the simplest reactive carbonyl species. In view of the harmfulness of formaldehyde in nature and humans, it is of great signifi cance to further elucidate roles and functions of formaldehyde by a noninvasive detection approach. Fluorescent probes have become a popular tool to track and detect formaldehyde in vitro and in vivo, which have attracted more and more interest recently. This review focuses on various reaction mechanisms to design the fluorescent probes for detecting formaldehyde.     

Highly selective two-photon fluorescent probe for imaging of nitric oxide in living cells简

A new two-photon fluorescent probe, ADNO, for nitric oxide （NO） based on intramolecular photoinduced electron transfer （PET） mechanism d/splays a rapid response to NO with a remarkable fluorescent enhancement in PBS buffer. The excellent chemoselectivity of ADNO for NO over other ROS/RNS （reactive oxygen species or nitrogen species） and common metal ions was observed. Moreover, ADNO has been successfully applied in fluorescence imaging of NO of living cells using both one-photon microscopy （OPM） and two-~hoton microscopy （TPM）,     

Organelle targetable fluorescent probes for hydrogen peroxide

Hydrogen peroxide(H_2 O_2), as important products of oxygen metabolism, plays an important role in many biological processes, such as immune responses and cellular signal transduction. However, abnormal production of H_2 O_2 can damage cellular biomolecules, which was closely associated with many diseases.Thus, it is urgent to monitor the level change of H_2 O_2 in living cells, particularly at subcellular levels.Toward this end, a wide variety of H_2 O_2 fluorescent probes have been designed, developed and applied for imaging of H_2 O_2 in subcellular levels. In this review, we highlight the representative cases of H_2 O_2 fluorescent probes with mitochondria, nuclei and lysosomes-targetable ability. The review contains organelle target strategies, structures, fluorescence behavior and biological applications of these probes.     

Organelle targetable fluorescent probes for hydrogen peroxide

The review summarized organelle target strategies, structures, fluorescence behavior and biological applications of H₂O₂ fluorescent probes with mitochondria, nuclei and lysosomes-targetable ability.     

A novel small molecule fluorescent sensor for Zn2+ based on pyridine-pyridone scaffold

The development of a water-soluble and small molecular weight fluorescent probe, 3-(4-methoxyphenyl)-4-(methylsulfanyl)-6-(pyridin-2-yl)pyridin-2(1H)-one (3), for detecting Zn²⁺ based on pyridine-pyridone skeleton is reported. We observed a clear chelation enhanced fluorescence effect of 3 in the presence of Zn²⁺. Other fluorescent properties of 3 are discussed.     

Recent advances in molecular fluorescent probes for organic phosphate biomolecules recognition

This review provided a systematic overview of the recent researches on the small-molecule fluorescent probes for recognition various organic phosphate biomolecules (OPBs) including nucleotides, NAD(P)H, FAD/FMN and PS. The general strategies and the recognition mechanisms for these OPBs probe designs were described and emphasized to inspire the better design for fluorescent probes in the future.     

香豆素类荧光探针对硫化氢检测的研究进展

硫化氢(H2S)是目前人们发现的第三类生物内源性“气体信使分子”。其及时检测对人类的健康有着非常大的意义。随着荧光探针技术的发展,有机小分子荧光探针受到广大学者的关注。其中,香豆素因其结构简单,荧光量子产率高以及易于功能化而备受青睐。本文根据探针的识别机理综述近三年来报道的香豆素类H2S荧光探针代表性研究成果,并对其进行了展望,为后续设计开发更具实用价值的H2S荧光探针提供一点有益的参考。     

An improved synthesis of a fluorescent gabapentin-choline conjugate for single molecule detection

Voltage-gated calcium ion channels comprise pore-forming α₁ and auxiliary α₂δ, β, and γ subunits. They are important molecular devices involved in a variety of cell functions. Fluorescently labeled acylcholine analogues are important in studies such as ion channel regulation. Cy3-3-acetylcholine has recently been synthesized for single molecule detection studies; albeit in an extremely low overall yield (0.06%). In this work, an alternative route to that used in the previous Cy3-3-acetylcholine synthesis was developed with a 90% yield at a significantly lower material cost.     

A bright two-photon fluorescent probe for real-time monitoring autophagy in living cells

A novel donor-acceptor(D-A) type of two-photon(TP) fluorescent probe,i.e.Lyso-OSC,based on the lysosome-targeting morpholine group was developed.The polarity sensing coumarin group was functionalized as the acceptor and the 1-vinyl-4-methoxybenzene group was engineered as the donor.The fluorescence intensity and emission maximum wavelength of Lyso-OSC are highly sensitive to the polarity changes of solvent.The two-photon absorption cross-section and tissue penetration depth are up to 254 GM and 150 μm,respectively.The strong fluorescence,high sensitivity to polarity,low cytotoxicity,and accurate lysosome-targeting ability entail Lyso-OSC the excellent performance in detecting the polarity changes ofcellular environment.To this end,a bright,real-time imaging autophagy of living cells has been achieved.     

Development of a water-soluble 3-formylBODIPY dye for fluorogenic sensing and cell imaging of sulfur dioxide derivatives

A new water-soluble, highly fluorogenic 3-formylBODIPY dye that enables the sensing of SO₂ derivatives in aqueous buffers and cancer cells is reported. The quaternary ammonium group appended through the meso-position of the BODIPY dye ensures water solubility. The probe exhibits high specificity for cytosolic (bi)sulfites and fluoresces brightly in human lung adenocarcinoma cells (A549).     

Recent developments in novel blue/green/red/NIR small fluorescent probes for in cellulo tracking of RNA/DNA G-quadruplexes

The detection and stabilization of G-quadruplexes (G4s) in living systems is of enormous applicability in the fields of chemical biology and therapeutic materials. Whereas DNA serves as a genetic material, RNA functions in the regulation and expression of genetic materials. Even there is various report on fluorescent probes invitro G4s recognitions, in this review we highlighted briefly, in-cellulo identification of G4s along with conventional methods principles. Although there are varieties of G4-forming sequences in the genome, targeting a specific type (topology) in living cells is highly challenging because of the high instability of G4s in cellular/subcellular systems. In contrast, several reports describe the in vitro identification of G4s, along with in-cell demonstrations, using efficient fluorescent probes, through either intrinsic or extrinsic approaches. In the intrinsic mode, the sensing results from the use of highly selective synthetic fluorescent oligonucleotides or proteins (a labeling approach). In the extrinsic mode, quencher-free small molecular probes are used to recognize specific G4s under physiological conditions. Because of their robustness, simplicity, and ease of handling, this review describes recent trends in the use of blue/green, green, red, and near-infrared (NIR) fluorescent probes for the recognition of G4s in live cells-and, particularly, those approaches employing quencher-free probes. Also highlighted are a few labeled probes, and their in cellulo localizations, which were accomplished upon the formation of non-canonical G4s under specified conditions and supplemented by exogenous G4-forming components, without harnessing cellular physiological conditions.     

Visualizing tributyltin (TBT) in bacterial aggregates by specific rhodamine-based fluorescent probes

Here we present the first examples of fluorescent and colorimetric probes for microscopic TBT imaging. The fluorescent probes are highly selective and sensitive to TBT and have successfully been applied for imaging of TBT in bacterial Rhodobacter ferrooxidans sp. strain SW2 cell-EPS-mineral aggregates and in cell suspensions of the marine cyanobacterium Synechococcus PCC 7002 by using confocal laser scanning microscopy.     

Allele specific C-bulge probes with one unique fluorescent molecule discriminate the single nucleotide polymorphism in DNA

A combination of an allele specific C-bulge probe and the fluorescent molecule N,N'-bis(3-aminopropyl)-2,7-diamino-1,8-naphthyridine (DANP) that binds specifically to the C-bulge provides a method for single nucleotide polymorphism (SNP) typing with only one fluorescent molecule without covalent modification of the DNA probe. The allele specific C-bulge probe contains one additional cytosine and produces a C-bulge directly flanking the SNP site upon hybridization to the target DNA. The C-bulge is a scaffold to recruit and retain DANP directly neighboring the SNP site. The DANP fluorescent probe was selectively modulated by the flanking matched and mismatched base pairs. The mutation type could be discriminated by the modulated fluorescent intensity with respect to the allele specific C-bulge probes used for the assay.     

Solid-state nanopores for ion and small molecule analysis

Solid-state nanopore in analytical chemistry has developed rapidly in the 1990s and it is proved to be a versatile new tool for bioanalytical chemistry. The research field of solid-state nanopore starts from mimicking the biological nanopore in living cells. Understanding the transport mechanism of biological nanopore in vivo is a big challenge because of the experimental difficulty, so it is essential to establish the basic research of artificial nanopores in vitro especially for the analysis of ions and small molecules. The performance of solid-state nanopores could be evaluated by monitoring currents when ions and molecules passed through. The comparison of the two types of nanopores based on current-derived information can reveal the principle of biological nanopores, while the solid-state nanopores are applied into practical bioanalysis. In this review, we focus on the researches of the solid-state nanopores in the fabrication process and in the analysis of ions and small molecules. Fabrication methods of nanopores, ion transport mechanism, small molecule analysis and theoretical studies are discussed in detail.