Other Analysis Dyes

NR-HOCl-TFMU is a HOCl-gated phosphonite fluorescent probe based on the Nebraska Red scaffold. NR-HOCl-TFMU undergoes HOCl-triggered oxidative ring-opening of the spirocyclic thioether and phosphonite hydrolysis to synchronously release the near-infrared reporter group NR₆₆₆-MSA (Ex 666 nm/Em 698 nm) and the cargo TFMU (Ex 405 nm/Em 510 nm). NR-HOCl-TFMU enables HOCl-selective fluorescence imaging and cargo release monitoring in vitro, in live cells and in vivo, and exerts gated selective cytotoxicity in HOCl-positive cells. NR-HOCl-TFMU can be used for studies related to acute myeloid leukemia.

P2-Aggregate is a polarity-sensitive fluorescent probe for protein aggregation, which is based on the Nile Red scaffold and modified with a morpholine ring to enhance water solubility. P2-Aggregate improves anti-precipitation ability in aqueous phase via morpholine ring modification, and enables site-specific labeling of target proteins by combining with HaloTag technology. Utilizing the property that its emission wavelength blue-shifts with decreasing local polarity (excited at 543 nm), P2-Aggregate quantitatively detects changes in local polarity during protein aggregation and polarity heterogeneity inside aggregates in living cells. P2-Aggregate can be used in the research of diseases associated with the aggregation of Htt-110Q and SOD1 proteins, such as Huntington's disease and amyotrophic lateral sclerosis.

TPEP-6-NH-MA is a Fluorescent probe that selectively detects cysteine (Cys) and homocysteine (Hcy) without interference from glutathione (GSH) and other amino acids, and can also be used for bioimaging of biothiols in living cells. Its detection mechanism relies on terminating the photoinduced electron transfer (PET) effect via a Michael addition reaction between the maleimide recognition moiety and the thiol group of Cys or Hcy. The excitation wavelength of TPEP-6-NH-MA is Ex = 361 nm.

DBHA is a long-wavelength polarity-sensitive fluorescent probe based on Nile Red. Under the catalysis of Pd (OAc)₂/TPPTS, DBHA site-selectively labels protein tyrosine residues via a π-allyl palladium complex intermediate. Utilizing the property that its maximum emission wavelength blue-shifts with decreasing local polarity (650 nm in aqueous solution → 584-608 nm in hydrophobic domains), it detects changes in local polarity and conformation of protein tyrosine domains under acid/thermal denaturation conditions. DBHA can be used in studies related to SOD1-associated oxidative stress neurodegenerative diseases.

BTCV-CO is a ratiometric AIE fluorescent probe for the detection and fluorescent imaging of carbon monoxide (CO). BTCV-CO reacts with CO under the mediation of Pd²⁺, undergoes allyl cleavage and cyclization to form the highly fluorescent product BTIC, resulting in enhanced fluorescence at 546 nm and weakened fluorescence at 710 nm. Ex/Em = 465/546 nm (λex = 465 nm in spectral experiments; λex = 476 nm in cell imaging).

ASSI-Leu is a novel AIE fluorescent probe based on an asymmetric tetraaryl imidazole skeleton, which can be used for ratiometric imaging detection of endogenous leucine aminopeptidase. ASSI-Leu contains an L-leucine-based recognition group that blocks the excited-state intramolecular proton transfer (ESIPT) in its 2-(2'-hydroxyphenyl) benzothiazole (HBT) skeleton, thereby generating an enol-form emission signal at Ex/Em = 365/417 nm. ASSI-Leu undergoes cleavage of the L-leucine group mediated by LAP to form ASSI-OH, which further activates aggregation-induced emission (AIE) and ESIPT, generating a keto-form emission signal at Ex/Em = 365/554 nm and producing a ratiometric fluorescent signal. ASSI-Leu enables real-time tracking of LAP in cancer cells and zebrafish models.\n

C-TPA is a fluorescent probe used for hypochlorite detection and bioimaging of lipid droplet polarity in cancer cells. For hypochlorite detection, when its derivative C-TPA-S is exposed to hypochlorite, an oxidative desulfurization reaction converts the thiocarbonyl group of C-TPA-S to the carbonyl group of C-TPA, thus restoring bright fluorescence from the almost non-fluorescent C-TPA-S. For bioimaging of lipid droplet polarity, the intramolecular charge transfer process between its Triphenylamine (HY-W011998) donor group and Coumarin (HY-N0709) acceptor group endows C-TPA with solvatochromism-it exhibits stronger fluorescence in less polar environments (such as lipid droplets in cancer cells) and weaker fluorescence in more polar environments (such as lipid droplets in normal cells), enabling the differentiation of cancer cells and cancer tissues from normal cells and normal tissues. The excitation wavelength of C-TPA is 405 nm, and the emission wavelengths used for cell and tissue imaging cover 425-475 nm and 500-550 nm; in solvents, its emission peak shifts from 494 nm in non-polar toluene to 528 nm in polar water.

HS-CyBz is a Fluorescent probe for H₂S detection, enabling ratiometric optical/photoacoustic dual-modality in/ex vivo imaging. Its detection mechanism relies on nucleophilic substitution of its benzoic ester group by HS⁻, which releases an enolic meso-hydroxyltricarboheptamethine cyanine that then undergoes keto-enol tautomerization to form Cy-ketone; this tautomerization causes distinct shifts in absorption and emission spectra, producing a ratiometric response that reduces interferences from tissue scattering, autofluorescence, and probe concentration. In its initial state, HS-CyBz has an excitation wavelength of 595 nm, with emission bands centered at 805 nm (main) and 630 nm (minor); upon reaction with H₂S, the 805 nm emission band decreases while the 630 nm band drastically increases, and its absorption spectrum shows a sharp band at 775 nm and a shoulder band at 708 nm, which decrease upon H₂S reaction with a minor increase at 850 nm and an isosbestic point at 825 nm. For in vivo optical imaging, excitation at 560 nm is used with emission channels at 620 nm and 790 nm, while in vivo photoacoustic imaging uses excitation at 775 nm and 825 nm. The detection limit of HS-CyBz for H₂S is 0.5 μM, and it shows high selectivity, with only H₂S inducing a distinct enhancement of the emission ratio F₆₃₀/F₈₀₅ and PA ratio PA₈₂₅/PA₇₇₅, while other biochemical species including cations, anions, reactive oxygen species, biothiols, and carboxylesterase trigger only minor changes and do not interfere with H₂S sensing. Tail intravenous injection of HS-CyBz leads to accumulation in the liver of mice, and it can be used to verify endogenous H₂S upregulation triggered by S-adenosyl-L-methionine via ratiometric optical/photoacoustic imaging.

CMTDP is a Fluorescent probe for detecting local polarity changes around the Cys34 domain of bovine serum albumin during pH-induced N→B conformational transition. It is a thiol-specific and polarity-sensitive probe; it covalently labels the free cysteine residue at position 34 (Cys34) of bovine serum albumin, and its fluorescence maximum emission wavelength shifts in response to solvent polarity, but not to pH and temperature. When labeled to BSA, as the local polarity around the Cys34 domain increases with rising pH, the probe shows a bathchromic shift in fluorescence emission wavelength and a decrease in fluorescence intensity, which allows quantification of the local polarity change via the relationship between emission wavelength shift and dielectric constant. CMTDP itself has absorption peaks at ~392 and 508 nm, and CMTDP-labeled BSA has excitation maxima at 376 and 470 nm at pH 6.0, with the shorter-wavelength excitation peak red-shifting as pH increases while the longer one remains stable; when excited at 470 nm, the fluorescence emission maximum shifts from 570 nm at pH 6.0 to 577 nm at pH 9.1, while free CMTDP at pH 7.4 has an emission maximum at 621 nm. The excitation/emission wavelengths for CMTDP-labeled BSA are Ex/Em = 376/570 nm at pH 6.0, Ex/Em = ~376+/573 nm at pH 7.4, Ex/Em = ~376+/575 nm at pH 8.0, Ex/Em = ~376+/577 nm at pH 9.1, and for free CMTDP at pH 7.4, Ex/Em (when excited at 470 nm) = 470/621 nm[1].

BDL-E5 is a fluorescent probe for detecting live induced pluripotent stem cells at the early reprogramming stage. Its detection mechanism involves specific binding to authentic reprogramming cells, which exhibit increased expression of pluripotency and epithelial genes and decreased expression of mesenchymal genes compared to non-reprogramming cells; it appears to co-localize more significantly with the Golgi complex than other organelle markers in reprogramming cells, and it does not require washing after staining to reduce background signals; fluorescence is generated upon binding to these early reprogramming cells, with positive cells appearing 7 days before iPS colonies are visible and stain positive for the conventional pluripotent marker TRA-1-60, and sorting BDL-E5-positive cells enriches populations that generate higher numbers and quality of iPS colonies. Its detection wavelength is Ex/Em = 578/599 nm.

MBCB is a two-photon Fluorescent probe for dual-detection of mitochondrial SO₂ derivatives and viscosity. For SO₂ derivatives detection, the probe utilizes a Michael addition mechanism: nucleophilic addition of SO₂ derivatives to the C=C bond between the carbazole skeleton and 3-methylbenzothiazolium moiety destroys the strong intramolecular charge transfer (ICT) system between these groups, while enhancing the weak ICT system between the benzothiazole group and carbazole framework; this causes the red emission at 600 nm to decrease and the blue emission at 434 nm to increase, creating a ratiometric response based on the I₄₃₄ₙₘ/I₆₀₀ₙₘ intensity ratio. For viscosity detection, in low-viscosity environments, steric hindrance creates a twisted ICT (TICT) system with weak fluorescence, while in high-viscosity environments, intramolecular rotation is blocked, the TICT state is disrupted, and the strong ICT system is recovered, leading to a strong red emission at 567 nm with negligible change to the short-wavelength emission at 415 nm, creating a ratiometric response based on the I₅₆₇ₙₘ/I₄₁₅ₙₘ intensity ratio that has a logarithmic linear relationship with viscosity. The probe has excitation/emission wavelengths of Ex/Em = 351/434, 600 nm for SO₂ derivatives detection and Ex/Em = 351/567 nm for viscosity detection, with two-photon excitation at 740 nm for bioimaging; it also exhibits good mitochondrial targeting ability with a Pearson's colocalization coefficient of 0.93 when paired with Mito-Tracker Green. The probe shows high sensitivity and selectivity for SO₂ derivatives, has low cell cytotoxicity, and can be applied to detect exogenous/endogenous HSO₃⁻ in living cells and in vivo, as well as visualize mitochondrial viscosity changes induced by nystatin[1].

HOTPy is a mitochondria-targeted fluorescent viscosity probe with aggregation-induced emission properties, which responds to microenvironmental viscosity. HOTPy can recognize the abnormal increase in mitochondrial viscosity and capture dynamic viscosity changes in acute alcoholic liver injury models at both cellular and in vivo levels. The maximum absorption peak of HOTPy in PBS solution is at 379 nm; its maximum emission peak reaches 611 nm in a high-viscosity glycerol system. HOTPy can be used for the research of acute alcoholic liver injury.

Biotin-V is a fluorescent probe targeting the biotin receptor (BiR), which can be used to detect changes in intracellular viscosity in cancer cells and tumor tissues. Biotin-V consists of a viscosity-responsive TICT (twisted internal charge transfer) fluorophore and a biotin-targeting moiety. In a high-viscosity environment, intramolecular rotation is restricted, which reduces non-radiative transitions and enhances fluorescence intensity and fluorescence lifetime. Biotin-V enters BiR-positive cancer cells via biotin receptor-mediated uptake, and mainly localizes to mitochondria, enabling dual-modal viscosity imaging (fluorescence intensity imaging and fluorescence lifetime imaging) (Ex/Em = 540/608 nm; cell imaging Ex/Em = 561/570-620 nm).

MC-PSE is a fluorescent probe that can be used for glutathione (GSH) detection, NIR-II fluorescence imaging and ratiometric photoacoustic imaging. MC-PSE spontaneously forms J-aggregates in aqueous solution through π-π stacking, and its phenylselenyl group acts as a fluorescence quencher and GSH recognition receptor, thereby eliminating intrinsic fluorescence and generating a maximum absorption peak at 1000 nm. The excitation/emission wavelengths of MC-PSE are Ex = 808 nm and Em = 940 nm. MC-PSE can be applied in tumor-related research.

Tz‑IFDL is a chemiluminescent probe for in vivo imaging of N‑methyl‑D‑aspartate receptors (NMDAR), which specifically binds to the NR2B subunit of NMDAR. Tz‑IFDL undergoes a bioorthogonal reaction with probe CL‑NC (HY-D3370), triggering molecular fragment release and chemiluminescence. The CL‑NC/Tz‑IFDL system composed of Tz‑IFDL exhibits a chemiluminescence emission wavelength of 710 nm. When combined with CL‑NC, Tz‑IFDL can be used for deep tissue imaging to distinguish NMDAR expression levels between Alzheimer's disease model mice and normal mice.

Pt-Luc is a bioluminescent probe used for real-time, non-invasive monitoring of Pt (IV) prodrug reduction in living cells and animal models. The detection mechanism of Pt-Luc relies on the intracellular reduction mediated by active cysteine residues in proteins. Pt-Luc can penetrate the membrane of living cells; after entering cells, active cysteine thiolates in high-molecular-weight protein components reduce the Pt (IV) complex, thereby cleaving the caged aminoluciferin substrate. The released free aminoluciferin is then oxidized by luciferase in the presence of ATP to generate a bioluminescent signal, whose intensity is directly correlated with the reduction degree of Pt (IV).

Rhobo6 is a cell-impermeable glycan-binding, fluorescence turn-on imaging agent with a K_d of 53 µM for glycans. Rhobo6 reversibly binds target glycans and enables wash-free live ECM visualization. Rhobo6 can be used for fluorescent labeling of ECM in living samples or decellularized tissues (Ex/Em = 488/561 nm).

CDr17 is a GLUT1 substrate and selective fluorescent dye staining M1 microphages. CDr17 utilizes the Gating-Oriented Live-cell Distinction (GOLD) mechanism to enter M1 macrophages (Ex/Em = 646/662 nm).

DUPA-FITC is a fluorescent reagent targeting PSMA, which specifically binds to prostate cancer cells expressing PSMA without non-specific binding to normal blood cells. DUPA-FITC can label PSMA-expressing prostate cancer cells in whole blood, followed by internalization and trafficking to acidic intracellular endosomes, during which the fluorescence is quenched. When combined with flow cytometry and density gradient centrifugation enrichment, DUPA-FITC enables quantitative analysis of circulating tumor cells in peripheral blood samples from prostate cancer patients.