Dyes

IQ-R is a novel hypoxia-sensitive fluorescent probe, consisting of an indolequinone unit and a rhodol fluorophore.

5(6)-TAMRA contains a carboxylic acid that can be used to react with primary amines via carbodiimide activation of the carboxylic acid; bright, orange-fluorescent dye produces conjugates with absorption/emission maxima of ~555/580 nm.

5-TAMRA (5-Carboxytetramethylrhodamine), SE and its conjugates yield bright, pH-insensitive orange-red fluorescence (approximate excitation/emission maxima ~546/579) with good photostability.

5(6)-FITC (Fluorescein 5(6)-isothiocyanate) is an amine-reactive derivative of fluorescein dye that has wide-ranging applications as a label for antibodies and other probes, for use in fluorescence microscopy, flow cytometry and immunofluorescence-based assays such as Western blotting and ELISA.

5(6)-Carboxyfluorescein contains a carboxylic acid that can be used to react with primary amines via carbodiimide activation of the carboxylic acid; cell-impermeant 5,6-FAM can also be used as a nonfixable polar tracer to investigate fusion, lysis and gap-junctional communication and to detect changes in cell or liposome volume.

6-FAM SE is another isomer of carboxyfluorescein. 6-FAM, SE is mainly used in sequencing of nucleic acids and labeling nucleotides.

5-FAM SE is a single isomer, it is one of the most popular green fluorescent reagents used for labeling peptides, proteins and nucleotides. It has also been used to prepare various small fluorescent molecules.

5(6)-FAM SE is an amine-reactive green fluorescent dye widely used for labeling proteins or other molecules that contain a primary or secondary aliphatic amine.

X-Gluc Dicyclohexylamine is used as a reagent to detect ??-glucuronidase, an enzyme produced by the E. Coli bacterium; is widely used in molecular biology experiments to mark and select the expression of target genes (GUS reporter system).

TMB-PS(102062-36-2) is N-(3-sulfopropyl)-3,3',5,5'-tetramenthylbenzidine sodium salt; White - pale yellow crystalline powder, soluble in water, can be used under neutral, acidic and alkaline conditions.

TMB (BM blue) is a chromogenic substrate used in staining procedures in immunohistochemistry as well as being a visualising reagent used in enzyme-linked immunosorbent assays (ELISA).

PNPP is a non-proteinaceous chromogenic substrate for alkaline and acid phosphatases used in ELISA and conventional spectrophotometric assays.

Hoechst 33258 is a fluorescent dye that emits blue fluorescence when bound to dsDNA.

Luminol(Diogenes reagent) is a versatile chemical that exhibits chemiluminescence, with a striking blue glow, when mixed with an appropriate oxidizing agent.

DHBS is Used in conjunction with 4-aminoantipyrine (4-AAP) and hydrogen peroxide (H2O2) for chromogenic quantitation of peroxidase in coupled enzymatic reactions. Component of Trinder reagent for use with peroxidase to measure generation of hydrogen peroxide in automated systems.

DAB (3,3' Diaminobenzidine Tetrahydrochloride) is an organic compound that is both chemically and thermodynamically stable; DAB has been used in immunohistochemical staining of nucleic acids and proteins.

Resorufin sodium salt (NSC 12097 sodium salt) is a highly fluorescent pink dye.

(±)-ANAP is the unnatural amino acid analog of prodan, acts as a fluorescent probes, and enhances environmental sensitivity.

D-Luciferin potassium salt is the substrate of luciferases that catalyze the production of light in bioluminescent insects.

EC-17 (disodium salt) is a folate receptor alpha (FRα) targeting contrast agent with fluorescent properties in the visible light spectrum.

D-Luciferin sodium salt is the substrate of luciferases that catalyze the production of light in bioluminescent insects.

BCIP(BCIP p-toluidine salt; X-phosphate p-toluidine salt) is an artificial chromogenic substrate used for the sensitive colorimetric detection of alkaline phosphatase activity.

GPDA(Glycylproline p-nitroanilide tosylate) is the substarate of X-Prolyl dipeptidyl-aminopeptidase in the enzyme assay.

ALPS(N-Ethyl-N-sulfopropylaniline sodium salt) is a bio-chemical reagents/chromogenic reagent.

ADOS(82692-96-4) is a biochemical reagent/chromogenic reagent.

Hydroxystilbamidine bis(methanesulfonate), a dye capable of binding to both DNA and RNA, has been found to be a powerful inhibitor of cellular ribonucleases.

CRANAD-28, a blood brain barrier (BBB) penetrable two-photon imaging probe, acts by labelling plaques and cerebral amyloid angiopathies (CAAs).

MSBN is a highly selective fluorogenic probe for thiols, selectively imaging thiols in live cells and specifically label protein thiols with a turn-on signal to determine diverse reversible protein thiol modifications.

Aka Lumine, a luciferin analogue, is a luciferase substrate emitting red, green, and blue light. The longest emission wavelength of Aka Lumine is recorded at 675 nm, which is within the NIR region.

MQAE is a fluorescent indicator that is quenched via collision with chloride, and is more sensitive and selective than 36Cl and microelectrode-based methods for chloride measurement in cells.

Thiazolyl Blue (MTT) is a colorimetric agent widely used to measure cell proliferation. Thiazolyl Blue (MTT) is reduced from yellow color to purple formazan in living cells.

DAPI Dihydrochloride is a cell-permeable fluorescent probe used to stain DNA and chromosomes, with a preference for adenine and thymine rich DNA.

Methoxy-PMS (1-Methoxy PMS), an active oxygen formation inducer, is stable electron-transport mediator between NAD(P)H and tetrazolium dyes.

2-Di-1-ASP (Compound 18a) is a mono-stryryl dye, and widely used as mitochondrial stain and groove-binding fluorescent probes for double-stranded DNA. 2-Di-1-ASP is selective for G-quadruplex (G4) and double-stranded DNA.

Ac-DEVD-AMC is a fluorescent substrate of caspase-3/caspase-7. When treating Ac-DEVD-AMC with cell lysate, Ac-DEVD-AMC releases amino-4-methylcoumarin (AMC) for fluorescence detection, with an excitation wavelength of 380 nm and an emission wavelength of 460 nm.

Z-IETD-AFC, a specific fluorescence substrate, can be used to determine the caspase-8 catalytic activity.

Mca-SEVNLDAEFK(Dnp)-NH2 contains a highly fluorescent 7-methoxycoumarin group that is efficiently quenched by resonance energy transfer to the 2,4-dinitrophenyl group. It can be used to measure the activities of peptidases that are capable of cleaving an amide bond between the fluorescent group and the quencher group, causing an increase in fluorescence, such as can be used to measure the activity of BACE-1.

HADA hydrochloride (HCC-Amino-D-alanine hydrochloride) is a blue-emitting (λ_em ≈ 450 nm) fluorescent D-amino acid (FDAA) used for labeling bacterial cell walls. FDAAs are incorporated into peptidoglycan (PG) at sites of active biosynthesis through the action of native transpeptidases, enabling specific and covalent labeling of growing bacterial cells with minimal disruption to normal physiology. HADA hydrochloride provides high spatial and temporal resolution for visualizing bacterial growth dynamics, cell wall synthesis, and morphogenesis in live-cell imaging studies, making it a powerful tool in microbiology and antibiotic mechanism research.

L-012 sodium salt is a luminol-based chemiluminescent probe widely used for the sensitive detection of reactive oxygen and nitrogen species (ROS and RNS) in biological systems. It is particularly effective in monitoring NADPH oxidase (Nox)-derived superoxide production, providing high signal intensity and low background interference. Compared with conventional luminol, L-012 offers enhanced chemiluminescence sensitivity and stability, enabling real-time detection of oxidative and nitrosative stress in cells, tissues, and *in vivo* models. It is a valuable tool for studying redox signaling, inflammation, and oxidative stress–related pathophysiology.

BODIPY 558/568 C12 is a fluorescent lipid probe based on the BODIPY (boron-dipyrromethene) dye structure. BODIPY dyes are small-molecule fluorophores characterized by strong ultraviolet-visible absorption, sharp fluorescence emission peaks, high quantum yields, and remarkable photostability. They are largely insensitive to environmental polarity and pH, maintaining consistent fluorescence under various physiological conditions. BODIPY 558/568 C12, due to its lipophilic alkyl chain, readily permeates cell membranes and specifically localizes to neutral lipid compartments, enabling selective staining of lipid droplets in both live and fixed cells. It serves as a reliable fluorescent marker for studying lipid metabolism, lipid droplet dynamics, and cellular lipid distribution. The dye exhibits maximum excitation and emission wavelengths at 558 nm and 568 nm, respectively.

Rhodamine B isothiocyanate (RBITC) is a reactive fluorescent dye widely used for covalent labeling of biomolecules in imaging and analytical applications. The isothiocyanate functional group readily reacts with primary amines on proteins, peptides, and other biomolecules to form stable thiourea linkages, enabling durable fluorescent tagging. RBITC emits bright orange-red fluorescence upon green light excitation, providing strong signal intensity and excellent photostability for visualization in complex biological systems. Owing to its high sensitivity, chemical stability, and compatibility with diverse assay conditions, RBITC is extensively utilized in cell biology, immunology, neurobiology, and fluorescence microscopy studies for tracking molecular localization and dynamics.

WSP-5 is a selective fluorescent probe designed for rapid detection of hydrogen sulfide (H₂S) in biological samples and live cells. It operates via a reaction-based “fluorescence turn-on” mechanism, in which WSP-5 reacts specifically and swiftly with H₂S to generate a highly fluorescent product. The probe exhibits excitation and emission maxima at 502 nm and 525 nm, respectively. Due to its excellent selectivity, sensitivity, and biocompatibility, WSP-5 is widely used in studies of H₂S biology, cellular signaling, and redox homeostasis.

AQC (6-Aminoquinolyl-N-hydroxysuccinimidyl carbamate) is a highly sensitive derivatization reagent used for amino acid and peptide analysis by high-performance liquid chromatography (HPLC) with fluorescence detection. It reacts rapidly with both primary and secondary amino groups to form stable fluorescent derivatives, enabling detection of amino acids at sub-picomolar concentrations. Due to its high reactivity, stability, and strong fluorescence yield, AQC is widely applied in protein sequencing, amino acid quantification, and metabolic profiling, providing exceptional sensitivity and reproducibility in analytical and biochemical studies.

Fluorescein-5-maleimide (N-(5-Fluoresceinyl)maleimide) is a thiol-reactive fluorescent dye widely used for covalent labeling of proteins, peptides, and other biomolecules containing cysteine residues. By forming stable thioether bonds with sulfhydryl groups, it enables precise detection and quantification of thiol-containing targets. Fluorescein-5-maleimide is employed to monitor the redox state of thiols in eukaryotic cells, label peptides or actin for protein–protein interaction studies—such as investigations of actin binding to cardiac myosin-binding protein C (cMyBP-C)—and to detect negatively charged nanoparticles. It also serves as a tool for screening mutant proteins containing cysteine residues. The dye exhibits strong fluorescence with excitation and emission maxima at 494 nm and 519 nm, respectively, making it highly suitable for fluorescence microscopy, flow cytometry, and biochemical assays.

Tartrazine (Acid Yellow 23; FD&C Yellow No. 5) is an orally active synthetic azo dye that appears as an orange-yellow, water-soluble powder producing a bright yellow coloration in solution. It is widely used as a food colorant and in pharmaceuticals and cosmetics due to its high chemical and photostability. Beyond its industrial applications, Tartrazine has been reported to induce mitochondria-mediated apoptosis and to exhibit potential biological effects, including neurodevelopmental toxicity, cytotoxicity, and genotoxicity under certain experimental conditions. It serves as a model compound in toxicological and biochemical studies investigating the safety and cellular impact of synthetic food dyes.

Dansyl chloride is a fluorescent labeling reagent that reacts with primary and secondary amines to form stable blue or blue-green fluorescent sulfonamide adducts. It readily labels aliphatic and aromatic amines through reaction with amino groups, making it a valuable tool for biochemical analysis. Dansyl chloride is widely used for amino acid derivatization, protein sequencing, and amino acid composition analysis, enabling sensitive fluorescence-based detection and quantification of amine-containing biomolecules.

Ethidium bromide is a fluorescent intercalating agent widely used in molecular biology as a nucleic acid stain. It inserts between DNA base pairs, allowing visualization of DNA and RNA under ultraviolet (UV) light during techniques such as agarose gel electrophoresis. Due to its high sensitivity and strong fluorescence, Ethidium bromide is a standard tool for nucleic acid detection, though it is handled with caution because of its mutagenic properties.

DiI is a long-chain lipophilic carbocyanine dye commonly used for fluorescent labeling of biological membranes. Due to its strong affinity for lipid bilayers, DiI efficiently integrates into cell membranes, making it ideal for tracing cells, organelles, liposomes, viruses, and lipoproteins. It exhibits bright fluorescence, high photostability, and minimal cytotoxicity, enabling long-term imaging and tracking in both fixed and live-cell applications.

Coumarin 6 is a fluorescent dye commonly used as a probe in drug delivery research. It serves as a tracer in microparticle and nanoparticle delivery systems, enabling *in vivo* tracking, cellular uptake analysis, and transport mechanism studies. Coumarin 6 exhibits strong fluorescence with excitation and emission maxima at λ_exc = 450 nm and λ_em = 505 nm, respectively, making it an ideal marker for evaluating drug distribution and release profiles in biological systems.

PKH26 is a red fluorescent dye that stably incorporates into the lipid regions of the cell membrane, emitting red fluorescence (Ex/Em: 551/567 nm). It is commonly used for in vitro cell labeling, cell proliferation assays, and both in vivo and in vitro cell tracking studies.