Fluorescein-5-maleimide (N-(5-Fluoresceinyl)maleimide) is a fluorescent thiol-reactive dye (excitation: 494 nm, emission: 519 nm).

Bromobimane (Monobromobimane) is a non-fluorescent substance, but reacts with thiols to produce a fluorescent product.Bromobimane is used as a probe, often in clinical medicine, to test for sulfide levels in blood.

5-IAF is a fluorescein derivative of indoleacetamide, a fluorescent probe that can be used to label proteins and others containing free thiols (cysteine side chains). 5-IAF can label the catalytic (alpha) subunit of dog kidney Na,K-ATPase.

TPE-MI (Tetraphenylethene maleimide) is an aggregation-induced luminescent agent that stains living cells, can be used to capture cysteines in exposed unfolded proteins, and detects protein damage after dihydroartemisinin studies of malaria parasites.

NBD-Cl (NBD chloride) is a nonfluorescent compound that becomes highly fluorescent after reaction with amino or thiol groups.

ABD-F (4-(Aminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole) is a highly reactive fluorescent reagent for the detection and quantification of thiol groups in thiol-containing amino acids, proteins, and tissues with maximum excitation and emission wavelengths of 389 nm and 513 nm, respectively.

CPM, a maleimide derivative, acts as a blue fluorescent thiol-reactive dye with excitation/emission maxima of 384/470 nm [1].

Tetramethylrhodamine-6-maleimide, a sulfhydryl-specific fluorescent dye, covalently bonds with cysteine. This compound is utilized as a label for real-time detection of local protein movements in fully active Na+/K+-ATPase [1] [2].

BODIPY-TS (also known as Thiol-green 2) is a highly efficient thiol-specific turn-on probe with a fast response. It incorporates a thiosulfonate scaffold as its thiol recognition unit. BODIPY-TS displays excellent selectivity, low detection limit, and quantitative reactivity towards thiols. Moreover, it exhibits low toxicity. Notably, BODIPY-TS exhibits excitation at 490 nm and emission at 515 nm.

Dibromobimane, a thiol-selective fluorescent imaging agent, is used to crosslink cysteine- and homocysteine-containing peptides [1].

BDP 558/568 maleimide is a boron-dipyrromethene (BODIPY) dye that contains a terminal maleimide group.

Alexa Fluor 647 C2-Maleimide 6C is a maleimide-functionalized derivative of Alexa Fluor 647, emitting far-red fluorescence with excitation/emission maxima around 651/670 nm. Its maleimide group specifically reacts with thiol (-SH) groups in proteins or peptides, enabling efficient labeling of cysteine residues and other thiol-containing molecules. This dye is widely used in cell biology, neuroscience, and disease research as a functional far-red fluorescent probe.

Naph-EA-mal (Thiol-green 1) is a highly efficient and rapid-response thiol fluorescence probe specifically designed for protein labeling and bioimaging applications. This compound provides ultrafast turn-on fluorescence upon interacting with thiols, allowing for thiol detection in live cells, protein thiol labeling, quantification of total thiol concentrations in cell lysates, and determination of reversible protein thiol oxidation in fixed cells. It has an excitation wavelength of 488 nM and an emission wavelength of 540 nM.

5MP-Fluorescein (compound 3e), a fluorescein dye derived from 5-Methylene pyrrolone (5MP), exemplifies a bioconjugation tool that is both highly thiol-specific and can be removed without a trace [1].

BDP 630/650 maleimide, a fluorophore compatible with the Cyanine5 channel, is valuable for fluorescence lifetime measurements due to its extended excited state lifetime [1].

BADAN (6-Bromoacetyl-2-dimethylaminonaphthalene) serves as a fluorescent probe that is sensitive to polarity [1].

JUN00887, also known as BP Fluor 594 C5 Maleimide, is a bright red fluorescent dye with excellent water solubility and pH stability between pH 4 and pH 10. Its absorption and emission peaks are at 590 nm and 617 nm, respectively.

DCI-Br-3 serves as a swift and selective probe with high sensitivity for thiol monitoring in the epileptic brain, exhibiting an excitation wavelength (λex) of 537 nm and an emission wavelength (λem) of 675 nm. It is also capable of efficiently penetrating the blood-brain barrier (BBB) [1].

N-(9-Acridinyl)maleimide is a maleimide-type fluorescent thiol probe that emits blue fluorescence upon thiol conjugation, with an excitation wavelength of 355 nm and emission wavelength of 465 nm. It can be used for detecting cysteine and glutathione.

BODIPY 630/650 Maleimide is a far-red fluorescent probe and the maleimide derivative of BODIPY 630/650. The maleimide group enables covalent conjugation with thiol (-SH) groups on proteins, peptides, and other biomolecules, forming stable thioether bonds for site-specific labeling. This dye features high quantum yield, narrow emission peak, and excellent photostability. Its far-red emission reduces interference from biological autofluorescence, making it widely used for protein labeling, cellular imaging, and multichannel fluorescence analysis.

Alexa Fluor 680 C2-Maleimide is a maleimide-functionalized derivative of Alexa Fluor 680, emitting near-infrared fluorescence with excitation/emission maxima around 680/705 nm. The maleimide group efficiently forms covalent bonds with thiol (-SH) groups in proteins or peptides, enabling specific labeling and tracking of cysteine residues. It is commonly used as a functional near-infrared fluorescent probe in life science research.

IRDye 800CW, Maleimide is a near-infrared (NIR) fluorescent dye that features a maleimide reactive group, enabling it to conjugate via thiol reactivity. It is ideal for use in live cell imaging.

N-4-(5,6-Dimethoxy-N-phthalimidinyl)phenylmaleimide serves as a fluorescence reagent specifically for thiol labeling [1].

N-(3-Fluoranthyl)maleimide, a thiol fluorescent probe with a lifetime of 20 nsec, has a maximum excitation wavelength of 370 nm and is suitable for studying time-dependent processes of biopolymers [1].