iFluor® 488 maleimide

iFluor® 488 Maleimide is a green-fluorescent, thiol-reactive dye for selective covalent labeling of proteins, antibodies, and other thiol-containing biomolecules in fluorescence-based research applications.

Thiol-Reactive Functionality: Maleimide group selectively reacts with thiols, including cysteine residues.
Spectral Properties: Excitation at 491 nm and emission at 516 nm.
Fluorescence Performance: Bright, photostable fluorescence with a quantum yield of 0.90.
pH Sensitivity: Maintains stable fluorescence across pH 4–10.
Applications: Suitable for fluorescent conjugation of antibodies and other thiol-containing proteins.

HeLa cells were stained with rabbit anti-tubulin followed by iFluor® 488 goat anti-rabbit IgG (H+L), and nuclei were stained with Nuclear Red™ DCS1 (Cat No. 17552).

Protocol

SDS

Catalog	Size	Price	Quantity
1062	1 mg	Price

Overview

Although FITC is still the most popular fluorescent labeling dye for preparing green fluorescent bioconjugates, there are certain limitations with FITC, such as severe photobleaching for microscope imaging and pH-sensitive fluorescence. Protein conjugates prepared with iFluor® 488 dyes are far superior to conjugates of fluorescein derivatives such as FITC. iFluor® 488 conjugates are significantly brighter than fluorescein conjugates and are much more photostable. Additionally, the fluorescence of iFluor® 488 is not affected by pH (4-10). This pH insensitivity is a major improvement over fluorescein, which emits its maximum fluorescence only at pH above 9. iFluor® 488 maleimide is reasonably stable and shows good reactivity and selectivity with the thiol group. This iFluor® 488 has spectral properties and reactivity similar to Alexa Fluor® 488 maleimide ( Alexa Fluor® is the trademark of Invitrogen).

Calculators

Common stock solution preparation

Table 1. Volume of DMSO needed to reconstitute specific mass of iFluor® 488 maleimide to given concentration. Note that volume is only for preparing stock solution. Refer to sample experimental protocol for appropriate experimental/physiological buffers.

	0.1 mg	0.5 mg	1 mg	5 mg	10 mg
1 mM	113.41 µL	567.048 µL	1.134 mL	5.67 mL	11.341 mL
5 mM	22.682 µL	113.41 µL	226.819 µL	1.134 mL	2.268 mL
10 mM	11.341 µL	56.705 µL	113.41 µL	567.048 µL	1.134 mL

Molarity calculator

Enter any two values (mass, volume, concentration) to calculate the third.

Mass (Calculate)		Molecular weight		Volume (Calculate)		Concentration (Calculate)		Moles
mg	÷	881.76 g/mol	=	mL	x	mM	=	mmol

Citations

View all 33 citations: Citation Explorer

The teneurin TEN-1 and its ligand LRON-11 support microbiota-induced neuroprotection and mechanosensory function in C. elegans

Authors:

Li, Jingxian and Castillo, Juan Pablo and Cheng, Shouqiang and Weathers, Indya and Nawrocka, Wioletta I and Alvarado, Jorge and Zhao, Minglei and Calixto, Andrea and {\"O}zkan, Engin and Ara{\c{c}}, Demet

Journal:

Current Biology (2026)

A Signal Peptide Screening Approach for Improved Fc-Fusion Expression in CHO-S Cells

Authors:

Holm, Isak

Fully Human Antagonistic Antibodies Targeting FPR2 Through Dual Extracellular-Loop Engagement for Gastric Cancer Therapy

Authors:

Kim, Min Su and Kang, Tae Hyun

Journal:

Antibody Therapeutics (2026): tbag035

Analysis of paired primary-metastatic renal cancer lesions reveals RCN3-MMP10 axis facilitates lung metastasis

Authors:

Lin, Wenhao and Wang, Qi and Xu, Kandi and Ding, Jiawei and Ma, Zhiyang and Xing, Siwei and Xu, Danfeng and He, Yayi and Chen, Lu

Journal:

Cellular Signalling (2026): 112534

Cationic mRNA Lipid Nanoparticles for Ex Vivo NanoCAR-T Cell Engineering

Authors:

Harinck, Laure and De Munter, Stijn and De Velder, Margo and Ingels, Joline and Berdecka, Dominika and Lentacker, Ine and De Vos, Winnok H and Vandekerckhove, Bart and Braeckmans, Kevin and Raemdonck, Koen

Journal:

Advanced Science (2026): e21507

References

View all 49 references: Citation Explorer

Sequential ordering among multicolor fluorophores for protein labeling facility via aggregation-elimination based beta-lactam probes

Authors:

Sadhu KK, Mizukami S, Watanabe S, Kikuchi K.

Journal:

Mol Biosyst (2011): 1766

Visualizing dengue virus through Alexa Fluor labeling

Authors:

Zhang S, Tan HC, Ooi EE.

Journal:

J Vis Exp. (2011)

Fluorescent "Turn-on" system utilizing a quencher-conjugated peptide for specific protein labeling of living cells

Authors:

Arai S, Yoon SI, Murata A, Takabayashi M, Wu X, Lu Y, Takeoka S, Ozaki M.

Journal:

Biochem Biophys Res Commun (2011): 211

Neuroanatomical basis of clinical joint application of "Jinggu" (BL 64, a source-acupoint) and "Dazhong" (KI 4, a Luo-acupoint) in the rat: a double-labeling study of cholera toxin subunit B conjugated with Alexa Fluor 488 and 594

Authors:

Cui JJ, Zhu XL, Ji CF, Jing XH, Bai WZ.

Journal:

Zhen Ci Yan Jiu (2011): 262

Simultaneous detection of virulence factors from a colony in diarrheagenic Escherichia coli by a multiplex PCR assay with Alexa Fluor-labeled primers

Authors:

Kuwayama M, Shigemoto N, Oohara S, Tanizawa Y, Yamada H, Takeda Y, Matsuo T, Fukuda S.

Journal:

J Microbiol Methods (2011): 119

Physical properties

Molecular weight	881.76
Solvent	DMSO

Spectral properties

Correction factor (260 nm)	0.21
Correction factor (280 nm)	0.11
Extinction coefficient (cm ^-1 M ^-1)	75000 ¹
Excitation (nm)	491
Emission (nm)	516
Quantum yield	0.9 ¹

Usage and storage

Intended use	Research Use Only (RUO)
Storage	Freeze (< -15 °C); Minimize light exposure

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Page updated on October 23, 2026