Name: iFluor® 690 maleimide
Brand: AAT Bioquest
SKU: 1410
Price: 355 USD
Availability: InStock

iFluor® 690 maleimide

iFluor® 690 maleimide is a thiol-reactive NIR dye that selectively conjugates to sulfhydryl groups via stable thioether bonds, offering superior brightness and photostability compared to Cy5 or Alexa Fluor® 680 for deep tissue imaging and multiplex detection applications.

Thiol-reactive maleimide group: enables site-specific conjugation to free sulfhydryl (–SH) groups on cysteine residues
High brightness and strong signal intensity: ensure sensitive detection in both in vitro and in vivo applications
Excellent photostability: reduces photobleaching for long-term imaging and analysis
Improved water solubility: supports efficient labeling under physiological conditions
Stable conjugation: via formation of irreversible thioether linkages ensures durable labeling

Protocol

SDS

Catalog	Size	Price	Quantity
1410	1 mg	Price

Overview

iFluor® 690 maleimide is a thiol-reactive, near-infrared fluorescent labeling dye developed for efficient and site-specific conjugation of biomolecules containing free sulfhydryl (–SH) groups, such as cysteine residues in proteins, peptides, and antibodies. With an excitation maximum around 685 nm and an emission maximum near 704 nm, iFluor® 690 provides strong near-infrared fluorescence with minimal background interference, making it particularly well-suited for applications requiring deep tissue penetration and reduced autofluorescence. The dye incorporates a maleimide functional group that reacts selectively and rapidly with thiol groups under mild physiological conditions, producing stable thioether linkages. Compared to conventional dyes such as Cy5 or Alexa Fluor® 680, iFluor® 690 maleimide demonstrates superior brightness, improved photostability, and enhanced water solubility, ensuring reliable performance in both in vitro and in vivo imaging. These properties make it an ideal reagent for antibody labeling, fluorescence microscopy, flow cytometry, immunoassays, multiplex detection, and in vivo imaging studies.

Calculators

Common stock solution preparation

Table 1. Volume of DMSO needed to reconstitute specific mass of iFluor® 690 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	83.736 µL	418.68 µL	837.36 µL	4.187 mL	8.374 mL
5 mM	16.747 µL	83.736 µL	167.472 µL	837.36 µL	1.675 mL
10 mM	8.374 µL	41.868 µL	83.736 µL	418.68 µL	837.36 µL

Molarity calculator

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

Mass (Calculate)		Molecular weight		Volume (Calculate)		Concentration (Calculate)		Moles
mg	÷	1194.23 g/mol	=	mL	x	mM	=	mmol

Physical properties

Molecular weight	1194.23
Solvent	DMSO

Spectral properties

Absorbance (nm)	682
Correction factor (260 nm)	0.09
Correction factor (280 nm)	0.06
Extinction coefficient (cm ^-1 M ^-1)	220000 ¹
Excitation (nm)	685
Emission (nm)	704
Quantum yield	0.30 ¹

Storage, safety and handling

H-phrase	H303, H313, H333
Hazard symbol	XN
Intended use	Research Use Only (RUO)
R-phrase	R20, R21, R22
Storage	Freeze (< -15 °C); Minimize light exposure

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Page updated on May 9, 2026