ICG-Sulfo-OSu sodium

Name: ICG-Sulfo-OSu sodium
Brand: BOC Sciences
Rating: 5 (1 reviews)

CAS No.: 190714-28-4

Cat No.: BP-500443 4.5

ICG-Sulfo-OSu sodium is a sulfonated N-hydroxysuccinimide (NHS) ester derivative of the near-infrared fluorophore ICG, supplied as a sodium salt. Structurally, it contains the ICG chromophore for optical tracking and an activated OSu (NHS-ester) leaving group that reacts readily with primary amines under mild aqueous conditions, forming stable amide bonds. In PROTAC and targeted degradation workflows, this linker enables covalent conjugation of the fluorophore to amine-bearing ligands or scaffold components, allowing researchers to monitor synthesis, quantify conjugation efficiency, and track cellular uptake or subcellular localization of degradation constructs. Its sulfonation improves aqueous solubility and reduces nonspecific hydrophobic interactions, supporting cleaner experimental readouts. Overall, it is a useful reagent for constructing fluorescently labeled targeted protein degradation probes and for validating linker chemistry and conjugate behavior during optimization.

Structure of 190714-28-4

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PROTAC Linker

Molecular Formula

C₄₉H₅₂N₃NaO₁₀S₂

Molecular Weight

930.07

* For research and manufacturing use only. Not for human or clinical use.

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Please store the product under the recommended conditions in the Certificate of Analysis.

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IUPACName

sodium;1-[6-[2-[7-[1,1-dimethyl-3-(4-sulfonatobutyl)benzo[e]indol-2-ylidene]hepta-1,3,5-trienyl]-1,1-dimethylbenzo[e]indol-3-ium-3-yl]hexanoyloxy]-2,5-dioxopyrrolidine-3-sulfonate

InChI Key

PUIWPNXPCPENEL-UHFFFAOYSA-M

InChI

InChI=1S/C49H53N3O10S2.Na/c1-48(2)41(23-9-6-5-7-10-24-42-49(3,4)46-37-22-15-13-20-35(37)27-29-39(46)51(42)31-17-18-32-63(56,57)58)50(38-28-26-34-19-12-14-21-36(34)45(38)48)30-16-8-11-25-44(54)62-52-43(53)33-40(47(52)55)64(59,60)61;/h5-7,9-10,12-15,19-24,26-29,40H,8,11,16-18,25,30-33H2,1-4H3,(H-,56,57,58,59,60,61);/q;+1/p-1

SMILES

CC1(C(=[N+](C2=C1C3=CC=CC=C3C=C2)CCCCCC(=O)ON4C(=O)CC(C4=O)S(=O)(=O)[O-])C=CC=CC=CC=C5C(C6=C(N5CCCCS(=O)(=O)[O-])C=CC7=CC=CC=C76)(C)C)C.[Na+]

1. Development of agents for reinforcement of fluorescence on near-infrared ray excitation for immunohistological staining

S Ito, N Muguruma, S Hayashi, S Taoka, T Bando, K Inayama, M Sogabe, T Okahisa, S Okamura, H Shibata, T Irimura, K Takesako, S Shibamura Bioorg Med Chem. 1998 May;6(5):613-8. doi: 10.1016/s0968-0896(98)00023-6.

Fluorescence intensity of indocyanine green (ICG) derivative (ICG-sulfo-OSu) was too low for its use to detect microlesions. Therefore, we examined the effects of reinforcement agents on ICG-sulfo-OSu labeled antibodies. Solutions of distearoylphosphatic acid sodium salt (DSPA) and octylglucoside (OG) in physiological phosphate buffered saline (PBS) were found to increase the intensity of fluorescence of ICG-sulfo-OSu labeled antibodies, with shift in the fluorescence peak wavelength from 804 to 821 nm.

ICG-Sulfo-OSu sodium is a sulfonate-functionalized N-hydroxysuccinimide (OSu) ester derivative of an anionic cyanine dye scaffold, designed to serve as a highly reactive PROTAC linker intermediate for conjugation workflows. Its OSu ester functionality enables efficient amide-bond formation with primary amines, supporting the modular assembly of targeted protein degradation constructs. The dye-bearing sulfonate group provides strong aqueous compatibility and convenient spectroscopic tracking, while the sodium counterion supports practical handling in biological buffer systems. Detailed structural and reactivity considerations are provided below.

Structure: The molecule contains an OSu ester electrophile embedded in a sulfonate-substituted cyanine dye framework. It features an anionic sulfonate group balanced by sodium, conjugated aromatic/heteroaromatic segments, and an activated ester susceptible to nucleophilic acyl substitution. Overall, it is water-compatible and chemically stable under controlled conditions.

Reactivity: The OSu ester undergoes nucleophilic acyl substitution with primary amines to form stable amide linkages, a common strategy for building PROTAC conjugates. Suitable conditions typically use mildly basic aqueous or mixed solvent systems to promote amine nucleophilicity while minimizing hydrolysis. No special catalysts are generally required; however, careful control of pH, temperature, and reagent stoichiometry helps preserve linker integrity.

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* Our calculator is based on the following equation:
Concentration (start) x Volume (start) = Concentration (final) x Volume (final)
It is commonly abbreviated as: C₁V₁ = C₂V₂