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Biotin-4-fluorescein Based Fluorescence Quenching Assay for Determination of Biotin Binding Capacity of Streptavidin Conjugated Quantum Dots

Biotin-4-fluorescein Based Fluorescence Quenching Assay for Determination of Biotin Binding Capacity of Streptavidin Conjugated Quantum Dots

Rowena Mittal, Marcel P Bruchez

Bioconjug Chem. 2011 Mar 16;22(3):362-8.

PMID: 21314110

Abstract:

The valency of quantum dot nanoparticles conjugated with biomolecules is closely related to their performance in cell tagging, tracking, and imaging experiments. Commercially available streptavidin conjugates (SAv QDs) are the most commonly used tool for preparing QD-biomolecule conjugates. The fluorescence quenching of biotin-4-fluorscein (B4F) provides a straightforward assay to quantify the number of biotin binding sites per SAv QD. The utility of this method was demonstrated by quantitatively characterizing the biotin binding capacity of commercially available amphiphilic poly(acrylic acid) Qdot ITK SAv conjugates and poly(ethylene glycol) modified Qdot PEG SAv conjugates with emission wavelengths of 525, 545, 565, 585, 605, 625, 655, 705, and 800 nm. Results showed that 5- to 30-fold more biotin binding sites are available on ITK SAv QDs compared to PEG SAv QDs of the same color with no systematic variation of biotin binding capacity with size.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
IAR424181	Biotin-4-Fluorescein			Price

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