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Covalent Conjugation of Avidin With Dye-Doped Silica Nanopaticles and Preparation of High Density Avidin Nanoparticles as Photostable Bioprobes

Covalent Conjugation of Avidin With Dye-Doped Silica Nanopaticles and Preparation of High Density Avidin Nanoparticles as Photostable Bioprobes

Ze-Zhong Chen, Li Cai, Xiao-Min Dong, Hong-Wu Tang, Dai-Wen Pang

Biosens Bioelectron. Aug-Sep 2012;37(1):75-81.

PMID: 22608767

Abstract:

Progress in biomedical imaging depends on the development of bioprobes with a high sensitivity and stability. Fluorescent silica nanoparticles (NPs) covalent conjugation of avidin has been proposed for cancer cells imaging by fluorescence microscopy. Uniform silica NPs were prepared using water-in-oil (W/O) microemulsion methods and primary amine groups were introduced onto the surface of the NPs by condensation of tetraethyl orthosilicate (TEOS). Optically stable organic dyes, tris(2,2'-bipyridyl) dichlororuthenium(II) hexahydrate (Rubpy), were doped inside the silica NPs. The amine functions were transferred to carboxyl groups coupled with a linker elongation. Avidin was immobilized at the surface of the NPs by covalent binding to the carboxyl linkers. The binding capacity of the avidin-covered NPs for ligand biotin was quantified by titration with biotin(5-fluorescein) conjugate to 1.25 biotin binding sites/100 nm(2). We used biotinylated antibody and cell recognition by fluorescence microscopy imaging technique. The lung carcinoma cells were identified easily with high efficiency using these antibody-coated NPs. By comparison with fluorescein isothiocyanate (FITC), dye-doped silica NPs display dramatically increased stability of fluorescence as well as photostability, as compared to the common organic dye, when under continuous irradiation.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP957494278	Biotin (5-fluorescein) conjugate		957494-27-8	Price

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