Estrogen conjugated fluorescent silica nanoparticles as optical probes for breast cancer cells imaging

Abstract

Fluorescent nanoparticles are promising tools for living cancer cell imaging and cancer targeting. In this study, estrogen conjugated dye-doped fluorescent nanoparticles (estrogen conjugated FNPs) were synthesized and characterized. The functionalized nanoparticles with low toxicity have shown high selectivity and sensitivity toward target cells. Based on the specific recognition between the estrogen and the estrogen receptor, estrogen conjugated FNPs have been employed as optical probes for specific targeting of estrogen receptor-positive cancer cells with fluorescence microscopy imaging technology. The results demonstrate that the estrogen conjugated FNPs can effectively recognize breast cancer cells with good sensitivity and exceptional photostability, which would offer a novel approach for the diagnosis of breast cancer cells, as well as a new method in detecting estrogen receptors.

Scheme 1.

Schematic illustration of estrogen conjugated FNPs probe synthesis.

FIG. 1.

TEM image of FNPs. Scale bar is 300 nm.

FIG. 2.

FTIR spectra of (a) amino-group functionalized FNPs and (b) estrogen conjugated FNPs.

FIG. 3.

Fluorescence emission spectra of fluorescent spectra of amino-group functionalized FNPs (a), estrogen conjugated FNPs (b), and Rubpy aqueous solution (c).

FIG. 4.

The cytotoxicity of estrogen conjugated FNPs. Error bars are expressed as SD (n = 5).

FIG. 5.

Fluorescence microscopy of MCF-7 cells labeled with 0.5 mg ml⁻¹ of estrogen conjugated FNPs (a), 0.5 mg ml⁻¹ of amino-group functionalized FNPs (b), and without FNPs (c). Red = Rubpy channel. Blue = DAPI channel. Scale bar is 25 μm.

FIG. 6.

Fluorescence microscopy of RAW264.7 cells labeled with estrogen conjugated FNPs (a), amino-group functionalized FNPs (b), MDCK cells labeled with estrogen conjugated FNPs (c) and amino-group functionalized FNPs (d). Red = Rubpy channel. Blue = DAPI channel. Scale bar is 25 μm.