Synthesis of a Red Fluorescent Dye-Conjugated Ag@SiO₂ Nanocomposite for Cell Immunofluorescence

Abstract

In this work we describe a one-step approach for incorporating a red fluorophore (2SBPO) into core-shell nanoparticles for metal-enhanced fluorescence immunolabels. The 2SBPO-MEF nanoparticles are particularly attractive as cell labels because their ∼ 670 nm emission has minimal overlap with cell autofluorescence and from overlap with many conventional probes. 2SBPO was incorporated through physical entrapment during the Stöber process. Antibody-based cell labels were then synthesized using covalent linkage. The nanoparticle fluorescence was 7.5-fold higher than control nanoparticles lacking a metal core. We demonstrated labeling of CD4 + HuT 78 T lymphocytes using anti-CD4-conjugated nanoparticle labels. Cells labeled with anti-CD4 nanoparticles showed a 35-fold fluorescence signal compared to anti-CD4 coreless controls. This simple synthesis protocol can be applied to a variety of hydrophilic fluorophore types and has broad potential in bioanalytical and biosensing applications.

Core size does not affect blinking behavior of dye-doped Ag@SiO2 core–shell nanoparticles for super-resolution microscopy

“…The uorescent nanoparticle was synthesized as described above, aer which 500 mL of the nanoparticle solution was reacted with 48 mg of sodium chloride for 24 hours to remove the silver cores. 33…”

Surface modification of plasmonic noble metal–metal oxide core–shell nanoparticles

“…Dong et al graed CD4 antibodies onto the surface of Ag@SiO 2 nanoparticles using sulfo-SMCC which were then used for cell labeling. 102 Maleimide-PEG-NHS molecules with different molecular weights were used to prepare active Aunanorod@SiO 2 surfaces for further conjugation to peptides with thiol groups such as tLyP-1 peptide and SH-RGD. 103,104 The modied nanostructures were used for targeting imaging, photothermal therapy (PPT) and drug delivery.…”

Synthesis and Characterization of Dye-Doped Au@SiO2 Core-Shell Nanoparticles for Super-Resolution Fluorescence Microscopy

“…Using the silica to create a shell around a metal core allows the fluorophores to be enhanced by the MEF effect, creating a bright self-blinking fluorescent probe. 8,10,11,15,[17][18][19][20][21] Localization-based super-resolution microscopy techniques such as STORM create composite images, which show spatially resolved structures below the optical diffraction limit. A series of images of sparsely dispersed fluorophores in different, nonoverlapping, positions is acquired to determine their precise position in the field of view.…”

“…The use of self-blinking probes eliminates the need for the multiple excitation sources normally needed to switch the fluorophores between states and simplifying the instrumentation needed for STORM superresolution. 6,8,10,11,17,18,25 The nanoparticles described in this work were synthesized based on the procedure developed by Lu et al 25 according to the scheme in Fig. 1.…”

“…MEF dye-doped core-shell nanoparticles meet the required criteria and have been shown to be well suited for this technique. 18,22,23,25 The advantage that nanomaterial probes have over single molecule fluorophores is that they are more photostable, have higher quantum yield, easily modified surfaces, and many exhibit self-blinking behavior wherein they switch “on” and “off” randomly when illuminated by a single excitation source. The use of self-blinking probes eliminates the need for the multiple excitation sources normally needed to switch the fluorophores between states and simplifying the instrumentation needed for STORM super-resolution.…”