Synthesis of highly stable cyanine-dye-doped silica nanoparticle for biological applications

Abstract

Cyanine dyes are widely used in biological labeling and imaging because of their narrow near infrared emission, good brightness and high flexibility in functionalization, which not only enables multiplex analysis and multi-color imaging, but also greatly reduces autofluorescence from biological matter and increases signal-to-noise ratio. Unfortunately, their poor chemical- and photo-stability strongly limits their applications. The incorporation of cyanine dyes in silica nanoparticles provides a solution to the problem. On one hand, the incorporation of cyanine dyes in silica matrix can enhance their chemical- and photo-stability and increase brightness of the nanomaterials. On the other hand, silica matrix provides an optimized condition to host the dye, which helps to maintain their fluorescent properties during application. In addition, the well-established silane technique provides numerous functionalities for diverse applications. However, commercially available cyanine dyes are not very stable at high alkaline conditions, which will gradually lose their fluorescence over time. Our results showed that cyanine dyes are very vulnerable in the reverse micelle system, in which they will lose their fluorescence in less than half an hour. The existence of surfactant could greatly promote degradation of cyanine dyes. Fluorescent silica nanoparticles cannot be obtained at the high alkaline condition with the existence of surfactant. In contrast, the cyanine dyes are relatively stable in Stöber media. Owing to the fast formation of silica particles in Stöber media, the exposure time of cyanine dye in alkaline solution was greatly reduced, and highly fluorescent particles with good morphology and size distribution could be obtained via Stöber approach. However, the increasing water content in the Stöber could reduce the stability of cyanine dyes, which should be avoided. This research here provides a clear guidance on how to successfully synthesize cyanine dye-doped silica nanoparticles with good morphology, size distribution, stability and brightness.

Liquid CO2 Formulated Mesoporous Silica Nanoparticles for pH-Responsive Oral Delivery of Meropenem

“…To investigate the quantitative (flow cytometry) and qualitative (confocal microscopy) intracellular uptake of MSNs, it was necessary to develop fluorescent MSNs. It has been reported that cyanine dyes have been covalently conjugated with APTES to successfully achieve their loading into silica particles. , Therefore, Eudragit S100 coated Cy5-MCM-NH 2 (Eud-Cy5-MCM) was selected for fluorescence imaging and flow cytometry studies.…”

“…It has been reported that cyanine dyes have been covalently conjugated with APTES to successfully achieve their loading into silica particles. 67,68 Therefore, Eudragit S100 coated Cy5-MCM-NH 2 (Eud-Cy5-MCM) was selected for fluorescence imaging and flow cytometry studies.…”

Optical and X-ray Fluorescent Nanoparticles for Dual Mode Bioimaging

“…The addition of APTES into the exhibited a strong emission centered at 695 nm, characteristic of Cy5.5, revealing that the reaction process did not alter or quench the Cy5.5 molecule, as previously reported (Figure S6). 27 To render the core−shell NPs with optical fluorescence, Cy5.5-APTES was conjugated to the SiO 2 shell. The integration process is not just a physical entrapment of the dye into the pores of SiO 2 , but its covalent incorporation into the shell through condensation.…”

“…The mixture was then stirred for 24 h at room temperature in a dark environment. The as-formed Cy5.5-APTES solution was then stored at 4 °C . For optical absorption and fluorescence characterization of the complex, 2 μL of Cy5.5-APTES solution were dispersed in 1 mL of DI water prior to measurements.…”

Fabrication of Double Emission Enhancement Fluorescent Nanoparticles with Combined PET and AIEE Effects

“…In particular, in vivo imaging is the leading biological application of FSNs [17,18]. The encapsulation of designated fluorophores determines the optical properties of the FSNs and their application, such as multicolor imaging [19] or NIR imaging [20,21]. As we expected, when fluorophores are incorporated into silica nanoparticles, FSN possesses a better photostability because the silica matrix (or shell) protects the fluorophores from oxygen and other harmful species, which may cause photobleaching.…”