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Updated: Jan 2, 2026
07:41
Advanced Compositional Analysis of Nanoparticle-polymer Composites Using Direct Fluorescence Imaging
Published on: July 19, 2016
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Dye Encapsulation in Fluorescent Core-Shell Silica Nanoparticles as Probed by Fluorescence Correlation Spectroscopy
Ferdinand F E Kohle1,2, Joshua A Hinckley1,2, Ulrich B Wiesner1
1Materials Science and Engineering, Cornell University, Ithaca, NY 14853.
The Journal of Physical Chemistry. C, Nanomaterials and Interfaces
|December 11, 2019
Summary
Fluorescent silica nanoparticles (SNPs) are used in cancer diagnostics. This study used fluorescence correlation spectroscopy (FCS) to reveal how dye molecules are incorporated into these tiny diagnostic probes.
Area of Science:
- Nanotechnology
- Materials Science
- Biophysics
Background:
- Ultrasmall (<10 nm) fluorescent poly(ethylene glycol)-coated (PEGylated) core-shell silica nanoparticles (SNPs) have shown promise in oncology diagnostics.
- Understanding dye incorporation and silica architecture is crucial for optimizing SNP probes.
- Current knowledge of dye encapsulation within these ultrasmall SNPs remains limited.
Purpose of the Study:
- To investigate the dye incorporation and local environment within PEGylated core-shell SNPs using advanced spectroscopy.
- To understand the photophysical properties of cyanine dyes within ultrasmall silica nanoparticles.
- To assess the utility of fluorescence correlation spectroscopy (FCS) for analyzing nanoparticle composition.
Main Methods:
- Utilized afterpulse-corrected fluorescence correlation spectroscopy (FCS) to monitor fast fluorescence fluctuations.
- Employed the cyanine dye Cy5 as a fluorescent probe within 5 nm silica cores of PEGylated core-shell SNPs (C dots).
- Combined FCS with time-correlated fluorescence decay measurements.
Main Results:
- Observed a decrease in photo-induced cis-trans isomerization amplitude upon silica shell deposition, indicating Cy5 dye proximity to the nanoparticle surface.
- Deduced radiative and non-radiative rates of the Cy5 dye within the SNP.
- Demonstrated that Cy5 dye conformational changes serve as indicators of the local environment in ultrasmall SNPs.
Conclusions:
- FCS is a powerful tool for investigating the photophysics of fluorescent nanoparticles.
- The conformational dynamics of cyanine dyes effectively report on their microenvironment within ultrasmall silica nanoparticles.
- This research provides insights into the structure-property relationships of SNP-based diagnostic probes.
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