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Fluorescent Nanoparticles for the Measurement of Ion Concentration in Biological Systems
Published on: July 4, 2011
Two-photon nano-PEBBLE sensors: subcellular pH measurements
Aniruddha Ray1, Yong-Eun Koo Lee, Tamir Epstein
1Biophysics, University of Michigan, Ann Arbor, MI, USA.
The Analyst
|July 21, 2011
Summary
We developed targeted, fluorescent nano-PEBBLE sensors for real-time intracellular pH mapping. These sensors effectively monitor pH in cancer cells, offering a promising tool for early cancer detection.
Area of Science:
- Biomedical Engineering
- Nanotechnology
- Cell Biology
Background:
- Intracellular pH is crucial for cellular functions and tissue pH mapping can indicate cancer onset.
- Accurate intracellular pH monitoring is essential for understanding cellular events and disease progression.
- Existing methods for pH measurement face limitations in cellular targeting and signal clarity.
Purpose of the Study:
- To develop and characterize a biocompatible, targeted, ratiometric, fluorescent pH sensing nano-PEBBLE (Photonic Explorer for Biomedical use with Biologically Localized Embedding) system for intracellular pH mapping.
- To evaluate the efficacy of F3 peptide-targeted nano-PEBBLEs in overcoming endosomal trapping compared to non-targeted sensors.
- To demonstrate the potential of two-photon excitation microscopy combined with targeted nano-PEBBLEs for real-time, non-invasive pH monitoring in cancer cells.
Main Methods:
- Fabrication of biocompatible, ratiometric, fluorescent pH sensing nano-PEBBLEs utilizing two-photon excitation.
- Incorporation of membrane impermeant dyes (HPTS) into PEBBLE nanosensors.
- Application of non-targeted and F3 peptide-targeted PEBBLE nanosensors for intracellular pH measurements in 9L cells.
- Utilizing two-photon microscopy to minimize photobleaching and cell autofluorescence, enhancing signal-to-noise ratio.
Main Results:
- Nano-PEBBLEs demonstrated effective intracellular pH sensing capabilities.
- Non-targeted nanosensors were primarily localized within acidic endosomes.
- F3 peptide-targeted nanosensors successfully escaped or avoided endosomal compartments, enabling better intracellular access.
- Two-photon excitation significantly improved signal quality by reducing photobleaching and autofluorescence.
Conclusions:
- Targeted nano-PEBBLEs offer a superior approach for intracellular pH monitoring compared to non-targeted sensors.
- The F3 peptide targeting strategy facilitates endosomal escape, allowing for more accurate pH measurements within the cell.
- The combination of targeted pH-sensitive PEBBLE nanoparticles and two-photon microscopy presents a powerful, non-invasive tool for real-time pH monitoring in cancer cells and tissues.
- This technology holds significant promise for advancing cancer diagnostics and research through precise cellular pH analysis.
