Unlocking Long-Term Stability of Upconversion Nanoparticles with Biocompatible Phosphonate-Based Polymer Coatings.
Karan Malhotra1, Richard Fuku1, Balmiki Kumar1
1Chemical Sensors Group, Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario, Canada L5L 1C6.
Nano Letters
|September 6, 2022
Summary
Stable upconversion nanoparticles (UCNPs) are crucial for bioimaging. New polymer coatings improve UCNP colloidal stability in biological buffers for up to four months, enabling nanomedicine applications.
Area of Science:
- Materials Science
- Nanotechnology
- Biomedical Engineering
Background:
- Achieving long-term colloidal stability of upconversion nanoparticles (UCNPs) in biological buffers is a significant challenge.
- This instability limits the practical use of UCNPs in bioimaging and nanomedicine.
Purpose of the Study:
- To develop and evaluate novel polymer coatings for enhancing the colloidal stability of UCNPs.
- To investigate the impact of polymer composition on UCNP stability in biologically relevant conditions.
Main Methods:
- Synthesized nine unique copolymer formulations based on poly(isobutylene-alt-maleic anhydride) (PIMA) backbone.
- Functionalized PIMA with varying ratios of phosphonate anchoring groups and poly(ethylene glycol) (PEG) moieties.
- Coated NaYF4:Yb3+,Er3+ UCNPs with copolymers and assessed colloidal stability in various buffers (e.g., PBS).
Main Results:
- Improved UCNP colloidal stability (up to 4 months) was achieved with copolymers containing higher proportions of anchoring groups and higher phosphonate valences.
- The developed polymer coatings effectively stabilized UCNPs in biologically relevant buffers.
- Demonstrated successful conjugation of small molecules to overcoated UCNPs via copper-free click chemistry.
Conclusions:
- The developed PIMA-based copolymers significantly enhance the long-term colloidal stability of UCNPs in biological buffers.
- These stabilized UCNPs are suitable for further functionalization, paving the way for advanced sensor and bioprobe development in nanomedicine and bioimaging.
