Upconversion Nanocrystals Mediated Lateral-Flow Nanoplatform for in Vitro Detection.

Area of Science:

• Materials Science
• Nanotechnology
• Biomedical Engineering

Background:

• Upconversion phosphors (UCPs) offer advantages for bioapplications due to minimal autofluorescence interference.
• Current UCPs require improvements in water dispersibility, size, and luminescence for broader use.
• Developing UCPs for in vitro diagnostics necessitates meeting these comprehensive criteria.

Purpose of the Study:

• To synthesize nanosized, highly luminous, and water-dispersible upconversion nanocrystals (UCNPs).
• To create UCNPs suitable for biomolecule conjugation and use as bioreporters.
• To develop a multiplexed assay for simultaneous detection of bacterial pathogens.

Main Methods:

• Synthesis of β-NaYF₄:Yb³⁺,Er³⁺ upconversion nanocrystals (UCNPs) codoped with Li⁺ and K⁺.
• Sol-gel surface modification to achieve water dispersibility and enable biomolecule conjugation.
• Integration of bioactivated UCNPs into a lateral flow assay for pathogen detection.

Main Results:

• Enhanced green and red emissions (7 and 10 times, respectively) in Li⁺/K⁺-codoped UCNPs compared to undoped counterparts.
• Successful production of water-dispersible UCNPs with covalent biomolecule conjugation capabilities.
• Development of a lateral flow assay for simultaneous detection of Yersinia pestis and Burkholderia pseudomallei with 10³ CFU/test sensitivity and no cross-interference.

Conclusions:

• Li⁺/K⁺-codoped UCNPs exhibit superior luminescence and suitable size for bioapplications.
• Surface modification enables water dispersibility and biomolecule attachment, creating effective bioreporters.
• The developed assay demonstrates a sensitive and specific method for simultaneous dual-pathogen detection in vitro.