Linker-protein G mediated functionalization of polystyrene-encapsulated upconversion nanoparticles for rapid gene assay using convective PCR

Phani R. Potluri, Vinoth Kumar Rajendran, Clara T. Tran, David R. McKenzie, Anwar Sunna

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The authors report on a simplified approach to encapsulate upconversion nanoparticles (UCNPs) in polystyrene spheres by mini-emulsion polymerisation. The resulting particles (PS-UCNP) are hydrophilic, stable and suitable for biomolecular recognition and biosensing applications. Also, a strategy was developed for bioconjugation of antibodies onto the surface of the PS-UCNPs by using the bifunctional fusion protein linker-protein G (LPG). LPG mediates the functionalisation of PS-UCNPs with antibodies against digoxigenin allowing for specific labelling of convective PCR (cPCR) amplicons. Lambda DNA was amplified using cPCR on a heat block for 30 min using the digoxigenin labelled forward and biotin labelled reverse primers. The antibody functionalised PS-UCNPs bind to the digoxigenin end of the cPCR amplicons. Finally, the streptavidin labelled magnetic beads were used to selectively capture the PS-UCNP-labelled cPCR amplicons and the upconversion signal was detected at 537 nm under 980 nm excitation. This sandwich approach enables direct recognition of the target lambda DNA with a detection limit of 103 copies μL−1. The upconversion signal decreased proportionally to the concentration of the lambda DNA with a linear response between 107 and 103 copies of DNA.
Original languageEnglish
Article number346
Pages (from-to)1-9
Number of pages9
JournalMicrochimica Acta
Issue number6
Publication statusPublished - Jun 2019



  • Amplification
  • Bioconjugation
  • Nucleic acid analysis
  • Mini-emulsion polymerisation
  • Surface functionalisation
  • Magnetic separation
  • Biosensing
  • Luminescence
  • Lanthanide-doped

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