Bio-conjugation of protein molecules to upconversion nanoparticles

Dayong Jin  Low Res Edit 00962 October 2015:

A novel, simple, and stable method for one-step bio-conjugation of protein molecules to upconversion nanoparticles is demonstrated in the latest paper released by CNBP researchers in the journal ‘Analytical Chemistry’.

The paper is titled “One-step Protein Conjugation to Upconversion Nanoparticles.”

Authors: Jie Lu, Yinghui Chen, Deming Liu, Wei Ren, Yiqing Lu, Yu Shi, James A. Piper, Ian T. Paulsen, and Dayong Jin.

The full paper is available online with the abstract included below.

Abstract: The emerging upconversion nanoparticles offer a fascinating library of ultrasensitive luminescent probes for a range of biotechnology applications from biomarker discovery, single molecule tracking, early disease diagnosis, deep tissue imaging, to drug delivery and therapies.

The effective bio-conjugation of inorganic nanoparticles to the molecule-specific proteins, free of agglomeration, non-specific binding or biomolecule de-activation, is crucial for molecular recognition of target molecules or cells.

The current available protocols require multiple steps which can lead to low probe stability, specificity and reproducibility. Here we report a simple and rapid protein bio-conjugation method based on a one-step ligand exchange using the DNAs as the linker. Our method benefits from the robust DNA-Protein conjugates as well as from multiple ions binding capability.

Protein can be pre-conjugated via an amino group at the 3’ end of a synthetic DNA molecule to the protein, so that the 5′ end phosphoric acid group and multiple phosphate oxygen atoms in the phosphodiester bonds are exposed to replace the oleic acid ligands on the surface of upconversion nanoparticles due to their stronger ions-chelating capability to lanthanides.

We demonstrated our method can efficiently pull out the upconversion nanoparticles from organic solvent into an aqueous phase. The upconversion nanoparticles then become hydrophilic, stable and specific biomolecules recognition. This allows us to successfully functionalize the upconversion nanoparticles with horseradish peroxidise (HRP) for catalytic colorimetric assay and for streptavidin (SA) biotin affinity assays.