Upconversion nanoparticles have been prepared by solution method, hydrothermal and solvothermal methods. The cubic and hexagonal phases of the upconversion nanoparticles synthesised have been confirmed by XRD and the particles sizes in the nanorange have been established by TEM and DLS. Advanced TEM characterization have been attempted for specific systems. Upconversion nano systems with different hosts BaYF5 and NaYF4 with Yb3+ as sensitizer and Er3+ as activator have been synthesised. Upconversion systems with various sensitisers/activators have also been synthesised. The hydrothermal methods cause a little aggregation with highly fluorescent red emission with cubic phase, while solvothermal method gives particles with hexagonal phase with very intense green fluorescence emission hexagonally shaped particles. The toxicity has been assessed by adopting MTT assay and the samples are found to be non toxic for further advanced applications. Silica substrates have been synthesised using sol-gel method. Initial biosensing trials have been done with cubic nanoparticles. Even if cubic and hexagonal particles have been synthesised, the hexagonal particles synthesised by solvothermal method were found to be much more ideal with respect to fluorescence intensity. Silanisation procedures were adopted as a part of attaching the bioreceptors to UCNPs. Trials have been made to silanize and bioconjugate with reduced antibodies, reduced antibodies and Affimers for biodetection. As initial trials, a competitive assay for ofloxacin using hexagonal antibodies were found to be successful. The detection of biomarkers using upconversion nanoparticles have been done for selected biomarkers and the limit of detection is found to be in the 10nM range. Trials are going on to reduce the detection limit by modifying the particle size and detection procedures. It has also been identified that these upconversion nanoparticles are ideal candidates for fluorescence imaging. Synthesis of NaGdF4/ Yb3+/Er3+ was also carried out expecting its application with respect to its dual property-magnetic as well as optical. Even if the optical properties and nanosize properties were characterised, the magnetic properties for dual mode detection and imaging is still in the preliminary stage. Conjugation of A15 peptides with hexagonal UCNPs were carried out with the aim of targeting thrombus diseased site and this work also in the initial stage. Collaboration with different schools involved in the project has been established. The upconversion nanotechnology and the advanced applications and challenges are established in University of Leeds through this project. The current work leads to a publication in J. Biophotonics (Just accepted, where the researcher is the First and Corresponding Author) and a publication in Scientific reports (Scientific Reports, (2018) 8:1106 | DOI:10.1038/s41598-018-19415-w) where the researcher is a co-author. Researcher presented two plenary talks in two international conferences (5th International Conference on Nanotechnology in Medicine cum 11th International Forum on Innovative Technologies for Medicine (ITMED), 2018, June 26-28th (2018), Manchester, UK.; 23rd International Conference on Nanomaterials and Nanotechnology-Nanomaterials 2018, March 15-16 (2018), London, UK). Discussions are going on with Research and Innovation at University of Leeds regarding IP aspects of UCNP synthesis and modifications, but this is in the very preliminary stage. The industrial links created by the researcher will be supportive for taking this work forward and for effective commercialisation in future.
