Upconversion nanoparticles coated with Alendronate and PEG-conjugated Alendronate

Upconverting nanoparticles (UCNPs) have gained traction as diagnostic and imaging probes for biological applications due to their many unique optical properties. This thesis describes the exploration of alendronate and polyethylene glycol (PEG) surface chemistries to impart NaYF4:Yb3+ /Er3+@NaYF4 core shell UCNPs with the colloidal and optical stability required for biological applications upon transference into aqueous environments. Prior to evaluating colloidal and optical stability, NMR studies to confirm binding and surface coverage studies of alendronate and alendronate PEG 5kDa were conducted yielding ligand densities of 2.56 +/- 0.16 nm-2 and 0.085 +/- 0.02 nm-2 , respectively. Alendronate PEG 5kDa coated UCNPs demonstrated enhanced colloidal stability in comparison to alendronate coated UCNPs in 1X PBS buffer. Both alendronate and alendronate PEG coating led to a significant decrease in optical intensity of the main green emission peak at 537 nm by 84% and 93%, respectively.%%%%M.Sc.