Method of one-pot synthesis of water-soluble nanoparticles exhibiting up-conversion luminescence

A method of synthesizing water-soluble particles, the method comprising:

• providing a solution comprising a halide compound, a first solvent, and a mixture of YCl3, YbCl3, and ErCl3, wherein
• the YbCl3 and total amount of the YCl3, YbCl3, and ErCl2 are in a mole ratio in the solution ranging from about 12% to about 20%, and
• the ErCl3 and the total amount of the YCl3, YbCl3 and ErCl3 are in a mole ratio in the solution ranging from about 1% to about 5%;
• introducing a capping agent, selected from the group consisting of 3-mercaptopropionic acid, 6-aminocaproic acid, and mixtures thereof, into the solution to form a mixture;
• heating the mixture under pressure to produce a plurality of particles;
• and
• recovering the particles from the mixture.