A method of preparing nano-carriers is disclosed. The method includes mixing an organic solution of a drug and an organic solution of a biological agent separately with a predetermined amount of water having one or more dissolved surfactants to obtain a first mixture and a second mixture respectively. Subsequently, the first mixture and the second mixture are homogenized separately to obtain a solution of nano-crystals of the drug and a solution of nano-particles of the biological agent respectively. Thereafter, the solution of nano-crystals of the drug and the solution of nano-particles of the biological agent are together subjected to an ultra-sound homogenization to obtain a solution of nano-carriers. An interfacial extraction and/or a dialysis are then performed on the solution of nano-carriers to obtain the nano-carriers. Formulations of the nano-carriers are also disclosed.
