Removal of lipid from lipid-bound protein such as human serum albumin to produce defatted protein enhances ability of the protein to bind therapeutic agents for use as a carrier for the therapeutic agent. The defatted protein may be reloaded with cationic and/or anionic lipids such as fatty acids, e.g. DC-Chol, to modify charge, hydrophilicity or hydrophobicity of the defatted protein to further enhance ability of the defatted protein to bind a therapeutic agent. A reloaded lipid itself may be a therapeutic agent. The defatted protein may be produced as microparticles by spray-drying. Defatting can be achieved by removing fatty acids with acidified activated charcoal, or by solvent extraction. A complex of DNA and a microparticle of defatted protein containing a cationic or anionic lipid molecule can be used for gene therapy. Defatted albumin may be reloaded with aminocaprylic acid to provide a microparticle for binding DNA for parenteral delivery. Microparticles of defatted protein having a modified predetermined fatty acid profile may be used as an enhanced ultrasound contrast agent.