A coaxial tri-capillary electrospray and template removal method was proposed to produce nanosized core-shell particles for encapsulating of proteins.Polyethylene glycol (PEG) and poly(D

L-lactide-co-glycolide) (PLGA) were used as corona and shell materials

while Bovine serum albumin (BSA)

as a model protein

was entrapped in the core.Microparticles with smooth surfaces and distinct core-shell-corona structures were obtained by coaxial tri-capillary electrospray and nanoparticles with diameter about 100 nm were achieved by removing the corona PEG template from core-shell-corona microparticles.Moreover

the nanoparticle size could be modulated by adjusting the feed rate of shell fluid

and the diameter of nanoparticles could be reduced to (688) nm when the shell fluid feed rate was decreased to 0.5 mL/h.The drug loading content and entrapment efficiency of BSA were 3.7% and 78.3%

respectively.It was also found that BSA released from nanoparticles in a typical bi-phased release profile and the process may last for 60 h.The second order structure of BSA released from particles was monitored with circular dichroism spectrum.The results showed that the electrospray process didn't affect the second order structure of proteins

implying that the denaturation of the protein didn't occur during the process of electrospraying encapsulation.