Objective      To determine the effect of concentration and size of self-assembly nanometer microsphere particles made by polyethylene glycol (peg) grafted poly (lactic acid) (PPLA) on hemolysis rate.       Methods      According to the national medical equipment biological evaluation ISO10993.1-1997 and GB/T16886.1-2001 standard and requirement

dialysis was carried out with a dynamic laser light scattering instrument (DLS) to measure particle size and Zeta potential. Different concentrations and particle sizes of PPLA self-assembly nanometer microspheres were prepared. Hemolysis rate of the nanometer microspheres was determined by water bath method and absorption value at 540 nm.       Results      With the increase of the concentration

hemolysis rate of microspheres was increased. For the microspheres in the size of 960.8 nm

they appeared light hemolysis when the concentration was 2.0 mg/mL. For the microspheres at the concentration of 1.0 or 1.5 mg/mL

their hemolysis rate was increased with the decrease of particle size (300 to 200 nm)

though less than 5%

indicating that they can be injected. In 0.9% NaCl solution

the critical hemolysis concentration of PPLA nanometer microspheres was 1.5 to 2.0 mg/mL

which was in this range accord of national drug standards hemolysis.       Conclusion       Our research shows the negative effects of the nano drug’ nano effect in the clinical application. Particle size exerts remarkable effect on hemolysis and other performance in the nanometer microspheres. When the concentration is same

the larger microspheres are

the lower hemolysis rate is.