Your problem is the excess EDC-NHS. Your absorbance readings are a byproduct of both any remaining albumin and the EDC-NHS which has now hydrolyzed probably aggregating and causing strange readings in both your Bradford and UV. Depending on your goals you can do two things,1) purify your supernatant albumin and then quantify, there are a number of commercial kits to purify albumin (I like pierce thermo) 2) Try to calculate the albumin on your silica directly (though I can tell you from experience this is very hard to do).   

Thank you so much, yes you are right. but I wash EDC activated nanoaprticles after activation to remove unreacted species and then add albumin solution. you mean it may remain some amount of free EDC in media?