I was reading this journal on FO-PPR sensor and had a doubt. Couldn't exactly google for an answer as it was unclear. "Integration of fiber optic-particle plasmon resonance biosensor with microfluidic chip" by a group of scientists. I have attached the pdf. Under the section "Preparation of AuNP" , it had (n=500) written in the end. I couldn't figure out what it meant . I will appreciate it , if you clear my doubt . Edit by Borek: pdf removed.