I am currently trying to optimize the reaction time it takes for the polydopamine to coat the nanoemulsion droplets and the concentration of polydopamine to be used. My samples comprise of:

- (1/1000) Nanoemulsion sample

- 50 mM phosphate buffer saline

- Polydopamine (0.1 mg/mL to 3 mg/mL, varying since I'm still optimizing)

However, after less than 24 hours, I observed that the polydopamine is greatly in excess even at 0.1 mg/mL since it autopolymerize by itself. My question is: should I put polydopamine as is on the final sample or divide the concentration by 1000, since the (1/1000) nanoemulsion just serves as a model for the whole system?

Thank you!