Fluorescent Polyacrylamide Nanoparticle Synthesis

Fluorescent polyacrylamide nanoparticles were synthesised by optimising the radical polymerisation protocol developed by Rahimi and colleagues [38 (link)]. A total of 222 mg of NIPAM, 28.6 mg of AAm, 76 mg of AH and 262 μL of BIS were dissolved in 10 mL of deionised water previously purged with argon at room temperature and under stirring. Next, 11.5 μL of 10% SDS solution was added, and the solution was purged with argon for 30 min. Then, 1 mg of Alexa Fluor 488 or Alexa Fluor 594 dyes was dissolved to stop the argon flow, and 15.6 mg of APS and 20 μL of TEMED were added. Finally, deionised water was added to the final volume of 20 mL, and the reaction was carried out at room temperature for 3 h under continuous stirring in darkness. Dialysis was performed by transferring the sample into a 10 kDa cut-off membrane kept in deionised water under stirring and replaced with new water 4 times per hour. Finally, the sample was concentrated in a 30 kDa Vivaspin^® tube (Sartorius, Goettingen, Germany) by centrifuging at 3000× g until 1 mL of nanoparticle suspension was obtained, and then kept at 4 °C.