2.4. Preparation of OHH NPs.
For synthesis of OHH NPs, 2 mg HMPB NPs and 2 mg ofloxacin were added to 1 mL of deionized water with stirring for 4 h. Then remove unbound ofloxacin by centrifugation. After centrifugation, 6 mg polyacrylic acid (PAA) was added into the mixture. Furthermore, the above solution was added 6 mg of EDC and 6 mg of NHS. After stirring for 2 h, 3 mg Haluronic acid (HA) was added into the mixed solution and further reacted overnight. Finally, OHH NPs were extracted by centrifugation.