BBR NPs were prepared as described above. Aqueous dopamine hydrochloride (PDA) (0.2 mg·mL−1) and Tris base solution (6 mg·mL−1) were added into the solution of BBR NP sequentially to obtain an alkaline environment at pH=8.5. Then, the Polydopamine-coated Berberine nanoparticles (PDA@BBR NPs) suspension was obtained by reacting for 6 h under magnetic stirring at room temperature. Finally, the product was purified by centrifugation at 13,000 r·min−1 for 15 min and washed three times with distilled water to remove the unloaded BBR.