2.2. Preparation of Nanoparticles

NaHCO₃-PLGA NPs were prepared using the ultrasound double emulsification method (water/oil/water, W/O/W). First, 40 mg PEG-PLGA-COOH (50:50, MW: 15,000) and 4 mg PTX were dissolved in 2 mL trichloromethane (CHCl₃). Once completely dissolved, 200 mL of 0.25% NaHCO₃ aqueous solution was added. The mixture was processed using an ultrasonic cell crusher (VCX150, Sonics & Materials, Inc., Newtown, CT, USA) at 105 W for 1 min 30 s to obtain the W/O emulsion. Next, 4 mL of 4% poly(vinyl alcohol) (PVA) aqueous solution was added [27] and the mixture was emulsified using an ultrasonic cell crusher at 105 W for 2 min 30 s to obtain W/O/W emulsion. Subsequently, 10 mL of a 2% isopropyl alcohol solution was added and the mixture was stirred for 6 h to volatilize the CHCl₃. Finally, the PTX-NaHCO₃-PLGA NPs were collected by centrifugation several times (10,000 rpm, 8 min).