DTX (Cayman Chemical, USA) was loaded onto TIPS microparticles using an antisolvent precipitation method.[14 (link)
] 5 mg of PLGA TIPS microparticles was transferred into 20 mL clear type 1B borosilicate glass vials and sealed with a butyl injection stopper. 4.5 mL of ultrapure water was added to the vial and vortexed for 10 s. 0.5 mL of 1 mg mL−1 DTX in ethanol was added using 1 mL syringe with a 25 G needle through the rubber stopper. The vial was then vortexed for 10 s and placed on the roller mixer (IKA Roller 6 digital; 60 rpm) at room temperature for 2 h.
DTX loading efficiency (DLE) onto the TIPS microparticles after 2 h incubation was calculated according to the following equation. The amount of free DTX left in the solution was measured by UV spectroscopy at the wavelength of 229 nm using a Nanodrop 2000c spectrophotometer (Thermo Scientific, Waltham, MA).
Unbound DTX and ethanol solution was removed from the microparticles by washing 3 × 5 mL ultrapure water, followed by desiccation under vacuum. Samples of the dried microparticles were coated with gold for 60 s using a Q150R ES gold coater (Quorum Technologies, Oxford, UK). Scanning electron microscopy (SEM; Hitachi S3400N scanning electron microscope) was used to confirm the presence of DTX on the surface of TIPS microparticles.
] 5 mg of PLGA TIPS microparticles was transferred into 20 mL clear type 1B borosilicate glass vials and sealed with a butyl injection stopper. 4.5 mL of ultrapure water was added to the vial and vortexed for 10 s. 0.5 mL of 1 mg mL−1 DTX in ethanol was added using 1 mL syringe with a 25 G needle through the rubber stopper. The vial was then vortexed for 10 s and placed on the roller mixer (IKA Roller 6 digital; 60 rpm) at room temperature for 2 h.
DTX loading efficiency (DLE) onto the TIPS microparticles after 2 h incubation was calculated according to the following equation. The amount of free DTX left in the solution was measured by UV spectroscopy at the wavelength of 229 nm using a Nanodrop 2000c spectrophotometer (Thermo Scientific, Waltham, MA).
Unbound DTX and ethanol solution was removed from the microparticles by washing 3 × 5 mL ultrapure water, followed by desiccation under vacuum. Samples of the dried microparticles were coated with gold for 60 s using a Q150R ES gold coater (Quorum Technologies, Oxford, UK). Scanning electron microscopy (SEM; Hitachi S3400N scanning electron microscope) was used to confirm the presence of DTX on the surface of TIPS microparticles.