|
In ethanol; lithium hydroxide monohydrate for 0.25h; |
2.3. Preparation of PTM-B-nanoparticles
PTM-B-loaded nanoparticles were prepared by the nanoprecipitation technique (Fessi et al., 1989). To this aim, SQ-COOH and PTM-B were co-dissolved in ethanol in different molar ratios (1:1, 2:1, 3:1, 4:1, 4.5:1, 5:1, 6:1). Practically, starting from an ethanolic SQ-COOH stock solution 5 mg/mL and an ethanolic PTM-B stock solution 5 mg/mL, the quantity of PTM-B (1 mg) was kept constant and different amounts of SQ-COOH (from 1.2 to 7.1 mg) were added to obtain 1:1, 2:1, 3:1, 4:1, 4.5:1, 5:1, 6:1 molar ratios. Then, each organic solution was added drop-wise under stirring to MilliQ water (volume ratio ethanol/water (Ve/Vw) 1:2). Nanoparticle formation occurred spontaneously without using any surfactant. After stirring for 15 min, the organic solvent was eliminated using the rotating evaporator to obtain an aqueous suspension of nanoparticles (total SQ-COOH/PTM-B concentration: 2 mg/mL). To investigate the influence of the volume ratio Ve/Vw, further tests were performed with the formulation SQ-COOH/PTM-B molar ratio 3:1, for which SQ-COOH and PTM-B were dissolved in different volumes of ethanol (0.2, 0.3, 0.5, 0.7 or 1 mL) and then each of them was added to 1 mL of water. To purify the nanoparticles from non-incorporated drug, PTM-loaded nanoparticles were dialyzed against MilliQ water at 4 C (Spectra/Por 3500 MWCO dialysis membrane, Spectrum, Huston, TX). Unloaded SQ-COOH nanoparticles (i.e., without PTM-B) were prepared as well. The nanoparticle suspensions were then stored at 4 C until further use. |
|
In ethanol; lithium hydroxide monohydrate for 0.25h; |
2.3. Preparation of PTM-B-nanoparticles
PTM-B-loaded nanoparticles were prepared by the nanoprecipitation technique (Fessi et al., 1989). To this aim, SQ-COOH and PTM-B were co-dissolved in ethanol in different molar ratios (1:1, 2:1, 3:1, 4:1, 4.5:1, 5:1, 6:1). Practically, starting from an ethanolic SQ-COOH stock solution 5 mg/mL and an ethanolic PTM-B stock solution 5 mg/mL, the quantity of PTM-B (1 mg) was kept constant and different amounts of SQ-COOH (from 1.2 to 7.1 mg) were added to obtain 1:1, 2:1, 3:1, 4:1, 4.5:1, 5:1, 6:1 molar ratios. Then, each organic solution was added drop-wise under stirring to MilliQ water (volume ratio ethanol/water (Ve/Vw) 1:2). Nanoparticle formation occurred spontaneously without using any surfactant. After stirring for 15 min, the organic solvent was eliminated using the rotating evaporator to obtain an aqueous suspension of nanoparticles (total SQ-COOH/PTM-B concentration: 2 mg/mL). To investigate the influence of the volume ratio Ve/Vw, further tests were performed with the formulation SQ-COOH/PTM-B molar ratio 3:1, for which SQ-COOH and PTM-B were dissolved in different volumes of ethanol (0.2, 0.3, 0.5, 0.7 or 1 mL) and then each of them was added to 1 mL of water. To purify the nanoparticles from non-incorporated drug, PTM-loaded nanoparticles were dialyzed against MilliQ water at 4 C (Spectra/Por 3500 MWCO dialysis membrane, Spectrum, Huston, TX). Unloaded SQ-COOH nanoparticles (i.e., without PTM-B) were prepared as well. The nanoparticle suspensions were then stored at 4 C until further use. |