Polymer hydrophobicity regulates paclitaxel distribution in microspheres, release profile and cytotoxicity in vitro

• Uniform-sized PLA, PLGA and PELA microspheres containing PTX were prepared by premix membrane emulsification technique.
• The different hydrophobicity of polymer demonstrated different distribution and crystal morphology of PTX in microspheres.
• These differences further resulted in different loading and encapsulation efficiency, release profile in vitro and cytotoxcity.

Water-insoluble drugs such as paclitaxel (PTX) face a huge challenge for clinical applications due to their low aqueous solubility. In this study, uniform-sized poly (dl-lactic acid) (PLA), poly(dl-lactic-co-glycolic acid) (PLGA) and poly(ethylene glycol-co-lactide acid) (PELA) microspheres containing PTX were prepared by premix membrane emulsification technique integrated with solvent evaporation method. The different hydrophobicity of polymer led to different distribution and crystal morphology of PTX in microspheres, which further resulted in different loading and encapsulation efficiency, release profile in vitro and cytotoxicity. The PLGA microspheres showed the highest loading and encapsulation efficiency of PTX (5.15%, 70.46%), followed by PLA microspheres (4.33%, 64.33%), together with PELA microspheres (3.35%, 56.68%). The results of PTX release profile in vitro suggested that PLGA and PELA microspheres achieved a more rapid release rate than PLA microspheres due to their hydrophilic property. The antitumor activity in vitro was also evaluated by Lewis Lung Cells (LLC). The PTX-PLGA microspheres exhibited excellent antitumor activity compared with PLA and PELA microspheres, even much better than Taxol®. Therefore, the PLGA microspheres show great potential in application as delivery carriers for water-insoluble drugs, PTX and others.

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