Selective crystallization of the metastable phase of indomethacin at the interface of liquid/air bubble induced by femtosecond laser irradiation
We describe a new method for the selective crystallization of the metastable phase (a form) of indomethacin. To obtain the a form, we prepared a highly supersaturated solution and then introduced forcible nucleation techniques, namely, laser irradiation and magnetic stirring. When the laser irradiated near the side wall, the a form crystallized within 24 h. The a form crystals showed temporal stability for at least 8 months in air ambient at room temperature. We conclude that control of the laser irradiation focal point is an effective way of selectively crystallizing the metastable phase of indomethacin with temporal stability.