Morphology control of electrosprayed core-shell particles via collection media variation

The electrospraying process has been exploited in recent times to prepare micro- and nano-scaled polymer based particulate structures for a range of biomedical and pharmaceutical applications. Conventionally, three main parameters (applied voltage, flow rate and base solvent in processing polymeric media) are used to manipulate their morphologies during preparation (size, surface and porosity). In this work, an un-conventional approach is demonstrated to yield biocompatible core-shell encapsulated (poly-ε-caprolactone (PCL) and silicon oil) particles with a range of structural morphologies (i.e., spherical, hemi-spherical and oblate shaped). Retaining its advantageous single-step fabrication aspect and by using two co-axial needles, a range of collection media was used to demonstrate shape and size variation (from ~28-48 μm) using optical and scanning electron microscopy. The morphological variation is directly linked to surface tension of the collection liquid. In addition, the non-volatile and flexible nature of the oil core plays a role in geometry formation. In vitro release from these structures demonstrates significant and non-significant variations; providing pathways to control release as well mimic release profile but alter other biomedical process (e.g. ultrasound). These findings demonstrate an alternative approach to manipulate the shape of bi-phasic structures which is an important functional property in several biomedical remits (e.g. drug delivery and ultrasound).