From honeycomb- to microsphere-patterned surfaces of poly(lactic acid) and a starch-poly(lactic acid) blend via the breath figure method

Purpose: In this paper we report the preparation of ordered patterned surfaces and/or microspheres from a natural-based polymer, using the breath figure and reverse breath figure method. Methods: Poly(D, L-lactic acid) and starch poly(lactic acid) solutions were precipitated in different conditions, namely polymer concentration, vapour atmosphere temperature and substrate, in order to evaluate the effect of these conditions on the morphology of the precipitates obtained. Results: The possibility to fine tune the properties of the final patterns simply by changing the vapour atmosphere was also here demonstrated using a range of compositions of the vapour phase. Porous films or discrete particles are formed when the differences in surface tension determine the ability of polymer solution to surround water droplets or methanol to surround polymer droplets, respectively. In vitro cytotoxicity was assessed applying a simple standard protocol in order to evaluate the possibility to use these materials in biomedical applications. Moreover, fluorescent microscopy images show the good interaction of cells with the material, which are able to adhere on the patterned surfaces after 24h in culture. Conclusions: The development of patterned surfaces using the breath figure method was tested in this work for the preparation of both poly-lactic acid (PDLLA) and a blend containing starch and poly- lactic acid (SPLA). The potential of these films to be used in the biomedical area was confirmed by a preliminary citotoxicity test and by morphological observation of cell adhesion.