Micro-structured and self-assembled patterns in PLA-cast films as a function of CTAB content, magnesium and substratum hydrophobicity

The fabrication of biomaterials with structured surfaces for medical purposes is a topic of great interest. Producing topographies with certain characteristics can benefit tissue formation and/or reduce the probability of developing an infection due to the hindrance shown by certain micro-structures to microbial adhesion. 
This work presents a new, economically attractive way to fabricate micro-structured patterns on the surface of 
one of the currently most interesting bioabsorbable polymeric materials, polylactic acid (PLA). Formation of 
homogeneously distributed holes is presented as a function of three factors: the concentration of cetyltrimethylammonium bromide (CTAB), the presence or not of the dispersant magnesium, and the hydrophobicity of the support used in the PLA-film fabrication, silicone or glass. The size of the holes increases with the CTAB concentration: from 1 to 5 µm on silicone and 2 to 20 µm on glass. Magnesium particles make CTAB to disperse better inside the PLA matrix, provoking the irregular holes observed on glass become regular with sizes between 0.5 and 2 µm. The topographies obtained on silicone are highly stable over time, while on glass they degrade after 28 days. Consequently, it is possible to design a wide spectrum of micro-structured topographies, covering both antimicrobial and tissue integration targets.