Building porous biopolymeric microstructures for controlled drug delivery devices using selective laser sintering

The capability to build parts with predetermined porous microstructure and dense walls using powdered biomaterials makes selective laser sintering (SLS), one of the more flexible rapid prototyping (RP) process, a strong candidate for building biodegradable controlled release drug delivery devices (DDD). The objective is to design a varying-porosity circular disc with outer region being denser acting as diffusion barrier region and inner more porous region acting as drug encapsulation region. This is to achieve a zero-order of release over a desired duration of time in drug administration. A key study in this paper was to determine the influence of critical SLS process parameters namely, laser power, laser scan speed and part bed temperature on dense wall formation and control of the porous microstructure of SLS-fabricated parts built with biomaterials. The physical characteristics of the fabricated devices were investigated through microstructure examination using the scanning electron microscope (SEM). Two biodegradable polymers, namely Polycaprolactone (PCL) and Poly (-L) Lactic Acid (PLLA), were investigated. For PCL varying-porosity disc, the laser power is set at 3 W (inner region) - 4 W (outer region), the scan speed at 5080 mm/s and the part bed temperature at 40 degrees C. For Poly(-L) Lactic Acid (PLLA), the laser power is set at 12 W, the scan speed at 1270 mm/s and the part bed temperature at 60 degrees C. With the set of SLS parameters tabulated for specific polymers, polymeric matrix with specific porosity can be fabricated as drug delivery devices.