## 3 Results and Discussion
### Antibacterial Micromolded Scaffolds  
An antibacterial scaffold was produced by introducing 6 wt-% of triclosan (TCS) to the previous formulation found out, namely combining the use of PEG and NaCl to obtain a proper pore interconnection and high porosity density. As concluded in the previous work [38]. TCS can be incorporated in the ultrasound micromolding of PLA without causing an appreciable degradation. Antibacterial scaffolds were therefore prepared with a PLA:PEG:NaClTCS mixture having 50 wt-%, 8 wt-%, 36 wt-% and 6 wt-% of each component, respectively (abbreviated as PLA:PEG-8:NaCl-36:TCS-6). GPC measurements indicated as previously explained a slight decrease on the PLA molecular weight (i.e., \(M_{n}=39,400\) g/mol). The porosity achieved after immersion on water was similar to that observed for the evaluated PLA:PEG-10:NaCl-40 scaffold. The incorporation of the hydrophobic TCS was performed through the slight decrease on the content of hydrophilic PEG and NaCl components, which may alter the surface characteristics of the molded specimens. However, contact angle measurements indicated a minimum increase from 46\({}^{\circ}\) to 48\({}^{\circ}\) (Figure 12) and consequently samples showed a good wettability as desired for a delivery application. Drug release, bacterial growth and cell proliferation assays were carried out to evaluate the bactericide and potential tissue engineering applications of the new processed scaffolds. Release experiments were firstly carried out in a PBS medium. Less than 0.2% of the TCS loaded in the specimen was released (profile not shown) due to the poor solubility of TCS. Therefore, a PBS-ethanol mixture containing 70% ethanol was used as a release medium, the presence of ethanol increased the medium hydrophobicity and enhanced the TCS solubility. It has also been reported in previous works that this medium with an ethanol supplement could simulate the release of TCS in a physiological medium with serum supplementation [53; 54]. As show in Figure 14 the drug release profile of the antibacterial scaffold (black line) was characterized by a first burst release. Thus, 56% of the loaded TCS was delivered in less than 10 h. A sustained release for a period longer than 150 h was subsequently observed. This release was defined for a first order kinetic profile with a \(k_{1}\) value of 0.019 h\({}^{-1}\). As a comparison the release profile of a non-porous PLA specimen with the same TCS load is also shown in Figure 14 (blue line). A burst release was not observed, indicating that less accessible surfaces for an immediate release were available. Furthermore, only 40% of TCS was released after 150 h of exposure, a value that clearly contrasts with the 84% reached with the porous sample. It is clear that the presence of a high density of pores has a dramatic effect and a considerably improvement of the TCS release, which should led to specimens with bactericide activity [38]. Figure 14: Release profiles in a PBS-EtOH 70% medium of the antibacterial scaffold (black) and non-porous (blue) micromolded PLA specimen. Both samples contained 6 wt-% of TCS. Figure 15a shows _E. coli_ (Gram-negative) and _S. epidermidis_ (Gram-positive) bacterial growth curves in presence of micromolded specimens of non-porous PLA (control), PLA porous scaffold (PLA:PEG-10:NaCl-40) and TCS loaded PLA scaffold. The unload scaffold displayed a similar bacterial growth curve than the non-porous PLA sample. Note that in both cases, the bacterial growth required a lag phase close to 4 h. However, bacterial growth in the porous scaffold was subsequently limited to a value around 80-90%. This low inhibition growth effect (in the stationary phase) could be explained taking into account that some NaCl remained in the piece. By contrast, the scaffolds loaded with TCS had a clear bactericide effect during the first 10 h that was followed by a bacteriostatic effect that kept the bacterial growth around 30-35%. Performance of TCS loaded specimens was similar for both Gram-positive and Gram-negative bacterial cultures.