## 3 Results
### Characterization of PLA Specimens Loaded with Drugs  
The influence of the incorporation of different amounts of TCS and CHX on the ultrasound micromodling processing of PLA was followed by FTIR spectroscopy and GPC measurements. Figure 5 shows that CHX can be detected in the FTIR spectra of specimens even for the lowest load. Thus, bands related to the biguanide compound appearing at 1640 cm\({}^{-1}\), 1530 cm\({}^{-1}\) and 1490 cm\({}^{-1}\) could be seen, even for a load of only 1%-wt. The intensity of those bands gets higher with the increase of the CHX amount. On the contrary, the infrared spectrum of TCS loaded samples did not show any characteristic band associated with the drug (i.e., those appearing at 1598, 1579, 1507, 1471, 1417 and 1392 cm\({}^{-1}\)) and only the spectra of PLA were detected (not shown). A potential explanation is the \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Modling b** & **Efficiency (\%) c** & \(M_{n}\) **(g/mol)** & \(M_{w}\) **(g/mol)** & \(M_{w}\)/\(M_{n}\) \\ \hline Raw & — & 43,000 & 69,100 & 1.64 \\
24-200-1.5 & 40 & 35,400 & 69,700 & 1.96 \\
24-300-1 & 100 & 34,500 & 68,600 & 1.98 \\
**24-300-1.2** & **100** & **38,800** & **72,200** & **1.88** \\
24-300-3 & 100 & 32,200 & 64,300 & 2.01 \\
24-400-1 & 80 & — & — & — \\
24-400-1.5 & 100 & 37,700 & 71,300 & 1.89 \\
24-500-1.5 & -Ovl- & 33,900 & 67,500 & 1.99 \\
24-600-1.5 & -Ovl- & — & — & — \\ \hline \hline \end{tabular}  
* Bold characters indicate the optimized conditions and the corresponding measurements. b Micro-molding conditions Amplitude (\(\upmu\)m), force (N) and time (s). c Mold filling, qualitative evaluation (i.e., 8 half pieces or 4 full corresponded to 50%). -Ovl-: Snortrode overload.  
\end{table} 
Table 1: Molding efficiency and molecular weight of a polylactide (PLA) sample molded under several conditions a.  
Figure 4: SEM micrographs taken at different magnifications of a PLA specimen molded at 24-300-1.2 condition. Figure 3: FTIR spectrum of polylactide (PLA) afore (black) and after (red) being molded. lower intensity of TCS bands but also to the hydrophobic character of TCS that could improve its dispersion in the PLA hydrophobic matrix. On the contrary, the high hydrophilicity of CHX may favor its disposition onto the PLA specimen surface, its detection by ATR measurements being increased. GPC curves were recorded for specimens loaded with different percentages of TCS and CHX and processed under the conditions optimized for the PLA matrix (24 \(\upmu\)m-300 N-1.2 s). In this way, the effect of the type of drug and percentage can be determined, it being possible in a subsequent work to change the ultrasound parameters (i.e., amplitude, force and time) in order to improve processing. Figure 6a shows similar GPC curves for the neat PLA, the ultrasound processed unloaded PLA sample and that loaded with the maximum amount of TCS (i.e., 6 wt-%). Basically, the maximum appeared at practically the same elution time (see dashed blue box) and differences can mainly be seen in the tail corresponding to higher elution times (i.e., fraction of low molecular weight chains) that slightly increased for the ultrasound processed samples (see dashed red box). Analyses indicated a slight decrease from an initial \(M_{n}\) value of 43,000 g/mol to 40,000-38,800 g/mol after processing. Figure 5: Infrared absorption spectra of PLA, PLA samples loaded with different amounts of chlorhexidine (CHX) and pure CHX. Dashed red boxes indicated bands associated with PLA. Figure 6: (a) Gel permeation chromatography (GPC) curves determined of initial powdered PLA, the molded PLA and its mixtures with the maximum assayed amounts of triclosan (TCS) and CHX; (b) comparison between GPC curves of processed PLA and PLA mixtures with the indicated percentages of CHX. For the sake of completeness, the curve corresponding to a molten PLA film loaded with 6 wt-% of CHX is also drawn (dotted curve).