Exploring the Diverse Morphology of Porous Poly(Lactic Acid) Fibers for Developing Long-Term Controlled Antibiotic Delivery Systems

Heat's Role in Solution Electrospinning: A Novel Approach to Nanofiber Structure Optimization

In this study, we explored an innovative application of heat-assisted solution electrospinning, a technique that significantly advances the control of phase separation in polystyrene (PS) fibers. Our experimental approach involved the use of direct heating and a convection air sheath applied through a coaxial needle, focusing on solvents with varying vapor pressures. This method enabled a detailed investigation into how solvent evaporation rates affect the morphology of the electrospun fibers. SEM and AFM measurements revealed that the application of direct heating and a heated air sheath offered precise control over the fiber morphology, significantly influencing both the surface and internal structure of the fibers. Additionally, we observed notable changes in fiber diameter, indicating that heat-assisted electrospinning can be effectively utilized to tailor fiber dimensions according to specific application requirements. Moreover, our research demonstrated the critical role of solvent properties, particularly vapor pressure, in determining the final characteristics of the electrospun fibers. By comparing fibers produced with different solvents, we gained insights into the complex interplay between solvent dynamics and heat application in fiber formation. The implications of these findings are far-reaching, offering new possibilities for the fabrication of nanofibers with customized properties. Furthermore, this could have profound impacts on various applications, from biomedical to environmental, where specific fiber characteristics are crucial. This study not only contributes to the understanding of phase separation in electrospinning but also opens avenues for further research on the optimization of fiber properties for diverse industrial and scientific applications.

A feasible strategy to balance the performance of stereo-complexed polylactide by incorporating poly(butylene adipate-co-terephthalate)

The raw material of polylactide (PLA) is lactic acid obtained by biological fermentation. PLA is the most promising degradable polymer to replace traditional plastics to address the pollution problems caused by their non-degradability. However, the application of PLA is hindered by its low softening temperature, easy hydrolysis, and poor toughness. Herein, the ternary composites with PLLA, PDLA and Poly (butylene adipate-co-terephthalate) (PBAT) were prepared by melt blending to balance its thermal stability, hydrolysis, and toughness. The effects of PBAT content (3 %, 6 %, 9 % and 12 %) and isothermal crystallization temperature on composite properties were fully investigated. The results show that the composite of stereo-complexed PLA (sc-PLA) with 6 % PBAT crystallized at 110 °C exhibits good comprehensive properties. Its vicat softening temperature (VST), mass loss rate under alkaline (pH = 12) and breaking elongation are 166 °C, 21.6 % and 4.40 %, respectively. Compared with the pure PLLA sample crystallized at same condition, the VST, mass loss rate and breaking elongation are 159 °C, 24.7 % and 3.76 % respectively, which increased by nearly 5 %, 13 % and 20 %. This indicates that this strategy is feasible to balance the heat resistance, hydrolysis resistance and toughness of PLA, while it sacrifices the tensile strength a little. This work provides a new way to modify and improve the PLA properties. Nonetheless, it is also necessary to coordinate the compatibility of PLA and PBAT.

Bacterial Response to the Surface Aging of PLA Matrices Loaded with Active Compounds

The use of active components in biomaterials improves the properties of existing ones and makes it possible to obtain new devices with antibacterial properties that prevent infections after implantation, thus guaranteeing the success of the implant. In this work, cetyltrimethylammonium bromide (CTAB) and magnesium particles were incorporated into polylactic acid (PLA) films to assess the extent to which progressive aging of the new surfaces resists bacterial colonization processes. For this purpose, the films' surface was characterized by contact angle measurements, ToF-SIMS and AFM, and adhesion, viability and biofilm growth of Staphylococcus epidermidis bacteria on these films were also evaluated. The results show that the inclusion of Mg and CTAB in PLA films changes their surface properties both before and after aging and also modifies bacterial adhesion on the polymer. Complete bactericidal activity is exhibited on non-degraded films and films with CTAB. This antibacterial behavior is maintained after degradation for three months in the case of films containing a higher amount of CTAB.

Antibacterial Porous Systems Based on Polylactide Loaded with Amikacin

Three porous matrices based on poly(lactic acid) are proposed herein for the controlled release of amikacin. The materials were fabricated by the method of spraying a surface liquid. Description is given as to the possibility of employing a modifier, such as a silica nanocarrier, for prolonging the release of amikacin, in addition to using chitosan to improve the properties of the materials, e.g., stability and sorption capacity. Depending on their actual composition, the materials exhibited varied efficacy for drug loading, as follows: 25.4 ± 2.2 μg/mg (matrices with 0.05% w/v of chitosan), 93 ± 13 μg/mg (with 0.08% w/v SiO₂ amikacin modified nanoparticles), and 96 ± 34 μg/mg (matrices without functional additives). An in vitro study confirmed extended release of the drug (amikacin, over 60 days), carried out in accordance with the mathematical Kosmyer–Pepas model for all the materials tested. The matrices were also evaluated for their effectiveness in inhibiting the growth of bacteria such as Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Concurrent research was conducted on the transdermal absorption, morphology, elemental composition, and thermogravimetric properties of the released drug.