Search Results (6)

Background/Objectives: Polymeric nanofibers are promising platforms for skin treatment applications due to their large surface area and high porosity, which promote enhanced drug delivery. This study aimed to develop and compare poly(lactic acid)-based (PLA) nanofibrous mats, using linear PLA and a star-like PLA-pentaerythritol (PLA-PE) copolymer, as carriers for transdermal delivery of the antibacterial agent levofloxacin (LEV). Methods: Electrospinning was employed to fabricate nanofibers from PLA and PLA-PE solutions. Spinning parameters and polymer concentrations (10% w/v PLA and 20% w/v PLA-PE) were optimized to produce uniform fibers. LEV was loaded at 10% and 20% w/w. A sum of complementary characterization techniques, including scanning electron microscopy (SEM), infrared spectroscopy (FTIR), X-ray diffraction (XRD), and differential scanning calorimetry (DSC), were applied to comparatively investigate the fibers’ morphology, structural properties, and crystallinity. Drug loading, porosity, degradation, and in vitro release profiles were evaluated. Results: PLA-PE nanofibers demonstrated smaller diameters and higher porosity (up to 90.1%) compared to PLA (82.4%), leading to enhanced drug loading (up to 34.78%) and faster degradation (55% vs. 43% mass loss over 60 days). Drug release exhibited a biphasic profile with an initial burst followed by sustained release. PLA-PE formulations released up to 60.2% LEV, compared to 38.1% for PLA counterparts. Conclusions: The star-like PLA-PE copolymer enhances nanofiber properties relevant to the desired application, including porosity, degradation rate, and drug release. These findings suggest that PLA-PE is a promising material for developing advanced transdermal antibiotic delivery systems. Full article

Biodegradable polyesters have been researched intensively over the last two decades because of their biodegradability and superb physical properties. However, the use of linear biodegradable polyesters, for the preparation of drug delivery systems (DDS), is hampered by several limitations. In view of this, scientific attention has been shifted to the employment of branched-chain (co-)polymers. In this context, we present herein the development of new melatonin (MLT) tablet formulations, using novel branched polylactide (PLA)-based copolymers of different architectures. Specifically, three PLA-polyol branched polyesters, namely, a three-arm copolymer based on glycerol (PLA-glycerol), a four-arm copolymer based on pentaerythritol (PLA-pentaerythritol), and a six-arm copolymer based on sorbitol (PLA-sorbitol), were utilized. The presence of these polyesters in the formulations was found to be crucial, as the sought MLT release, regarding its use in confronting sleep onset and/or sleep maintenance dysfunctions, was achieved. The copresence of the other excipients in the matrix tablets (lactose monohydrate, hydroxypropylmethylcellulose, microcrystalline cellulose, and sodium alginate) led to a concentration-dependent synergistic effect on the MLT release. To the best of our knowledge, this is the first investigation with these specific polymeric materials, concerning MLT modified release from matrix tablets. Full article

This study provides insight into the accelerated hydrolysis of polyester PLA through the addition of phosphites based on pentaerythritol. To control hydrolysis and ensure processing stability, different types of phosphites and combinations of phosphites with acid scavengers were studied. Therefore, commercially available PLA was compounded with selected additives on a twin-screw extruder, and hydrolysis experiments were performed at 23 °C, 35 °C and 58 °C in deionized water. Hydrolysis of PLA was evaluated by the melt volume rate (MVR) and size-exclusion chromatography (SEC). For example, after 4 days of water storage at 58 °C, the number average molecular weight of the PLA comparison sample was reduced by 31.3%, whereas PLA compounded with 0.8% phosphite P1 had a 57.7% lower molecular weight. The results are in good agreement with the expected and tested stability against hydrolysis of the investigated phosphite structures. ³¹P-NMR spectroscopy was utilized to elucidate the hydrolysis of phosphites in the presence of lactic acid. With the addition of phosphites based on pentaerythritol, the hydrolysis rate can be enhanced, and faster biodegradation behavior of biodegradable polyesters is expected. Accelerated biodegradation is beneficial for reducing the residence time of polymers in composting facilities or during home composting and as litter or microplastic residues. Full article

New organophilic montmorillonites with oligomers of lactic acid and other compounds such as citric acid, stearic acid, maleic anhydride, pentaerythritol and ε-caprolactone were synthesized. They were characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), elemental analysis and swelling capacity in water. In all tested composites, an increase in the montmorillonite interlayer distance resulting from intercalation of the modifying substance in the montmorillonite was found by means of XRD. Elemental analysis and FTIR showed that all of the tested samples contained an organic segment in the montmorillonite structure. TGA studies revealed that composites modified with lactic acid oligomers, stearic acid or ε-caprolactone had the highest thermal stability. They also exhibited the lowest swelling capacity which was 2–3 times lower than that for unmodified sodium montmorillonite. Some preliminary studies on the mechanical properties of PLA/modified montmorillonite are also presented and discussed. Full article

The objective of this study is to assess the efficiency of biobased carbonization agent in intumescent formulations (IFRs) to examine the flame retardant properties of polylactic acid (PLA) composites and to investigate their melt-spinnability. We used phosphorous-based halogen free flame retardant (FR) and kraft lignin (KL) as bio-based carbonization agent. After melt compounding and molding into sheets by hot pressing various fire related characteristics of IFR composites were inspected and were characterized by different characterization methods. It was fascinating to discover that the introduction of 5–20 wt% FR increased the limiting oxygen index (LOI) of PLA composites from 20.1% to 23.2–33.5%. The addition of KL with content of 3–5 wt% further increased the LOI up to 36.6–37.8% and also endowed PLA/FR/KL composites with improved anti-dripping properties. Cone calorimetry revealed a 50% reduction in the peak heat release rate of the IFR composites in comparison to 100% PLA and confirmed the development of an intumescent char structure containing residue up to 40%. For comparative study, IFR composites containing pentaerythritol (PER) as a carbonization agent were also prepared and their FR properties were compared. IFR composites were melt spun and mechanical properties of multifilament yarns were tested. The analysis of char residues by energy dispersive X-ray spectrometry (EDS) and SEM images confirmed that PLA/FR/KL composites developed a thicker and more homogeneous char layer with better flame retardant properties confirming that the fire properties of PLA can be enhanced by using KL as a carbonization agent. Full article

Polylactide (PLA) is one of the most widely used organic bio-degradable polymers. However, it has poor flame retardancy characteristics. To address this disadvantage, we performed melt-blending of PLA with intumescent flame retardants (IFRs; melamine phosphate and pentaerythritol) in the presence of organically modified montmorillonite (OMMT), which resulted in nanobiocomposites with excellent intumescent char formation and improved flame retardant characteristics. Triphenyl benzyl phosphonium (OMMT-1)- and tributyl hexadecyl phosphonium (OMMT-2)-modified MMTs were used in this study. Thermogravimetric analysis in combination with Fourier transform infrared spectroscopy showed that these nanocomposites release a smaller amount of toxic gases during thermal degradation than unmodified PLA. Melt-rheological behaviors supported the conclusions drawn from the cone calorimeter data and char structure of the various nanobiocomposites. Moreover, the characteristic of the surfactant used for the modification of MMT played a crucial role in controlling the fire properties of the composites. For example, the nanocomposite containing 5 wt.% OMMT-1 showed significantly improved fire properties with a 47% and 68% decrease in peak heat and total heat release rates, respectively, as compared with those of unmodified PLA. In summary, melt-blending of PLA, IFR, and OMMT has potential in the development of high-performance PLA-based sustainable materials. Full article