Nowadays, extensive environmental problems due to the use of synthetic polymers have provoked efforts for their replacement with biopolymers as the most important research priorities. Polylactic acid (PLA) is one of the well-known biodegradable biopolymers. In this work, for the first time, PLA was modified with hydrophilic triazine-based dendrimers to obtain PLA with improved hydrophilic properties. In this regard, at first, DL-lactic acid (DLLA) was polymerized through the melt polycondensation to obtain poly-DL-lactic acid (PDLLA). The effects of reaction time and catalyst types on the molecular weight of the PDLLA were investigated. Also, the thermal behavior of PDLLAs with different molecular weights was evaluated using differential scanning calorimetry (DSC) technique. The obtained results from the DSC analysis showed that the PDLLA with higher molecular weight has a higher glass transition temperature (Tg) and melting point (Tm). In the following, various generations (G) of the triazine-based dendrimers were synthesized. To increase the hydrophilicity of the prepared PDLLA, chemical modification of PDLLA with the different generations of triazine-based dendrimer (G1, G1. 5 and G2) was performed. Due to the modification of PDLLA with dendrimers, the number of functional groups and hydrophilicity of PDLLA increased. Based on the obtained results, it is expected that the prepared systems could be a good and promising candidate for the production of biocompatible plastics with more hydrolytic degradation ability.

Objective(s): In this study, drug loaded electrospun nanofibrous mats were prepared and drug release and mechanism from prepared nanofibers were investigated.Materials and Methods: Paclitaxel (PTX) loaded polylactic acid (PLA) nanofibers were prepared by electrospinning. The effects of process parameters, such as PTX concentration, tip to collector distance, voltage, temperature and flow rate on the mean diameter of electrospun PTX loaded PLA nanofibers were investigated. Scanning electron microscopy (SEM) was used to investigate the fiber morphology and mean fiber diameter of prepared nanofibers. Response surface methodology was used to model the average diameter of electrospun PLA/PTX nanofibers.Results: The predicted fiber diameter was in good agreement with the experimental result. In Vitro drug release in phosphate buffer solution (PBS) and acetate buffer for the produced samples showed that diffusion is the dominant drug release mechanism for PTX loaded ubers.Conclusion: Electro spinning was shown to be very promising approach to the formulation of Paclitaxel in order to enhance its release in a sustained and prolonged manner.

Gelatin-hydroxyapatite-polylactic acid (PLA) nanocomposites were synthesized using five different formulations. The nanocomposites were loaded with ibuprofen and the amount of drug in the carriers was determined. X-ray diffraction (XRD) analysis was conducted before and after drug loading to ensure the presence of ibuprofen on the nanocomposites. Drug delivery was evaluated in phosphate buffered saline (PBS) solution at pH 7. 4 and 37° C. The results of XRD analysis showed acceptable synthesis of hydroxyapatite and the composites, confirming the loading of ibuprofen onto the synthesized nanocarriers. The results showed that maximum drug loading (58. 2%) was recorded for sample D (30% gelatin, 40% nHA and 30% PLA), and minimum loading was recorded for sample E (30% gelatin, 30% nHA and 40% PLA). The maximum percentage of drug release over the course of 72 h (95. 8%) was for nanocomposite D (30% gelatin, 40% nHA and 30% PLA). The minimum percentage of drug delivery (77%) was for nanocomposite E (30% gelatin, 30% nHA, 40% PLA), which contained the maximum PLA content.

In this study, biodegradable polylactic acid (PLA)/chitosan (Cs) composites were produced via melt compounding and compression molding techniques. Various chitosan loadings of 2. 5, 5, 7. 5 and 10 parts per hundred parts of polymer (php) were incorporated into PLA and its effects on thermal, water absorption kinetics, tensile and morphological characteristics were investigated systematically. Thermal analysis indicated that an increase in chitosan loading of up to 10 php enhanced the crystallinity percentage (χ, c) of neat PLA to an extent of 51%, yet reduced the thermal stability of the resulting biocomposites. The kinetic study results revealed that water absorption of PLA/Cs biocomposites approached the Fickian diffusion behavior. The maximum water uptake (Msat) increased with chitosan addition, which can be attributed to stronger water–, filler interaction. This was correlated to higher diffusion (D), solubility (S) and permeability (P) coefficients, which suggested the acceleration in diffusion rate and better water permeation through the biocomposites. In addition, the tensile results of dry samples showed enhancement in tensile strength and tensile modulus by 2% and 14%, respectively, relative to neat PLA through the incorporation of 2. 5 php of chitosan loading. However, the water-immersed biocomposites demonstrated deterioration in all tensile properties (tensile strength, tensile modulus, and elongation-at-break values) which signified hydrolytic polymer degradation. This was confirmed by the FESEM micrographs of the fractured surfaces which exhibited filler pulled-out phenomenon and cavity formation after 50 days of water immersion.

Kinetics of thermal degradation of polylactic acid (PLA), a biodegradable and bioabsorbable polyester, under atmosphere of inert gas has been investigated. Isothermal and dynamic heating techniques of thermogravimetry have been used in this study. The weight loss data versus time were recorded at the temperatures of 180, 200, 220, 240, 260 and 280° C, in the isothermal heating experiments. Also, the weight loss data versus temperature were collected in dynamic heating runs conducted with the heating rates of 10, 15, 20 and 25 °C/min. Two kinetic models, one for isothermal and the other for dynamic heating experiments were utilized to fit the data. It is elucidated that the thermal degradation of PLA is a single stage process within the range 0-30% of weight loss, having activation energy of 21-23 kJ/mol.