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Interaction Of Microcapsules With Blood Components
Published in Max Donbrow, Microcapsules and Nanoparticles in Medicine and Pharmacy, 2020
Poly(l-lactide) is a synthetic biodegradable polymer. Hence, drug-loaded microcapsules made of the polymer are expected to undergo degradation in the body to give l-lactic acid as the final product after releasing the drug over a period of time. The rate of in vitro degradation of poly(l-lactide) microcapsules is high at high ionic strength if pH of the medium is either high or low.2,4 Recently, Makino et al.5 found that the presence of plasma proteins in the medium enhances the in vitro degradation rate of poly(l-lactide) microcapsules. Some of their experimental results are briefly mentioned and then their analysis7,8 of the experimental data is given on the basis of their new membrane model6 which assumes layered distribution of fixed-charges and penetration of mobile ions into the charged layers.
Targeted Delivery Systems Based on Polymeric Nanoparticles for Biomedical Applications
Published in Anil K. Sharma, Raj K. Keservani, Rajesh K. Kesharwani, Nanobiomaterials, 2018
Sa Yang, Can Huang, Zhi-Ping Li, Qian Ning, Wen Huang, Wen-Qin Wang, Cui-Yun Yu
Poly (l-lactide) (PLA) is a aliphatic polyester that is produced from lactic acid, either by the direct polycondensation of lactic acid or via the ring-opening polymerization of lactide, approved by the US Food and Drug Administration and is widely studied to encapsulate hydrophobic anticancer drugs (Sharma et al., 2015; Yuan et al., 2015). PLA own properties of high biocompatibility, non-toxicity. Moreover, another merits of PLA used as nanoparticles is biodegradability, which is important to maintain clearance of the nanoconstruct after injection and delivery of the cargo and to minimize the risk of toxic buildup of the polymer carrier in tissue (Tang et al., 2013). PLA hydrolyzes into nontoxic hydroxyl-carboxylic acid through ester bond cleavage and enters into citric acid cycle, finally metabolizing into water and carbon dioxide (Garofal et al., 2014). Owing to above advantages, PCL become a commonly used material of nano-sized delivery carrier. Thu and colleagues successfully prepared paclitaxel loaded nanoparticles composed by PLA–TPGS copolymer through a simple modified modification/solvent evaporation method. The results showed that PTX loaded nanoparticles exhibit great advantages compared to free PTX and the folate decoration significantly improve the targeted delivery of drug to cancer cell in both in vitro and in vivo (Thu et al., 2015).
Selected Topics
Published in Charles E. Carraher, Carraher's Polymer Chemistry, 2017
Several new ventures are based on using natural, renewable materials as the starting materials instead of petrochemicals. These products are known as “green” products since they are made from renewable resources and they can be composted. Along with the microbial production of PDO by Shell and Dupont to produce nylon 4,6, Cargill Dow is making polylactide (PLA) beginning with corn-derived dextrose. PLA (19.53) is made from corn-derived dextrose, which is fermented, making lactic acid. The lactic acid is converted into lactide, a ring compound, that is polymerized through ring opening.
Modifications of the optical and vibrational properties in polylactic acid films by the addition of gold nanoparticles produced by laser ablation in chloroform
Published in Radiation Effects and Defects in Solids, 2023
L. Silipigni, M. Cutroneo, A. Torrisi, L. Torrisi
PLA is mostly produced by the polymerization of lactic acid, a naturally occurring organic acid that can be produced by fermentation. It can be also prepared by ring-opening polymerization of lactide, a cyclic dimer of lactic acid (4). It is insoluble in water, has a density of about 1.3 g/cm3 and a melting point of 150°C. Its structure ranges from amorphous glassy to semi-crystalline to highly crystalline. PLA has a glass transition at about 65°C and Young's modulus of 2.7–16 GPa. PLA is soluble in many organic solvents, such as chloroform, ethyl acetate and others. Its mechanical properties of PLA depend on its molecular weight and degree of crystallinity. Semi-crystalline PLA exhibits a tensile modulus of about 3 GPa, a tensile strength of about 50-70 MPa, a flexural modulus of about 5 GPa, and a flexural strength of about 100 MPa (5). Being an innovative and thermoplastic biopolymer, PLA is highly versatile for many biomedical applications: it can be used for skin and tendon healing, tissue regenerative in medicine, cardiovascular implants, orthopedic devices, cancer therapy, and to wrap organic food and tissues (6).
Mechanical and drilling characterization of biodegradable PLA particulate green composites
Published in Journal of the Chinese Institute of Engineers, 2022
In recent years, there has been a high rise in the development of renewable materials due to awareness of environmental care. Green composites have gained greater research interest as ecological awareness and ecological risk have grown, as they can be more appealing than standard petroleum-based composites. Green composites offer a wide range of applications, including aerospace, electronics, and domestic uses, due to their lightweight, environmentally friendly production, and acoustic insulation. Poly (lactic acid) or Polylactic acid (PLA) is one of the green, biodegradable thermoplastics because it is derived from renewable resources, such as corn starch, wheat, or rice (Shogrena et al. 2003). PLA is made from lactic acid, which is produced by fermenting agricultural items like corn. It can also make through ring-opening polymerization of the cyclic lactide or direct condensation of lactic acid (Bajpai, Singh, and Madaan 2012). PLA has strength and rigidity like polyethylene terephthalate and processing qualities as polystyrene; however, it has limited impact and heat resistance. With less than 10% elongation at break, PLA is typically too brittle for commercial purposes. This disadvantage restricts its use in engineering and structural products that require excellent toughness. The most appealing and practical method to increase the mechanical properties of this polymer matrix composites (PMCs) is to combine PLA with other materials in the form of powders, particles, and fibers. Due to their lignocellulosic properties, rice husk, sawdust, bagasse, byproducts of rice milling, wood sawing (neem tree), and sugar factory processes are possible reinforcing fillers for these composites. These fillers have the following benefits: simple processing, high volume availability, lightweight, and competitive particular mechanical properties. These natural fibers in composites can accelerate the biodegradability of the polymeric composites, increase the thermal stability, and increase the wetting/interfacial surface and interlocking between matrix and reinforcements to enhance the performance of PLA.
Fabrication and characterization of poly (ethylenimine) modified poly (l -lactic acid) nanofibrous scaffolds
Published in Journal of Biomaterials Science, Polymer Edition, 2019
Rongying Guo, Shunyu Chen, Xiufeng Xiao
The scaffold material plays a vital role in the process of bone repair. Many synthetic biodegradable polymers such as Poly(lactic acid) (PLA), poly(Lactide-co-glycolide) (PLGA), poly(caprolactone) (PCL), poly(urethane) (PU) and their copolymers have been widely used to fabricate biocompatible scaffolds for the substitutions of conventional materials because of their outstanding properties [12–19]. Among those polymers, Poly (lactide) (PLLA) has attracted more attention in recent years as biomaterials, which is owed greatly to its favorable properties like biocompatibility and safe degradation products, etc. [20–22]. However, the poor cytocompatibility of PLA caused by the inherent shortcomings such as the intrinsic hydrophobicity, lacking of active functional groups and low cell adhesion, etc. limits its broad application. Several strategies have been developed to overcome these drawbacks such as alkaline hydrolysis, plasma treatment, coating and aminolysis, etc. [3, 23–27]. The aminolysis is a convenient and cost effective technique for enhancing cell attachment and proliferation, and can be followed with other chemical treatment for example: layer-by-layer assembly. Poly(ethylenimine), with a high density of primary, secondary, and tertiary amines in the structure, has been widely used in gene delivery and as a precursor base layer for multilayer film fabrication. The purpose of PEI aminolysis is to introduce free amino groups through the reaction between the amine groups of PEI and the ester groups of PLLA for boosting hydrophilicity to promote the cell adhesion on the surface of PLLA scaffold [24, 28, 29]. Zhong et al. [24] used PEI as aminolysis agent to graft–NH2 on poly (propylene carbonate) membranes for more chemical functional groups. Khaliliazar et al. [23] prepared surface modified PLLA grafting with –NH2 in a one step process by using poly (ethylenimine) dendrimer as the modifier. However, no detailed radical modification studies of PLLA in a homogeneous solution system with PEI have been reported. In this work, PLLA/dioxane/PEI ternary system was initially used to prepare modified PLLA nanofibrous scaffolds by aminolysis combined with thermally induced phase separation technique, PEI acting as the modifier. The microstructure, mechanical property and hydrophilicity of the PEI-modified PLLA scaffolds were evaluated. Meanwhile, FTIR, 1H NMR, XPS and GPC were used to confirm the occurrence of the ammonolysis reaction between PLLA and PEI. Furthermore, biomineralization activity and cytocompatibility of the scaffolds were also investigated.