Polylactic Acid Polymer Research Articles

Alkaline Amendment for the Enhancement of Compost Degradation for Polylactic Acid Biopolymer Products

abstractThis research evaluates the addition of alkaline amendments to enhance the degradation of polylactic acid polymers (PLA) in compost conditions. The use of compostable biopolymers is increasing in part because they are advertised as compostable. However, PLA degrades slowly compared to the organic wastes in compost and even when processed in commercial composting facilities may not fully break down. This results in the accumulation of biopolymers in compost facilities and increased difficulty in identifying and removing contamination from traditional plastics. Alkaline amendments were used to accelerate the degradation of two PLA products in compost conditions. Six flasks containing food scraps, compost inoculant, and an alkaline amendment were set up as bioreactors with half containing clear PLA and the others including opaque PLA. The six bioreactors were incubated for 22 days. The mass loss and final visual inspection, including microscopy, showed increased degradation within the bioreactors containing the alkaline treatments. These results show that the addition of alkaline amendment to composting systems may enable more effective processing of biopolymers, expanding the range and quantity of wastes that can be processes. The enhanced degradation of biopolymers in compost may enable greater diversion rates for institutions and cities by enabling the acceptance of biopolymers and any mixed organics stream which includes biopolymers wastes.

Bio-safe processing of polylactic-co-caprolactone and polylactic acid blends to fabricate fibrous porous scaffolds for in vitro mesenchymal stem cells adhesion and proliferation

In this study, the design and fabrication of porous scaffolds, made of blends of polylactic-co-caprolactone (PLC) and polylactic acid (PLA) polymers, for tissue engineering applications is reported. The scaffolds are prepared by means of a bio-safe thermally induced phase separation (TIPS) approach with or without the addition of NaCl particles used as particulate porogen. The scaffolds are characterized to assess their crystalline structure, morphology and mechanical properties, and the texture of the pores and the pore size distribution. Moreover, in vitro human mesenchymal stem cells (hMSCs) culture tests have been carried out to demonstrate the biocompatibility of the scaffolds. The results of this study demonstrate that all of the scaffold materials processed by means of TIPS process are semi-crystalline. Furthermore, the blend composition affected polymer crystallization and, in turn, the nano and macro-structural properties of the scaffolds. Indeed, neat PLC and neat PLA crystallize into globular and randomly arranged sub micro-size scale fibrous conformations, respectively. Concomitantly, the addition of NaCl particles during the fabrication route allows for the creation of an interconnected network of large pores inside the primary structure while resulted in a significant decrease of scaffolds mechanical response. Finally, the results of cell culture tests demonstrate that both the micro and macro-structure of the scaffold affect the in vitro hMSCs adhesion and proliferation.

Beneficial Effects of a Novel Bioabsorbable Polymer Coating on Enhanced Coronary Vasoconstricting Responses After Drug-Eluting Stent Implantation in Pigs in Vivo.

The aim of this study was to examine which component of drug-eluting stents (DES) plays a major role in enhanced coronary vasoconstricting responses after DES implantation in pigs. Recent studies have reported unremitting angina due to vasomotion abnormalities even after successful DES implantation. However, it remains to be elucidated which component of DES (metal stent, polymer coating, or antiproliferative drug) is responsible for DES-induced coronary hyperconstricting responses. We developed poly-dl-lactic acid and polycaprolactone (PDLLA-PCL) copolymer technology with higher biocompatibility that is resorbed within 3 months. Four types of coronary stents were made: 1) a stent with polylactic acid (PLA) polymer coating containing antiproliferative drug (P1+D+); 2) a stent with PLA polymer coating alone without any drug (P1+D-); 3) a stent with novel PDLLA-PCL polymer coating alone (P2+D-); and 4) a bare metal stent (P-D-). The 4stents were randomly deployed in the left anterior descending and left circumflex coronary arteries in 12 pigs. After 1 month, coronary vasoconstriction by intracoronary serotonin was enhanced at P1+D+ and P1+D- stent edges compared with P2+D- and P-D- stent edges and was prevented by a specific Rho-kinase (a central molecule of coronary spasm) inhibitor, hydroxyfasudil. Immunostainings showed that inflammatory changes and Rho-kinase activation were significantly enhanced at P1+D+ and P1+D- sites compared with P2+D- and P-D- sites. There were significant positive correlations between the extent of inflammation or Rho-kinase expression/activation and that of coronary vasoconstriction. These results indicate the important roles of PLA polymer coating in DES-induced coronary vasoconstricting responses through inflammatory changes and Rho-kinase activation in pigs invivo, which are ameliorated by PDLLA-PCL copolymers.

Preparation, dynamic rheological behavior, crystallization, and mechanical properties of inorganic whiskers reinforced polylactic acid/hydroxyapatite nanocomposites

ABSTRACTThe novel inorganic SiO2–MgO–CaO whiskers (SMCWs) were incorporated into nano hydroxyapatite (HA) contained polylactic acid (PLA) system to prepare the reinforced PLA/HA/SMCWs nanocomposite. Maleic anhydride grafted PLA (PLA‐g‐MAH) was then used to modify the interface between filler and matrix. The morphology, rheological behavior, crystallization, and mechanical property of the prepared nanocomposites were systematically investigated using scanning electronic microscope, dynamic rheometer, differential scanning calorimeter, polarized light microscope, and mechanical test, respectively. The results showed that the introduced PLA‐g‐MAH obviously improves the filler dispersion and the filler–matrix interfacial compatibility. Interestingly, the incorporated whiskers obviously decrease the complex viscosity and hence could significantly improve the processability of system. However, the introduction of PLA‐g‐MAH increases the complex viscosity to a greater extent. In addition, the added whiskers were found to have complicated influences on the PLA crystallization. On one hand, the incorporated whiskers can enhance the melt crystallization capability of PLA macromolecular chains; on the other hand, the introduced whiskers also show the inhibitive effect on the nucleation of PLA polymer chains and the inhibition degree is related to the loading of whiskers. The combination of whiskers and PLA‐g‐MAH could remarkably improve the mechanical performance of PLA/HA nanocomposite. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43381.

Degradation study of polylactic acid textile structure under commercial fabrication conditions

Event Abstract Back to Event Degradation study of polylactic acid textile structure under commercial fabrication conditions Xiaoqi Tang1, Ting He1 and Martin W. King1, 2 1 North Carolina State University, College of Textiles, United States 2 Donghua University, College of Textiles, China Introduction: Polylactic acid (PLA) is one of the commonly used yarn materials in bio-medical textile products[1], such as vascular grafts and hernia meshes[2]. The degradability of PLA structure is critical to its performance after implantation as well as the quality control of the product during manufacture. The rate of degradation of PLA polymer under in vitro conditions has been intensively researched[3]. However, the degradation performance of PLA yarns during processing under industrial textile manufacturing conditions has not been addressed. Materials and Methods: This research project studied the change of weight, tensile properties and molecular weight of PLA yarns with different fiber morphologies under the influence of moisture, temperature, and exposure time. The PLA pellets were extruded into yarns with round and grooved fiber cross-sections (Figure 1), and then cut into 100 meter lengths. The round and grooved yarns and an equal amount of pellets were exposed to 7 different conditions: four reference conditions that relative humidity (RH) was controlled at 0, 35%, 65%, and 100%; a standard environment of 65% RH and 21oC; an experimental textile knitting lab without moisture or temperature control; a manufacturing facility with limited moisture and temperature control. All the conditions are compared to the frozen-sealed storage condition. The samples were simultaneously exposed to these conditions for up to 21 weeks. Every two weeks, 3 samples of each yarn and pellets were retrieved. The bone dry weight, tensile strength, tensile strain, Young’s modulus and molecular weight of the PLA yarns are measured before and after the exposure. Figure 1: the tropology information of PLA yarns. The results indicated that, the rate of molecular weight loss of the PLA yarns and pellets accelerated over time, with less than 10% in the first 12 weeks, but more than 10% in the following 9 weeks. The grooved fibers with a larger surface area were more sensitive to the moisture (Figure 2). And the pellets showed more weight loss than the fully drawn yarns (Figure 2). Figure 2: the molecular weight of PLA after 12 weeks degradation in manufacturing knitting facilities. Both the round and grooved yarns experience tensile strength loss after 12 weeks, and the average decrease of tensile strength was lower than 5%. The round yarns showed more loss of Young’s Modulus than the grooved yarns (Figure 3). Figure 3: the change of Young’s Modulus of round and grooved yarns after 6 and 12 weeks exposure in the experimental knitting lab and manufacture knitting facility, in comparison with the yarn sample stored in a frozen and sealed condition (control). The outcomes of this research illustrate that industry should lower the relative humidity to maintain the necessary properties. In order to minimize the degradation during the manufacturing, the whole process after yarn extrusion till the end of fabrication should be managed within 12 weeks under optimal moisture conditions. Further study is required to identify the rate and extent of degradation associated with the cleaning and sterilization procedures following fabrication. Brian Davis, Knitting Lab Manager, North Carolina State University; Birgit Andersen, TECS Lab Manager, North Carolina State University

Cytocompatibility, mechanical and dissolution properties of high strength boron and iron oxide phosphate glass fibre reinforced bioresorbable composites

In this study, Polylactic acid (PLA)/phosphate glass fibres (PGF) composites were prepared by compression moulding. Fibres produced from phosphate based glasses P2O5–CaO–MgO–Na2O (P45B0), P2O5–CaO–MgO–Na2O–B2O3 (P45B5), P2O5–CaO–MgO–Na2O–Fe2O3 (P45Fe3) and P2O5–CaO–MgO–Na2O–B2O3–Fe2O3 (P45B5Fe3) were used to reinforce the bioresorbable polymer PLA. Fibre mechanical properties and degradation rate were investigated, along with the mechanical properties, degradation and cytocompatibility of the composites. Retention of the mechanical properties of the composites was evaluated during degradation in PBS at 37°C for four weeks. The fibre volume fraction in the composite varied from 19 to 23%. The flexural strength values (ranging from 131 to 184MPa) and modulus values (ranging from 9.95 to 12.29GPa) obtained for the composites matched those of cortical bone. The highest flexural strength (184MPa) and modulus (12.29GPa) were observed for the P45B5Fe3 composite. After 28 days of immersion in PBS at 37°C, ~35% of the strength profile was maintained for P45B0 and P45B5 composites, while for P45Fe3 and P45B5Fe3 composites ~40% of the initial strength was maintained. However, the overall wet mass change of P45Fe3 and P45B5Fe3 remained significantly lower than that of the P45B0 and P45B5 composites. The pH profile also revealed that the P45B0 and P45B5 composites degraded quicker, correlating well with the degradation profile. From SEM analysis, it could be seen that after 28 days of degradation, the fibres in the fractured surface of P45B5Fe3 composites remain fairly intact as compared to the other formulations. The in vitro cell culture studies using MG63 cell lines revealed both P45Fe3 and P45B5Fe3 composites maintained and showed higher cell viability as compared to the P45B0 and P45B5 composites. This was attributed to the slower degradation rate of the fibres in P45Fe3 and P45B5Fe3 composites as compared with the fibres in P45B0 and P45B5 composites.

Supercritical assisted injection in a liquid antisolvent for PLGA and PLA microparticle production

Biodegradable and biocompatible polymers PLA (poly lactic acid) and PLGA (poly lactic-co-glycolic acid) have been processed using supercritical assisted injection in a liquid antisolvent (SAILA), to evaluate the possibility to produce microparticles of controlled size and distribution. SAILA experiments were performed varying the process parameters, studying the influence of temperature, gas to liquid ratio (GLR) and polymer concentration on particle size distribution. Spherical, smooth and not coalescing particles were obtained at all process conditions; sub-microparticles (0.46±0.17μm) and microparticles (2.1±0.84μm) of PLA and PLGA have been produced with a fairly good control of particle size distribution.Preliminary encapsulation tests have also been performed, using Piroxicam as a model drug. An encapsulation efficiency of about 60% has been obtained. Coprecipitated drug/polymer microparticles allowed a controlled release of the drug for about 5days.

Biomimetic repeat protein derived from Xenopus tropicalis for fibrous scaffold fabrication.

Collagen, silk, and elastin are the fibrous proteins consist of representative amino acid repeats. Because these proteins exhibited distinguishing mechanical properties, they have been utilized in diverse applications, such as fiber-based sensors, filtration membranes, supporting materials, and tissue engineering scaffolds. Despite their infinite prevalence and potential, most studies have only focused on a few repeat proteins. In this work, the hypothetical protein with a repeat motif derived from the frog Xenopus tropicalis was obtained and characterized for its potential as a novel protein-based material. The codon-optimized recombinant frog repeat protein, referred to as 'xetro', was produced at a high rate in a bacterial system, and an acid extraction-based purified xetro protein was successfully fabricated into microfibers and nanofibers using wet spinning and electrospinning, respectively. Specifically, the wet-spun xetro microfibers demonstrated about 2- and 1.5-fold higher tensile strength compared with synthetic polymer polylactic acid and cross-linked collagen, respectively. In addition, the wet-spun xetro microfibers showed about sevenfold greater stiffness than collagen. Therefore, the mass production potential and greater mechanical properties of the xetro fiber may result in these fibers becoming a new promising fiber-based material for biomedical engineering.

Halloysite nanotube reinforced polylactic acid composite

Polylactic acid (PLA) has a long history in medical applications. Reinforced PLA has the potential to be used in the medical applications that require high mechanical strength such as coronary stents and bone fixation devices. Halloysite nanotube (HNT) has received considerable attention recently due to its tubular structure, high aspect ratio, high mechanical strength, thermal stability, biocompatibility and sustained drug releasing properties. Halloysite has been investigated in compounding with many polymers. However, the research in compounding halloysite with biodegradable materials for use in biological applications is sparse. In this study various weight fractions of HNT was compounded with the biodegradable polymer PLA using a melt compounding method. Tensile test, Fourier infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), contact angle test, scanning electron microscopy (SEM), void content and thermogravimetric analysis (TGA) were carried out to study the PLA/HNT composite. Tensile test results indicated that Young's modulus and stiffness of PLA were enhanced with the addition of HNT; FTIR spectra showed the interaction between the PLA and HNT; whereas contact angle measurements indicated that the wettability of the PLA/HNT composite was not affected by the addition of HNT. However, the thermal stability of PLA was adversely effected by the addition of HNT which may be related to the presence of voids between the polymer and matrix. Nevertheless, the reinforced PLA/HNT composite, which maintains the surface characteristics, may prove beneficial for use in biological applications. POLYM. COMPOS., 38:2166–2173, 2017. © 2015 Society of Plastics Engineers

Thermo-sensitive drug controlled release PLA core/PNIPAM shell fibers fabricated using a combination of electrospinning and UV photo-polymerization

In this research a thermo-sensitive drug loaded core–shell fibers were prepared by UV photo-polymerization combined with electrospinning technology. The biodegradable polymer polylactic acid (PLA) was used as the core with electrospinning and the N-isopropylacrylamide (NIPAM) was selected to be shell of the fibers via UV photo-polymerization, respectively. Combretastatin A4 (CA4) was used as the model drug loaded in PLA (core structure) to test the thermo-sensitivity of the core–shell fibers. SEM was performed to observe the morphology of the fibers. TEM was carried out to confirm the core–shell structure of the fibers. Furthermore, XPS and FTIR results demonstrated that the core–shell structure had been fabricated as designed. Water contact angle (WCA) test indicated that the fibers show different wettability when the temperature was below or above the lower critical solution temperature (LCST). Moreover, in vitro drug release test was conducted to explore the difference of the drug release when the temperature was at 25°C and 40°C. The cell culture studies showed that the prepared core–shell structure nanofibers have a potential application in the biomedical fields as tissue engineering.

New Polylactic Acid Composites for Packaging Applications: Mechanical Properties, Thermal Behavior, and Antimicrobial Activity

The interest in antimicrobial packaging materials based on polylactic acid (PLA) polymers has increased due to the need to improve food safety and environment quality and also to find alternatives to synthetic polymers made from petrochemicals. PLA films by addition of different fillers (grape wastes and celery fibers) were obtained. The mechanical, thermal, surface, and antimicrobial properties of the films were evaluated. The incorporation of inexpensive fillers into the PLA matrix could reduce costs and the studied formulations offer approaches to realize composites with high performances and antimicrobial response, suitable for film food-active packaging materials, especially by use of grape wastes.

Intracellular Targeting of the Oncogenic MUC1-C Protein with a Novel GO-203 Nanoparticle Formulation.

The MUC1-C oncoprotein is an intracellular target that is druggable with cell-penetrating peptide inhibitors. However, development of peptidyl drugs for treating cancer has been a challenge because of unfavorable pharmacokinetic parameters and limited cell-penetrating capabilities. Encapsulation of the MUC1-C inhibitor GO-203 in novel polymeric nanoparticles was studied for effects on intracellular targeting of MUC1-C signaling and function. Our results show that loading GO-203 into tetrablock polylactic acid (PLA)-polyethylene glycol (PEG)-polypropylene glycol (PPG)-PEG copolymers is achievable and, notably, is enhanced by increasing PEG chain length. In addition, we found that release of GO-203 from these nanoparticles is controllable over at least 7 days. GO-203/nanoparticle treatment of MUC1-C-positive breast and lung cancer cells in vitro was more active with less frequent dosing than that achieved with nonencapsulated GO-203. Moreover, treatment with GO-203/nanoparticles blocked MUC1-C homodimerization, consistent with on-target effects. GO-203/nanoparticle treatment was also effective in downregulating TIGAR, disrupting redox balance, and inhibiting the self-renewal capacity of cancer cells. Significantly, weekly administration of GO-203/nanoparticles to mice bearing syngeneic or xenograft tumors was associated with regressions that were comparable with those found when dosing on a daily basis with GO-203. These findings thus define an effective approach for (i) sustained administration of GO-203 in polymeric PLA-(PEG-PPG-PEG) nanoparticles to target MUC1-C in cancer cells and (ii) the potential delivery of other anticancer peptide drugs.

Novel Applications for Biomaterials: The Case of Remediation of Wine Taints Using Poly-Lactic Acid Polymer

Wine is the world’s oldest alcoholic beverage and the most consumed in at least 20 countries. However, taints detract from its quality and acceptance, significantly reducing the value of wine. In this study we investigated the capacity of a poly-lactic acid (PLA) biopolymer to reduce concentrations of four odorants responsible for tainting many red wines:isopropyl-methoxypyrazine (IPMP),isobutyl–methoxypyrazine (IBMP), 4-ethylphenol (4-EP) and 4-ethylguaiacol (4-EG). Red wine was spiked with either IPMP [20 ng/L] and IBMP [20 ng/L] (Study 1) or 4-EP [200 ug/L] and 4-EG [200 ug/L] (Study 2) and then treated with a PLA film [surface area 350 cm2/L]. Solid Phase Micro-Extraction Multi-Dimensional Gas Chromatography–Mass Spectrometry and Gas Chromatography-Mass Spectrometry were used to measure the methoxypyrazines and ethylphenols, respectively, both before and after treatment with PLA. Results showed significant reductions in all of the target odorants after 8hrs treatment: IPMP (51%), IBMP (26%), 4-EP (21%) and 4-EG (20%). Taken overall, the data suggest potential for the use of PLA in treating common wine faults, particularly ‘ladybug taint’, which is caused by elevated levels of IPMP.

MRI-ASSESSMENT OF COMPOSITE INTERFERENCE SCREWS AFTER RECONSTRUCTION OF THE ANTERIORCRUCIATE LIGAMENT

In the article authors describe the results of MRI studies of patients after reconstruction of the anterior cruciate ligament. The potential of biodegradable implants, timing of their location in the bone. The evaluation of bone response to biodegradable screws. The authors defined the terms of biodegradation clips from polylactic acid polymer and tricalcium phosphate.

The influence of multiple modified MMT on the thermal and fire behavior of poly (lactic acid) nanocomposites

This work reported the preparation and physical properties of biodegradable nanocomposites fabricated using polylactic acid (PLA) and multiple organic modified montmorillonite (MMT). In order to improve the chemical compatibility between PLA and Na‐MMT, the surface of Na‐MMT was first organically modified by cetyl trimethyl ammonium bromide (CTAB) and resorcinol bis(diphenyl phosphate) (RDP) using ion‐exchange and adsorption technique. Both Fourier transform infrared and X‐ray diffraction (XRD) results indicated that CTAB and RDP molecules were intercalated into the galleries of MMT sheets to enlarge the interlayer spacing. Then, the PLA/MMT nanocomposites were prepared by a simple melt‐blending method. The XRD and TEM results of the nanocomposites indicated that the PLA polymer chains inserted into the galleries of co‐modified MMT (C‐MMT) and contained disorderedly intercalated layered silicate layers within a PLA matrix. The C‐MMT nanolayers were homogenously dispersed in PLA matrix, resulting in various property enhancement. The fabricated PLA/C‐MMT nanocomposites with 5.0 wt% addition showed significant enhancements (176%) in the storage modulus compared to that of neat PLA. The thermal stability and fire resistance were also remarkably improved. These improvements are probably because of both the physical barrier effect of the MMT nanosheets and charring effect of the C‐MMT. Copyright © 2015 John Wiley & Sons, Ltd.

Synthesis, photophysical and antimicrobial activity of new water soluble ammonium quaternary benzanthrone in solution and in polylactide film

The synthesis of a new cationic water soluble fluorescent 1-[(7-oxo-7H-benzo[de]anthracen-3-ylcarbamoyl)-methyl]-triethylammonium chloride (B) has been described. Due to the presence of the quaternary amino group, the compound is soluble in water. Its photophysical characteristics in aqueous solution and organic solvents with different polarity have been determined using absorption and fluorescence spectroscopy. The photostability of compound B has been investigated in aqueous media. The newly synthesized compound has been tested in vitro for its antimicrobial activity against eight bacterial and two yeasts cultures. The results obtained suggest that the newly synthesized compound is effective in treating the relevant pathogens and is suitable in designing new effective antimicrobial preparations. The incorporation of the compound into thin polylactic acid film and its release into water solution has been also investigated. It was demonstrated that the compound released from the polymer polylactic acid matrix exhibited a prolonged good antibacterial activity.

Properties and medical applications of polylactic acid: A review

Polylactic acid (PLA), one of the well-known biodegradable polyesters, has been studied extensively for tissue engineering and drug delivery systems, and it was also used widely in human medicine. A new method to synthesize PLA (ring-opening polymerization), which allowed the economical production of a high molecular weight PLA polymer, broad- ened its applications, and this processing would be a potential substitute for petroleum-based products. This review described the principles of the polymerization reactions of PLA and, then, outlined the various materials properties affect- ing the performance of PLA polymer, such as rheological, mechanical, thermal, and barrier properties as well as the pro- cessing technologies which were used to fabricate products based on PLA. In addition, the biodegradation processes of products which were shaped from PLA were discussed and reviewed. The potential applications of PLA in the medical fields, such as tissue engineering, wound management, drugs delivery, and orthopedic devices, were also highlighted.

Clinical, Imaging and Pathological Characteristics of Brain Implanted Polylactic Co-Glycolic Acid Polymers Conjugated with Temozolomide

Definitive treatments for primary brain tumours are still sought. Slow-release local chemotherapy may provide a good effect and poly (lactide-co-glycolide) (PLGA) microcylinders could allow this. We evaluated the neurological and histopathological consequences, and MRI visibility, of PLGA microcylinders conjugated with temozolomide and gadolinium implanted in normal canine brains. Eight purpose-bred beagles had cerebral implantation of microcylinders combined with temozolomide and gadolinium. MRI was performed following implantation and 28d later prior to necropsy and brain histopathology. All adverse events were associated with implantation and resolved. Dogs with six microcylinders at 0 and 6.25% gadolinium had mild inflammation and all other dogs had greater brain inflammation, which increased with higher gadolinium concentrations and microcylinder number. Microcylinders with gadolinium were identifiable on MRI. Brain implantation of PLGA microcylinders conjugated with gadolinium and temozolomide is tolerated in healthy beagles. The lowest gadolinium percentage and microcylinder number should be used if this therapy is pursued.

Resveratrol-loaded polymeric nanoparticles suppress glucose metabolism and tumor growth in vitro and in vivo

Resveratrol (RSV) is a natural phenol with promising anti-tumor activities, but its use for in vivo cancer treatment is limited by low aqueous solubility and poor stability. In this study, we prepared RSV-loaded polyethylene glycol–polylactic acid (PEG–PLA; M.W. 5000-5000) polymer nanoparticles (NPs) for improved stability and controlled delivery, and investigated its metabolic and anti-tumor effect in vitro and in vivo. CT26 colon cancer cells displayed significantly reduced cell number to 5.6% and colony forming capacity to 6.3% of controls by 72h treatment with 40 and 20μM of RSV-NP, respectively. Flow cytometry and western blots demonstrated increased apoptotic cell death, and 18F FDG uptake and reactive oxygen species was significantly reduced by RSV-NP. All of these effects were comparable to or greater in potency compared to free RSV. When RSV-NP was intravenously administered to CT26 tumor bearing mice, there was a reduction of 18F FDG uptake on PET/CT by day 4. Longer treatment led to retardation of tumor growth accompanied by an improvement in survival compared to empty NP-injected controls. These results demonstrate that the in vitro and in vivo metabolic and anti-tumor effects of RSV is preserved by PEG–PLA NP loading, and provide an encouraging outlook on the potential of polymeric NPs as an effective method to deliver RSV for cancer therapy.

In depth investigation of the accelerated ring opening polymerization of L-lactide

The current research describes the ring opening polymerization of lactide starting with monomer synthesis up to accelerated polymerization. Different analytical techniques such as DSC, FTIR, GC, GPC, hot-stage optical microscopy, and rheometry were used to study the monomer synthesis/purification and the accelerated polymerization in the presence of tin (II) octate and triphenyl phosphate. It is shown that the catalyst/accelerator concentration has a significant influence on the polymerization rate, final product properties, and polymer morphology. Polylactic acid polymers with weight average molecular weight of more than 200 kg/mol and monomer conversion above 97% were achieved in 15 min.