Novel Aphid-Repellent Fiber Mats Based on Poly(lactic acid)-Containing Ionic Liquids.

To protect crops as well as human and animal health, the development of novel repellents based on biopolymers is critical for a growing world population. Here, novel aphid-repellent electrospun mats containing epoxidized ionic liquids (ILs) covalently bonded to the carboxyl or hydroxyl groups of poly(lactic acid) (PLA) were designed to produce nonwoven mats. First, di-, tri-, and tetra-epoxidized imidazolium ILs were synthesized and incorporated in different weight fractions (3, 5, and 10 wt %) into the PLA solution. Then, the effect of ILs' microstructure, thermal properties, mechanical performance, and hydrophobic behavior were investigated. It was found that the incorporation of ILs resulted in a reduction of the fiber diameters while the mechanical properties of the mats, i.e., the three-dimensional fibrous porous structure, were maintained. Finally, the effect of these three ILs against the pea aphid Acyrthosiphon pisum (Harris) was evaluated for the first time, showing an attractive effect for the diepoxidized IL and a repellent effect for the tri- and tetra-epoxidized ILs. By exploiting the chemical nature of ILs, an environmentally friendly strategy can be developed to limit the need for chemical pesticides and petroleum-based polymers.

Biodegradable Electrospun Conduit with Aligned Fibers Based on Poly(lactic-co-glycolic Acid) (PLGA)/Carbon Nanotubes and Choline Bitartrate Ionic Liquid.

Functionally active aligned fibers are a promising approach to enhance neuro adhesion and guide the extension of neurons for peripheral nerve regeneration. Therefore, the present study developed poly(lactic-co-glycolic acid) (PLGA)-aligned electrospun mats and investigated the synergic effect with carbon nanotubes (CNTs) and Choline Bitartrate ionic liquid (Bio-IL) on PLGA fibers. Morphology, thermal, and mechanical performances were determined as well as the hydrolytic degradation and the cytotoxicity. Results revealed that electrospun mats are composed of highly aligned fibers, and CNTs were aligned and homogeneously distributed into the fibers. Bio-IL changed thermal transition behavior, reduced glass transition temperature (Tg), and favored crystal phase formation. The mechanical properties increased in the presence of CNTs and slightly decreased in the presence of the Bio-IL. The results demonstrated a decrease in the degradation rate in the presence of CNTs, whereas the use of Bio-IL led to an increase in the degradation rate. Cytotoxicity results showed that all the electrospun mats display metabolic activity above 70%, which demonstrates that they are biocompatible. Moreover, superior biocompatibility was observed for the electrospun containing Bio-IL combined with higher amounts of CNTs, showing a high potential to be used in nerve tissue engineering.

Epoxidized Ionic Liquids as Processing Auxiliaries of Poly(Lactic Acid) Matrix: Influence on the Manufacture, Structural and Physical Properties.

In this study, we set out to modify poly(lactic acid) (PLA) by incorporating epoxidized ionic liquids (ILs) that were specifically designed with imidazolium-NTf2 moieties. First, we synthesized di-, tri- and tetra-epoxidized ILs, which were incorporated into a PLA matrix at 3, 5, and 10 wt% through a melt extrusion process. We investigated the relationship between the structure and properties of the resulting materials in terms of thermal, mechanical, rheological, and surface properties. The results showed the potential of ILs to impact these properties. Notably, the tri- and tetra-epoxidized ILs enhanced the thermal stability of the PLA matrix as well as the crystallinity while reducing the glass transition temperature and melting point, which is promising for reactive extrusion processing. Overall, this research opens new routes for using reactive ILs to improve the processing and properties of PLA polymers.

Prophylactic intraoperative uterine artery embolization for the management of major placenta previa.

PURPOSE: Placenta previa is a major cause of maternal morbidity and mortality, associated to a high risk of peripartum hemorrhage and hysterectomy. We aimed to verify if prophylactic intraoperative uterine artery embolization in patients with placenta previa and at least one additional risk of bleeding (major placenta previa), can reduce hemorrhage, need for blood transfusions, peripartum hysterectomy and maternal morbidity. MATERIALS AND METHODS: We enrolled 76 patients with major placenta previa; a specific multidisciplinary protocol was designed for management, including ultrasound evaluation, hospitalization at 34 weeks, antenatal corticosteroids and scheduled cesarean section at 35-36 weeks. 44 patients (control group or CTR) were treated with elective cesarean section, 32 patients (embolized group or EMB) underwent selective catheterization of bilateral uterine arteries before cesarean section and subsequent uterine embolization. In both cases cesarean section was performed by a senior surgeon. RESULTS: Significant differences were found in term of intraoperative blood loss (CTR: 1431 ml; EMB: 693 ml); despite an high percentage of CTR patients had a bleeding greater than 1000 ml (56%), the need for blood transfusion was not significantly different between the two groups. Time of surgery was higher in the EMB group, considering that embolization procedure required approximatively 30 min. Three patients from the CTR group needed hysterectomy and ICU admission, compared to none in the EMB group. Duration of hospitalization and neonatal outcome were similar. Uterine embolization was not related to any short or long-term complications; return to normal menses and preservation of fertility were confirmed at follow up. CONCLUSIONS: Our results are promising, although we believe that a major contribution is referable to the multidisciplinary approach rather than the procedure itself. Nevertheless, we demonstrated the feasibility and safety of preventive uterine embolization in patients with placenta previa; in order to establish its prophylactic role in the prevention of peripartum hemorrhage, randomized trial should be carried out, on a larger population.

Aligned electrospun nerve conduits with electrical activity as a strategy for peripheral nerve regeneration.

Peripheral nerve injuries affect the quality of life of people worldwide. Despite advances in materials and processing in recent decades, nerve repair remains a challenge. The autograft is considered the most effective nerve repair in cases of serious injuries in which direct suture is not applied. However, the autograft causes the loss of functionality of the donor site, and additionally, there is a limited availability of donor nerves. Nerve conduits emerge as an alternative to the autograft and nowadays some conduits are available for clinical use. Nevertheless, they still need to be optimized for better functional nerve response. This review proposes to analyze the use of aligned electrospun nerve conduits with electrical activity as a strategy to enhance a satisfactory nerve regeneration and functional recovery.

A Carbocationic Triarylmethane-Based Porous Covalent Organic Network.

A thermally stable carbocationic covalent organic network (CON), named RIO-70 was prepared from pararosaniline hydrochloride, an inexpensive dye, and triformylphloroglucinol in solvothermal conditions. This nanoporous organic material has shown a specific surface area of 990 m2 g-1 and pore size of 10.3 Å. The material has CO2 uptake of 2.14 mmol g-1 (0.5 bar), 2.7 mmol g-1 (1 bar), and 6.8 mmol g-1 (20 bar), the latter corresponding to 3 CO2 molecules adsorbed per pore per sheet. It is shown to be a semiconductor, with electrical conductivity (σ) of 3.17×10-7  S cm-1 , which increases to 5.26×10-4  S cm-1 upon exposure to I2 vapor. DFT calculations using periodic conditions support the findings.

In vitro evaluation of bilayer membranes of PLGA/hydroxyapatite/ß-tricalcium phosphate for guided bone regeneration.

Membranes for guided bone regeneration represent valuable resources, preventing fibroblast infiltration and aiding anatomical bone reconstruction. Nonetheless, available membranes lack bone regenerative capacity, suitable mechanical behavior, or adequate degradation profile. Therefore, to overcome these limitations, this study developed bilayer membranes with a dense layer (dry phase inversion) of PLGA (poly(lactic-co-glycolic acid)):HAp (hydroxyapatite) - 95:05 (wt%) - and an electrospun layer of PLGA and HAp:ß-TCP (ß-tricalcium phosphate) with ratios of 60:40, 70:30 and 85:15 (wt%), evaluating its mechanical, morphological and in vitro properties. The bilayer membranes displayed adequate interlayer adhesion, dense layer pore size of 4.20 µm and electrospun layer with porosity degree of 38.2%, thus capable of preventing fibroblast infiltration while allowing osteoblast migration and nutrient permeation. They also showed Tg of 82 °C and higher storage modulus, which was constant up to 54.6 °C, characteristics important for membrane implantation and use with no mechanical compromise. In vitro degradation mass loss was only 10% after 60 days, a profile suitable for the application requirement. Membranes with calcium phosphates had better osteoblast attachment, proliferation and migration. Taken together, results indicate the great potential of PLGA/HAp/ß-TCP bilayer membranes on bone reconstruction with proper degradation profile, morphology, mechanical behavior and bone regenerative capacity.

Manufacturing and characterization of plates for fracture fixation of bone with biocomposites of poly (lactic acid-co-glycolic acid) (PLGA) with calcium phosphates bioceramics.

Commercially, there are several plates and screws for bone fracture fixation made with PLA, however, its long degradation time and lack of integration with bone structure, provides interest in research using polymers with faster degradation, such as PLGA, and together with bioceramics, in order to improve bioactivity in bone regeneration. Based on this, in this study, bone fracture fixation plates composed of PLGA polymer matrix and combinations of 5 and 10%wt. of bioceramics were processed by microinjection. The bioceramics used comprehend nanostructured hydroxyapatite (n-HA), ß-tricalcium phosphate (ß-TCP) and calcium phosphate with ion substitution of magnesium (Mg-Ca/P) and strontium (Sr-Ca/P). The introduction of bioceramics modified thermal and mechanical properties of the polymer. The TGA analysis showed that there was a variation on the ceramic's mass inserted in relation to the expected values (5% and 10%wt.) in all groups of biocomposites. In general, Tg values obtained by DMA were slightly increased in almost all the biocomposites. The storage modulus (E') of biocomposites was higher for almost all groups of inserted ceramics, with exception of 5%n-HA. In the flexural tests, the biocomposites obtained a great dispersion in average values of fracture loading, presented lower values in relation to pure PLGA. There were difficulties in the processing of biocomposites with Mg-Ca/P and Sr-Ca/P, a factor that can be attributed to lack of homogeneity in the material mixing process. The results suggest modifications in thermal and mechanical properties of the PLGA plates with the bioceramics insertion and provide improvement understanding about of manufactured composites with PLGA and bioceramics.