Hydrogels of semi-interpenetrating networks composed of poly(acrylamide) (PAAm) and poly(γ-glutamic acid) (γ-PGA) with different proportions were studied as potential amoxicillin controlled-release ...devices. The effects of the hydrogels composition, pH, and temperature on the kinetics and final release of amoxicillin were determined in batch experiments. The release kinetic tests were conducted using a buffer solution as the release medium under pH conditions of 3 and 7.2, and temperature of 25, 37, and 45 °C. The final percentage of amoxicillin released from the hydrogels was found to increase with temperature, pH, and the amount of γ-PGA in the hydrogels formulation. Overall, equilibrium conditions in the kinetics experiments were achieved within 240 min of hydrogel–solution contact. The overall rate of amoxicillin release was represented with a two-parameter empirical model as a function of time.
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•Emulsion polymerization of polypyrrole (PPy) nanoparticles using the biosurfactant sodium taurocholate (Tch) was performed.•H2O2 was used as a green oxidant to maintain ...environmentally friendly synthesis conditions.•The Tch and Tch/Tween20 micelles promote the formation and stabilization of electroconductive PPy nanoparticles.•This novel synthesis is a green alternative to obtain electrically conductive polymer nanoparticles.
We report, for the first time, the use of a bile salt, the sodium taurocholate (Tch), as a surface-active agent in the emulsion synthesis of electroactive polypyrrole (PPy) nanoparticles. PPy was obtained under mild and environmentally friendly conditions, using hydrogen peroxide (H2O2) as a green oxidant. The combined addition of a non-ionic surfactant, Tween 20 (Tw), was also studied. The electrical, structural, morphological, and colloidal properties of reaction products were analyzed in detail to find the best conditions of synthesis. The pre-polymerization emulsion systems were studied by osmometric measurements, isothermal titration calorimetry (ITC), and dynamic light scattering (DLS). A consistent mechanism of nucleation and growth of PPy colloids is proposed. The Tch acts as an emulsifier of the reaction media, a doping agent of oxidized chain of PPy, and a stabilizer of the resulting colloids. The main advantage of this work is the preparation of polymer colloids through a completely green alternative route, which could open up new possibilities for obtaining nanoparticles through an effective and non-toxic method.
Chemical hydrogel based on poly(γ-glutamic acid) obtained from
Bacillus licheniformis (
ATCC-9945a) and using urea as a crosslinking agent was synthesized. The hydrogel was characterized by infrared ...spectroscopy, scanning electron microscopy, thermal analysis and swelling capacity. The crosslinking of the biopolymer was evidenced by changes in the intensities of signals in the infrared spectrum corresponding to amide groups, with respect to the spectrum of the pure biopolymer. Moreover, a porous structure, characteristic of hydrogels, with average pore size of 80 ± 31 μm was confirmed. The hydrogel showed a glass transition temperature of 144.5 °C and a decomposition temperature of 219 °C. The swelling ratio of the hydrogel increased with the increase of contact time with the swelling medium and pH, presenting values at equilibrium of 6.6, 13.4 and 15.3 at pH 3.6, 7.4 and 10, respectively; meanwhile, little influence of temperature on the swelling of the material was observed. Moreover, through the use of mathematical models, it is deduced that the swelling of the hydrogel in the buffer solutions occurs through lower Fickian and Fickian type mechanisms, and in deionized water an anomalous mechanism predominates.
Graphical abstract
Polypyrrole (PPy) was synthesized by enzyme mediated oxidation of pyrrole using naturally occurring compounds as redox mediators. The catalytic mechanism is an enzymatic cascade reaction in which ...hydrogen peroxide is the oxidizer and soybean peroxidase, in the presence of acetosyringone, syringaldehyde or vanillin, acts as a natural catalysts. The effect of the initial reaction composition on the polymerization yield and electrical conductivity of PPy was analyzed. Morphology of the PPy particles was studied by scanning electron microscopy and transmission electron microscopy whereas the chemical structure was studied by X-ray photoelectron and Fourier transformed infrared spectroscopic techniques. The redox mediators increased the polymerization yield without a significant modification of the electronic structure of PPy. The highest conductivity of PPy was reached when chondroitin sulfate was used simultaneously as dopant and template during pyrrole polymerization. Electroactive properties of PPy obtained from natural precursors were successfully used in the amperometric quantification of uric acid concentrations. PPy increases the amperometric sensitivity of carbon nanotube screen-printed electrodes toward uric acid detection.
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•A new method of pyrrole polymerization using naturally occurring redox mediators and doping agents was studied.•The catalytic efficiency of different redox mediators toward pyrrole oxidation was evaluated.•Two different naturally occurring polymers were studied as bifunctional steric stabilizer/doping agents.•Polypyrrole improves the amperometric response of carbon nanotube screen printed electrodes toward uric acid sensing.
Resumen Introducción: Muchas veces se propagan mitos y creencias sobre la higiene íntima femenina, que podrían traer consecuencias en muchos aspectos. Objetivo: Determinar la asociación entre los ...mitos y creencias del cuidado e higiene íntima y los cuidados reales de higiene íntima en mujeres peruanas jóvenes. Método: Se realizó un estudio transversal analítico, que presentó una revisión del tema para realizar una encuesta de 21 interrogantes, en temas comunes en la higiene íntima, post piloto, se preguntó de su realización y la frecuencia semanal; esta última se asoció a variables socio-educativas. Resultados: De las 600 mujeres jóvenes encuestadas, hubo diferencia en cuanto la edad según la percepción del uso de ropa interior de algodón (p=0,013), la limpieza de la zona íntima de adelante hacia atrás (p<0,001), el uso de ropa interior no muy ajustada (p<0,001), el uso de ropa sintética (p=0,045), el uso de jabón exclusivo para la zona íntima (p<0,001), la edad de inicio de relaciones sexuales (p=0,031) y el uso de métodos anticonceptivos como causantes de flujo (p=0,008). En cuanto al ser o no estudiantes, hubo diferencia en la percepción de que el rasurado del pubis para la limpieza (p=0,018) y que los ejercicios de relajación disminuyen el flujo vaginal (p=0,030). Conclusiones: Se describió algunos mitos y creencias en cuanto a la limpieza íntima; a su vez, se encontró que algunas prácticas de higiene tienen asociación con la edad y el ser estudiante. Esto debe ser estudiado a profundidad, ya que, esto podría llevar a problemas mayores.
Pancreatic ductal adenocarcinoma (PDAC) is usually detected late in the disease process. Clinical workup through imaging and tissue biopsies is often complex and expensive due to a paucity of ...reliable biomarkers. We used an advanced multiplexed plasmonic assay to analyze circulating tumor-derived extracellular vesicles (tEVs) in more than 100 clinical populations. Using EV-based protein marker profiling, we identified a signature of five markers (PDAC
signature) for PDAC detection. In our prospective cohort, the accuracy for the PDAC
signature was 84% 95% confidence interval (CI), 69 to 93% but only 63 to 72% for single-marker screening. One of the best markers, GPC1 alone, had a sensitivity of 82% (CI, 60 to 95%) and a specificity of 52% (CI, 30 to 74%), whereas the PDAC
signature showed a sensitivity of 86% (CI, 65 to 97%) and a specificity of 81% (CI, 58 to 95%). The PDAC
signature of tEVs offered higher sensitivity, specificity, and accuracy than the existing serum marker (CA 19-9) or single-tEV marker analyses. This approach should improve the diagnosis of pancreatic cancer.
Thermosensitive polymers based on poly(N‐isopropylacrylamide) (pNIPAM) have been widely evaluated in a variety of biomedical applications due to their particular thermal behavior in aqueous ...solutions. Despite this, few works have focused on the complementary analysis of the thermal transitions of pNIPAM polymers in linear and crosslinked form. In this work, linear and crosslinked poly(N‐isopropylacrylamide‐co‐acrylic acid) p(NIPAM‐co‐AA) copolymers were synthesized at similar NIPAM/AA feed composition and their thermosensitive behavior was studied by turbidimetric methods, FTIR spectroscopy analysis, and temperature‐dependent swelling measurements. The intermolecular crosslinking hindered the hydrophobic aggregation of chain segments, leading to higher transition temperatures of synthesized polymers. AA units promoted the intersegment hydrogen bonds during heating and strengthened the hydrogen bond interactions water‐network. The effect of the thermosensitive behavior of p(NIPAM‐co‐AA) copolymer on curcumin (CUR) release kinetic was also studied. The low uptake level of p(NIPAM‐co‐AA) hydrogel, partially shrunken at 37°C, produced a CUR sustained delivery, reaching the release equilibrium state up to 18 h. Hydrogels of p(NIPAM‐co‐AA) with a suitable composition exhibited a promising performance for the CUR controlled delivery at physiological conditions.
Curcumin controlled release of a crosslinked copolymer system based on N‐isopropylacrylamide and acrylic acid.
A novel semi-interpenetrating polymer network (s-IPN) based on the entrapment of a thermosensitive polymer, the poly(vinyl methyl ether) (PVME), within a crosslinked 3D structure of poly(vinyl ...alcohol) (PVA) and poly(vinyl methyl ether-
alt
-maleic acid) (COP) was synthesized by an autoclaving process. The preparation method avoids the use of toxic crosslinkers and allows the simultaneous sterilization of material. The PVA/COP/PVME hydrogel were characterized by Fourier transform infrared spectroscopy, thermal techniques, swelling kinetic measurements, scanning electron microscopy, and rheological analysis. The entrapment of PVME within the hydrated polymer framework significantly modified its transition temperature at pH 7.4 and pH 3 conditions. The swelling kinetics of the s-IPN were dependent on pH (7.4, 3 and 1), and temperature (25 and 37 °C). The interpenetrated polymer chains reduced the internal pore sizes of crosslinked network without altering its elastic, solid-like behavior. The loading and
in vitro
release of 5-fluorouracil, a chemotherapeutic agent, from hydrogel systems were studied at different temperature and pH values. The hydrogels showed a sustained drug release up to 5 h at 37 °C, in different pH media. The s-IPN exhibited a promising performance for a range of biomedical applications, in particular, for the controlled drug delivery in response to the pH and temperature conditions.
In this study, we report the lowest energy structure of bare Cu13 nanoclusters as a pair of enantiomers at room temperature. Moreover, we compute the enantiomerization energy for the interconversion ...from minus to plus structures in the chiral putative global minimum for temperatures ranging from 20 to 1300 K. Additionally, employing nanothermodynamics, we compute the probabilities of occurrence for each particular isomer as a function of temperature. To achieve that, we explore the free energy surface of the Cu13 cluster, employing a genetic algorithm coupled with density functional theory. Moreover, we discuss the energetic ordering of isomers computed with various density functionals. Based on the computed thermal population, our results show that the chiral putative global minimum strongly dominates at room temperature.
We describe the most widely used temporary hospital in Europe during the first pandemic wave, its structure, function, and achievements. Other models of care developed during the pandemic around the ...world were reviewed including their capacity, total bed/ICU bed ratio and time of use. We particularly analyzed the common and differential characteristics of this type of facilities. IFEMA Exhibition Center was transformed into a temporary 1,300-bed hospital, which was in continuous operation for 42 days. A total of 3,817 people were treated, generally patients with mild to moderate COVID-19, 91% of whom had pneumonia. The average length of stay was 5 to 36 days. The most frequent comorbidities were hypertension (16.5%), diabetes mellitus (9.1%), COPD (6%), asthma (4.6%), obesity (2.9%) and dementia (1.6%). A total of 113 patients (3%) were transferred to another centers for aggravation, 19 (0.5%) were admitted to ICU and 16 patients (0.4%) died. An element of great help to reducing the overload of care in large hospitals during peaks of health emergencies could be these flexible structures capable of absorbing the excess of patients. These must be safe, breaking domestic transmission and guarantee social and emotional needs of patients. The success of these structures depends on delimitation in admission criteria taking into account the proportion of patients who may require, during admission, assistance in the critical care area.
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