Droplet microfluidics for the highly controlled synthesis of branched gold nanoparticles

The synthesis of anisotropic metallic nanoparticles (NPs) has been a field of intense and challenging research in the past decade. In this communication, we report on the reproducible and highly controllable synthesis of monodisperse branched gold nanoparticles in a droplet-based microfluidics platform. The process has been automated by adapting two different bulk synthetic strategies to microdroplets, acting as microreactors, for NP synthesis: a surfactant-free synthesis and a surfactant-assisted synthesis. Microdroplets were generated in two different microfluidic devices designed to accommodate the requirements of both bulk syntheses. The epitaxial growth of AuNSTs inside the microdroplets allowed for a fine control of reagent mixing and local concentrations during particle formation. This is the first time branched gold NPs have been synthesised in a microfluidics platform. The monodispersity of the product was comparable to the synthesis in bulk, proving the potential of this technology for the continuous synthesis of high quality anisotropic NPs with improved reproducibility.This work was supported by EU Framework Programme for Research and Innovation H2020 COFUND, Grant Agreement 713640 (SAC) and by FAPESP, project No. 2015/01685-2 (PTB). MGO acknowledges FAPESP, project No 2016/02414-5

Nitric oxide released from luminal s-nitroso-n-acetylcysteine increases gastric mucosal blood flow

Nitric oxide (NO)-mediated vasodilation plays a key role in gastric mucosal defense, and NO-donor drugs may protect against diseases associated with gastric mucosal blood flow (GMBF) deficiencies. In this study, we used the ex vivo gastric chamber method and Laser Doppler Flowmetry to characterize the effects of luminal aqueous NO-donor drug S-nitroso-N-acetylcysteine (SNAC) solution administration compared to aqueous NaNO2 and NaNO3 solutions (pH 7.4) on GMBF in Sprague-Dawley rats. SNAC solutions (600 μM and 12 mM) led to a rapid threefold increase in GMBF, which was maintained during the incubation of the solutions with the gastric mucosa, while NaNO2 or NaNO3 solutions (12 mM) did not affect GMBF. SNAC solutions (600 μM and 12 mM) spontaneously released NO at 37 °C at a constant rate of 0.3 or 14 nmol·mL-1·min-1, respectively, while NaNO2 (12 mM) released NO at a rate of 0.06 nmol·mL-1·min-1 and NaNO3 (12 mM) did not release NO. These results suggest that the SNAC-induced GMBF increase is due to their higher rates of spontaneous NO release compared to equimolar NaNO2 solutions. Taken together, our data indicate that oral SNAC administration is a potential approach for gastric acid-peptic disorder prevention and treatment.Nitric oxide (NO)-mediated vasodilation plays a key role in gastric mucosal defense, and NO-donor drugs may protect against diseases associated with gastric mucosal blood flow (GMBF) deficiencies. In this study, we used the ex vivo gastric chamber method and Laser Doppler Flowmetry to characterize the effects of luminal aqueous NO-donor drug S-nitroso-N-acetylcysteine (SNAC) solution administration compared to aqueous NaNO2 and NaNO3 solutions (pH 7.4) on GMBF in Sprague-Dawley rats. SNAC solutions (600 μM and 12 mM) led to a rapid threefold increase in GMBF, which was maintained during the incubation of the solutions with the gastric mucosa, while NaNO2 or NaNO3 solutions (12 mM) did not affect GMBF. SNAC solutions (600 μM and 12 mM) spontaneously released NO at 37 °C at a constant rate of 0.3 or 14 nmol·mL-1·min-1, respectively, while NaNO2 (12 mM) released NO at a rate of 0.06 nmol·mL-1·min-1 and NaNO3 (12 mM) did not release NO. These results suggest that the SNAC-induced GMBF increase is due to their higher rates of spontaneous NO release compared to equimolar NaNO2 solutions. Taken together, our data indicate that oral SNAC administration is a potential approach for gastric acid-peptic disorder prevention and treatment2034109412

Droplet microfuidics for the highly controlled synthesis of branched gold nanoparticles

The synthesis of anisotropic metallic nanoparticles (NPs) has been a feld of intense and challenging research in the past decade. In this communication, we report on the reproducible and highly controllable synthesis of monodisperse branched gold nanoparticles in a droplet-based microfuidics platform. The process has been automated by adapting two diferent bulk synthetic strategies to microdroplets, acting as microreactors, for NP synthesis: a surfactant-free synthesis and a surfactantassisted synthesis. Microdroplets were generated in two diferent microfuidic devices designed to accommodate the requirements of both bulk syntheses. The epitaxial growth of AuNSTs inside the microdroplets allowed for a fne control of reagent mixing and local concentrations during particle formation. This is the frst time branched gold NPs have been synthesised in a microfuidics platform. The monodispersity of the product was comparable to the synthesis in bulk, proving the potential of this technology for the continuous synthesis of high quality anisotropic NPs with improved reproducibility.8FAPESP – Fundação de Amparo à Pesquisa Do Estado De São Paulo2015/01685-2; 2016/02414-

New versus naturally aged greenhouse cover films: degradation and micro and nanoplastics characterisation under sunlight exposure

The understanding of microplastic degradation and its effects remains limited due to the absence of accurate analytical techniques for detecting and quantifying micro- and nanoplastics. In this study, we investigated the release of nanoplastics and small microplastics in water from low-density polyethylene (LDPE) greenhouse cover films under simulated sunlight exposure for six months. Our analysis included both new and naturally aged (used) cover films, enabling us to evaluate the impact of natural aging. Additionally, photooxidation effects were assessed by comparing irradiated and non-irradiated conditions. Scanning electron microscopy (SEM) and nanoparticle tracking analysis (NTA) confirmed the presence of particles below 1 ?m in both irradiated and non-irradiated cover films. NTA revealed a clear effect of natural aging, with used films releasing more particles than new films but no impact of photooxidation, as irradiated and non-irradiated cover films released similar amounts of particles at each time point. Raman spectroscopy demonstrated the lower crystallinity of the released PE nanoplastics compared to the new films. Flow cytometry and total organic carbon data provided evidence of the release of additional material besides PE, and a clear effect of both simulated and natural aging, with photodegradation effects observed only for the new cover films. Finally, our results underscore the importance of studying the aging processes in both new and used plastic products using complementary techniques to assess the environmental fate and safety risks posed by plastics used in agriculture

Taylor dispersion analysis and release studies of β-carotene-loaded PLGA nanoparticles and liposomes in simulated gastrointestinal fluids

β-Carotene (βC), a natural carotenoid, is the most important and effective vitamin A precursor, known also for its antioxidant properties. However, its poor water solubility, chemical instability, and low bioavailability limit its effectiveness as an orally delivered functional nutrient. Nanoparticle encapsulation improves βC's bioaccessibility by enhancing its stability and solubility. This study compares two formulations, i.e. βC-loaded poly(lactic-co-glycolic acid) (PLGA) NPs and liposomes before and after exposure to simulated gastrointestinal fluids using various methods such as Taylor dispersion analysis (TDA), cryo-transmission electron microscopy, dynamic light scattering (DLS), and nanoparticle tracking analysis (NTA). TDA, a microfluidic technique, proved more effective than DLS and NTA in determining nanoparticle size in simulated gastrointestinal fluids. This highlights TDA's potential for assessing nanoparticle colloidal stability in simulated gastro-intestinal fluids, crucial for evaluating encapsulated bioactives' bioavailability. High-performance liquid chromatography (HPLC) revealed that PLGA nanoparticles incorporate and preserve βC more effectively during long-term storage compared to liposomes. Adding ascorbic acid significantly reduced degradation in simulated gastrointestinal fluids. Release studies showed that liposomes released 52% of βC after 36 hours, while PLGA nanoparticles released only 9% over 168 hours. These results provide valuable insights for selecting an appropriate βC nanocarrier for oral delivery based on desired release rates.</p

Ventral swimming starts, changes and recent evolution: A systematic review (Cambios y reciente evolución de las salidas ventrales de natación: revisión sistemática)

The purpose of this study was two-fold: to define the characteristics and to analyse the advantages of the last changes produced in the swimming starts as a consequence of the implementation of kick-start; and with the aim to present topics for future studies and guidance for coaches and swimmers. Fifty studies were reviewed: forty-eight related to the grab start, six focused on the track start and studied the kick-start. Nine additional studies are were comparisons between the grab start and track start, six compared the track start and kick-start and just one compared the three start techniques. The outcomes of the studies included in this review showed clear advantages in the kick-start performance with respect to the grab start or track start. The back plate implementation enhanced the force development on the block resulting in larger horizontal take-off velocities and shorter block times. These advantages induced significant improvements in the flight phase with larger distance travelled in less time and shorter time to 5, 10 and 15 m. The use of flexibility training programs as well as lower body strength and power are recommended for an improvement in kick-start technique. For an improvement in kick-start technique is recommended for coaches and swimmers the use of training programs designed to improve the lower body strength and power and the use of flexibility training programs.  Resumen. El propósito de esta revisión fue definir las características y analizar las ventajas de los últimos cambios producidos en las salidas de natación debido a la aparición de un nuevo poyete implementado con un apoyo posterior y con el objetivo de presentar temas para futuras investigaciones y una guía para entrenadores y nadadores. Para llevar a cabo dichos objetivos, cincuenta estudios fueron revisados de los cuales cuarenta y ocho analizaron la salida de agarre, seis incluyeron la salida de atletismo y diez la salida de atletismo con apoyo posterior. Además, una comparación entre el rendimiento de la salida de agarre y la salida de atletismo fue llevada a cabo en nueve de los Nueve estudios incluidos en esta revisión más compararon la salida de agarre y la salida de atletismo, seis compararon la salida de atletismo y la salida de atletismo con apoyo posterior y solamente uno incluyó una comparativa entre comparó las tres técnicas. Los resultados de los estudios mostraron claras ventajas en el rendimiento de total la salida desde con los nuevos poyetes con apoyo posterior con en comparación respecto a la salida de agarre o la salida de atletismo. La implementación del apoyo posterior incrementó la fuerza generada en el poyete permitiendo obtener una mayor velocidad horizontal en el despegue y un menor tiempo de poyete. Estas ventajas dieron lugar a una mejoras significativa en la fase de vuelo (tiempo de vuelo y distancia de vuelo) con mayores distancias recorridas en un tiempo más corto y en los tiempos de salida a menores tiempos a los 5, 10 y 15 m. Para la mejora de la salida de atletismo con apoyo posterior se recomienda a entrenadores y nadadores incluir programas de entrenamiento dirigidos a una mejor aplicación de fuerza en el poyete con apoyo posterior la mejora de la fuerza de los miembros inferiores y la potencia así como el uso de programas de flexibilidad

Precision of Taylor dispersion

Taylor dispersion is capable of measuring accurately the hydrodynamic radius over several orders of magnitude. Accordingly, it is now a highly competitive technique dedicated to characterizing small molecules, proteins, macromolecules, nanoparticles, and their self-assembly. Regardless, an in-depth analysis addressing the precision of the technique, being a key indicator of reproducibility, is not available. Benefiting from analytical modeling and statistical analysis, we address error propagation and present a comprehensive theoretical study of the precision of Taylor dispersion. Theory is then compared against experiment, and we find full consistency. Our results are most helpful when the design, objectives, or control of analytical quality is in focus

Polydopamine nanoparticle doped nanofluid for solar thermal energy collector efficiency increase

Polydopamine can form black nanoparticles and has recently been gaining attention due to its extraordinary heating properties upon excitation with light. Herein, polydopamine hybrid nanoparticles are synthesized in different sizes and subsequently added to a solar fluid to analyze heating ability. The solar fluids with the differently sized hybrid polydopamine particles are compared to a solar fluid containing food coloring (i.e., micrometer‐sized soot particles, similar to India Ink) and silver nanoparticles. The hybrid polydopamine nanoparticles are found to heat more efficiently than silver nanoparticles or food coloring, respectively. In addition, no hybrid polydopamine nanoparticle deposits are found in the direct absorption solar collector in comparison to the solar fluids doped with silver nanoparticles or food coloring. Thus, this work shows that hybrid polydopamine nanoparticles are promising candidates to increase the efficiency of solar fluids

Correlative Light, Electron Microscopy and Raman Spectroscopy Workflow To Detect and Observe Microplastic Interactions with Whole Jellyfish.

Many researchers have turned their attention to understanding microplastic interaction with marine fauna. Efforts are being made to monitor exposure pathways and concentrations and to assess the impact such interactions may have. To answer these questions, it is important to select appropriate experimental parameters and analytical protocols. This study focuses on medusae of Cassiopea andromeda jellyfish: a unique benthic jellyfish known to favor (sub-)tropical coastal regions which are potentially exposed to plastic waste from land-based sources. Juvenile medusae were exposed to fluorescent poly(ethylene terephthalate) and polypropylene microplastics (<300 μm), resin embedded, and sectioned before analysis with confocal laser scanning microscopy as well as transmission electron microscopy and Raman spectroscopy. Results show that the fluorescent microplastics were stable enough to be detected with the optimized analytical protocol presented and that their observed interaction with medusae occurs in a manner which is likely driven by the microplastic properties (e.g., density and hydrophobicity)

Reversible assembly of metal nanoparticles induced by penicillamine. Dynamic formation of SERS hot spots

We report a systematic study of the surface modification of gold and silver nanoparticles with dl-penicillamine (PEN) and N-acetyl-dl-penicillamine (NAP), motivated by the possibility of inducing pH-controlled reversible nanoparticle assembly. The interaction of PEN and NAP with the metal nanoparticle surface was studied by isothermal titration calorimetry (ITC). The results indicate that equilibrium is reached with the formation of a submonolayer corresponding to ca. 40% and 64% of total surface coverage for PEN and NAP, respectively. Both PEN and NAP modified nanoparticles could be reversibly aggregated at acidic pH due to the protonation of the carboxylic groups, leading to a decrease in their stability by electrostatic interactions and the advent of hydrogen bonding interactions which promote interparticle linkage. The process was monitored by UV-Vis spectroscopy, transmission electron microscopy (TEM) and surface enhanced Raman scattering (SERS) spectroscopy. Interestingly, the SERS characterization demonstrated the pH-controlled formation of hot-spots