Addressing underestimation of waterborne disease risks due to fecal indicator bacteria bound in aggregates.

Aims: This study aims to identify and address significant limitations in current culture-based regulatory methods used for monitoring microbiological water quality. Specifically, these methods' inability to distinguish between planktonic forms and aggregates containing higher bacterial loads and associated pathogens may lead to a severe underestimation of exposure risks, with critical public health implications.

Methods And Results: We employed a novel methodology combining size fractionation with ALERT (Automatic Lab-in-a-vial E.

Evaluation of All-Atom and Martini 3 Coarse-Grained Force Fields from the Structural Investigation of Nitroxide Spin Probes and Their Confinement in Beta-Cyclodextrin.

Nitroxide radicals have found wide applications as spin labels or probes, and their guest-host interactions with cyclodextrins exhibit enhanced applications in electron spin resonance (ESR) spectroscopy and imaging due to improved biostability toward reducing agents. Although the computational prediction of the guest-host binding has become increasingly common for small ligands, molecular simulations regarding the conformational preferences of hosted spin probes have not been conducted. Here we present molecular dynamics simulations at an atomistic level for a set of four TEMPO (2,2,6,6-tetramethylpiperidine 1-oxyl) spin probes and thereafter develop coarse-grained models compatible with the recent version of the Martini force field (v 3.

Molecular modeling of the carbohydrate corona formation on a polyvinyl chloride nanoparticle and its impact on the adhesion to lipid bilayers.

The pervasive presence of nanoplastics (NPs) in the environment has gained increasing attention due to their accumulation in living organisms. These emerging contaminants inevitably interact with extracellular polymeric substances along respiratory or gastrointestinal tracts, and diverse organic coating on the surface of NPs, known as bio- or eco-corona, is formed. Although its impact on altering the NP properties and potential cell internalization has been extensively examined, studies on its role in NP partitioning in the cell membrane are elusive yet.

Coarse-Grained Model of Phytic Acid for Predicting the Supramolecular Architecture of Ionically Cross-Linked Chitosan Hydrogels.

Phytic acid is a polyphosphate whose ionized form is used as a cross-linking agent to formulate chitosan-based nanoparticles and hydrogels as carriers with remarkable adhesivity and biocompatibility. To predict the underlying cross-linking pattern responsible for the structural arrangement in the chitosan hydrogels, we put forth coarse-grained parametrization of the phytic acid compatible with the Martini 2.3P force field.

Polymorphism of chitosan-based networks stabilized by phytate investigated by molecular dynamics simulations.

Chitosan can associate in the presence of polyphosphates into insoluble hydrogels capable of drug encapsulation and safe and efficient release. On the one hand, chitosan hydrogels were synthesized using the phytate anion as a crosslinking agent and were characterized by employing dynamic light scattering (DLS) and Fourier transform infrared spectroscopy (FTIR). On the other hand, an effective chitosan-phytate model with atomistic details was created to examine the underlying physical crosslinking pattern, and the structure and dynamics of the chitosan-phytate complex were systematically investigated by using molecular dynamics (MD) simulations.

Structural behavior of amphiphilic polyion complexes interacting with saturated lipid membranes investigated by coarse-grained molecular dynamic simulations.

Neutral polyelectrolyte complexes (PECs) made from an amphiphilic multiblock copolymer of type (A B ) and an oppositely charged polyion and interacting with a dipalmitoylphosphatidylcholine (DPPC) lipid membrane have been examined employing a coarse-grained model with implicit solvent and molecular dynamics simulations. One systematically explored the influence of the size of the hydrophobic block B and of the number of these blocks per chain on the PEC tendency to adhere to the membrane surface and to intercalate into the membrane core. Simulation results showed that PECs bound irreversibly to the lipid bilayer without polyion unwinding from the complex and the adsorbed conformation was strongly affected by the size of the hydrophobic block B.

Spectroscopic, molecular dynamics simulation and biological studies of Flavin MonoNucleotide and Flavin Adenine Dinucleotide in biomimetic systems.

The present study describes a comprehensive investigation of the spectroscopic characteristics, stability and in vitro antioxidant and cytotoxic properties of the Flavin MonoNucleotide (FMN) and Flavin Adenine Dinucleotide (FAD) in Dextran70 (Dx70) and Dx70/phospatidylcholine (PC) biomimetic systems by means of the UV-Vis absorption, fluorescence spectroscopy, chemiluminescence and Neutral Red assay. The affinity of FMN, FAD and the precursor riboflavin (RF) to an unsaturated phospholipid bilayer model as well as the location of the probes within the lipid bilayer were assessed from united-atom molecular dynamics simulations carried out on an unsaturated phospholipid bilayer model system, and the theoretical and experimental characterization of the two probes within biomembranes was complemented with the light microscopy survey of the cell morphology of L929 fibroblast cells cultivated in the presence of various dosage of FAD/FMN. In lipid bilayers, FMN/FAD resulted in a noticeable improvement of the antioxidant activity (the scavenging of reactive oxygen species up to 40%) and a significant effect on cellular viability in the L929 fibroblast cells.

Chitosan-polyglycidol complexes to coating iron oxide particles for dye adsorption.

The study sheds light on the interaction between chitosan (Ch) and polyglycidol (PGL) and uses their interpolymer complex in hydrophilic coating of iron oxide particles (M). Preliminary investigations were performed by modeling chitosan and polyglycidol chains interactions using coarse grained beads approximation and molecular dynamics simulations. The results revealed that Ch and PGL chains associate together forming weak strength complexes, which was experimentally confirmed by surface tension, fluorescence and FTIR.

Interaction of piroxicam with bovine serum albumin investigated by spectroscopic, calorimetric and computational molecular methods.

The binding of drugs to serum proteins is governed by weak non-covalent forces. In this study, the nature and magnitude of the interactions between piroxicam (PRX) and bovine serum albumin (BSA) was assessed using spectroscopic, calorimetric and computational molecular methods. The fluorescence data revealed an atypical behavior during PRX and BSA interaction.

Coarse-grained simulation studies on the adsorption of polyelectrolyte complexes upon lipid membranes.

Coarse-grained molecular dynamics simulations have been applied to explore the adsorption of oppositely charged polyelectrolyte complexes (PECs) on an electronically neutral dipalmitoylphosphatidylcholine (DPPC) lipid bilayer. The membrane model implied an implicit solvent description, and the DPPC parametrization is capable of reproducing relatively well the main physical properties of the bilayer such as the area per lipid, bending modulus, bilayer thickness, orientation order parameter and internal pressure distribution. It has been furthermore shown that the lipid model can be applied to investigate the dynamics and adsorption structures of PECs with a varying polyanion-to-polycation charge ratio.

Autonomous system for rapid field quantification of Escherichia coli in surface waters.

Aims: The purpose of this work is to present and evaluate the performance of a novel Automatic Lab-in-vial Escherichia coli Remote Tracking technology based on an automated real-time defined substrate approach, implemented in both portable and in situ instruments.

Methods And Results: We present the fresh water calibration procedure, and assess performance using side-by-side comparison with most probable number (MPN) approaches in terms of accuracy, reproducibility and capability to correctly generate early-warning alerts. Long-term data from an operational in situ deployment at a potential bathing site is presented as well.

Tubular and Spherical SiO₂ Obtained by Sol Gel Method for Lipase Immobilization and Enzymatic Activity.

A wide range of hybrid biomaterials has been designed in order to sustain bioremediation processes by associating sol-gel SiO₂ matrices with various biologically active compounds (enzymes, antibodies). SiO₂ is a widespread, chemically stable and non-toxic material; thus, the immobilization of enzymes on silica may lead to improving the efficiency of biocatalysts in terms of endurance and economic costs. Our present work explores the potential of different hybrid morphologies, based on hollow tubes and solid spheres of amorphous SiO₂, for enzyme immobilization and the development of competitive biocatalysts.

Assembled viral-like nanoparticles from elastic capsomers and polyion.

Molecular dynamics simulations are carried out on a coarse-grained model to describe the polyion driven co-assembly of elastic capsomers as viral-like aggregates. The kinetics and structural properties of the complexes are examined using cationic capsomers, an anionic polyion, both modelled using beads connected by springs, and counterions neutralizing separately the two charged species. Polyion overcharging the capsid is encapsulated owing to combined effects of the capsomer-capsomer short-range interactions, the polyion ability to follow a Hamiltonian path, and Donnan equilibrium.

Yield-stress fluids foams: flow patterns and controlled production in T-junction and flow-focusing devices.

We study the formation of yield-stress fluid foams in millifluidic flow-focusing and T-junction devices. First, we provide a phase diagram for the unsteady operating regimes of bubble production when the gas pressure and the yield-stress fluid flow rate are imposed. Three regimes are identified: a co-flow of gas and yield-stress fluid, a transient production of bubble and a flow of yield-stress fluid only.

Localized Fibrous Tumor of the Pleura An Unusual Cause of Severe Hypoglycaemia. Case Report.

Localized fibrous tumors of the pleura are rare. If there are symptomatic, the symptoms are based on hormone production or size. Complete resection offers the best results.

Influence of the shell thickness and charge distribution on the effective interaction between two like-charged hollow spheres.

The mean-force and the potential of the mean force between two like-charged spherical shells were investigated in the salt-free limit using the primitive model and Monte Carlo simulations. Apart from an angular homogeneous distribution, a discrete charge distribution where point charges localized on the shell outer surface followed an icosahedral arrangement was considered. The electrostatic coupling of the model system was altered by the presence of mono-, trivalent counterions or small dendrimers, each one bearing a net charge of 9 e.

Branched-linear polyion complexes at variable charge densities.

Structural behavior of complexes formed by a charged and branched copolymer and an oppositely charged and linear polyion was examined by Monte Carlo simulations employing a coarse-grained bead-spring model. The fractional bead charge and the branching density were systematically varied; the former between 0e and 1e and the latter such that both the comb-polymer and the bottle-brush limits were included. The number of beads of the main chain of the branched copolymer and of the linear polyion was always kept constant and equal, and a single side-chain length was used.

Physicochemical Characterization and In Vitro Cytotoxic Effect of 3-Hydroxyflavone in a Silver Nanoparticles Complex.

The aim of this work was to characterize the physico-chemical properties of 3-hydroxyflavone (3-HF) in a silver nanoparticles complex (SNPs) using UV-vis and Fluorescence spectroscopy, Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM) analysis. One also evaluated its effect on the cell viability and morphology of L929 mouse fibroblast cells in vitro. The contribution of the carrier protein, Bovine Serum Albumin (BSA) to 3-HF properties has also been investigated.

Bubble Formation in Yield Stress Fluids Using Flow-Focusing and T-Junction Devices.

We study the production of bubbles inside yield stress fluids (YSFs) in axisymmetric T-junction and flow-focusing devices. Taking advantage of yield stress over capillary stress, we exhibit a robust break-up mechanism reminiscent of the geometrical operating regime in 2D flow-focusing devices for Newtonian fluids. We report that when the gas is pressure driven, the dynamics is unsteady due to hydrodynamic feedback and YSF deposition on the walls of the channels.

Enhanced microgas chromatography using correlation techniques for continuous indoor pollutant detection.

We present for the first time a proof-of-concept system implementing the stochastic injection techniques within a silicon-based microgas chromatograph (μGC) which differs from standard laboratory chromatographs by its small size, shorter column and corresponding elution times, and potential low cost when batch manufactured in high volumes. We demonstrate that stochastic injection techniques can enable the continuous detection of pollutants or toxic gases, with high temporal resolution (5 s) and order-of-magnitude improvements in limit of detection compared to a standard single-injection technique, thus greatly improving performance of air quality monitoring devices. Since micro-GC systems have the potential to 1 day become ubiquitous in indoor environments, such stochastic injection techniques could enable faster detection of toxic compounds at lower concentrations in both industrial and residential settings.

Static and dynamic aspects of black silicon formation.

We present a combination of experimental data and modeling that explains some of the important characteristics of black silicon (BSi) developed in cryogenic reactive ion etching (RIE) processes, including static properties (dependence of resulting topography on process parameters) and dynamic aspects (evolution of topography with process time). We generate a phase diagram predicting the RIE parameter combinations giving rise to different BSi geometries and show that the topographic details of BSi explain the metamaterial characteristics that are responsible for its low reflectivity. In particular, the unique combination of needle and hole features of various heights and depths, which is captured by our model and confirmed by focused ion beam nanotomography, creates a uniquely smooth transition in refractive index.

Branched-linear polyion complexes investigated by Monte Carlo simulations.

Complexes formed by one charged and branched copolymer with an oppositely charged and linear polyion have been investigated by Monte Carlo simulations. A coarse-grained description has been used, in which the main chain of the branched polyion and the linear polyion possess the same absolute charge and charge density. The spatial extension and other structural properties, such as bond-angle orientational correlation function, asphericity, and scaling analysis of formed complexes, at varying branching density and side-chain length of the branched polyion, have been explored.

Optical trapping and binding of particles in an optofluidic stable Fabry-Pérot resonator with single-sided injection.

In this article, microparticles are manipulated inside an optofluidic Fabry-Pérot cylindrical cavity embedding a fluidic capillary tube, taking advantage of field enhancement and multiple reflections within the optically-resonant cavity. This enables trapping of suspended particles with single-side injection of light and with low optical power. A Hermite-Gaussian standing wave is developed inside the cavity, forming trapping spots at the locations of the electromagnetic field maxima with a strong intensity gradient.

Simultaneous measurement of liquid absorbance and refractive index using a compact optofluidic probe.

We present a novel optical technique for simultaneously measuring the absorbance and the refractive index of a thin film using an infrared optofluidic probe. Experiments were carried on two different liquids and the results agree with the bibliographical data. The ultimate goal is to achieve a multi-functional micro-optical device for analytical applications.