Superparamagnetic iron oxide nanoparticles for their application in the human body: Influence of the surface.

Iron oxide nanoparticles (IONs) are of great interest in nanomedicine for imaging, drug delivery, or for hyperthermia treatment. Although many research groups have focused on the synthesis and application of IONs in nanomedicine, little is known about the influence of the surface properties on the particles' behavior in the human body. This study analyzes the impact of surface coatings (dextran, polyvinyl alcohol, polylactide-co-glycolide) on the nanoparticles' cytocompatibility, agglomeration, degradation, and the resulting oxidative stress induced by the particle degradation. All particles, including bare IONs (BIONs), are highly cytocompatible (>70%) and show no significant toxicity towards smooth muscle cells. Small-angle X-ray scattering profiles visualize the aggregation behavior of nanoparticles and yield primary particle sizes of around 20 nm for the investigated nanoparticles. A combined experimental setup of dynamic light scattering and phenanthroline assay was used to analyze the long-term agglomeration and degradation profile of IONs in simulated body fluids, allowing fast screening of multiple candidates. All particles degraded in simulated endosomal and lysosomal fluid, confirming the pH-dependent dissolution. The degradation rate decreased with the shrinking size of particles leading to a plateau. The fastest Fe2+ release could be measured for the polyvinyl-coated IONs. The analytical setup is ideal for a quick preclinical study of IONs, giving often neglected yet crucial information about the behavior and toxicity of nanoparticles in the human body. Moreover, this study allows for the development and evaluation of novel ferroptosis-inducing agents.

Inflammatory biomarkers and nanotechnology: new insights in pancreatic cancer early detection.

BACKGROUND: Poor prognosis of pancreatic ductal adenocarcinoma (PDAC) is mainly due to the lack of effective early-stage detection strategies. Even though the link between inflammation and PDAC has been demonstrated and inflammatory biomarkers proved their efficacy in predicting several tumours, to date they have a role only in assessing PDAC prognosis. Recently, the studies of interactions between nanosystems and easily collectable biological fluids, alone or coupled with standard laboratory tests, have proven useful in facilitating PDAC diagnosis. Notably, tests based on magnetic levitation (MagLev) of biocoronated nanosystems have demonstrated high diagnostic accuracy in compliance with the criteria stated by WHO. Herein, the author developed a synergistic analysis that combines a user-friendly MagLev-based approach and common inflammatory biomarkers for discriminating PDAC subjects from healthy ones. MATERIALS AND METHODS: Plasma samples from 24 PDAC subjects and 22 non-oncological patients have been collected and let to interact with graphene oxide nanosheets.Biomolecular corona formed around graphene oxide nanosheets have been immersed in a Maglev platform to study the levitation profiles.Inflammatory biomarkers such as neutrophil-to-lymphocyte ratio (NLR), derived-NLR (dNLR), and platelet to lymphocyte ratio have been calculated and combined with results obtained by the MagLev platform. RESULTS: MagLev profiles resulted significantly different between non-oncological patients and PDAC and allowed to identify a MagLev fingerprint for PDAC. Four inflammatory markers were significantly higher in PDAC subjects: neutrophils ( P =0.04), NLR ( P =4.7 ×10 -6 ), dNLR ( P =2.7 ×10 -5 ), and platelet to lymphocyte ratio ( P =0.002). Lymphocytes were appreciably lower in PDACs ( P =2.6 ×10 -6 ).Combining the MagLev fingerprint with dNLR and NLR returned global discrimination accuracy for PDAC of 95.7% and 91.3%, respectively. CONCLUSIONS: The multiplexed approach discriminated PDAC patients from healthy volunteers in up to 95% of cases. If further confirmed in larger-cohort studies, this approach may be used for PDAC detection.

Ethanol Preference Leads to Alterations in Telomere Length, Mitochondria Copy Number, and Antioxidant Enzyme Activity in Zebrafish Brains.

BACKGROUND: The motivations for and effects of ethanol consumption vary considerably among individuals, and as such, a significant proportion of the population is prone to substance abuse and its negative consequences in the physical, social, and psychological spheres. In a biological context, the characterization of these phenotypes provides clues for understanding the neurological complexity associated with ethanol abuse behavior. Therefore, the objective of this research was to characterize four ethanol preference phenotypes described in zebrafish: Light, Heavy, Inflexible, and Negative Reinforcement. METHODS: To do this, we evaluated the telomere length, mtDNA copy number using real-time quantitative PCR (qPCR), and the activity of these antioxidant enzymes: catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) in the brain, and the interactions between these biomarkers. Changes observed in these parameters were associated with ethanol consumption and alcohol abuse. RESULTS: The Heavy, Inflexible, and Negative Reinforcement phenotypes showed ethanol preference. This was particularly the case with the Inflexible phenotype, which was the group with the greatest ethanol preference. These three phenotypes showed telomere shortening as well as high SOD/CAT and/or GPx activities, while the Heavy phenotype also showed an increase in the mtDNA copy number. However, the Light phenotype, containing individuals without ethanol preference, did not demonstrate any changes in the analyzed parameters even after being exposed to the drug. Additionally, the PCA analysis showed a tendency to cluster the Light and Control groups differently from the other ethanol preference phenotypes. There was also a negative correlation between the results of the relative telomere length and SOD and CAT activity, providing further evidence of the biological relationship between these parameters. CONCLUSIONS: Our results showed differential molecular and biochemistry patterns in individuals with ethanol preference, suggesting that the molecular and biochemical basis of alcohol abuse behavior extends beyond its harmful physiological effects, but rather is correlated with preference phenotypes.

Acute ethanol exposure leads to long-term effects on memory, behavior, and transcriptional regulation in the zebrafish brain.

Alcohol consumption is associated with alterations in memory and learning processes in humans and animals. In this context, research models such as the zebrafish (Danio rerio) arise as key organisms in behavioral and molecular studies that attempt to clarify alterations in the Central Nervous System (CNS), like those related to alcohol use. Accordingly, we used the zebrafish as a model to evaluate the effects of ethanol on the learning and memory process, as well as its relationship with behavior and transcriptional regulation of lrfn2, lrrk2, grin1a, and bdnf genes in the brain. To this end, for the memory and learning evaluation, we conducted the Novel Object Recognition test (NOR); for behavior, the Novel Tank test; and for gene transcription, qPCR, after 2 h, 24 h, and 8 days of ethanol exposure. As a result, we noticed in the NOR that after 8 days of ethanol exposure, the control group spent more time exploring the novel object than when compared to 2 h post-exposure, indicating that naturally zebrafish remember familiar objects. In animals in the Treatment group, however, no object recognition behavior was observed, suggesting that alcohol affected the learning and memory processes of the animals and stimulated an anxiolytic effect in them. Regarding transcriptional regulation, 24 h after alcohol exposure, we found hyper-regulation of bdnf and, after 8 days, a hypo-regulation of lrfn2 and lrrk2. To conclude, we demonstrated that ethanol exposure may have influenced learning ability and memory formation in zebrafish, as well as behavior and regulation of gene transcription. These data are relevant for further understanding the application of zebrafish in research associated with ethanol consumption and behavior.

Squid Skin Cell-Inspired Refractive Index Mapping of Cells, Vesicles, and Nanostructures.

The fascination with the optical properties of naturally occurring systems has been driven in part by nature's ability to produce a diverse palette of vibrant colors from a relatively small number of common structural motifs. Within this context, some cephalopod species have evolved skin cells called iridophores and leucophores whose constituent ultrastructures reflect light in different ways but are composed of the same high refractive index material─a protein called reflectin. Although such natural optical systems have attracted much research interest, measuring the refractive indices of biomaterial-based structures across multiple different environments and establishing theoretical frameworks for accurately describing the obtained refractive index values has proven challenging. Herein, we employ a synergistic combination of experimental and computational methodologies to systematically map the three-dimensional refractive index distributions of model self-assembled reflectin-based structures both in vivo and in vitro. When considered together, our findings may improve understanding of squid skin cell functionality, augment existing methods for characterizing protein-based optical materials, and expand the utility of emerging holotomographic microscopy techniques.

Carboxymethyl-Dextran-Coated Superparamagnetic Iron Oxide Nanoparticles for Drug Delivery: Influence of the Coating Thickness on the Particle Properties.

Carboxymethyl-dextran (CMD)-coated iron oxide nanoparticles (IONs) are of great interest in nanomedicine, especially for applications in drug delivery. To develop a magnetically controlled drug delivery system, many factors must be considered, including the composition, surface properties, size and agglomeration, magnetization, cytocompatibility, and drug activity. This study reveals how the CMD coating thickness can influence these particle properties. ION@CMD are synthesized by co-precipitation. A higher quantity of CMD leads to a thicker coating and a reduced superparamagnetic core size with decreasing magnetization. Above 12.5−25.0 g L−1 of CMD, the particles are colloidally stable. All the particles show hydrodynamic diameters < 100 nm and a good cell viability in contact with smooth muscle cells, fulfilling two of the most critical characteristics of drug delivery systems. New insights into the significant impact of agglomeration on the magnetophoretic behavior are shown. Remarkable drug loadings (62%) with the antimicrobial peptide lasioglossin and an excellent efficiency (82.3%) were obtained by covalent coupling with the EDC/NHS (N-ethyl-N'-(3-(dimethylamino)propyl)carbodiimide/N-hydroxysuccinimide) method in comparison with the adsorption method (24% drug loading, 28% efficiency). The systems showed high antimicrobial activity with a minimal inhibitory concentration of 1.13 µM (adsorption) and 1.70 µM (covalent). This system successfully combines an antimicrobial peptide with a magnetically controllable drug carrier.

Tailoring Lipid-Based Drug Delivery Nanosystems by Synchrotron Small Angle X-ray Scattering.

Thanks to specific physico-chemical properties, drug delivery systems based on nanoparticles have proven to effectively transport delicate molecules for therapeutic purposes, protecting them from degradation, increasing their stability in the blood circulation and allowing to convey and release the transported substances in specific areas of the body. Nanoparticles obtained from biopolymers for applications in medicine and pharmaceutics have become particularly popular in recent years due to the enormous research effort in the field of vaccines to respond to the pandemic emergency. Among the various types of biopolymers used to produce nanoparticles for therapeutics, lipids have characteristics that make them biocompatible, with low toxicity and ease of clearance. They can be synthesized by designing their characteristics according to the foreseen administration path, or to the target of the transported drug. The analytical methods mostly used to evaluate the characteristics of lipid nanosytems for drug delivery involve studying their effects on cells, in vitro and in vivo. Although it is often considered a "niche technique" for research in the bio-related sciences, Small Angle X-ray Scattering (SAXS) is a versatile tool to study the structure of nanosystems based on lipids, both ex situ and in situ. Therefore, it allows to evaluate both the effect of the different synthesis parameters and of the exposure of lipid nanoparticles to physiological conditions, which is of fundamental importance to design efficient drug delivery systems. In this mini-review, we will report some recent examples of characterization and design of nanoparticles based on lipids, where SAXS has been a fundamental step both to guide the synthesis of nanomaterials with tailored characteristics, and to understand the interaction between nanomaterials and cells.

Magnetic Levitation Patterns of Microfluidic-Generated Nanoparticle-Protein Complexes.

Magnetic levitation (MagLev) has recently emerged as a powerful method to develop diagnostic technologies based on the exploitation of the nanoparticle (NP)-protein corona. However, experimental procedures improving the robustness, reproducibility, and accuracy of this technology are largely unexplored. To contribute to filling this gap, here, we investigated the effect of total flow rate (TFR) and flow rate ratio (FRR) on the MagLev patterns of microfluidic-generated graphene oxide (GO)-protein complexes using bulk mixing of GO and human plasma (HP) as a reference. Levitating and precipitating fractions of GO-HP samples were characterized in terms of atomic force microscopy (AFM), bicinchoninic acid assay (BCA), and one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (1D SDS-PAGE), and nanoliquid chromatography-tandem mass spectrometry (nano-LC-MS/MS). We identified combinations of TFR and FRR (e.g., TFR = 35 µL/min and FRR (GO:HP) = 9:1 or TFR = 3.5 µL/min and FRR (GO:HP) = 19:1), leading to MagLev patterns dominated by levitating and precipitating fractions with bulk-like features. Since a typical MagLev experiment for disease detection is based on a sequence of optimization, exploration, and validation steps, this implies that the optimization (e.g., searching for optimal NP:HP ratios) and exploration (e.g., searching for MagLev signatures) steps can be performed using samples generated by bulk mixing. When these steps are completed, the validation step, which involves using human specimens that are often available in limited amounts, can be made by highly reproducible microfluidic mixing without any ex novo optimization process. The relevance of developing diagnostic technologies based on MagLev of coronated nanomaterials is also discussed.

Detection of Pancreatic Ductal Adenocarcinoma by Ex Vivo Magnetic Levitation of Plasma Protein-Coated Nanoparticles.

Pancreatic Ductal Adeno Carcinoma (PDAC) is one of the most lethal malignancies worldwide, and the development of sensitive and specific technologies for its early diagnosis is vital to reduce morbidity and mortality rates. In this proof-of-concept study, we demonstrate the diagnostic ability of magnetic levitation (MagLev) to detect PDAC by using levitation of graphene oxide (GO) nanoparticles (NPs) decorated by a biomolecular corona of human plasma proteins collected from PDAC and non-oncological patients (NOP). Levitation profiles of corona-coated GO NPs injected in a MagLev device filled with a paramagnetic solution of dysprosium(III) nitrate hydrate in water enables to distinguish PDAC patients from NOP with 80% specificity, 100% sensitivity, and global classification accuracy of 90%. Our findings indicate that Maglev could be a robust and instrumental tool for the early detection of PDAC and other cancers.

Correction: Structural insights into fusion mechanisms of small extracellular vesicles with model plasma membranes.

Correction for 'Structural insights into fusion mechanisms of small extracellular vesicles with model plasma membranes' by Fabio Perissinotto et al., Nanoscale, 2021, 13, 5224-5233, DOI: .

Microfluidic Formulation of DNA-Loaded Multicomponent Lipid Nanoparticles for Gene Delivery.

In recent years, lipid nanoparticles (LNPs) have gained considerable attention in numerous research fields ranging from gene therapy to cancer immunotherapy and DNA vaccination. While some RNA-encapsulating LNP formulations passed clinical trials, DNA-loaded LNPs have been only marginally explored so far. To fulfil this gap, herein we investigated the effect of several factors influencing the microfluidic formulation and transfection behavior of DNA-loaded LNPs such as PEGylation, total flow rate (TFR), concentration and particle density at the cell surface. We show that PEGylation and post-synthesis sample concentration facilitated formulation of homogeneous and small size LNPs with high transfection efficiency and minor, if any, cytotoxicity on human Embryonic Kidney293 (HEK-293), spontaneously immortalized human keratinocytes (HaCaT), immortalized keratinocytes (N/TERT) generated from the transduction of human primary keratinocytes, and epidermoid cervical cancer (CaSki) cell lines. On the other side, increasing TFR had a detrimental effect both on the physicochemical properties and transfection properties of LNPs. Lastly, the effect of particle concentration at the cell surface on the transfection efficiency (TE) and cell viability was largely dependent on the cell line, suggesting that its case-by-case optimization would be necessary. Overall, we demonstrate that fine tuning formulation and microfluidic parameters is a vital step for the generation of highly efficient DNA-loaded LNPs.

Functionalized Mesoporous Thin Films for Biotechnology.

Mesoporous materials bear great potential for biotechnological applications due to their biocompatibility and versatility. Their high surface area and pore interconnection allow the immobilization of molecules and their subsequent controlled delivery. Modifications of the mesoporous material with the addition of different chemical species, make them particularly suitable for the production of bioactive coatings. Functionalized thin films of mesoporous silica and titania can be used as scaffolds with properties as diverse as promotion of cell growth, inhibition of biofilms formation, or development of sensors based on immobilized enzymes. The possibility to pattern them increase their appeal as they can be incorporated into devices and can be tailored both with respect to architecture and functionalization. In fact, selective surface manipulation is the ground for the fabrication of advanced micro devices that combine standard micro/nanofluids with functional materials. In this review, we will present the advantages of the functionalization of silica and titania mesoporous materials deposited in thin film. Different functional groups used to modify their properties will be summarized, as well as functionalization methods and some examples of applications of modified materials, thus giving an overview of the essential role of functionalization to improve the performance of such innovative materials.

Continuous Microfluidic Production of Citrem-Phosphatidylcholine Nano-Self-Assemblies for Thymoquinone Delivery.

Lamellar and non-lamellar liquid crystalline nanodispersions, including liposomes, cubosomes, and hexosomes are attractive platforms for drug delivery, bio-imaging, and related pharmaceutical applications. As compared to liposomes, there is a modest number of reports on the continuous production of cubosomes and hexosomes. Using a binary lipid mixture of citrem and soy phosphatidylcholine (SPC), we describe the continuous production of nanocarriers for delivering thymoquinone (TQ, a substance with various therapeutic potentials) by employing a commercial microfluidic hydrodynamic flow-focusing chip. In this study, nanoparticle tracking analysis (NTA) and synchrotron small-angle X-ray scattering (SAXS) were employed to characterize TQ-free and TQ-loaded citrem/SPC nanodispersions. Microfluidic synthesis led to formation of TQ-free and TQ-loaded nanoparticles with mean sizes around 115 and 124 nm, and NTA findings indicated comparable nanoparticle size distributions in these nanodispersions. Despite the attractiveness of the microfluidic chip for continuous production of citrem/SPC nano-self-assemblies, it was not efficient as comparable mean nanoparticle sizes were obtained on employing a batch (discontinuous) method based on low-energy emulsification method. SAXS results indicated the formation of a biphasic feature of swollen lamellar (Lα) phase in coexistence with an inverse bicontinuous cubic Pn3m phase in all continuously produced TQ-free and TQ-loaded nanodispersions. Further, a set of SAXS experiments were conducted on samples prepared using the batch method for gaining further insight into the effects of ethanol and TQ concentration on the structural features of citrem/SPC nano-self-assemblies. We discuss these effects and comment on the need to introduce efficient microfluidic platforms for producing nanocarriers for delivering TQ and other therapeutic agents.

µDrop: a system for high-throughput small-angle X-ray scattering measurements of microlitre samples.

An automatic sample changer system for measurements of large numbers of liquid samples - the µDrop Sample Changer - is presented. It is based on a robotic arm equipped with a pipetting mechanism, which is combined with a novel drop-based sample holder. In this holder a drop of liquid is suspended between two parallel plates by surface tension. The absence of a transfer line benefits the cleaning, improving the background as well as making it faster and more efficient than most comparable capillary-based systems. The µDrop Sample Changer reaches cycle times below 35 s and can process up to 480 samples in a single run. Sample handling is very reliable, with a drop misplacement chance of about 0.2%. Very low sample volumes (<20 µl) are needed and repeatable measurements were performed down to 6 µl. Using measurements of bovine serum albumin and lysozyme, the performance of the instrument and quality of the gathered data of low and high concentrations of proteins are presented. The temperature of samples can also be controlled during storage and during measurement, which is demonstrated by observing a phase transition of a mesophase-forming lipid solution. The instrument has been developed for use in small-angle X-ray scattering experiments, which is a well established technique for measuring (macro-)molecules. It is commonly used in biological studies, where often large sets of rare samples have to be measured.

Structural insights into fusion mechanisms of small extracellular vesicles with model plasma membranes.

Extracellular vesicles (EVs) are a potent intercellular communication system. Such small vesicles transport biomolecules between cells and throughout the body, strongly influencing the fate of recipient cells. Due to their specific biological functions they have been proposed as biomarkers for various diseases and as optimal candidates for therapeutic applications. Despite their extreme biological relevance, their mechanisms of interaction with the membranes of recipient cells are still hotly debated. Here, we propose a multiscale investigation based on atomic force microscopy, small angle X-ray scattering, small angle neutron scattering and neutron reflectometry to reveal structure-function correlations of purified EVs in interaction with model membrane systems of variable complex compositions and to spot the role of different membrane phases on the vesicle internalization routes. Our analysis reveals strong interactions of EVs with the model membranes and preferentially with the borders of protruding phase domains. Moreover, we found that upon vesicle breaking on the model membrane surface, the biomolecules carried by/on EVs diffuse with different kinetics rates, in a process distinct from simple fusion. The biophysical platform proposed here has clear implications on the modulation of EV internalization routes by targeting specific domains at the plasma cell membrane and, as a consequence, on EV-based therapies.

Structure, self-assembly, and properties of a truncated reflectin variant.

Naturally occurring and recombinant protein-based materials are frequently employed for the study of fundamental biological processes and are often leveraged for applications in areas as diverse as electronics, optics, bioengineering, medicine, and even fashion. Within this context, unique structural proteins known as reflectins have recently attracted substantial attention due to their key roles in the fascinating color-changing capabilities of cephalopods and their technological potential as biophotonic and bioelectronic materials. However, progress toward understanding reflectins has been hindered by their atypical aromatic and charged residue-enriched sequences, extreme sensitivities to subtle changes in environmental conditions, and well-known propensities for aggregation. Herein, we elucidate the structure of a reflectin variant at the molecular level, demonstrate a straightforward mechanical agitation-based methodology for controlling this variant's hierarchical assembly, and establish a direct correlation between the protein's structural characteristics and intrinsic optical properties. Altogether, our findings address multiple challenges associated with the development of reflectins as materials, furnish molecular-level insight into the mechanistic underpinnings of cephalopod skin cells' color-changing functionalities, and may inform new research directions across biochemistry, cellular biology, bioengineering, and optics.

Behavioral plasticity and gene regulation in the brain during an intermittent ethanol exposure in adult zebrafish population.

Ethanol consumption is correlated with different neurobiological and behavioral impairments. Acute and chronic exposure to this drug is associated with alterations in the regulation of the mesolimbic dopaminergic system as well as with transcriptional modulation of other receptors in the central nervous system and can unleash seeking behavior or behavioral adaptations and phenotypes such as loss of control, dependence and tolerance. In the present work, we characterized the chronological effects of acute and chronic intermittent exposure to ethanol (1% v/v) in an adult zebrafish population (Danio rerio). During sixteen days of ethanol exposure, we associated the neuromodulation of target genes (drd1, drd2, gabra2a, gabbr1a, gabbr1b) in the central nervous system with behavioral parameters, assessed by social preference, antipredatory capacity and anxiety-like analysis. Transcriptional and behavioral data were collected in days 0, 1, 4, 8, 12 and 16, after ethanol exposure. In days 1 and 4, ethanol exposure increased exploratory behavior regardless of the risk involved (less time spent close to conspecifics and lower avoidance reaction to predator). Along with the reduction of drd2, grin1a and gabra2a transcription seen in the same days, these results suggest an anxiolytic effect of acute ethanol exposure. Interestingly, in days 8, 12 and 16, an attenuation of the behavioral effects was observed. The social preference, antipredatory behavior, perception and exploration parameters were reconstituted. This behavioral re-establishment, accompanied by the increase in drd1, drd2 and gabbr1a transcription in the 8th day could be an indicative of an adaptation to chronic exposure to ethanol. The modulation of drd2 gene combined with the behavioral characterization observed in the study suggests this signalling pathway as a key participant in the phenotypic outcomes of a long-term chronic exposure to ethanol. Lastly, our results reaffirm the ethanol deleterious impacts in perception, ability to respond to adverse stimuli and in anxiety-like behavior.

The boundary lipid around DMPC-spanning influenza A M2 transmembrane domain channels: Its structure and potential for drug accommodation.

We have investigated the perturbation of influenza A M2TM in DMPC bilayers. We have shown that (a) DSC and SAXS detect changes in membrane organization caused by small changes (micromolar) in M2TM or aminoadamantane concentration and aminoadamantane structure, by comparison of amantadine and spiro[pyrrolidine-2,2'-adamantane] (AK13), (b) that WAXS and MD can suggest details of ligand topology. DSC and SAXS show that at a low M2TM micromolar concentration in DPMC bilayers, two lipid domains are observed, which likely correspond to M2TM boundary lipids and bulk-like lipids. At higher M2TM concentrations, one domain only is identified, which constitutes essentially all of the lipid molecules behaving as boundary lipids. According to SAXS, WAXS, and DSC in the absence of M2TM, both aminoadamantane drugs exert a similar perturbing effect on the bilayer at low concentrations. At the same concentrations of the drug when M2TM is present, amantadine and, to a lesser extent, AK13 cause, according to WAXS, a significant disordering of chain-stacking, which also leads to the formation of two lipid domains. This effect is likely due, according to MD simulations, to the preference of the more lipophilic AK13 to locate closer to the lateral surfaces of M2TM when compared to amantadine, which forms stronger ionic interactions with phosphate groups. The preference of AK13 to concentrate inside the lipid bilayer close to the exterior of the hydrophobic M2TM helices may contribute to its higher binding affinity compared to amantadine.

Comparative Perturbation Effects Exerted by the Influenza A M2 WT Protein Inhibitors Amantadine and the Spiro[pyrrolidine-2,2'-adamantane] Variant AK13 to Membrane Bilayers Studied Using Biophysical Experiments and Molecular Dynamics Simulations.

Aminoadamantane drugs are lipophilic amines that block the membrane-embedded influenza A M2 WT (wild type) ion channel protein. The comparative effects of amantadine ( Amt) and its synthetic spiro[pyrrolidine-2,2'-adamantane] (AK13) analogue in dimyristoylphosphatidylcholine (DMPC) bilayers were studied using a combination of experimental biophysical methods, differential scanning calorimetry (DSC), X-ray diffraction, solid-state NMR (ssNMR) spectroscopy, and molecular dynamics (MD) simulations. All three experimental methods pointed out that the two analogues perturbed drastically the DMPC bilayers with AK13 to be more effective at high concentrations. AK13 was tolerated in lipid bilayers at very high concentrations, while Amt was crystallized. This is an important consideration in the formulations of drugs as it designates a limitation of Amt incorporation. MD simulations verify provided details about the strong interactions of the drugs in the interface region between phosphoglycerol backbone and lipophilic segments. The two drugs form hydrogen bonding with both water and sn-2 carbonyls in their amine form or water and phosphate oxygens in their ammonium form. Such localization of the drugs explains the DMPC bilayers reorientation and their strong perturbing effect evidenced by all biophysical methodologies applied.

Periodic Mesoporous Organosilica Films with a Tunable Steady-State Mesophase.

The mesophase formation in spin-coated periodic mesoporous organosilica (PMO) films aged at a controlled ambient humidity is investigated by time-resolved grazing-incidence small-angle X-ray scattering (GISAXS). The investigation demonstrates the existence of a tunable steady state in PMO spin-coated films. Thus, a film deposited at a relative humidity of 20 % has a lamellar mesophase, whereas a subsequent increase to 70 % leads to a phase transformation resulting in a P63 /mmc space group. On the other hand, an increase of the surfactant to organosilica molar ratio of between 0.26 and 0.31 results in films which at 70 % humidity form a mix of 2D and 3D hexagonal phases. A further increase of the surfactant amount leads to films with a 2D hexagonal phase. Finally, the different mesophases observed as a function of the solution aging emphasize the importance of the degree of polycondensation of the organosilica oligomers.