Evaluating xanthochromia in the diagnosis of subarachnoid haemorrhage in Scotland in the Era of modern computed tomography.

AIM: Cerebrospinal fluid (CSF) analysis for xanthochromia is routinely used to exclude subarachnoid haemorrhage (SAH). In this study, we evaluated the sensitivity and specificity of xanthochromia (by NEQAS-spectrophotometry) in routine clinical practice in three acute hospitals, in patients with suspected SAH. We explored whether including CSF red cell count (RCC) with xanthochromia improved diagnostic accuracy. METHODS: In this retrospective analysis, all xanthochromia results were assessed over three consecutive years. Clinical information and Registry data were analysed to find all patients diagnosed with SAH. We correlated xanthochromia data with clinical and radiological findings. RESULTS: There were 1761 xanthochromia performed. Of these, 26 (1.5%) were positive, 1624 (92%) negative and 72 (4.1%) were inconclusive. Of the 26 tests that were positive, 9 (35%) had confirmed SAH, 17 (65%) were falsely positive, with no false negative tests in our series. Xanthochromia identified 6% of all SAH diagnosed in the study. Incorporating RCC <1000 with xanthochromia, reducing false positive tests by 38% and inconclusive test by 85%. CONCLUSION: The positive yield of xanthochromia is low but identified 6% of SAH. NEQAS-spectrophotometry is an excellent diagnostic method with 100% sensitivity, 99% specificity. Incorporating RCC markedly reduces false positive and inconclusive tests reducing need for further imaging.

Inverted Micelle-in-Micelle Configuration in Cationic/Carbohydrate Surfactant Mixtures.

Nuclear magnetic resonance is applied to investigate the relative positions and interactions between cationic and non-ionic carbohydrate-based surfactants in mixed micelles with D2 O as the solvent. This is accomplished by using relaxation measurements [spin-lattice (T1 ) and spin-spin (T2 ) analysis] and nuclear Overhauser effect spectroscopy (NOESY). This study focuses on the interactions of n-octyl ß-d-glucopyranoside (C8G1) and ß-d-xylopyranoside (C8X1) with the cationic surfactant hexadecyltrimethylammonium bromide (C16 TAB). Whereas the interactions between carbohydrate and cationic surfactants are thermodynamically favorable, the NOESY results suggest that both of the sugar head groups are located preferentially at the interior core of the mixed micelles, so that they are not directly exposed to the bulk solution. The more hydrophilic sugar headgroups of C8G1 have more mobility than sugar heads of C8X1 owing to increased hydration. Herein, an inverted carbohydrate configuration in mixed micelles is proposed for the first time and supported by fluorescence spectroscopy experiments. This inverted carbohydrate headgroup configuration would limit the use of these mixed surfactants when access to the carbohydrate headgroup is important, but may present new opportunities where the carbohydrate-rich core of the micelles can be exploited.

Lipid Pore-Filled Silica Thin-Film Membranes for Biomimetic Recovery of Dilute Carbohydrates.

Selectively permeable biological membranes containing lipophilic barriers inspire the design of biomimetic carrier-mediated membranes for aqueous solute separation. The recovery of glucose, which can reversibly bind to boronic acid (BA) carriers, is examined in lipid pore-filled silica thin-film composite membranes with accessible mesopores. The successful incorporation of lipids (1,2-dipalmitoyl-sn-glycero-3-phosphocholine, DPPC) and BA carriers (4-((N-Boc-amino)methyl)phenylboronic acid, BAMP-BA) in the pores of mesoporous silica (∼10 nm pore diameter) through evaporation deposition is verified by confocal microscopy and differential scanning calorimetry. In the absence of BA carriers, lipids confined inside the pores of silica thin films (∼200 nm thick) provide a factor of 14 increase in diffusive transport resistance to glucose, relative to traditional supported lipid bilayers formed by vesicle fusion on the porous surface. The addition of lipid-immobilized BAMP-BA (59 mol % in DPPC) facilitates the transport of glucose through the membrane; glucose flux increases from 45 × 10-8 to 225 × 10-8 mol/m2/s in the presence of BAMP-BA. Furthermore, the transport can be improved by environmental factors including pH gradient (to control the binding and release of glucose) and temperature (to adjust lipid bilayer fluidity). The successful development of biomimetic nanocomposite membranes demonstrated here is an important step toward the efficient dilute aqueous solute upgrading or separations, such as the processing of carbohydrates from lignocellulose hydrolysates, using engineered carrier/catalyst/support systems.

Pore orientation effects on the kinetics of mesostructure loss in surfactant templated titania thin films.

The mesostructure loss kinetics are measured as a function of the orientation of micelles in 2D hexagonal close packed (HCP) columnar mesostructured titania thin films using in situ grazing incidence small angle X-ray scattering (GISAXS). Complementary supporting information is provided by ex situ scanning electron microscopy. Pluronic surfactant P123 acts as the template to synthesize HCP structured titania thin films. When the glass substrates are modified with crosslinked P123, the micelles of the HCP mesophase align orthogonal to the films, whereas a mix of parallel and orthogonal alignment is found on unmodified glass. The rate of mesostructure loss of orthogonally oriented (o-HCP) thin films (∼60 nm thickness) prepared on modified substrate is consistently found to be less by a factor of 2.5 ± 0.35 than that measured for mixed orientation HCP films on unmodified substrates. The activation energy for mesostructure loss is only slightly greater for films on modified glass (155 ± 25 kJ mol(-1)) than on unmodified (128 kJ mol(-1)), which implies that the rate difference stems from a greater activation entropy for mesostructure loss in o-HCP titania films. Nearly perfect orthogonal orientation of micelles on modified surfaces contributes to the lower rate of mesostructure loss by supporting the anisotropic stresses that develop within the films during annealing due to continuous curing, sintering and crystallization into the anatase phase during high temperature calcination (>450 °C). Because the film thickness dictates the propagation of orientation throughout the films and the degree of confinement, thicker (∼250 nm) films cast onto P123-modified substrates have a much lower activation energy for mesostructure loss (89 ± 27 kJ mol(-1)) due to the mix of orientations found in the films. Thus, this kinetic study shows that thin P123-templated o-HCP titania films are not only better able to achieve good orthogonal alignment of the mesophase relative to thicker films or films on unmodified substrates, but that alignment of the mesophase in the films stabilizes the mesophase against thermally-induced mesostructure loss.

Auscultating heart and breath sounds through patients' gowns: who does this and does it matter?

BACKGROUND: Doctors are taught to auscultate with the stethoscope applied to the skin, but in practice may be seen applying the stethoscope to the gown. OBJECTIVES: To determine how often doctors auscultate heart and breath sounds through patients' gowns, and to assess the impact of this approach on the quality of the sounds heard. METHODS: A sample of doctors in the west of Scotland were sent an email in 2014 inviting them to answer an anonymous questionnaire about how they auscultated heart and breath sounds. Normal heart sounds from two subjects were recorded through skin, through skin and gown, and through skin, gown and dressing gown. These were played to doctors, unaware of the origin of each recording, who completed a questionnaire about the method and quality of the sounds they heard. RESULTS: 206 of 445 (46%) doctors completed the questionnaire. 124 (60%) stated that they listened to patients' heart sounds, and 156 (76%) to patients' breath sounds, through patients' gowns. Trainees were more likely to do this compared with consultants (OR 3.39, 95% CI 1.74 to 6.65). Doctors of all grades considered this practice affected the quality of the sounds heard. 32 doctors listened to the recorded heart sounds. 23 of the 64 (36%) skin and 23 of the 64 (36%) gown recordings were identified. The majority of doctors (74%) could not differentiate between skin or gown recordings, but could tell them apart from the double layer recordings (p=0.02). Trainees were more likely to hear artefactual added sounds (p=0.04). CONCLUSIONS: Many doctors listen to patients' heart and breath sounds through hospital gowns, at least occasionally. In a short test, most doctors could not distinguish between sounds heard through a gown or skin. Further work is needed to determine the impact of this approach to auscultation on the identification of murmurs and added sounds.

Effect of Pore Confinement of Ionic Liquids on Solute Diffusion within Mesoporous Silica Microparticles.

The transport properties of the ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) confined within silica microparticles with well-ordered, accessible mesopores (5.4 or 9 nm diameter) were investigated. [BMIM][PF6] confinement was confirmed by using differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. The transport properties of the confined IL were studied using the neutral and cationic fluorescent probes 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM) and rhodamine 6G, respectively, through fluorescence recovery after photobleaching (FRAP) in confocal microscopy. The diffusivity of DCM in 9 nm pores is 0.026 ± 0.0091 µm2/s, which is 2 orders of magnitude less than in the bulk ionic liquid. The pore size did not affect the diffusivity of DCM in unmodified silica nanopores. The diffusivity of the cationic probe is reduced by 63% relative to that of the neutral probe. Diffusivity is increased with water content, where equilibrium hydration of the system leads to a 37% increase in DCM diffusivity. The most dramatic impact on diffusivity was caused by tethering an IL-like methylimidazolium chloride group to the pores, which increased the pore hydrophobicity and resulted in 3-fold higher diffusivity of DCM compared to bare silica pores. Subsequent exchange of the chloride anion from the tethering group with PF6- decreased the diffusivity to half that of bare silica. The diffusion of probe molecules is affected most strongly by the pore wall effects on probe interactions rather than by the pore size itself, which suggests that understanding pore wall diffusion is critical to the design of nanoconfined ILs for separations, catalysis, and energy storage.

Cardiovascular Eligibility Criteria and Adverse Event Reporting in Combined Immune Checkpoint and VEGF Inhibitor Trials.

Background: Combination therapy with immune checkpoint inhibitors (ICIs) and vascular endothelial growth factor inhibitors (VEGFIs) has improved cancer outcomes and is increasingly used. These drug classes are associated with cardiovascular toxicities when used alone, but heterogeneity in trial design and reporting may limit knowledge of toxicities in patients receiving these in combination. Objectives: The aim of this study was to assess consistency and clarity in definitions and reporting of cardiovascular eligibility criteria, baseline characteristics, and cardiovascular adverse events in ICI and VEGFI combination trials. Methods: A scoping review was conducted of phase 2 to 4 randomized controlled trials of ICI and VEGFI combination therapy for solid tumors. Trial cardiovascular eligibility criteria and baseline cardiovascular characteristic reporting in trial publications was assessed, and cardiovascular adverse event definitions and reporting criteria were also examined. Results: Seventeen trials (N = 10,313; published 2018-2022) were included. There were multiple cardiovascular exclusion criteria in 15 trials. No primary trial publication reported baseline cardiovascular characteristics. Thirteen trials excluded patients with prior heart failure, myocardial infarction, hypertension, or stroke. There was heterogeneity in defining cardiovascular conditions. "Grade 1 to 4" cardiovascular adverse events were reported when incidence was ≥5% to 25% in 15 trials. Incident hypertension was recorded in all trials, but other cardiovascular events were not consistently reported. No trial specifically noted the absence of cardiovascular events. Conclusions: In ICI and VEGFI combination trials, there is heterogeneity in cardiovascular exclusion criteria, reporting of baseline characteristics, and reporting of cardiovascular adverse events. This limits an optimal understanding of the incidence and severity of events relating to these combinations. Better standardization of these elements should be pursued. (Exclusions and Representation of Patients With Kidney Disease and Cardiovascular Disease in Drug Trials of the Novel Systemic Anti-Cancer Therapies VEGF-Signalling Pathway Inhibitors Alone or in Combination With Immune Checkpoint Inhibitors; CRD42022337942).

Arterial effects of anthracycline: structural and inflammatory assessments in non-human primates and lymphoma patients using 18F-FDG positron emission tomography.

Background: Anthracyclines, such as doxorubicin, are important anti-cancer therapies but are associated with arterial injury. Histopathological insights have been limited to small animal models and the role of inflammation in the arterial toxic effects of anthracycline is unclear in humans. Our aims were: 1) To evaluate aortic media fibrosis and injury in non-human primates treated with anthracyclines; 2) To assess the effect of anthracycline on aortic inflammation in patients treated for lymphoma. Methods: 1) African Green monkeys (AGM) received doxorubicin (30-60 mg/m2/biweekly IV, cumulative dose: 240 mg/m2). Blinded histopathologic analyses of collagen deposition and cell vacuolization in the ascending aorta were performed 15 weeks after the last doxorubicin dose and compared to 5 age- and gender-matched healthy, untreated AGMs. 2) Analysis of the thoracic aorta of patients with diffuse large B-cell lymphoma (DLBCL), at baseline and after doxorubicin exposure, was performed using 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) in this observational study. The primary outcome was change in maximal tissue-to-background ratio (TBRmax) of the thoracic aorta from baseline to their end-of-treatment clinical PET/CT. Results: In AGMs, doxorubicin exposure was associated with greater aortic fibrosis (collagen deposition: doxorubicin cohort 6.23±0.88% vs. controls 4.67±0.54%; p=0.01) and increased intracellular vacuolization (doxorubicin 66.3 ± 10.1 vs controls 11.5 ± 4.2 vacuoles/field, p<0.0001) than untreated controls.In 101 patients with DLBCL, there was no change in aortic TBRmax after anthracycline exposure (pre-doxorubicin TBRmax 1.46±0.16 vs post-doxorubicin TBRmax 1.44±0.14, p=0.14). The absence of change in TBRmax was consistent across all univariate analyses. Conclusions: In a large animal model, anthracycline exposure was associated with aortic fibrosis. In patients with lymphoma, anthracycline exposure was not associated with aortic inflammation.Further research is required to elucidate the mechanisms of anthracycline-related vascular harm.

DFT investigation of NH3 physisorption on CuSO4 impregnated SiO2.

In this quantum chemical investigation, NH(3) physisorption onto a model of copper sulfate impregnated silica is compared with pure silica and copper sulfate adsorbents. The physisorption process is modeled as direct binding of the NH(3) molecule to the adsorption site of the dry adsorbents and as displacement of a H(2)O molecule by NH(3) in the hydrated complexes. The surface of silica is represented by a hydroxyl group attached to a silsesquioxane cage, H(7)Si(8)O(12)(OH) and silica impregnated with CuSO(4) by the most stable configuration of the cluster containing a CuSO(4) ion pair placed adjacent to the silica cage. H(2)O is systematically added to the dehydrated adsorbents to investigate the role of water in NH(3) adsorption. Modeling hydrated environments of each type of adsorbent is focused on H(2)O molecules that directly coordinate with the active sites. The results indicate that the binding energy of adsorbing NH(3) onto the mixed adsorbent is greater than in pure silica. This enhanced binding in the mixed adsorbent is consistent with improved Brønsted acidity of the silanol in the presence of CuSO(4).

Density functional theory study of semiquinone radical anions of polychlorinated biphenyls in the syn- and anti-like conformation.

Polychlorinated biphenyls (PCBs) can be metabolized to reactive metabolites, such as PCB semiquinone radical anions (SQ(•-)), whose structure and role in PCB-induced toxicity are difficult to investigate due to their relative instability. The unrestricted UB3LYP/6-311G** method was used to investigate several molecular descriptors of the syn- and anti-like conformation of SQs(•-). The bond lengths and angles of the quinone moiety of the SQs(•-) were in between the values reported for PCB quinones and hydroquinones, which is consistent with the distribution of the α highest occupied molecular orbital (α-HOMO). The dihedral angles between the two ring systems increased in the presence of ortho chlorine substituents and were smaller compared to the corresponding PCB quinones. The ground-state energies indicate that the anti-like conformation of the SQs(•-) is more favorable than the syn-like conformation. Molecular descriptor used for modeling of quantitative structure-activity relationships displayed some dependence on the conformation. These findings suggest that SQs(•-) in both the syn- and antilike conformation may interact differently with target molecules, which may have implications for the toxicity of PCBs.

Complexation of Lignin Dimers with ß-Cyclodextrin and Binding Stability Analysis by ESI-MS, Isothermal Titration Calorimetry, and Molecular Dynamics Simulations.

Lignin derived from lignocellulosic biomass is the largest source of renewable bioaromatics present on earth and requires environmentally sustainable separation strategies to selectively obtain high-value degradation products. Applications of supramolecular interactions have the potential to isolate lignin compounds from biomass degradation fractions by the formation of variable inclusion complexes with cyclodextrins (CDs). CDs are commonly used as selective adsorbents for many applications and can capture guest molecules in their internal hydrophobic cavity. The strength of supramolecular interactions between CDs and lignin model compounds that represent potential lignocellulosic biomass degradation products can be characterized by assessing the thermodynamics of binding stability. Consequently, the inclusion interactions of ß-CD and lignin model compounds G-(ß-O-4')-G, G-(ß-O-4')-truncG (guaiacylglycerol-ß-guaiacyl ether), and G-(ß-ß')-G (pinoresinol) were investigated empirically by electrospray ionization mass spectrometry and isothermal titration calorimetry, complemented by molecular dynamics (MD) simulations. Empirical results indicate that there are substantial differences in binding stability dependent on the linkage type. The lignin model ß-ß' dimer showed more potential bound states including 1:1, 2:1, and 1:2 (guest:host) complexation and, based on binding stability determinations, was consistently the most energetically favorable guest. Empirical results are supported by MD simulations that reveal that the capture of G-(ß-ß')-G by ß-CD is promising with a 66% probability of being bound for G-(ß-O-4')-truncG compared to 88% for G-(ß-ß')-G (unbiased distance trajectory and explicit counting of bound states). These outcomes indicate CDs as a promising material to assist in separations of lignin oligomers from heterogeneous mixtures for the development of environmentally sustainable isolations of lignin compounds from biomass fractions.

International Hand Function Study Following Distal Radial Access: The RATATOUILLE Study.

BACKGROUND: Distal radial access (DRA) has been proposed to improve procedure ergonomics and favor radial artery patency. Although promising data, nothing is known on evolving hand function after DRA. OBJECTIVES: This study sought to comprehensively evaluate hand function in patients undergoing DRA. METHODS: Real-world patients undergoing DRA undertook a thorough multimodality assessment of hand function implementing multidomain questionnaires (Disabilities of the Arm, Shoulder and Hand and Levine-Katz), and motor (pinch grip test) and sensory (Semmes-Weinstein monofilaments test) examinations of both hands. All assessments were performed at preprocedural baseline and planned at 1-, 6-, and 12-month follow-up (FU). Adverse clinical and procedural events were documented too. RESULTS: Data of 313 patients (220 men, age 66 ± 10 years) from 9 international centers were analyzed. The Disabilities of the Arm, Shoulder and Hand and the Levine-Katz scores slightly improved from baseline to FU (P = 0.008 and P = 0.029, respectively). Pinch strength mildly improved from baseline to FU (P < 0.001 for both the left and right hands). Similarly, touch pressure threshold appeared to faintly improve in both the left and right hands (P < 0.012 for all the sites). For both motor and sensory function tests, comparable findings were found for the DRA hand and the contralateral one, with no significant differences between them. Repeated assessment of all tests over all FU time points similarly showed lack of worsening hand function. Access-related adverse events included 19 harmless bleedings and 3 forearm radial artery and 3 distal radial artery occlusions. None affected hand function at FU. CONCLUSIONS: In a systematic multidimensional assessment, DRA was not associated with hand function impairment. Moreover, DRA emerges as a safe alternative vascular access.

Strategy for Conjugating Oligopeptides to Mesoporous Silica Nanoparticles Using Diazirine-Based Heterobifunctional Linkers.

Successful strategies for the attachment of oligopeptides to mesoporous silica with pores large enough to load biomolecules should utilize the high surface area of pores to provide an accessible, protective environment. A two-step oligopeptide functionalization strategy is examined here using diazirine-based heterobifunctional linkers. Mesoporous silica nanoparticles (MSNPs) with average pore diameter of ~8 nm and surface area of ~730 m2/g were synthesized and amine-functionalized. Tetrapeptides Gly-Gly-Gly-Gly (GGGG) and Arg-Ser-Ser-Val (RSSV), and a peptide comprised of four copies of RSSV (4RSSV), were covalently attached via their N-terminus to the amine groups on the particle surface by a heterobifunctional linker, sulfo-succinimidyl 6-(4,4'-azipentanamido)hexanoate (sulfo-NHS-LC-diazirine, or SNLD). SNLD consists of an amine-reactive NHS ester group and UV-activable diazirine group, providing precise control over the sequence of attachment steps. Attachment efficiency of RSSV was measured using fluorescein isothiocyanate (FITC)-tagged RSSV (RSSV-FITC). TGA analysis shows similar efficiency (0.29, 0.31 and 0.26 mol peptide/mol amine, respectively) for 4G, RSSV and 4RSSV, suggesting a generalizable method of peptide conjugation. The technique developed here for the conjugation of peptides to MSNPs provides for their attachment in pores and can be translated to selective peptide-based separation and concentration of therapeutics from aqueous process and waste streams.

Hierarchically porous titania thin film prepared by controlled phase separation and surfactant templating.

Poly(propylene glycol) (PPG) of moderately high molecular weight (M(n) = 3500 Da) exhibits amphibious behavior in aqueous solution in that it is hydrophilic at low temperature but hydrophobic at high temperature. This property is utilized to generate porous titania thin films with a hierarchical structure consisting of macroporous voids/cracks in films with mesoporous walls. The smaller mesopores result from the self-assembly of the Pluronic block copolymer P123 to form micellar templates in well-ordered arrays with hexagonal symmetry. The larger pores are generated from the phase separation of PPG during aging of the films. The PPG acts to a limited degree as a swelling agent for the P123 micelles, but because the films are aged at a low temperature where PPG is hydrophilic, much of the PPG remains in the polar titania phase. Upon heating, the PPG phase separates to form randomly dispersed, large pores throughout the film while retaining the ordered mesoporous P123-templated structure in the matrix of the material. TEM and SEM imaging confirm that calcined titania thin films have interconnected hierarchical porous structures consisting of ordered mesopores 4-12 nm in diameter and macroporous voids >100 nm in size. The density and size of the voids increase as more PPG is added to the films.

Mechanism of Mesoporous Silica Nanoparticle Interaction with Hairy Root Cultures during Nanoharvesting of Biomolecules.

Cellular uptake and expulsion mechanisms of engineered mesoporous silica nanoparticles (MSNPs) are important in their design for novel biomolecule isolation and delivery applications such as nanoharvesting, defined as using nanocarriers to transport and isolate valuable therapeutics (secondary metabolites) out of living plant organ cultures (e.g., hairy roots). Here, temperature-dependent MSNP uptake and recovery processes in hairy roots are examined as a function of surface chemistry. MSNP uptake into hairy roots and time-dependent expulsion are quantified using Ti content (present for biomolecule binding) and fluorescence spectroscopy of fluorescently tagged MSNPs, respectively. The results suggest that functionalization and surface charge (regulated by amine group attachment) play the biggest role in the effectiveness of uptake and recovery. Comparison of MSNP interactions with hairy roots at 4 and 23 °C shows that weakly charged MSNPs functionalized only with Ti are taken up and expelled by thermally activated mechanisms, while amine-modified positively charged particles are taken up and expelled mainly by direct penetration of cell walls. Amine-functionalized MSNPs move spontaneously in and out of plant cells by dynamic exchange with a residence time of 20 ± 5 min, suggesting promise as a biomolecule nanoharvesting platform for plant organ cultures.

Interaction of lignin dimers with model cell membranes: A quartz crystal microbalance and molecular dynamics simulation study.

A study of the interaction between cell membranes and small molecules derived from lignin, a protective phenolic biopolymer found in vascular plants, is crucial for identifying their potential as pharmacological and toxicological agents. In this work, the interactions of model cell membranes [supported 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) lipid bilayers] are compared for three ßO4 dimers of coniferyl alcohol (G lignin monomer): guaiacylglycerol guaiacol ester with a hydroxypropenyl (HOC3H4-) tail (G-ßO4'-G), a truncated GG dimer without HOC3H4- (G-ßO4'-truncG), and a benzylated GG dimer (benzG-ßO4'-G). The uptake of the lignin dimers (per mass of lipid) and the energy dissipation (a measure of bilayer disorder) are higher for benzG-ßO4'-G and G-ßO4'-truncG than those for G-ßO4'-G in the gel-phase DPPC bilayer, as measured using quartz crystal microbalance with dissipation (QCM-D). A similar uptake of G-ßO4'-truncG is observed for a fluid-phase bilayer of 1,2-dioleoyl-sn-glycero-3-phosphocholine, suggesting that the effect of the bilayer phase on dimer uptake is minimal. The effects of increasing lignin dimer concentration are examined through an analysis of density profiles, potential of mean force curves, lipid order parameters, and bilayer area compressibilities (disorder) in the lipid bilayers obtained from molecular dynamics simulations. Dimer distributions and potentials of mean force indicate that the penetration into bilayers is higher for benzG-ßO4'-G and G-ßO4'-truncG than that for G-ßO4'-G, consistent with the QCM-D results. Increased lipid tail disorder due to dimer penetration leads to a thinning and softening of the bilayers. Minor differences in the structure of lignin derivatives (such as truncating the hydroxypropenyl tail) have significant impacts on their ability to penetrate lipid bilayers.

Relating Mobility of dsRNA in Nanoporous Silica Particles to Loading and Release Behavior.

Nanoparticle delivery of polynucleic acids traditionally relies on the modulation of surface interactions to achieve loading and release. This work investigates the additional role of confinement in mobility of dsRNA (84 and 282 base pair (bp) sequences of Spodoptera frugiperda) as a function of silica nanopore size (nonporous, 3.9, 8.0, and 11.3 nm). Amine-functionalized nanoporous silica microspheres (NPSMs, ∼10 µm) are used to directly visualize the loading and exchange of fluorescently labeled dsRNA. Porous particles are fully accessible to both lengths of dsRNA by passive diffusion, except for 282 bp dsRNA in 3.9 nm pores. The stiffness of dsRNA suggests that encapsulation occurs by threading into nanopores, which is inhibited when the ratio of dsRNA length to pore size is large. The mobility of dsRNA at the surface and in the core of NPSMs, as measured by fluorescence recovery after photobleaching, is similar. The mobility increases with pore size (from 0.0002 to 0.001 µm2/s for 84 bp dsRNA in 3.9-11.3 nm pores) and decreases with the length of dsRNA. However, when the dsRNA is unable to load into the pores (on nonporous particles and for 282 bp dsRNA in 3.9 nm pores), surface mobility is not detectable. The pore structure appears to serve as a "source" to provide a mobile network of dsRNA at the particle surface. The importance of mobility is demonstrated by exchange experiments, where NPSMs saturated with mobile dsRNA can exchange dsRNA with the surrounding solution, while immobile dsRNA is not exchanged. These results indicate that nanoparticle synthesis techniques that provide pores large enough to take up polynucleic acids internally (and not simply on the external surface of the particle) can be harnessed to design polynucleic acid/nanoporous silica combinations for controlled mobility as a path forward toward effective nanocarriers.

Determination of 29Si-1H spin-spin coupling constants in organoalkoxysilanes with nontrivial scalar coupling patterns.

Application of polarization transfer techniques such as DEPT and INEPT in (29)Si NMR investigation of bridged silane polymerization requires knowledge of indirect (29)Si-(1)H scalar coupling constants in the silane system. However, the fully coupled (29)Si NMR spectra of these molecules, specifically those containing ethylene bridging groups, are too complicated to measure the coupling constants directly by visual inspection. This is because unlike hydrocarbon systems where one-bond proton-carbon coupling constants exceed other coupling constants by an order of magnitude, in silanes the closest proton-silicon pairs are separated by two bonds and all coupling coefficients (both homonuclear and heteronuclear) are of similar magnitude. In these systems, theoretical tools are required to interpret the spectra of even simple molecules. Here, we determine density functional theory estimates of (29)Si-(1)H scalar coupling constants and use these along with homonuclear coupling constant estimates to resolve the nontrivial nature of these spectra. We also report a Karplus equation consistent with the dihedral angle dependence of the three-bond homo- and heteronuclear coupling in the ethylene bridge. By thermal averaging of DFT coupling constants, a good initial guess of the coupled (29)Si spectral pattern is made, which is easily refined by curve fitting to determine estimates of all coupling constants in the system.

DFT calculations of indirect 29Si-1H spin-spin coupling constants in organoalkoxysilanes.

The performance of four basis sets (6-311+G(2d,p), IGLO-III, cc-PVTZ, and 6-31G) is evaluated in order to find a quantum mechanical technique that can be used to accurately estimate (29)Si-(1)H spin-spin coupling constants in organoalkoxysilanes. The 6-31G basis set with the B3LYP functional is found to be an accurate, efficient, and cost-effective density functional theory method for predicting spin-spin coupling constants of organoalkoxysilanes. Knowledge of these scalar coupling constants and their dependence on structural variations is important to be able to fine-tune NMR experiments that rely on polarization transfer among nuclei, such as (29)Si distortionless enhancement by polarization transfer (DEPT). The effects of size and the number of unhydrolyzable alkyl groups attached to silicon and the effects of substitution of alkoxy groups with hydroxyl groups on (29)Si-(1)H spin-spin coupling constants are investigated using this DFT method. The results show that the predicted scalar coupling between silicon and organic groups depends weakly on the degree of hydrolysis of the alkoxysilanes. The effectiveness of this method is also illustrated for the determination of spin-spin coupling constants in a species containing a siloxane bond.

Nanoharvesting of bioactive materials from living plant cultures using engineered silica nanoparticles.

Plant secondary metabolites are valuable therapeutics not readily synthesized by traditional chemistry techniques. Although their enrichment in plant cell cultures is possible following advances in biotechnology, conventional methods of recovery are destructive to the tissues. Nanoharvesting, in which nanoparticles are designed to bind and carry biomolecules out of living cells, offers continuous production of metabolites from plant cultures. Here, nanoharvesting of polyphenolic flavonoids, model plant-derived therapeutics, enriched in Solidago nemoralis hairy root cultures, is performed using engineered mesoporous silica nanoparticles (MSNPs, 165 nm diameter and 950 m2/g surface area) functionalized with both titanium dioxide (TiO2, 425 mg/g particles) for coordination binding sites, and amines (NH2, 145 mg/g particles) to promote cellular internalization. Intracellular uptake and localization of the nanoparticles (in Murashige and Skoog media) in hairy roots were confirmed by tagging the particles with rhodamine B isothiocyanate, incubating the particles with hairy roots, and quenching bulk fluorescence using trypan blue. Nanoharvesting of biologically active flavonoids was demonstrated by observing increased antiradical activity (using 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay) by nanoparticles after exposure to hairy roots (indicating general antioxidant activity), and by the displacement of the radio-ligand [3H]-methyllycaconitine from rat hippocampal nicotinic receptors by solutes recovered from nanoharvested particles (indicating pharmacological activity specific to S. nemoralis flavonoids). Post-nanoharvesting growth suggests that the roots are viable after nanoharvesting, and capable of continued flavonoid synthesis. These observations demonstrate the potential for using engineered nanostructured particles to facilitate continuous isolation of a broad range of biomolecules from living and functioning plant cultures.