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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,585 records · Page 88
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

MicroRNA-630 inhibits breast cancer progression by directly targeting BMI1

Highlights: • MiR-630 initiates apoptosis, blocks cell cycle progression and suppresses cell proliferation in breast cancer cells. • BMI1, a member of polycomb group family, is identified as a novel direct target of miR-630. • BMI1 mediates miR-630-suppressed breast cancer progression including apoptosis induction, cell cycle arrest, and proliferation inhibition. MicroRNAs (miRNAs) play critical roles in breast cancer cell biological processes, including proliferation and apoptosis by inhibiting the expression of their target genes. Herein, we reported that miR-630 overexpression initiates apoptosis, blocks cell cycle progression and suppresses cell proliferation in breast cancer cells. Furthermore, BMI1, a member of polycomb group family, was identified as a direct target of miR-630, and there was a negative correlation between the expression levels of BMI1 and miR-630 in human breast cancer samples. With a series of biology approaches, subsequently, we proved that BMI1 was a functional downstream target of miR-630 and mediated the property of miR-630-dependent inhibition of breast cancer progression. Taken together, these findings provide further evidence on the tumor-suppression function of miR-630 in breast cancer, and clarify BMI1 as a novel functional target gene of miR-630.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

mmu-miR-1963 negatively regulates the ameloblast differentiation of LS8 cell line by directly targeting Smoc2 3’UTR

Highlights: • mmu-miR-1963 could downregulate the expression of Smoc2 by binding to its 3’UTR. • Smoc2 could promote the amelogenic differentiation of LS8. • mmu-miR-1963 inhibits the ameloblast differentiation of LS8 via Smoc2. RUNX2 is a key regulator of osteogenic differentiation and odontoblastic differentiation. RUNX2 mutations could cause Cleidocranial dysplasia (CCD; OMIM119600), which is featured by abnormal development of bone and teeth. By using microRNA array, we identified a large number of microRNAs that showed different expression between wild-type Runx2 group and mutant groups. The aim of this study is to find out the effect of mmu-miR-1963, which was downregulated in all mutant Runx2 groups, on the ameloblast differentiation of LS8 cells. qPCR and Western Blot results showed the suppressive effect of mmu-miR-1963 on ameloblast differentiation of LS8 cell line. We further confirmed Smoc2 as one direct target of mmu-miR-1963. For the first time, we showed that mmu-miR-1963 could regulate the ameloblast differentiation of LS8 by targeting Smoc2. This study suggests the suppressive role of mmu-miR-1963 on ameloblast differentiation of LS8 via directly targeting the 3’UTR of Smoc2. We also demonstrated that Smoc2 itself could promote the ameloblast differentiation of LS8 for the first time. Our results indicate a novel explanation to the enamel hypoplasia phenotype in part of CCD patients.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

MiR-124 induces autophagy-related cell death in cholangiocarcinoma cells through direct targeting of the EZH2–STAT3 signaling axis

Cholangiocarcinoma (CCA) is a lethal cancer associated with chronic inflammation that has increased in prevalence in recent decades. The dysregulated expression of microRNAs (miRNAs) has been detected in various types of malignancies, and depending on the target genes this can result in miRNAs functioning as tumor suppressors or oncogenes. In this study, we investigated the role of miR-124 in cholangiocarcinoma (CCA) and found that its expression was significantly downregulated in the tumor tissue of patients and in CCA cell lines. Our results provided evidence that miR-124 induces apoptotic cell death and triggers the autophagic flux in CCA cells. EZH2 and STAT3 were identified as direct targets of miR-124. The effect of miR-124 on EZH2 expression in CCA cells was evaluated using cell transfection, xenotransplantation into nude mice and a luciferase reporter assay. Silencing of EZH2 restored the effects of miR-124, whereas overexpression of EZH2 abrogated the effects of miR-124. Silencing of Beclin1 or ATG5 abrogated the effects of miR-124 or siEZH2. In vivo, overexpression of miR-124 dramatically induced autophagy-related cell death and suppressed tumorigenicity. Taken together, our findings indicated that downregulation of miR-124 expression was associated with disease progression in human CCA and we revealed that miR-124 exerts a tumor suppressive function in CCA by inducing autophagy-related cell death via direct targeting of the EZH2–STAT3 signaling axis.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

CCL20, a direct-acting pro-angiogenic chemokine induced by hepatitis C virus (HCV): Potential role in HCV-related liver cancer

The CCL20/CCR6 chemokine/receptor axis has previously been shown to contribute to the initiation and progression of hepatocellular carcinoma (HCC) through the recruitment of CCR6-positive leukocytes to the tumor microenvironment. In particular, high serum levels of CCL20 are reported in patients with HCC induced by the hepatitis C virus (HCV). A potential non-immune role for the CCL20/CCR6 axis in HCC development has not yet been investigated. Microarray analysis (Benkheil et al., paper submitted for publication), revealed that CCL20 is highly upregulated in hepatoma cells infected with HCV compared with non-infected hepatoma cells. To determine the role of the CCL20/CCR6 axis in HCV-related HCC, we first explored which cell populations express CCR6 in human liver tissue with chronic disease or HCC. Immunohistochemical (IHC) analysis revealed that CCR6 is present on endothelial cells (ECs) of portal blood vessels in livers with chronic HCV infection and in HCV- and alcoholic-HCC tissue. In addition, we found CCR6 to be expressed on primary macrovascular (HUVECs) and microvascular ECs (HMVEC-ds) where it co-expressed with the endothelial marker CD31. In vitro angiogenesis experiments revealed that CCL20 is a direct pro-angiogenic molecule that induces EC invasion, sprouting and migration through CCR6. Moreover, using the angiogenesis matrigel plug assay in immunodeficient NMRI-nu mice, we clearly showed that CCL20 induces blood vessel formation, by attracting CCR6-positive ECs. Finally, we demonstrated that HCV-induced CCL20 protein expression and secretion in hepatoma cells could be abolished by antiviral treatment, indicating that CCL20 expression is dependent on HCV replication. In contrast to HCV, HBV-infection resulted in a decreased expression of CCL20, implying a virus-specific effect. Taken together, we identified HCV-induced CCL20 as a direct pro-angiogenic factor that acts on endothelial CCR6. These results suggest that the CCL20/CCR6 axis contributes to hepatic angiogenesis, promoting the hypervascular state of HCV-HCC.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Glioblastoma cell migration is directed by electrical signals

Electric field (EF) directed cell migration (electrotaxis) is known to occur in glioblastoma multiforme (GBM) and neural stem cells, with key signalling pathways frequently dysregulated in GBM. One such pathway is EGFR/PI3K/Akt, which is down-regulated by peroxisome proliferator activated receptor gamma (PPARγ) agonists. We investigated the effect of electric fields on primary differentiated and glioma stem cell (GSCs) migration, finding opposing preferences for anodal and cathodal migration, respectively. We next sought to determine whether chemically disrupting Akt through PTEN upregulation with the PPARγ agonist, pioglitazone, would modulate electrotaxis of these cells. We found that directed cell migration was significantly inhibited with the addition of pioglitazone in both differentiated GBM and GSCs subtypes. Western blot analysis did not demonstrate any change in PPARγ expression with and without exposure to EF. In summary we demonstrate opposing EF responses in primary GBM differentiated cells and GSCs can be inhibited chemically by pioglitazone, implicating GBM EF modulation as a potential target in preventing tumour recurrence.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Clustering instabilities in sedimenting fluid–solid systems: critical assessment of kinetic-theory-based predictions using direct numerical simulation data

In this paper the quantitative and qualitative ability of a kinetic-theory-based two-fluid model (KT-TFM) is assessed in a state of fully periodic sedimentation (fluidization), with a focus on statistically steady, unstable (clustered) states. The accuracy of KT-TFM predictions is evaluated via direct comparison to direct numerical simulation (DNS) data. The KT-TFM and DNS results span a rather wide parameter space: mean-flow Reynolds numbers on the order of 1 and 10, mean solid volume fractions from 0.1 to 0.4, solid-to-fluid density ratios from 10 to 1000 and elastic and moderately inelastic (restitution coefficient of 0.9) conditions. Data from both KT-TFM and DNS display a rich variety of statistically steady yet unstable structures (clusters). Instantaneous snapshots of KT-TFM and DNS demonstrate remarkable qualitative agreement. This qualitative agreement is quantified by calculating the critical density ratio at which the structure transitions from a chaotic, dynamic state to a regular, plug-flow state, with good overall comparisons. Further quantitative assessments of mean and fluctuating velocities show good agreement at high density ratios but weaker agreement at intermediate to low density ratios depending on the mean-flow Reynolds numbers and solid fractions. Deviations of the KT-TFM results from the DNS data were traced to a breakdown in one of the underlying assumptions of the kinetic theory derivation: high thermal Stokes number. Surprisingly, however, even though the low Knudsen number assumption, also associated with the kinetic theory derivation, is violated throughout most of the parameter space, it does not seem to affect the good quantitative accuracy of KT-TFM simulations.

42 ENGINEERING↗
DOE OSTI2018

A direct comparison of particle-resolved and point-particle methods in decaying turbulence

We use particle-resolved direct numerical simulation (PR-DNS) as a model-free physics-based numerical approach to validate particle acceleration modelling in gas-solid suspensions. To isolate the effect of the particle acceleration model, we focus on point-particle direct numerical simulation (PP-DNS) of a collision-free dilute suspension with solid-phase volume fraction $\unicode[STIX]{x1D719}=0.001$ in a decaying isotropic turbulent particle-laden flow. The particle diameter $d_{p}$ in the suspension is chosen to be the same as the initial Kolmogorov length scale $\unicode[STIX]{x1D702}_{0}$ ( $d_{p}/\unicode[STIX]{x1D702}_{0}=1$ ) in order to overlap with the regime where PP-DNS is valid. We assess the point-particle acceleration model for two different particle Stokes numbers, $St_{\unicode[STIX]{x1D702}}=1$ and 100. For the high Stokes number case, the Stokes drag model for particle acceleration under-predicts the true particle acceleration. In addition, second moment quantities which play key roles in the physical evolution of the gas–solid suspension are not correctly captured. Considering finite Reynolds number corrections to the acceleration model improves the prediction of the particle acceleration probability density function and second moment statistics of the point-particle model compared with the particle-resolved simulation. We also find that accounting for the undisturbed fluid velocity in the acceleration model can be of greater importance than using the most appropriate acceleration model for a given physical problem.

Mechanics↗
DOE OSTI2019

A semi-Lagrangian direct-interaction closure of the spectra of isotropic variable-density turbulence

A study of variable-density homogeneous stationary isotropic turbulence based on the sparse direct-interaction perturbation (SDIP) and supporting direct numerical simulations (DNS) is presented. The non-solenoidal flow considered here is an example of turbulent mixing of gases with different densities. The spectral statistics of this type of flow are substantially more difficult to understand theoretically than those of the similar solenoidal flows. In the approach described here, the nonlinearly coupled velocity and scalar (which determine the density of the fluid) equations are expanded in terms of a normalised density ratio parameter. A new set of coupled integro-differential SDIP equations are derived and then solved numerically for the first-order correction to the incompressible equations in the variable-density expansion parameter. By adopting a regular expansion approach, one obtains leading-order corrections that are universal and therefore interesting in their own right. The predictions are then compared with DNS of forced variable-density flow with different density contrasts. It is found that the velocity spectrum owing to variable density is indistinguishable from that of constant-density turbulence, as it is supported by a wealth of indirect experimental evidence, but the scalar spectra show significant deviations, and even loss of monotonicity, as a function of the type and strength of the large-scale source of the mixing. Furthermore, the analysis helps clarify what may be the proper approach to interpret the power spectrum of variable-density turbulence.

Mechanics↗
DOE OSTI2020

Roles of Alkali Metals and Ionic Networks in Directing the Formation of Anionic Metal–Organic Frameworks

Integrating different types of fundamental chemical interactions to direct the self-assembly processes and to control the dimension of the network formed by each type of interactions is a promising strategy to develop advanced functional materials. Here, the ionic interaction of alkali metals (Na, K, Cs) towards multi-functional 2,2’-disulfo-4,4’-oxydibenzoic acid is utilized in two solvent systems, aqueous-amide and uro-amide, to synthesize six novel anionic framework materials with dramatically different features and dimensionalities: (Na 3 [Zn 4 O(L 4- ) 3 (e-murea)(H 2 O) 3 ](H 2 N(CH 3 ) 2 +) 3 (CPM-s1), [Zn 4 O(L 4- ) 3 (DMF)]((NH 2 (CH 3 ) 2 +) 6 ) (CPM-s2), Na 6 [(Zn 2 OH 2 ) 3 (L 3- ) 6 ](H 2 O) 3 (CPM-s3), K 3 [Zn 2 (L 4- ) 2 ](H 2 N(CH 3 ) 2 +)(e-murea) 2 (H 2 O) 3 (CPM-s4), K 4 [Zn(L 3- ) 2 ](H 2 O) 2 (CPM-s5), and Cs 6 [Zn(L 4- ) 2 ](H 2 O) 2 (CPM-s6), L 4- = 2,2’-disulfo-4,4’-oxydibenzoate, DMF = N,N-dimethylformamide, e-murea = 1,3-dimethyl-1-2-imidazolidinone). In CPM-s1 to CPM-s6, the alkali-sulfonate ionic bonding networks transformed from 0D clusters with Na + to 1D chains and 2D sheets with K + , and 3D network with Cs + . These vastly differing ionic domains influenced the coordination modes and spatial arrangements of the metal-carboxylate linkers, which consequently, directed the dimensionality of the coordination networks from 3D with Na + to 1D with Cs + . CPM-s1 and CPM-s2, made from tetrameric Zn 4 O clusters are rare examples of anionic MOF-5-type structures. CPM-s3 features an unprecedented hexameric Zn 6 cluster. Even though a large portion of the charge-balancing cations in these materials would hamper hydrogen bonding networks, some of them still exhibit very high ionic conductivity (e.g. 1.25 x 10 -3 S cm -1 in CPM-s3), suggesting the potential of these materials as solid-state electrolytes.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Polymers for Extreme Conditions Designed Using Syntax-Directed Variational Autoencoders

We report the design/discovery of new materials is highly nontrivial owing to the near-infinite possibilities of material candidates and multiple required property/performance objectives. Thus, machine learning tools are now commonly employed to virtually screen material candidates with desired properties by learning a theoretical mapping from material-to-property space, referred to as the forward problem. However, this approach is inefficient and severely constrained by the candidates that the human imagination can conceive. Thus, in this work on polymers, we tackle the materials discovery challenge by solving the inverse problem: directly generating candidates that satisfy desired property/performance objectives. We utilize syntax-directed variational autoencoders (VAE) in tandem with Gaussian process regression (GPR) models to discover polymers expected to be robust under three extreme conditions: (1) high temperatures, (2) high electric field, and (3) high temperature and high electric field, useful for critical structural, electrical, and energy storage applications. This approach to learn from and augment) human ingenuity is general and can be extended to discover polymers with other targeted properties and performance measures.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Direct Synthesis of Six-Monolayer (1.9 nm) Thick Zinc-Blende CdSe Nanoplatelets Emitting at 585 nm

Here, quasi-two-dimensional semiconductor nanoplatelets (NPLs) have garnered widespread interest because of their uniquely narrow emission spectra and favorable characteristics for optical gain and lasing.(1–5) Strongly quantum confined along thickness, NPLs exhibit the electronic structure of quantum wells determined by their thickness, which can be controlled with atomic precision.(6–10) Among all semiconductor NPLs, CdSe NPLs are probably the most studied. So far, four kinds of CdSe NPLs, emitting at around 396 nm, 463 nm, 513m, and 553 nm, have been intensely investigated for almost a decade.(11–18) Despite some early confusions in identifying actual thicknesses of those NPLs, they have been successfully assigned to be 2-monolayer (2 ML) to 5-monolayer (5 ML) thickness by high-resolution TEM.(19) Here, nML thickness corresponds to n chalcogen layers sandwiched between n + 1 metal layers. Another kind of NPLs with 6MLs of CdSe, once briefly mentioned in 2013,(20) however, was not explored, likely because its synthesis proved hard to reproduce. The 6 ML CdSe NPLs can be prepared by the colloidal atomic layer deposition (c-ALD) method,(21) but there have been no reports on direct synthesis of 6 ML CdSe NPLs, and their direct synthesis has been in doubt as being difficult by traditional approaches.(22,23)

36 MATERIALS SCIENCE↗
DOE OSTI2020

Direct Conversion of Biomass Carbohydrates to Platform Chemicals: 5-Hydroxymethylfurfural (HMF) and Furfural

5-hydroxymethylfurfural (HMF) and furfural are promising platform molecules which can be converted to fuel intermediates and hydrocarbon fuels. Herein, one-step, direct conversion of the carbohydrates in never treated biomass to HMF and furfural in a microwave reactor was investigated. The influence of reaction temperature, time, feedstock, addition of Lewis and Bronsted acids, solvent and solvent to aqueous ratio were studied to find the optimum process conditions to maximize the yields of furfurals. The reaction conditions of 200 degrees C for 5 min with 33 mM HCl and 8 mM AlCl 3 using a dioxane/water (4:1) miscible solvent system were found to be the most conducive for direct dehydration of the glucan and hemicelluloses present in untreated poplar wood to furfural and HMF in yields of 91 and 69%, respectively. Furfural could be easily produced in yields greater than 80%, and once formed, it was found to be stable under the various process conditions explored. In contrast, HMF yields varied with both reaction time and temperature, as it readily underwent rehydration to levulinic acid in yields approaching 25-30% at increased reaction severity. The additions of both Bronsted (HCl) and Lewis (AlCl 3 ) acids in catalytic amounts, i.e., 33 and 8 mM, respectively, were required to maximize the yield of furfurals. Reactions were also performed on other feedstocks (corn stover, switchgrass, loblolly pine, and pure cellulose) to investigate the effect of feedstock type on furfurals yields. Results showed that HMF and furfural yields were primarily dependent on hexosan and pentosan loading regardless of the type of feedstock. In addition, biomass physical features, such as crystallinity or the presence of other biomass constituents, such as lignin, had little influence on furfurals yields.

09 BIOMASS FUELS↗
DOE OSTI2025

Seeding Advanced Treated Wastewater for Purposes of Direct Potable Reuse

Direct potable reuse (DPR) is a promising solution to address water scarcity. However, a better understanding of how introducing advanced treated water (ATW) affects microbial communities present in distribution systems is needed. Here, in this study, we measured changes to the microbial water quality in simulated distribution systems that were conditioned using treated, unimpaired surface water (SW) and then transitioned to ATW. In addition, we investigated whether adding a biological filtration step would seed the microbial community of the ATW and whether the influence would persist in the simulated distribution systems. We found that the bulk water in the ATW-fed distribution systems had lower cell counts and ATP concentrations and a distinct microbial community (based on 16S amplicon sequencing) compared to the SW-fed or the seeded ATW-fed systems. However, biofilm community composition and biomass remained consistent regardless of the feedwater. Increased microbial biomass and diversity were present in the seeded ATW, with several amplicon sequence variants identified as being introduced by the biological filter. Our results suggest that directly introducing ATW to distribution systems could disturb the existing microbial community. Preparing ATW for distribution via biological filtration may deliver more predictable and stable microbial water quality than introducing unseeded ATW.

16S↗
DOE OSTI2021

Multiscale Modeling of a Direct Nonoxidative Methane Dehydroaromatization Reactor with a Validated Model for Catalyst Deactivation

Due to the recent boom in shale gas production, aromatics production using direct nonoxidative methane dehydroaromatization (DHA) is being investigated extensively. However, due to rapid coke formation, catalysts in the nonoxidative methane DHA reactors get deactivated, which is one of the critical issues for the commercial success of the methane DHA process. In this paper, a model for catalyst deactivation is developed. Rate models for other DHA reactions are developed by considering the decrease in the catalyst activity with time. Due to the very fast coke formation rate on the fresh catalyst, there is coke formation immediately upon the introduction of the feed. Therefore, an algorithm is developed for estimation of the initial state of the reactor and the kinetic parameters by coupling an iterative direct substitution approach with an optimization approach. Transient experimental data from an in-house reactor are first reconciled and then used for developing the kinetic model including the coke formation model. Using the rate model, a dynamic, heterogeneous, multiscale reactor model with embedded heating is developed. Here, the model couples the catalyst pellet level model with a reactor level model. Impacts of temperature, L/D ratio, and scheduling of reactors on variability in conversion and yield with time are studied.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Direct Measurement of the Selective Microwave-Induced Heating of Agglomerates of Dipolar Molecules: The Origin of and Parameters Controlling a Microwave Specific Superheating Effect

Agglomerates of polar molecules in nonpolar solvents are selectively heated by microwave radiation. The magnitude of the selective heating was directly measured by using the temperature dependence of the intensities of the Stokes and anti-Stokes bands in the Raman spectra of p-nitroanisole (pNA) and mesitylene. Under dynamic heating conditions, a large apparent temperature difference (ΔT) of over 100 °C was observed between the polar pNA solute and the nonpolar mesitylene solvent. This represents the first direct measurement of the selective microwave heating process. The magnitude of the selective microwave heating was affected by the properties of the agglomerated pNA. As the concentration of the pNA increases, the magnitude of the selective heating of the pNA was observed to decrease. This is explained by the tendency of the pNA dipoles to orient in an antiparallel fashion in the aggregates as measured by the Kirkwood g value, which decreased with increasing concentration. This effect reduces the net dipole moment of the agglomerates, which decreases the microwave absorption. After the radiation was terminated, the effective temperature of the dipolar molecules returned slowly to that of the medium. The slow heat transfer was modeled successfully by treating the solutions as a biphasic solvent/solute system. Based on modeling and the fact that the agglomerate can be heated above the boiling temperature of the solvent, an insulating layer of solvent vapor is suggested to form around the heated agglomerate, slowing convective heat transfer out of the agglomerate. Furthermore, this is an effect unique to microwave heating.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Complex-Valued Intermolecular Coupling Enables Directional Exciton Transport in Excitonic Circuits

Molecular systems capable of directing the flow of excitons are key to the development and optimization of optoelectronic materials. The transport of excitons across multiple molecules is governed by an intermolecular electronic coupling network. In this article, we consider the effects of complex-valued intermolecular electronic coupling on exciton transport. Here, we present a molecular motif capable of generating complex-valued coupling under excitation with circularly polarized light. We use theoretical modeling and simulation to illustrate how complex coupling can be leveraged to drive the rotational flux of excitons in cyclic molecular networks and direct the exciton population in branched molecular networks.

chromophores↗
DOE OSTI2018

Insights on the Alumina–Water Interface Structure by Direct Comparison of Density Functional Simulations with X-ray Reflectivity

Density functional theory molecular dynamics (DFT-MD) simulations are frequently used to predict the interfacial structures and dynamical processes at solid-water interfaces in efforts to gain a deeper understanding of these systems. However, the accuracy of these predictions of interfacial structure has not been rigorously quantified. Here, direct comparisons between large-scale DFT-MD simulations and high-resolution X-ray reflectivity (XR) measurements of the well-defined Al2O3(001)-water interface reveal the relative accuracy of these two methods to describe interfacial structure, a comparison that is enabled by XR’s high sensitivity to atomic-scale displacements. The DFT-MD simulated and XR model-fit structures are qualitatively similar, but XR signals calculated directly from the DFT-MD predictions deviate significantly from the experimental data, revealing discrepancies in these two approaches. Differences in the derived interfacial Al2O3 relaxation profiles of ~0.02 A within the top 5 layers are significant to XR but at the limit of the accuracy of DFT. Further differences are found in the surface hydration layer with a simulated average water layer height ~0.2 A higher than that observed experimentally. This is outside the accuracy of both XR and DFT and is not improved by the inclusion of a phenomenological correction for hydrogen bonding (e.g., Grimme).

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2022

Discrete Orientations of Interfacial Waters Direct Crystallization of Mica-Binding Proteins

Understanding the basis of templated molecular assembly on a solid surface requires a fundamental comprehension of both short- and long-range aqueous response to the surface under a variety of solution conditions. Herein we provide a detailed picture of how the molecular-scale response to different mica surfaces yields distinct solvent orientations that produce quasi-static directional potentials onto which macromolecules can adsorb. We connect this directionality to observed (a)symmetric epitaxial alignment of designed proteins onto these surfaces, corroborate our findings with 3D atomic force microscopy experiments, and identify slight differences in surface structure as the origin of this effect. Furthermore, our work provides a detailed picture of the intrinsic electrolyte response in the vicinity of mineral interfaces, with clear predictions for experiment, and highlights the role of solvent on the predictive assembly of hierarchical materials on mineral surfaces.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗