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1.
Sci Rep ; 14(1): 18430, 2024 Aug 08.
Artículo en Inglés | MEDLINE | ID: mdl-39117792

RESUMEN

Asphaltene deposition may pose serious challenges to flow assurance of crude oil in well columns. Different aggregation kinetics would partly be responsible for asphaltene particle growth ending in deposition on the surface of well columns. This work primarily investigates the thermophoretic deposition velocity caused by temperature gradients inside well columns for various asphaltene aggregation kinetics, including crossover behaviour, sedimentation, reaction-limited aggregation (RLA), and diffusion-limited aggregation (DLA). To do so, the experimental observations of size distribution for a live crude oil was performed at 80 °C and pressure range of 4500-5500 psia. Moreover, various patterns of different size distributions were gathered from the literature for the sake of comparison. Next, a well column in southern Iran was selected to study the kinetic behaviour of thermophoretic velocity of deposition, with a difference between geothermal and static temperatures of around 5 to 50 °C. The non-isothermal deposition velocity was shown to decrease from the top to the bottom of the well column, according to the findings of the study. The results also revealed that the thermophoretic velocity decreases as particle size increases and vice versa. This was confirmed by examining a comparably large range of asphaltene particle sizes, ranging from approximately 100 nm to roughly 9 µm. Practical implications of these findings were also discussed which would provide guidance for mitigation of asphaltene deposition in well columns.

2.
Front Plant Sci ; 15: 1425759, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-39119497

RESUMEN

Introduction: Currently, the development of new antiviral drugs against COVID-19 remains of significant importance. In traditional Chinese medicine, the herb Euphorbia fischeriana Steud is often used for antiviral treatment, yet its therapeutic effect against the COVID-19 has been scarcely studied. Therefore, this study focuses on the roots of E. fischeriana Steud, exploring its chemical composition, antiviral activity against COVID-19, and the underlying basis of its antiviral activity. Methods: Isolation and purification of phytochemicals from E. fischeriana Steud. The elucidation of their configurations was achieved through a comprehensive suite of 1D and 2D NMR spectroscopic analyses as well as X-ray diffraction. Performed cytopathic effect assays of SARS-CoV-2 using Vero E6 cells. Used molecular docking to screen for small molecule ligands with binding to SARS-CoV-2 RdRp. Microscale thermophoresis (MST) was used to determine the dissociation constant Kd. Results: Ultimately, nine new ent-atisane-type diterpenoid compounds were isolated from E. fischeriana Steud, named Eupfisenoids A-I (compounds 1-9). The compound of 1 was established as a C-19-degraded ent-atisane-type diterpenoid. During the evaluation of these compounds for their antiviral activity against COVID-19, compound 1 exhibited significant antiviral activity. Furthermore, with the aid of computer virtual screening and microscale thermophoresis (MST) technology, it was found that this compound could directly bind to the RNA-dependent RNA polymerase (RdRp, NSP12) of the COVID-19, a key enzyme in virus replication. This suggests that the compound inhibits virus replication by targeting RdRp. Discussion: Through this research, not only has our understanding of the antiviral components and material basis of E. fischeriana Steud been enriched, but also the potential of atisane-type diterpenoid compounds as antiviral agents against COVID-19 has been discovered. The findings mentioned above will provide valuable insights for the development of drugs against COVID-19.

3.
Bio Protoc ; 14(15): e5041, 2024 Aug 05.
Artículo en Inglés | MEDLINE | ID: mdl-39131194

RESUMEN

Microscale thermophoresis (MST) is a technique used to measure the strength of molecular interactions. MST is a thermophoretic-based technique that monitors the change in fluorescence associated with the movement of fluorescent-labeled molecules in response to a temperature gradient triggered by an IR LASER. MST has advantages over other approaches for examining molecular interactions, such as isothermal titration calorimetry, nuclear magnetic resonance, biolayer interferometry, and surface plasmon resonance, requiring a small sample size that does not need to be immobilized and a high-sensitivity fluorescence detection. In addition, since the approach involves the loading of samples into capillaries that can be easily sealed, it can be adapted to analyze oxygen-sensitive samples. In this Bio-protocol, we describe the troubleshooting and optimization we have done to enable the use of MST to examine protein-protein interactions, protein-ligand interactions, and protein-nanocrystal interactions. The salient elements in the developed procedures include 1) loading and sealing capabilities in an anaerobic chamber for analysis using a NanoTemper MST located on the benchtop in air, 2) identification of the optimal reducing agents compatible with data acquisition with effective protection against trace oxygen, and 3) the optimization of data acquisition and analysis procedures. The procedures lay the groundwork to define the determinants of molecular interactions in these technically demanding systems. Key features • Established procedures for loading and sealing tubes in an anaerobic chamber for subsequent analysis. • Sodium dithionite (NaDT) could easily be substituted with one electron-reduced 1,1'-bis(3-sulfonatopropyl)-4,4'-bipyridinium [(SPr)2V•] to perform sensitive biophysical assays on oxygen-sensitive proteins like the MoFe protein. • Established MST as an experimental tool to quantify binding affinities in novel enzyme-quantum dot biohybrid complexes that are extremely oxygen-sensitive.

4.
Int J Mol Sci ; 25(14)2024 Jul 12.
Artículo en Inglés | MEDLINE | ID: mdl-39062914

RESUMEN

The Ezrin/Radixin/Moesin (ERM) family of proteins act as cross-linkers between the plasma membrane and the actin cytoskeleton. This mechanism plays an essential role in processes related to membrane remodeling and organization, such as cell polarization, morphogenesis and adhesion, as well as in membrane protein trafficking and signaling pathways. For several human aquaporin (AQP) isoforms, an interaction between the ezrin band Four-point-one, Ezrin, Radixin, Moesin (FERM)-domain and the AQP C-terminus has been demonstrated, and this is believed to be important for AQP localization in the plasma membrane. Here, we investigate the structural basis for the interaction between ezrin and two human AQPs: AQP2 and AQP5. Using microscale thermophoresis, we show that full-length AQP2 and AQP5 as well as peptides corresponding to their C-termini interact with the ezrin FERM-domain with affinities in the low micromolar range. Modelling of the AQP2 and AQP5 FERM complexes using ColabFold reveals a common mode of binding in which the proximal and distal parts of the AQP C-termini bind simultaneously to distinct binding sites of FERM. While the interaction at each site closely resembles other FERM-complexes, the concurrent interaction with both sites has only been observed in the complex between moesin and its C-terminus which causes auto-inhibition. The proposed interaction between AQP2/AQP5 and FERM thus represents a novel binding mode for extrinsic ERM-interacting partners.


Asunto(s)
Acuaporina 2 , Acuaporina 5 , Proteínas del Citoesqueleto , Unión Proteica , Humanos , Proteínas del Citoesqueleto/metabolismo , Proteínas del Citoesqueleto/química , Acuaporina 5/metabolismo , Acuaporina 5/química , Acuaporina 2/metabolismo , Acuaporina 2/química , Sitios de Unión , Acuaporinas/metabolismo , Acuaporinas/química , Dominios Proteicos , Modelos Moleculares , Proteínas de Microfilamentos/metabolismo , Proteínas de Microfilamentos/química , Proteínas de la Membrana/metabolismo , Proteínas de la Membrana/química
5.
Biomedicines ; 12(7)2024 Jul 05.
Artículo en Inglés | MEDLINE | ID: mdl-39062057

RESUMEN

BACKGROUND AND AIM: Chamomile tea, renowned for its exquisite taste, has been appreciated for centuries not only for its flavor but also for its myriad health benefits. In this study, we investigated the preventive potential of chamomile (Matricaria chamomilla L.) towards cancer by focusing on its anti-inflammatory activity. METHODS AND RESULTS: A virtual drug screening of 212 phytochemicals from chamomile revealed ß-amyrin, ß-eudesmol, ß-sitosterol, apigenin, daucosterol, and myricetin as potent NF-κB inhibitors. The in silico results were verified through microscale thermophoresis, reporter cell line experiments, and flow cytometric determination of reactive oxygen species and mitochondrial membrane potential. An oncobiogram generated through comparison of 91 anticancer agents with known modes of action using the NCI tumor cell line panel revealed significant relationships of cytotoxic chamomile compounds, lupeol, and quercetin to microtubule inhibitors. This hypothesis was verified by confocal microscopy using α-tubulin-GFP-transfected U2OS cells and molecular docking of lupeol and quercetin to tubulins. Both compounds induced G2/M cell cycle arrest and necrosis rather than apoptosis. Interestingly, lupeol and quercetin were not involved in major mechanisms of resistance to established anticancer drugs (ABC transporters, TP53, or EGFR). Performing hierarchical cluster analyses of proteomic expression data of the NCI cell line panel identified two sets of 40 proteins determining sensitivity and resistance to lupeol and quercetin, further pointing to the multi-specific nature of chamomile compounds. Furthermore, lupeol, quercetin, and ß-amyrin inhibited the mRNA expression of the proinflammatory cytokines IL-1ß and IL6 in NF-κB reporter cells (HEK-Blue Null1). Moreover, Kaplan-Meier-based survival analyses with NF-κB as the target protein of these compounds were performed by mining the TCGA-based KM-Plotter repository with 7489 cancer patients. Renal clear cell carcinomas (grade 3, low mutational rate, low neoantigen load) were significantly associated with shorter survival of patients, indicating that these subgroups of tumors might benefit from NF-κB inhibition by chamomile compounds. CONCLUSION: This study revealed the potential of chamomile, positioning it as a promising preventive agent against inflammation and cancer. Further research and clinical studies are recommended.

6.
mBio ; 15(7): e0114424, 2024 Jul 17.
Artículo en Inglés | MEDLINE | ID: mdl-38916345

RESUMEN

The cAMP receptor proteins (CRPs) play a critical role in bacterial environmental adaptation by regulating global gene expression levels via cAMP binding. Here, we report the structure of DdrI, a CRP family protein from Deinococcus radiodurans. Combined with biochemical, kinetic, and molecular dynamics simulations analyses, our results indicate that DdrI adopts a DNA-binding conformation in the absence of cAMP and can form stable complexes with the target DNA sequence of classical CRPs. Further analysis revealed that the high-affinity cAMP binding pocket of DdrI is partially filled with Tyr113-Arg55-Glu65 sidechains, mimicking the anti-cAMP-mediated allosteric transition. Moreover, the second syn-cAMP binding site of DdrI at the protein-DNA interface is more negatively charged compared to that of classical CRPs, and manganese ions can enhance its DNA binding affinity. DdrI can also bind to a target sequence that mimics another transcription factor, DdrO, suggesting potential cross-talk between these two transcription factors. These findings reveal a class of CRPs that are independent of cAMP activation and provide valuable insights into the environmental adaptation mechanisms of D. radiodurans.IMPORTANCEBacteria need to respond to environmental changes at the gene transcriptional level, which is critical for their evolution, virulence, and industrial applications. The cAMP receptor protein (CRP) of Escherichia coli (ecCRP) senses changes in intracellular cAMP levels and is a classic example of allosteric effects in textbooks. However, the structures and biochemical activities of CRPs are not generally conserved and there exist different mechanisms. In this study, we found that the proposed CRP from Deinococcus radiodurans, DdrI, exhibited DNA binding ability independent of cAMP binding and adopted an apo structure resembling the activated CRP. Manganese can enhance the DNA binding of DdrI while allowing some degree of freedom for its target sequence. These results suggest that CRPs can evolve to become a class of cAMP-independent global regulators, enabling bacteria to adapt to different environments according to their characteristics. The first-discovered CRP family member, ecCRP (or CAP) may well not be typical of the family and be very different to the ancestral CRP-family transcription factor.


Asunto(s)
Proteínas Bacterianas , Proteína Receptora de AMP Cíclico , AMP Cíclico , Deinococcus , Unión Proteica , Deinococcus/genética , Deinococcus/metabolismo , Proteína Receptora de AMP Cíclico/metabolismo , Proteína Receptora de AMP Cíclico/genética , Proteína Receptora de AMP Cíclico/química , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/química , AMP Cíclico/metabolismo , Sitios de Unión , ADN Bacteriano/genética , ADN Bacteriano/metabolismo , Simulación de Dinámica Molecular , Conformación Proteica , Proteínas de Unión al ADN/metabolismo , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/química , Regulación Bacteriana de la Expresión Génica
7.
Int J Mol Sci ; 25(12)2024 Jun 16.
Artículo en Inglés | MEDLINE | ID: mdl-38928339

RESUMEN

Receptors of cytokines are major regulators of the immune response. In this work, we have discovered two new ligands that can activate the TNFR1 (tumor necrosis factor receptor 1) receptor. Earlier, we found that the peptide of the Tag (PGLYRP1) protein designated 17.1 can interact with the TNFR1 receptor. Here, we have found that the Mts1 (S100A4) protein interacts with this peptide with a high affinity (Kd = 1.28 × 10-8 M), and that this complex is cytotoxic to cancer cells that have the TNFR1 receptor on their surface. This complex induces both apoptosis and necroptosis in cancer cells with the involvement of mitochondria and lysosomes in cell death signal transduction. Moreover, we have succeeded in locating the Mts1 fragment that is responsible for protein-peptide interaction, which highly specifically interacts with the Tag7 protein (Kd = 2.96 nM). The isolated Mts1 peptide M7 also forms a complex with 17.1, and this peptide-peptide complex also induces the TNFR1 receptor-dependent cell death. Molecular docking and molecular dynamics experiments show the amino acids involved in peptide binding and that may be used for peptidomimetics' development. Thus, two new cytotoxic complexes were created that were able to induce the death of tumor cells via the TNFR1 receptor. These results may be used in therapy for both cancer and autoimmune diseases.


Asunto(s)
Apoptosis , Receptores Tipo I de Factores de Necrosis Tumoral , Humanos , Receptores Tipo I de Factores de Necrosis Tumoral/metabolismo , Receptores Tipo I de Factores de Necrosis Tumoral/química , Apoptosis/efectos de los fármacos , Unión Proteica , Simulación del Acoplamiento Molecular , Línea Celular Tumoral , Péptidos/química , Péptidos/farmacología , Péptidos/metabolismo , Simulación de Dinámica Molecular , Transducción de Señal/efectos de los fármacos , Necroptosis/efectos de los fármacos , Oligopéptidos/química , Oligopéptidos/farmacología , Oligopéptidos/metabolismo , Citocinas
8.
Int J Biol Macromol ; 271(Pt 1): 132510, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38821797

RESUMEN

Gum Arabic underwent enzymatic modification with curcumin oxidation products, prompting self-assembly in water at lower concentrations than native gum Arabic, which was fully soluble. The resulting particles displayed a narrow size distribution, suggestive of a micellization mechanism akin to Critical Micellization Concentration (CMC) in surfactants or Critical Aggregation Concentration (CAC) in polymers. Accurately determining CAC is vital for utilizing polymers in molecule encapsulation, but precise measurement is challenging, requiring multiple techniques. Initially, CAC was probed via turbidity measurements, dynamic light scattering (DLS), and isothermal calorimetric titration (ITC), yielding a range of 0.0015 to 0.01 %. Micro-scale thermophoresis (MST) was then employed for the first time to define CAC more precisely, facilitated by the intrinsic fluorescence of modified gum Arabic. Using MST, CAC was pinpointed at 0.001 % (w/v), a novel approach. Furthermore, MST revealed a low EC50 value of 0.007 % (w/t) for self-assembly, signifying uniformity among GAC sub-units and assembly stability upon dilution.


Asunto(s)
Curcumina , Goma Arábiga , Oxidación-Reducción , Agua , Goma Arábiga/química , Curcumina/química , Agua/química , Micelas
9.
J Biol Chem ; 300(6): 107396, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38777142

RESUMEN

Fatty acid binding proteins (FABPs) are a family of amphiphilic transport proteins with high diversity in terms of their amino acid sequences and binding preferences. Beyond their main biological role as cytosolic fatty acid transporters, many aspects regarding their binding mechanism and functional specializations in human cells remain unclear. In this work, the binding properties and thermodynamics of FABP3, FABP4, and FABP5 were analyzed under various physical conditions. For this purpose, the FABPs were loaded with fatty acids bearing fluorescence or spin probes as model ligands, comparing their binding affinities via microscale thermophoresis (MST) and continuous-wave electron paramagnetic resonance (CW EPR) spectroscopy. The CW EPR spectra of non-covalently bound 5- and 16-DOXYL stearic acid (5/16-DSA) deliver in-depth information about the dynamics and chemical environments of ligands inside the binding pockets of the FABPs. EPR spectral simulations allow the construction of binding curves, revealing two different binding states ('intermediately' and 'strongly' bound). The proportion of bound 5/16-DSA depends strongly on the FABP concentration and the temperature but with remarkable differences between the three isoforms. Additionally, the more dynamic state ('intermediately bound') seems to dominate at body temperature with thermodynamic preference. The ligand binding studies were supplemented by aggregation studies via dynamic light scattering and bioinformatic analyses. Beyond the remarkably fine-tuned binding properties exhibited by each FABP, which were discernible with our EPR-centered approach, the results of this work attest to the power of simple spectroscopic experiments to provide new insights into the ligand binding mechanisms of proteins in general on a molecular level.


Asunto(s)
Proteína 3 de Unión a Ácidos Grasos , Proteínas de Unión a Ácidos Grasos , Unión Proteica , Proteínas de Unión a Ácidos Grasos/metabolismo , Proteínas de Unión a Ácidos Grasos/química , Humanos , Proteína 3 de Unión a Ácidos Grasos/metabolismo , Proteína 3 de Unión a Ácidos Grasos/química , Espectroscopía de Resonancia por Spin del Electrón , Ligandos , Termodinámica , Ácidos Grasos/metabolismo , Ácidos Grasos/química , Sitios de Unión
10.
Methods Mol Biol ; 2024 Mar 06.
Artículo en Inglés | MEDLINE | ID: mdl-38441723

RESUMEN

Myriad proteins are involved in the process of autophagy, which they participate in via their protein-protein interactions (PPI). Herein we outline a methodology for examining such interactions utilizing the case of intrinsically disordered protein (IDP) TNIP1 and its interaction with linear M1-linked polyubiquitin. This includes methods for recombinant production, purification, immuno-identification, and analysis of an IDP associated with autophagy, its ordered binding partner, and means of quantitatively analyzing their interaction.

11.
Methods Mol Biol ; 2778: 159-183, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38478278

RESUMEN

Gram-negative bacteria coordinate the biosynthesis of their different cell envelope components. Growth of the outer membrane (OM) requires the essential ß-barrel assembly machine (BAM), which inserts OM proteins (OMPs) into the OM. The underlying peptidoglycan (PG) sacculus grows by the insertion of nascent glycan chains. We have previously identified interactions between BAM and PG in E. coli and showed that these interactions coordinate OM biogenesis with PG growth. BAM responds to the maturation state of the PG, and this mechanism activates preferentially BAM complexes at sites of active PG synthesis. Here we present protocols to purify soluble Bam proteins and full-length BamABCDE, isolate PG and soluble PG fragments, and study BAM-PG interactions with the isolated components. We also describe the protocol to detect interactions between Bam proteins and PG in cells.


Asunto(s)
Proteínas de Escherichia coli , Escherichia coli , Escherichia coli/metabolismo , Proteínas de Escherichia coli/metabolismo , Peptidoglicano/metabolismo , Membrana Celular/metabolismo , Pared Celular/metabolismo , Proteínas de la Membrana Bacteriana Externa/metabolismo , Pliegue de Proteína
12.
Methods Mol Biol ; 2754: 205-217, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38512669

RESUMEN

Aggregated fibrillar tau protein is a pathological hallmark of several neurodegenerative diseases. Small molecules that bind to tau fibrils may be applied for their detection and quantification. This is of great importance as they can potentially be used for earlier diagnosis of disease and disease progression. Microscale thermophoresis (MST) enables the detection of biomolecular interactions in an aqueous environment in which no immobilization of either reaction partner is required. Here, an MST assay methodology is described for the detection of the interaction between a variety of small molecules and tau fibrils. The results of this study demonstrate that MST is a practical methodology to quantify interactions between small molecules and tau fibrillar aggregates.


Asunto(s)
Agregado de Proteínas , Proteínas tau , Unión Proteica
13.
Arch Microbiol ; 206(4): 140, 2024 Mar 05.
Artículo en Inglés | MEDLINE | ID: mdl-38441642

RESUMEN

Limosilactobacillus reuteri is an indigenous inhabitant of the animal gut known for its probiotic effects on the host. In our previous study, a large number of L. reuteri strains were isolated from the gastrointestinal tract of mice recovering from ulcerative colitis, from which we randomly selected L. reuteri RE225 for whole genome sequencing to explore its probiotic properties. The results of next-generation sequencing and third-generation single molecule sequencing showed that L. reuteri RE225 contained many genes encoding functional proteins associated with adhesion, anti-inflammatory and pathogen inhibition. And compared to other L. reuteri strains in NCBI, L. reuteri RE225 has unique gene families with probiotic functions. In order to further explore the probiotic effect of the L. reuteri RE225, the derived peptides were identified by LC-MS/MS, and the peptides with tumor necrosis factor-α binding ability were screened by reverse molecular docking and microscale thermophoresis. Finally, cell experiments demonstrated the anti-inflammatory ability of the peptides. Western blotting and qPCR analyses confirmed that the selected peptides might alleviate LPS-induced inflammation in NCM460 cells by inhibiting JAK2/STAT3 pathway activation.


Asunto(s)
Colitis Ulcerosa , Limosilactobacillus reuteri , Animales , Ratones , Limosilactobacillus reuteri/genética , Colitis Ulcerosa/tratamiento farmacológico , Cromatografía Liquida , Simulación del Acoplamiento Molecular , Espectrometría de Masas en Tándem , Péptidos/genética , Péptidos/farmacología , Secuenciación Completa del Genoma
14.
Eur J Med Chem ; 270: 116328, 2024 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-38552426

RESUMEN

The vast majority of current cereblon (CRBN) ligands is based on the thalidomide scaffold, relying on glutarimide as the core binding moiety. With this architecture, most of these ligands inherit the overall binding mode, interactions with neo-substrates, and thereby potentially also the cytotoxic and teratogenic properties of the parent thalidomide. In this work, by incorporating a spiro-linker to the glutarimide moiety, we have generated a new chemotype that exhibits an unprecedented binding mode for glutarimide-based CRBN ligands. In total, 16 spirocyclic glutarimide derivatives incorporating an isoxazole moiety were synthesized and tested for different criteria. In particular, all ligands showed a favorable lipophilicity, and several were able to outperform the binding affinity of thalidomide as a reference. In addition, all compounds showed favorable cytotoxicity profiles in myeloma cell lines and human peripheral blood mononuclear cells. The novel binding mode, which we determined in co-crystal structures, provides explanations for these improved properties: The incorporation of the spiro-isoxazole changes both the conformation of the glutarimide moiety within the canonical tri-trp pocket and the orientation of the protruding moiety. In this new orientation it forms additional hydrophobic interactions and is not available for direct interactions with the canonical neo-substrates. We therefore propose this chemotype as an attractive building block for the design of PROTACs.


Asunto(s)
Antineoplásicos , Talidomida , Humanos , Leucocitos Mononucleares/metabolismo , Ubiquitina-Proteína Ligasas , Teratógenos , Ligandos , Péptido Hidrolasas/metabolismo
15.
Sci Rep ; 14(1): 6908, 2024 Mar 22.
Artículo en Inglés | MEDLINE | ID: mdl-38519526

RESUMEN

Nanofluid is a specially crafted fluid comprising a pure fluid with dispersed nanometer-sized particles. Incorporation these nanoparticles into pure fluid results in a fluid with improved thermal properties in comparison of pure fluid. The enhanced properties of nanofluids make them highly sought after, in diverse applications, consisting of coolant of devices, heat exchangers, and thermal solar systems. In this study hybrid nanofluid consisting of copper, alumina and titanium nanoparticles on a curved sheet has investigated with impact of chemical reactivity, magnetic field and Joule heating. The leading equations have converted to normal equations by using appropriate set of variables and has then evaluated by homotopy analysis method. The outcomes are shown through Figures and Tables and are discussed physically. It has revealed in this study that Cu-nanofluid flow has augmented velocity, temperature, and volume fraction distributions than those of Al2O3-nanofluid and TiO2-nanofluid. Also, the Cu-nanofluid flow has higher heat and mass transfer rates than those of Al2O3-nanofluid and TiO2-nanofluid.

16.
Nano Lett ; 24(9): 2798-2804, 2024 Mar 06.
Artículo en Inglés | MEDLINE | ID: mdl-38408429

RESUMEN

Thermophoresis allows for the manipulation of colloids in systems containing a temperature gradient. A deep understanding of the phenomena at the molecular level allows for increased control and manipulation strategies. We developed a microscopic model revealing different coupling mechanisms for colloid thermophoresis under local thermodynamic equilibrium conditions. The model has been verified through comparison with a variety of previously published experimental data and shows good agreement across significantly different systems. We found five different temperature-dependent contributions to the Soret coefficient, two from bulk properties and three from interfacial interactions between the fluid medium and the colloid. Our analysis shows that the Soret coefficient for nanosized particles is governed by the competition between the electrostatic and hydration interfacial interactions, while bulk contributions become more pronounced for protein systems. This theory can be used as a guide to design thermophoretic transport, which is relevant for sensing, focusing, and separation at the microscale.

17.
Biofabrication ; 16(2)2024 Mar 04.
Artículo en Inglés | MEDLINE | ID: mdl-38377611

RESUMEN

The extracellular matrix presents spatially varying physical cues that can influence cell behavior in many processes. Physical gradients within hydrogels that mimic the heterogenous mechanical microenvironment are useful to study the impact of these cues on cellular responses. Therefore, simple and reliable techniques to create such gradient hydrogels are highly desirable. This work demonstrates the fabrication of stiffness gradient Gellan gum (GG) hydrogels by applying a temperature gradient across a microchannel containing hydrogel precursor solution. Thermophoretic migration of components within the precursor solution generates a concentration gradient that mirrors the temperature gradient profile, which translates into mechanical gradients upon crosslinking. Using this technique, GG hydrogels with stiffness gradients ranging from 20 to 90 kPa over 600µm are created, covering the elastic moduli typical of moderately hard to hard tissues. MC3T3 osteoblast cells are then cultured on these gradient substrates, which exhibit preferential migration and enhanced osteogenic potential toward the stiffest region on the gradient. Overall, the thermophoretic approach provides a non-toxic and effective method to create hydrogels with defined mechanical gradients at the micron scale suitable forin vitrobiological studies and potentially tissue engineering applications.


Asunto(s)
Hidrogeles , Microfluídica , Ingeniería de Tejidos/métodos , Matriz Extracelular
18.
Front Microbiol ; 15: 1341451, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38322321

RESUMEN

Background: Generally, enterococci bacteria cause nosocomial infections and are major indicators of bacterial contamination in marine bathing beach. However, a method for the rapid and simultaneous detection of multiple pathogenic enterococci has not been developed on account of the wide variety of pathogenic enterococci and their existence in complex matrices. Methods: Immunoinformatics tools were used to design a multi-epitope antigen for the detection of various pathogenic enterococci by using the sequence of dltD gene on enterococci lipoteichoic acid (LTA) surface, which is associated with toxicological effects. The multi-epitopes included enterococci such as Enterococcus faecalis, E. gallinarum, E. raffinosus, E. durans, E. faecium, E. hirae, E. thailandicus, E. casseliflavus, E. avium, E. mundtii, E. lactis, E. solitarius, E. pseudoavium, and E. malodoratum. Microscale thermophoresis (MST) and western blot were carried out to detect the affinity between multi-epitope antigens and antibodies and between multi-epitope antibodies and bacteria. Furthermore, the detection of pathogenic enterococci was carried out by using immunomagnetic beads (IMBs) and immune chromatographic test strip (ICTS). Results: The multi-epitope antibody had a satisfactory affinity to the antigen and enterococci. IMBs and ICTS were detected with a minimum of 101 CFU/mL and showed incompatibility for Vibrio parahemolyticus, V. vulnifcus, V. harveyi, V. anguillarum, and Edwardsiella tarda. Implication: The present study demonstrated that the multi-epitope antigens exhibited excellent specificity and sensitivity, making them highly suitable for efficient on-site screening of enterococci bacteria in marine bathing beaches.

19.
Heliyon ; 10(3): e25102, 2024 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-38322951

RESUMEN

In this study, the computational analysis of entropy generation optimization for synthetic cilia regulated ternary hybrid Jeffery nanofluid (Ag-Au-TiO2/PVA) flow through a peristaltic vertical channel with swimming motile Gyrotactic microorganisms is investigated. Understanding the intricate interaction of multiple physical phenomena in biomedical applications is essential for optimizing entropy generation and advancing microfluidic systems. The characteristics of nanofluid are explored for the electroosmotic MHD fluid flow in the presence of thermophoresis and Brownian motion, viscous dissipation, Ohmic heating and chemical reaction. Using the appropriate transformations, a set of ordinary differential equations are created from the governing partial differential equations. The resulting ODEs are numerically solved using the shooting technique using BVP5C in MATLAB after applying the long-wavelength and low Reynolds number approximation. The velocity, temperature, concentration, electroosmosis, and microorganism density profiles are analyzed graphically for different emerging parameters. Graphical investigation of engineering interest quantities like heat transfer rate, mass transfer rate, skin friction coefficient, and entropy generation optimization are also presented. It is observed that the rate of mass transfer increases for increasing thermophoretic parameter, while reverse effect is noted for Brownian motion parameter, Schmidt number, and chemical reaction number. The outcomes of present study can be pertinent in studying Cilia properties of respiratory tract, reproductive system, and brain ventricles.

20.
Molecules ; 29(4)2024 Feb 14.
Artículo en Inglés | MEDLINE | ID: mdl-38398600

RESUMEN

Aptamers are currently being investigated for their potential to improve virotherapy. They offer several advantages, including the ability to prevent the aggregation of viral particles, enhance target specificity, and protect against the neutralizing effects of antibodies. The purpose of this study was to comprehensively investigate an aptamer capable of enhancing virotherapy. This involved characterizing the previously selected aptamer for vaccinia virus (VACV), evaluating the aggregation and molecular interaction of the optimized aptamers with the recombinant oncolytic virus VV-GMCSF-Lact, and estimating their immunoshielding properties in the presence of human blood serum. We chose one optimized aptamer, NV14t_56, with the highest affinity to the virus from the pool of several truncated aptamers and built its 3D model. The NV14t_56 remained stable in human blood serum for 1 h and bound to VV-GMCSF-Lact in the micromolar range (Kd ≈ 0.35 µM). Based on dynamic light scattering data, it has been demonstrated that aptamers surround viral particles and inhibit aggregate formation. In the presence of serum, the hydrodynamic diameter (by intensity) of the aptamer-virus complex did not change. Microscale thermophoresis (MST) experiments showed that NV14t_56 binds with virus (EC50 = 1.487 × 109 PFU/mL). The analysis of the amplitudes of MST curves reveals that the components of the serum bind to the aptamer-virus complex without disrupting it. In vitro experiments demonstrated the efficacy of VV-GMCSF-Lact in conjunction with the aptamer when exposed to human blood serum in the absence of neutralizing antibodies (Nabs). Thus, NV14t_56 has the ability to inhibit virus aggregation, allowing VV-GMCSF-Lact to maintain its effectiveness throughout the storage period and subsequent use. When employing aptamers as protective agents for oncolytic viruses, the presence of neutralizing antibodies should be taken into account.


Asunto(s)
Aptámeros de Nucleótidos , Virus Oncolíticos , Humanos , Virus Vaccinia/genética , Aptámeros de Nucleótidos/metabolismo , Anticuerpos Neutralizantes
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