Search

Gas aggregation and formation of interfacial nanobubbles (INBs) provide challenges and opportunities in the operation of micro-/nanofluidic devices. In the current study, we used molecular dynamics(MD) simulations to investigate the effects of hydrophobicity and various homogeneous surface conditions on gas aggregation and INB stability with a series of 3D argon–water–solid and water–solid systems. Among various signatures of surface hydrophobicity, the potential of mean force (PMF) minima exhibited the strongest correlation with the water molecular orientation at the liquid–solid interface, compared to the depletion layer width and the droplet contact angle. Our results indicated that argon aggregation on the substrate was a function of hydrophobicity as well as competition between gas–solid and water–solid PMFs. Thus, one precondition for gas aggregation on a surface is that the free energy minima of gas induced by the surface be much lower than that induced by water. We found that although the presence of gas molecules had little effect on the measures of wettability, it enhanced density fluctuations near liquid–solid interfaces. The PMF of gas along the surface tangential plane exhibited a small energy barrier between the epitaxial gas layer (EGL) in the bubble and the gas enrichment layer (GEL) in the liquid, which may benefit nanobubble stability. Much lower PMF in the EGL compared to that in the GEL indicated that gas molecules could migrate from the GEL to the nanobubble basement. However, density fluctuations enhanced by the GEL could reduce the energy barrier, thus reducing the stability of INBs.

Background: Polyalthia longifolia is a popular medicinal plant and has been widely used as a traditional remedy for centuries in curing of various ailments. The purpose of this study was conducted to determine the in situ antimicrobial synergistic effects between Polyalthia longifolia leaf ethyl acetate fraction (PLEAF) and ampicillin against MRSA local isolate by using modern microscopy technique. Methods: Hence, the evaluation of the synergistic activity of PLEAF and ampicillin against MRSA local isolate was conducted with scanning electron microscopy (SEM). Results: The combinational effect of PLEAF fraction and ampicillin exhibited significant antibacterial activity against MRSA. Bacterial cells observations showed invagination, impaired cell division, extensive wrinkles, cell shrinkage, the appearance of a rougher cell with fibrous matrix and clustered cells which confirmed the synergistic effect of PLEAF and ampicillin against MRSA local isolate by SEM. Conclusion: Conclusively, the in situ SEM observation proved the synergistic antimicrobial activity between PLEAF fraction and ampicillin to destroy the MRSA resistance bacteria which is an important aspect of PLEAF fraction to be used in the future combinational therapy.

Parkinson's disorder (PD) is a chronic and central nervous system disorder that occurs when neurons in the area of the brain impairs or dies, in particular, it affects the dopamine-producing neurons. People having PD also loose chemical messenger norepinephrine, which involves in regulating the main function of physiological systems, such as heart rate and blood pressure. Researchers are working on to identify PD with a suitable biomarker and alpha-synuclein is the presynaptic neuronal protein, in the neurological lesions (Lewy bodies). This research was focused to develop an alpha-synuclein biosensor on an iron oxide (IO) nanomaterial-modified interdigitated electrode surface. Anti-alpha-synuclein aptamer was attached on IO through the amine-linker and aggregated alpha-synuclein was sandwiched between aptamer and antibody. To enhance the analytical performance, antibody was modified with gold nanoparticles and reached the detection limit of 10 aM, determined on a linear range between 101and 107aM [y = 2.5812×-0.0081; R2 = 0.9729]. Further, control molecules failed to increase the current responses indicating the specific detection of alpha-synuclein and the CSF-spiked alpha-synuclein increases the current responses, confirming the selective detection.

We investigated how the stability of aqueous argon surface nanobubbles on hydrophobic surfaces depends on gas adsorption, solid–gas interaction energy, and the bulk gas concentration using molecular dynamics simulation with the SPC/E water solvent. We observed stable surface nanobubbles without surface pinning sites for longer than 160 ns, contrary to previous findings using monoatomic Lennard-Jones solvent. In addition, the hydrophobicity of a substrate has an effect to reduce the requirement degree of oversaturation on water bulk. We found that the gas enrichment layer, gas adsorption monolayer on the hydrophobic substrate, and water hydrogen bonding near the interface are likely necessary conditions for nanobubble stability. We concluded that gas nanobubble stability does not necessarily require three-phase pinning sites.

Cassia(C.) surattensisBurm. f. (Leguminosae) is a flowering plant that has been traditionally used in many countries for food and medicinal purposes. The present study was conducted to determine in vitro cytotoxicity and anti-genotoxic activity of the seed extract of C. surattensis. The cytotoxic and anti-genotoxic activities were evaluated against Vero cell line using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and comet assays. In vitro cytotoxicity evaluation demonstrated that seed extract of C. surattensis was non-cytotoxic against the Vero cells. The 50 % cytotoxic concentration (CC50) value from MTT cytotoxicity assay was 332.87 µg/ml. The seed extract of C. surattensisexhibited strong inhibitory effects against H2O2-mediated DNA damage in Vero cells as observed in Comet assay. The presence of antioxidant activity in the seed extract was associated with the antigenotoxic property of C. surattensis. In summary, the present study demonstrated an efficient antigenotoxic property of C. surattensis, which is significant for future investigation for human applications.

Biosensing technology represents a superior way of identifying a wide range of biomolecules that exist in the human body, food, water, and other environmental sources. In this regard, human health issues are a growing global concern, and the development of effective methods for the detection and differentiation of biomolecules during diagnosis and/or treatment of diseases is essential. However, achieving adequate levels of sensitivity and specificity will be fundamental for the successful clinical application of biosensing technology. Notably, sensitivity and specificity are highly dependent on non-fouling (specificity) of biomolecules on the sensing surfaces, particularly with regard to nanoparticle-tagged biomolecules. Here, the authors have evaluated bio-fouling (i.e., biological non-specificity) by analysing four distinct sensing substrates (gold, silicon, silica and platinum) using anti-mouse immunoglobulin-conjugated gold nanoparticles. As evidenced by scanning electron microscopy and ultraviolet–visible–near-infrared recording spectrophotometry, silica (SiO2) lacked bio-fouling, whereas gold (Au) showed high bio-fouling potential. Indeed, Raman spectroscopic analysis further confirmed these results. Thus, the present findings indicate that SiO2is an optimal substrate for biosensor development.

Candida albicanshas become resistant to the commercially available, toxic, and expensive anti-Candidaagents that are on the market. These factors force the search for new antifungal agents from natural resources. Cassia spectabilishad been traditionally employed by healers for many generations. The possible mechanisms of the C. spectabilisleaf extract were determined by potassium leakage study and the effect of the extract on the constituents of the cell wall and enzymes as well as the morphological changes on C. albicanscells were studied along with cytotoxicity assays. The cytotoxicity result indicated that the extract is nontoxic as was clearly substantiated by a half maximal inhibitory concentration (IC50) value of 59.10 μg/mL. The treated cells (C. spectabilisextract) demonstrated potassium leakage of 1039 parts per million (ppm) compared to Amphotericin B (AmpB)-treated cells with a released potassium value of 1115 ppm. The effects of the extract on the cell wall proteins illustrated that there were three major types of variations in the expression of treated cell wall proteins: the presence of new proteins, the absence of proteins, and the amount of expressed protein. The activities of two enzymes, α-glucosidase and proteinase, were determined to be significantly high, thereby not fully coinciding with the properties of the antifungal reaction triggered by C. spectabilis. The morphology of C. albicanscells treated with the C. spectabilisextract showed that the cells had abnormalities and were damaged or detached within the microcolonies. Our study verifies C. spectabilisleaf extract as an effective anti-C. albicansagent.

Computational modeling has become increasingly important in biophysics, but the great challenge in numerical simulations due to the multiscale feature of biological systems limits the capability of modeling in making discoveries in biology. Innovative multiscale modeling approaches are desired to bridge different scales from nucleic acids and proteins to cells and tissues. Although all-atom molecular dynamics has been successfully applied in many microscale biological processes such as protein folding, it is still prohibitively expensive for studying macroscale problems such as biophysics of cells and tissues. On the other hand, continuum-based modeling has become a mature procedure for analysis and design in many engineering fields, but new insights for biological systems in the microscale are limited when molecular details are missing in continuum-based modeling. In this context, mesoscale modeling approaches such as Langevin dynamics, lattice Boltzmann method, and dissipative particle dynamics have become popular by simultaneously incorporating molecular interactions and long-range hydrodynamic interactions, providing insights to properties on longer time and length scales than molecular dynamics. In this review, we summarized several mesoscale simulation approaches for studying two model systems in biophysics: red blood cells (RBCs) and deoxyribonucleic acids (DNAs). The RBC is a model system for cell mechanics and biological membranes, while the DNA represents a model system for biopolymers. We introduced the motivations of studying these problems and presented the key features of different mesoscale methods. Furthermore, we described the latest progresses in these methods and highlighted the major findings for modeling RBCs and DNAs. Finally, we also discussed the challenges and potential issues of different approaches.

For years researchers have exerted every effort to improve the influential roles of microRNA (miRNA) in regulating genes that direct mammalian cell development and function. In spite of numerous advancements, many facets of miRNA generation remain unresolved due to the perplexing regulatory networks. The biogenesis of miRNA, eminently endures as a mystery as no universal pathway defines or explicates the variegation in the rise of miRNAs. Early evidence in biogenesis ignited specific steps of being omitted or replaced that eventuate in the individual miRNAs of different mechanisms. Understanding the basic foundation concerning how miRNAs are generated and function will help with diagnostic tools and therapeutic strategies. This review encompasses the canonical and the non-canonical pathways involved in miRNA biogenesis, while elucidating how miRNAs regulate genes at the nuclear level and also the mechanism that lies behind circulating miRNAs.

The Young–Laplace equation suggests that nanosized gas clusters would dissolve under the effects of perturbation. The fact that nanobubbles are observed raises questions as to the mechanism underlying their stability. In the current study, we used all-atom molecular dynamics simulations to investigate the gas–water interfacial properties of gas clusters. We employed the instantaneous coarse-graining method to define the fluctuating boundaries and analyze the deformation of gas clusters. Fourier transform analysis of the cluster morphology revealed that the radius and morphology deformation variations exhibit power law relationships with the vibrational frequency, indicating that the surface energy dissipated through morphology variations. Increasing pressure in the liquid region was found to alter the network of water molecules at the interface, whereas increasing pressure in the gas region did not exhibit this effect. The overall gas concentration was oversaturated and proportional to the gas density inside the clusters. However, the result of comparison with Henry’s law reveals that the gas pressure at the interface reduced by the interfacial effects is much lower than that inside the gas region, thus reducing the demanding degree of oversaturation. Originating from the interfacial charge allocation, the magnitude of the electrostatic stress is greater than that of the gas pressure inside the cluster. However, the magnitude of the reversed tension induced by electrostatic stress is far below the value of interfacial tension. The potential of mean force (PMF) profiles revealed that a barrier potential at the interface hindered gas particles from escaping the cluster. Several effects contribute to stabilizing the gas clusters in water, including high-frequency morphological deformation, electrostatic stress, reduced interfacial tension, and gas oversaturation conditions. Our results suggest that gas clusters can exist in water under gas oversaturation conditions in the absence of hydrophobic contaminants or pinning charges at interfaces.

ABSTRACTLoop-mediated isothermal amplification (LAMP), a rapid nucleic acid amplification method, was developed for the clinical diagnosis of toxoplasmosis. Three LAMP assays based on the SAG1, SAG2, and B1genes of Toxoplasma gondiiwere developed. The sensitivities and specificities of the LAMP assays were evaluated by comparison with the results of conventional nested PCR. The LAMP assays were highly sensitive and had a detection limit of 0.1 tachyzoite, and no cross-reactivity with the DNA of other parasites was observed. Blood was collected from 105 individuals to test the LAMP assays: 40 patients with active toxoplasmosis, 40 negative controls, and 25 patients with other parasitic infections. The SAG2-based LAMP (SAG2-LAMP) had a greater sensitivity (87.5%) than the SAG1-LAMP (80%), B1-LAMP (80%), and nested PCR (62.5%). All the LAMP assays and nested PCR were 100% specific. This is the first report of a study which applied the LAMP method to diagnose toxoplasmosis from human blood samples. Due to its simplicity, sensitivity, and specificity, LAMP is suggested as an appropriate method for routine diagnosis of active toxoplasmosis in humans.

Monotherapy is recommended for schizophrenia treatment, but the risk-benefit issue of antipsychotic drug combination (except for clozapine) remains unclear. Risperidone, an atypical antipsychotic drug, has a lower incidence of extrapyramidal syndrome but higher risks of prolactinemia and metabolic syndrome than haloperidol, a typical agent. This study compared efficacy and safety of risperidone monotherapy versus low-dose risperidone plus low-dose haloperidol in schizophrenia. In this 6-week, double-blind study, patients were randomized to the combination group (2-mg/d risperidone plus 2-mg/d haloperidol, n = 46) or the monotherapy group (4-mg/d risperidone, n = 42). Efficacy assessments included Clinical Global Impression-Severity, Positive and Negative Syndrome Scale and subscales, Calgary Depression Scale, Global Assessment of Functioning, and Medical Outcomes Study Short-Form 36. Safety was rigorously monitored. Response was defined as 30% reduction in the Positive and Negative Syndrome Scale total score. The 2 treatment groups were similar in (1) demographic and clinical characteristics at baseline, (2) response rate, and (3) improvement in various psychopathological measures and quality of life at end point. The monotherapy group had a higher increase in prolactin levels (P= 0.04) and Simpson-Angus Scale scores (P= 0.04) and a higher percentage of biperiden use (P= 0.045). There were no significant between-group difference in changes in weight, vital signs, corrected QT interval, liver/renal function, fasting glucose level, and lipid profiles. The findings suggest that risperidone monotherapy may yield higher prolactin levels than a combination of low-dose risperidone plus low-dose haloperidol. The 2 treatment groups are similar in efficacy, life quality, and other safety profiles. Future long-term studies are warranted.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.