Downeypeck6702

Highly specific enrichment of phosphopeptides from complex biological samples was a precondition for further studying its physiological and pathological processes due to the important and trace amounts of phosphopeptides. In this work, phytic acid (PA) functionalized magnetic cerium and zirconium bimetallic metal-organic framework nanocomposites (denoted as Fe3O4@SiO2@Ce-Zr-MOF@PA) were fabricated by a facile yet efficient method. The as-prepared nanomaterial exhibited high sensitivity (0.1 fmol μL-1), high selectivity toward phosphopeptides from β-casein tryptic digests/BSA (1  800), and good reusability of five cycles for enriching phosphopeptides. This affinity probe was applied to biological samples, and 19, 4 and 15 phosphopeptides were identified from non-fat milk, human serum and human saliva, respectively. The above marked advantages are attributed to the strong affinity of the abundant Ce-O and Zr-O nanoclusters on the surface of the MOF shell with the improved hydrophilicity from a great number of phosphate groups. Therefore, the novel Fe3O4@SiO2@Ce-Zr-MOF@PA nanospheres could not only enrich phosphopeptides effectively, but also reduce the adsorption of phosphopeptides, manifesting great potential in the identification and further analysis of low abundance phosphopeptides in complex biological samples.The correct execution of many cellular processes, such as division and motility, requires the cell to adopt a specific shape. Physically, these shapes are determined by the interplay of the plasma membrane and internal cellular driving factors. While the plasma membrane defines the boundary of the cell, processes inside the cell can result in the generation of forces that deform the membrane. These processes include protein binding, the assembly of protein superstructures, and the growth and contraction of cytoskeletal networks. Due to the complexity of the cell, relating observed membrane deformations back to internal processes is a challenging problem. Here, we review cell shape changes in endocytosis, cell adhesion, cell migration and cell division and discuss how by modeling membrane deformations we can investigate the inner working principles of the cell.Fibrinogen participates in many physiological processes and is a biomarker for a variety of diseases. On this account, the development of a sensitive method for fibrinogen assay is particularly important. Herein, we demonstrate a new color-coded single-particle detection (SPD) method for fibrinogen detection by using platelet membrane-coated fluorescent polystyrene nanoparticles (PNPs) as the probes. Due to the specific interactions between fibrinogen and integrin receptors on platelet membranes, PNPs can form aggregated structures in the presence of fibrinogen. Therefore, colocalization events between green and red PNPs and the corresponding Pearson's correlation coefficient vary with the concentrations of fibrinogen. The sensing ability shows a linear range of 30-300 μg mL-1 and a limit of detection (LOD) of 3.9 μg mL-1 (11.3 nM) for fibrinogen detection. selleck inhibitor Moreover, it has been validated that the proposed biosensor can selectively detect fibrinogen and shows a good performance in real sample applications.MAX and MXene have received considerable attention owing to their outstanding performance in fields like battery and catalysis. However, their possible biomedical applications have rarely been considered, especially the affinity chromatographic applications in proteomics. In this work, considering the large number of exposed metal sites, small binding potential resistance and fast mass transfer speed, layered ternary carbides MAX-Ti3AlC2 and MXene-Ti3C2 with a two-dimensional nanostructure were successfully explored for the first time as affinity chromatography stationary phases for the specific capture of phosphopeptides from complex biological samples. Helium ion microscopy, transmission electron microscopy, atomic force microscopy, X-ray diffraction spectra, X-ray photoelectron spectroscopy and zeta potential measurement results confirmed that the MXene-Ti3C2 was well exfoliated from the pristine MAX-Ti3AlC2. Ti3AlC2 showed better enrichment specificity than MXene-Ti3C2. The detection limit of Ti3AlC2 was as low as 5 fmol. Even when the molar ratio of BSA to β-casein tryptic digests increased to 1000  1, two characteristic phosphopeptides with a relatively clear background could be detected after enrichment. After five cycles of repeated use, the enrichment specificity of Ti3AlC2 still remains. Furthermore, 91 and 830 unique phosphopeptides from 23 and 525 phosphoproteins were identified from milk and BEL7402 cells, respectively. Among them, 27 and 170 phosphopeptides, 12 and 56 phosphoproteins identified from milk and BEL7402 cells were not detected with commercial TiO2 after three independent replicates, which have great potential in providing complementary coverage of phosphoproteome. This work opens up new applications of Ti3AlC2 and MXene-Ti3C2, and will play more important role for phosphorylated proteomics in biomedicine.Microbes form integral components of all natural ecosystems. In most cases, the surrounding micro-environment has physical variations that affect the movements of micro-swimmers, including solid objects of varying size, shape and density. As swimmers move through viscous environments, a combination of hydrodynamic and steric forces are known to significantly alter their trajectories in a way that depends on surface curvature. In this work, our goal was to clarify the role of steric forces when rod-like swimmers interact with solid objects comparable to cell size. We imaged hundreds-of-thousands of scattering interactions between swimming bacteria and micro-fabricated pillars with radii from ∼1 to ∼10 cell lengths. Scattering interactions were parameterized by the angle of the cell upon contact with the pillar, and primarily produced forward-scattering events that fell into distinct chiral distributions for scattering angle - no hydrodynamic trapping was observed. The chirality of a scattering event was a stochastic variable whose probability smoothly and symmetrically depended on the contact angle. Neglecting hydrodynamics, we developed a model that only considers contact forces and torques for a rear-pushed thin-rod scattering from a cylinder - the model predictions were in good agreement with measured data. Our results suggest that alteration of bacterial trajectories is subject to distinct mechanisms when interacting with objects of different size; primarily steric for objects below ∼10 cell lengths and requiring incorporation of hydrodynamics at larger scales. These results contribute to a mechanistic framework in which to examine (and potentially engineer) microbial movements through natural and synthetic environments that present complex steric structure.