The conformational flexibility of antibodies in solution directly affects their immune function. Namely, the flexible hinge regions of immunoglobulin G (IgG) antibodies are essential in epitope-specific antigen recognition and biological effector function. The antibody structure, which is strongly related to its functions, has been partially revealed by electron microscopy and X-ray crystallography, but only under non-physiological conditions. Here we observed monoclonal IgG antibodies in aqueous solution by high-resolution frequency modulation atomic force microscopy (FM-AFM). We found that monoclonal antibodies self-assemble into hexamers, which form two-dimensional crystals in aqueous solution. Furthermore, by directly observing antibody-antigen interactions using FM-AFM, we revealed that IgG molecules in the crystal retain immunoactivity. As the self-assembled monolayer crystal of antibodies retains immunoactivity at a neutral pH and is functionally stable at a wide range of pH and temperature, the antibody crystal is applicable to new biotechnological platforms for biosensors or bioassays.

Local hydration structures at the solid–liquid interface around boundary edges on heterostructures are key to an atomic-level understanding of various physical, chemical and biological processes. Recently, we succeeded in visualising atomic-scale three-dimensional hydration structures by using ultra-low noise frequency-modulation atomic force microscopy. However, the time-consuming three-dimensional-map measurements on uneven heterogeneous surfaces have not been achieved due to experimental difficulties, to the best of our knowledge. Here, we report the local hydration structures formed on a heterogeneously charged phyllosilicate surface using a recently established fast and nondestructive acquisition protocol. We discover intermediate regions formed at step edges of the charged surface. By combining with molecular dynamics simulations, we reveal that the distinct structural hydrations are hard to observe in these regions, unlike the charged surface regions, possibly due to the depletion of ions at the edges. Our methodology and findings could be crucial for the exploration of further functionalities.

Background. The area near the left gastric vein (LGV) is a challenging site at which to perform dissection of the lymph nodes during gastrectomy. Therefore, knowledge of the precise location of the LGV is important. The objective of this study was to examine the usefulness of multidetector computed tomography (MDCT) for the identifi cation of the LGV. Methods. Eighty-one patients with gastric cancer underwent MDCT, which was performed with contrast media in 76 patients and without contrast media in 5 patients. A 5-mm thin slice of the frontal image was reconstructed. These images were examined preoperatively to detect the location of the LGV. Upon gastrectomy, the LGV was identifi ed and its location compared to that determined by MDCT. Results. The LGV was identifi ed by MDCT in 76 of the 81 patients (93.8%). The LGV was subsequently located during the operation in all 81 patients. The LGV was located dorsal to the common hepatic artery in 40 patients (49.4%), ventral to the common hepatic artery in 18 patients (22.2%), ventral to the splenic artery in 17 patients (21.0%), dorsal to the splenic artery in 2 patients (2.5%) and in other positions in 4 patients (4.9%). In all patients, the location of the LGV detected using MDCT was consistent with that identifi ed during gastrectomy. In the 4 patients with relatively unusual locations of the LGV, these 4 LGV variants were identifi ed preoperatively by MDCT. Conclusion. MDCT was useful for identifying the location of the LGV prior to gastrectomy.