Molecular imaging:design mechanism and bioapplications

Molecular imaging is a non-invasive method to image and analyze the concentration and activity of functional biomolecules in cells or in vivo at molecular level,and plays an increasing role in deep understanding of biological processes,early and accurate diagnosis of diseases,and evaluation of treatment.Nowadays,numerous novel molecular imaging probes have been developed,involving every biomedical imaging modality,such as optical imaging,photoacoustic imaging,magnetic resonance imaging,single-photon-emission computed tomography,and positron emission tomography.In this review,we summarize the development of current state-of-the-art molecular imaging probes.We introduce the design strategies of molecular probes and detailed imaging modalities,and highlight the properties of probes and biomedical imaging applications in cells and in vivo,including disease diagnosis,drug tracking,and imaging-guided surgery.Then we discuss the perspectives and challenges in this emerging field.We expect this review could inspire more effective molecular imaging probes to be developed,achieving the goal towards clinical practices.

Generating Giant Membrane Vesicles from Live Cells with Preserved Cellular Properties

Biomimetic giant membrane vesicles,with size and lipid compositions comparable to cells,have been recognized as an attractive experimental alternative to living systems.Due to the similarity of their membrane structure to that of body cells,cell-derived giant plasma membrane vesicles have been used as a membrane model for studying lipid/protein behavior of plasma membranes.However,further application of biomimetic giant membrane vesicles has been hampered by the side-efects of chemical vesiculants and the utilization of osmotic bufer.We herein develop a facile strategy to derive giant membrane vesicles(GMVs)from mammalian cells in biofriendly medium with high yields.Tese GMVs preserve membrane properties and adaptability for surface modifcation and encapsulation of exogenous molecules,which would facilitate their potential biological applications.Moreover,by loading GMVs with therapeutic drugs,GMVs could be employed for drug transport to tumor cells,which represents another step forward in the biomedical application of giant membrane vesicles.Tis study highlights biocompatible GMVs with biomimicking membrane surface properties and adaptability as an ideal platform for drug delivery strategies with potential clinical applications.

State-of-the-art on resistance of bearing-type bolted connections in high strength steel

With the recent development of material science,high strength steel(HSS)has become a practical solution for landmark buildings and major projects.The current codes for design of bearing-type bolted connections of steel constructions were established based on the research of conventional steels.Since the mechanical properties of HSS are different from those of conventional steels,more works should be done to develop the appropriate approach for the design of bearing-type bolted connections in HSS.A review of the research carried out on bearing-type bolted connections fabricated from conventional steel and HSS is presented.The up-to-date tests conducted at Tongji University on four connection types fabricated from three grades of HSS with nominal yield strengths of 550,690,and 890 MPa are presented.The previous research on failure modes,bearing resistance and the design with consideration of bolt hole elongation are summarized.It is found that the behavior of bolted connections in HSS have no drastic difference compared to that of conventional steel connections.Although the ductility is reduced,plastic deformation capacity of HSS is sufficient to ensure the load redistribution between different bolts with normal construction tolerances.It is also found that behavior of each bolt of multi-bolt connections arranged in perpendicular to load direction is almost identical to that of a single-bolt connection with the same end distance.For connections with bolts arranged in parallel to load direction,the deformation capacity of the whole connection depends on the minimum value between the end distance and the spacing distances in load direction.The comparison with existing design codes shows that Eurocode3 and Chinese GB50017-2017 are conservative for the design of bolted connections in HSS while AISC 360-16 may overestimate the bearing resistance of bolted connections.