Fluorescent Protein–photoprotein Fusions and Their Applications in Calcium Imaging

Calcium‐activated photoproteins, such as aequorin, have been used as luminescent Ca²⁺ indicators since 1967. After the cloning of aequorin in 1985, microinjection was substituted by its heterologous expression, which opened the way for a widespread use. Molecular fusion of green fluorescent protein (GFP) to aequorin recapitulated the nonradiative energy transfer process that occurs in the jellyfish Aequorea victoria, from which these two proteins were obtained, resulting in an increase of light emission and a shift to longer wavelength. The abundance and location of the chimera are seen by fluorescence, whereas its luminescence reports Ca²⁺ levels. GFP‐aequorin is broadly used in an increasing number of studies, from organelles and cells to intact organisms. By fusing other fluorescent proteins to aequorin, the available luminescence color palette has been expanded for multiplexing assays and for in vivo measurements. In this report, we will attempt to review the various photoproteins available, their reported fusions with fluorescent proteins and their biological applications to image Ca²⁺ dynamics in organelles, cells, tissue explants and in live organisms.     

Functional Polymer‐Opals from Core–Shell Colloids

Colloidal photonic crystals were prepared from monodisperse core–shell particles. The shell is hereby formed from a functional monomer, such as glycidylmethacrylate or different reactive ester monomers, which can perform chemical reactions and the core from a standard monomer, which yields highly monodisperse colloids. It was possible to crystallize the core–shell particles into artificial opals with excellent optical properties. Reactions on the functional surface of the colloids were carried out, which lead to a dramatic rise in the mechanical stability or to a functionalization of His‐tagged silicatein, which acts as nanoreactor to synthesize and immobilize gold nanoparticles from auric acid onto the core–shell colloids.

     

Electronic Currents Induced by Optical Fields and Rotatory Power Density in Chiral Molecules

The electric dipole–magnetic dipole polarizability tensor κ′, introduced to interpret the optical activity of chiral molecules, has been expressed in terms of a series of density functions kαβ′, which can be integrated all over the three-dimensional space to evaluate components καβ′ and trace καα′. A computational approach to kαβ′, based on frequency-dependent electronic current densities induced by monochromatic light shining on a probe molecule, has been developed. The dependence of kαβ′ on the origin of the coordinate system has been investigated in connection with the corresponding change of καβ′. It is shown that only the trace kαα′ of the density function defined via dynamic current density evaluated using the continuous translation of the origin of the coordinate system is invariant of the origin. Accordingly, this function is recommended as a tool that is quite useful for determining the molecular domains that determine optical activity to a major extent. A series of computations on the hydrogen peroxide molecule, for a number of different HO–OH dihedral angles, is shown to provide a pictorial documentation of the proposed method.     

Electric field-induced self-assembly of micro- and nanoparticles of various shapes at two-fluid interfaces

Particle lithography which explores the capability of particles to self-assemble offers an attractive means to manufacture nanostructured materials. Although traditional techniques typically lead to the formation of dense crystals, adjustable non-close-packed crystals are crucial in a number of applications. We have recently proposed a novel method to assemble spherical micro- and nanoparticles into monolayers. The technique consists of trapping particles at a liquid-fluid interface and applying an electric field normal to the interface. Particles rearrange themselves under the influence of interfacial and electrostatic forces to form 2-D hexagonal arrays of long-range order and whose lattice constant depends on the electric field strength and frequency. Furthermore, the existence of an electric field-induced capillary force makes the technique applicable to submicron and nanosized particles. Although spherical particles are often used, non-spherical particles can be beneficial in practice. Here, we review the method, discuss its applicability to particles of various shapes, and present results for particles self-assembly on air-liquid and liquid-liquid interfaces. In the case of non-spherical particles, the self-assembly process, while still taking place, is more complex as particles experience a torque which causes them to rotate relative to one another. This leads to a final arrangement displaying either a dominant orientation or no well-defined orientation. We also discuss the possibility of dislodging the particles from the interface by applying a strong electric field such that the Weber number is of order 1 or larger, a phenomenon which can be utilized to clean particles from liquid-fluid surfaces.     

Synthesis of rigid multivalent scaffolds based on adamantane

An efficient route to novel 1,3,5,7-tetrasubstituted derivatives of adamantane is described. This route starts from adamantane and gives the tetrafunctionalized derivative 9 in eight steps with an overall yield of 23%. These tetrahedrally shaped molecules possess three identical arms terminated by an activated carboxylic acid derivative and a protected amino function in the 1-position. We propose these tetravalent cage compounds such as 9 as scaffolds for the assembly of ligand/marker conjugates for studies of multivalent ligand receptor interactions. [reaction: see text]     

Algebra properties for Sobolev spaces — applications to semilinear PDEs on manifolds

In this work, we aim to prove algebra properties for generalized Sobolev spaces W ^s,p ?? L ^?? on a Riemannian manifold (or more general homogeneous type space as graphs), where W ^s,p is of Bessel-type W ^s,p := (1+L)^?s/m (L ^p ) with an operator L generating a heat semigroup satisfying off-diagonal decays. We do not require any assumption on the gradient of the semigroup. Instead, we propose two different approaches (one by paraproducts associated to the heat semigroup and another one using functionals). We also study the action of nonlinearities on these spaces and give applications to semi-linear PDEs. These results are new on Riemannian manifolds (with a non-bounded geometry) and even in euclidean space for Sobolev spaces associated to second order uniformly elliptic operators in divergence form.     

Enhanced Maturation of 3D Bioprinted Skeletal Muscle Tissue Constructs Encapsulating Soluble Factor-Releasing Microparticles

Several microfabrication technologies have been used to engineer native-like skeletal muscle tissues. However, the successful development of muscle remains a significant challenge in the tissue engineering field. Muscle tissue engineering aims to combine muscle precursor cells aligned within a highly organized 3D structure and biological factors crucial to support cell differentiation and maturation into functional myotubes and myofibers. In this study, the use of 3D bioprinting is proposed for the fabrication of muscle tissues using gelatin methacryloyl (GelMA) incorporating sustained insulin-like growth factor-1 (IGF-1)-releasing microparticles and myoblast cells. This study hypothesizes that functional and mature myotubes will be obtained more efficiently using a bioink that can release IGF-1 sustainably for in vitro muscle engineering. Synthesized microfluidic-assisted polymeric microparticles demonstrate successful adsorption of IGF-1 and sustained release of IGF-1 at physiological pH for at least 21 days. Incorporating the IGF-1-releasing microparticles in the GelMA bioink assisted in promoting the alignment of myoblasts and differentiation into myotubes. Furthermore, the myotubes show spontaneous contraction in the muscle constructs bioprinted with IGF-1-releasing bioink. The proposed bioprinting strategy aims to improve the development of new therapies applied to the regeneration and maturation of muscle tissues.     

Synthesis and isolation of {110}-faceted gold bipyramids and rhombic dodecahedra

Two {110}-faceted gold nanostructures--rhombic dodecahedra and obtuse triangular bipyramids--have been synthesized via a Ag-assisted, seed-mediated growth method. The combination of a Cl(-)-containing surfactant with a low concentration of Ag(+) plays a role in the stabilization of the {110} facets. To the best of our knowledge, this is the first reported synthesis of a {110}-faceted bipyramid structure.     

Critical node/edge detection problems on trees

4OR - We consider the problem of removing a limited subset of nodes and/or edges from a graph in order to minimize the so-called pairwise connectivity of the residual graph, which is defined as the...