Bioengineering of a functional cardiac tissue composed of primary cardiomyocytes has great potential for myocardial regeneration and in vitro tissue modeling. However, its applications remain limited because the cardiac tissue is a highly organized structure with unique physiologic, biomechanical, and electrical properties. In this study, we undertook a proof-of-concept study to develop a contractile cardiac tissue with cellular organization, uniformity, and scalability by using three-dimensional (3D) bioprinting strategy. Primary cardiomyocytes were isolated from infant rat hearts and suspended in a fibrin-based bioink to determine the priting capability for cardiac tissue engineering. This cell-laden hydrogel was sequentially printed with a sacrificial hydrogel and a supporting polymeric frame through a 300-μm nozzle by pressured air. Bioprinted cardiac tissue constructs had a spontaneous synchronous contraction in culture, implying in vitro cardiac tissue development and maturation. Progressive cardiac tissue development was confirmed by immunostaining for α-actinin and connexin 43, indicating that cardiac tissues were formed with uniformly aligned, dense, and electromechanically coupled cardiac cells. These constructs exhibited physiologic responses to known cardiac drugs regarding beating frequency and contraction forces. In addition, Notch signaling blockade significantly accelerated development and maturation of bioprinted cardiac tissues. Our results demonstrated the feasibility of bioprinting functional cardiac tissues that could be used for tissue engineering applications and pharmaceutical purposes.

Functional quantum dot (QD)-based nanostructures are often constructed through the self-assembly of QDs with binding partners (molecules or other nanoparticles), a process that leads to a statistical distribution of the number of binding partners. Using single QD fluorescence spectroscopy, we probe this distribution and its effect on the function (electron-transfer dynamics) in QD-C60 complexes. Ensemble-averaged transient absorption and fluorescence decay as well as single QD fluorescence decay measurements show that the QD exciton emission was quenched by electron transfer from the QD to C60 molecules and the electron-transfer rate increases with the C60-to-QD ratio. The electron-transfer rate of single QD-C60 complexes fluctuates with time and varies among different QDs. The standard deviation increases linearly with the average of electron-transfer rates of single QD-C60 complexes, and the distributions of both quantities obey Poisson statistics. The observed distributions of single QD-C60 complexes and ensemble-averaged fluorescence decay kinetics can be described by a model that assumes a Poisson distribution of the number of adsorbed C60 molecules per QD. Our findings suggest that, in self-assembled QD nanostructures, the statistical distribution of the number of adsorbed partners can dominate the distributions of the averages and standard deviation of their interfacial dynamical properties.

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Highlights d Six high-quality ixodid tick genomes and 678 re-sequenced tick specimens d Insights into the genetic basis of tick hematophagy and related phenotypes d Population structure and genetic diversity of six tick species d Tick-borne pathogen composition and distribution by metagenome analyses

Liposomes ( approximately 100-nm diameter) containing Ru(bpy)32+ (bpy = 2,2'-bipyridine) were prepared as an electrogenerated chemiluminescent (ECL) tag for a sandwich-type immunoassay of human C-reactive protein (CRP). Polyclonal human CRP antibodies were introduced onto liposomes and magnetic beads through biotin-streptavidin interaction. The antigen-antibody conjugates formed on addition of a CRP-containing sample were separated from unreacted species magnetically. Addition of 0.1 M tri-n-propylamine and 0.1 M phosphate buffer (pH 7.6) containing 0.1 M NaCl and 1% (v/v) Triton X-100 caused liberation of the Ru(bpy)32+ from the liposome. ECL obtained in this medium showed a detection limit of 100 ng/mL for human CRP with good linearity of ECL intensity versus antigen concentration over the range 100 ng/mL-10 microg/mL.

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The hydrothermal reaction of phosphonoacetic acid (H2PO3CH2C(O)OH, PAA) with UO3 and Cu(C2H3O2)2 .H2O results in the formation of the crystalline heterobimetallic uranium(VI)/copper(II) phosphonates UO2Cu(PO3CH2CO2)(OH)(H2O)2 ( UCuPAA-1), (UO2) 2Cu(PO3CH2CO2)2(H2O)3 (UCuPAA-2), and [H3O][(UO2) 2Cu2(PO3CH2CO2)3(H2O)2 ( UCuPAA-3). The addition of sodium hydroxide to the aforementioned reactions results in the formation of Na[UO2(PO3CH2CO2)].2H2O (NaUPAA-1). These compounds display 1D (UCuPAA-1), 2D (UCuPAA-2, NaUPAA-1), and 3D (UCuPAA-3) architectures wherein the phosphonate portion of the ligand primarily coordinates the uranium(VI) centers; whereas the carboxylate moiety preferentially, but not exclusively, binds to the copper(II) ions. Fluorescence measurements on all four compounds demonstrate that the presence of copper(II) mostly quenches the emission from the uranyl moieties.