Griffithbranch0769

Development of in vitro, preclinical cancer models that contain cell-driven microenvironments remains a challenge. Engineering of millimeter-scale, in vitro tumor models with spatially distinct regions that can be independently assessed to study tumor microenvironments has been limited. Here, we report the use of porous silk scaffolds to generate a high cell density neuroblastoma (NB) model that can spatially recapitulate changes resulting from cell and diffusion driven changes. Using COMSOL modeling, a scaffold holder design that facilitates stacking of thin, 200 μm silk scaffolds into a thick, bulk millimeter-scale tumor model (2, 4, 6, and 8 stacked scaffolds) and supports cell-driven oxygen gradients was developed. Cell-driven oxygen gradients were confirmed through pimonidazole staining. Post-culture, the stacked scaffolds were separated for analysis on a layer-by-layer basis. The analysis of each scaffold layer demonstrated decreasing DNA and increasing expression of hypoxia related genes (VEGF, CAIX, and GLUT1) from the exterior scaffolds to the interior scaffolds. Furthermore, the expression of hypoxia related genes at the interior of the stacks was comparable to that of a single scaffold cultured under 1% O2 and at the exterior of the stacks was comparable to that of a single scaffold cultured under 21% O2. The four-stack scaffold model underwent further evaluation to determine if a hypoxia activated drug, tirapazamine, induced reduced cell viability within the internal stacks (region of reduced oxygen) as compared with the external stacks. Decreased DNA content was observed in the internal stacks as compared to the external stacks when treated with tirapazamine, which suggests the internal scaffold stacks had higher levels of hypoxia than the external scaffolds. This stacked silk scaffold system presents a method for creating a single culture model capable of generating controllable cell-driven microenvironments through different stacks that can be individually assessed and used for drug screening.We report the syntheses, structures, magnetic and electrochemical properties of MRhRh metal cores helically wrapped by four dpa- (2,2'-dipyridylamide) ligands. We successfully synthesized the precursor Rh2(dpa)4 (1) in high yield and characterized its structure including its oxidized form (1+) which facilitated the syntheses of this series of metal springs. By the reactions of (1) and the metal ions of group 7 to group 12 (M = Mn(2), Fe(3), Co(4), Ni(5), Cu(6), Pd(8), Pt(9), Ru(10), Ir(11) and Rh(12)), ten MRh2(dpa)4Cl2 complexes were successfully isolated. Note that Cd(7) can only be obtained by the one-pot method. The yield of Rh3(dpa)4Cl2 (12) is also improved by this stepwise method. The oxidized complexes [MRh2(dpa)4Cl2](PF6) (M Ni(5+), Ru(10+), Ir(11+)) are also synthesized for the studies of electronic structures and magnetic properties. The X-ray diffraction technique is applied to characterize all of their structures. The results of these structural, magnetic, and electrochemical studies provide us with in-depth knowledge and comprehensive insight into metal-metal bonds and interactions for this new series of metal strings. In particular, four metal-metal bonds with short distances are found Pd-Rh (2.372(13) Å), Pt-Rh (2.385(7) Å), Ru-Rh (2.33(3) Å), and Ir-Rh (2.373(5) Å). The remaining ones show no evidence of covalent metal bonds judging from their metal-metal distances, magnetic behaviour, and redox couples in electrochemical analysis. Besides, two unique tetranuclear MRhRhM(dpa)4X2 (M Cu+(13) and Ag+(14)) complexes with a Rh2(dpa)4 framework are developed. Four metals are aligned linearly. This coordination mode of metal strings provides a unique synthetic route for constructing longer metal chains from a smaller number of dentate ligands.Blood compatibility generally requires two contradictory characteristics reduced protein/platelet adhesion and excellent endothelium-related cell affinity. To understand the effect of cell adhesion peptides on blood compatibility, the peptides REDV, RGD, and hemocompatible peptide-1 (HCP-1) were immobilized on an expanded polytetrafluorethylene (ePTFE) surface and evaluated in vitro, in situ, and in vivo. Since the terminal amino groups of functional peptides often have an important effect, a cysteine residue was added to the C terminal and used for immobilization to keep the terminal amino groups free. Maleimide groups were added to carboxylic groups of highly hydrophilic and biologically inert (bioinert) polymer chains grafted onto ePTFE and coupled with cysteine residues. In vitro tests revealed that free N-terminal HCP-1 and RGD-immobilized surfaces improved the adhesion and spread of human umbilical vein endothelial cells (HUVECs), while, unexpectedly, a free N-terminal adjacent to REDV suppressed cell affinity. In situ evaluation with a porcine closed-circuit system for 2 h showed that no platelets adhered to the modified ePTFE sutures due to the bioinert graft chain containing phosphorylcholine groups. Simultaneously, leukocyte-related and endothelium-related cells were observed on RGD-immobilized ePTFE sutures because RGD was recognized by broad types of cells. These cells were not observed on the HCP-1- and REDV-immobilized ePTFE sutures, which may be due to insufficient exposure time. HCP-1-modified ePTFE graft implantation in a porcine femorofemoral (FF) bypass model for 10 days showed that the thrombus layer was clearly mitigated by HCP-1 immobilization. This study suggests that the HCP-1-immobilized ePTFE surface has potential for long-term application by mitigating thrombus and supporting endothelial cell adhesion.Cyclopentane modified FIT-PNA (cpFIT-PNA) probes are reported as highly emissive RNA sensors with the highest reported brightness for FIT-PNAs. Inhibitor Library in vitro Compared to FIT-PNAs, cpFIT-PNAs have improved mismatch discrimination for several pyrimidine-pyrimidine single nucleotide variants (SNVs).Structural organization of hydrogen and oxygen functionalized nanodiamond (ND) particles in hydrosols was investigated using a cryo-TEM method. The formation of chain-like structures was observed for hydrogen functionalized NDs while oxygen functionalized NDs tend to form more compact structures. In order to understand possible interaction mechanisms between NDs in hydrosols and to explain these experimental results, first-principles calculations were performed. Charged H-terminated ND particles and particles with partially dissociated hydroxyl and carboxyl groups on the surface were investigated as models of a real ND particle in solution. For positively charged H-terminated particles, it was established that charge distribution is determined by the values of valence band maximum for the particle facets. For negatively charged oxygen functionalized particles, the charge is localized near functional groups. In both cases, interaction is determined by the interplay between Coulomb interaction and van der Waals attraction.