Abstract.Information from theoretical models of redox enzyme linked biosensors highlights the importance of membrane thickness and enzyme loading on signal response in regard to both sensitivity and reproducibility. The conclusions are substantiated by examination of practical examples in the literature and, with a view to the importance of the character of the enzyme layer and overlayers, immobilization techniques are assessed which are in current use.

The indentation response of Nickel nano double gyroid films has been measured using a Berkovich nano indenter and the effective mechanical properties of the Ni double gyroid lattices inferred via a multi-scale finite element analysis. The 1 μm thick double gyroid films were manufactured by block copolymer self-assembly followed by electrodeposition of the Ni resulting in two interpenetrating single gyroids of opposite chirality, an overall relative density of 38% and a cell size of about 45 nm. The measured hardness was ~ 0.6 GPa with no discernable indentation size effect. A multi-scale finite element (FE) analysis revealed that the uniaxial compressive strength is approximately equal to the hardness for this compressible lattice. Thus, the 38% relative density Ni double gyroid has a strength equal to or greater than the strongest fully dense bulk Ni alloys. The FE calculations revealed that this was a consequence of that fact that the Ni in the 13 nm gyroid struts was essentially dislocation free and had a strength of about 5.7 GPa, i.e. approaching the theoretical strength value of Ni. The measurements and calculations reported here suggest that inspite of the nano gyroids having a bending-dominated topology they attain strengths higher than those reported for stretching-dominated micron scale lattice materials made via 3D printing. We thus argue that relatively fast and easy selfassembly processes are a competitive alternative to 3D printing manufacture methods for making high strength lattice materials.

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The differentiation of the pancreatic endocrine cells in the lizard Anolis carolinensis following oviposition was examined. Immediately postoviposition (PO) there was no apparent differentiation of epithelioid cells into endocrine or exocrine components. Individual subpopulations of the endocrine-like cells, which could not be identified during the early PO period on the basis of either their tinctorial properties at the light-microscopic level or their granule morphologies at the electron-microscopic level, exhibited specific hormonal localization by peroxidase-antiperoxidase complex immunocytochemistry. All four hormones searched for, insulin, glucagon, somatostatin, and pancreatic polypeptide (PP), were present in epithelioid cells shortly after oviposition. However, the immunostained secretory granules in the early PO period were smaller than those of the adult. Secretory granule morphologies that are typical of the adult were acquired at different times during development. Delta granules were observed first and were followed by alpha granules, and beta granules which appeared shortly before birth. The secretory granules of the PP-containing F cells could not be readily placed within this maturation sequence. Mosaic cells (containing more than one hormone) were not seen. Levels of immunoreactive insulin and glucagon in the pancreas increased several fold from day 10 to day 28 PO, but the attainment of adult beta-granule morphologies did not appear to be directly related to insulin itself. The results show that cytodifferentiation of the anolian endocrine pancreas occurs postoviposition and that immunocytochemical methods can be used to follow an organelle sequence during development. These findings suggest that subcellular organelles undergo structural remodeling during maturation which, at least in the case of secretory granules, may have functional significance.