We developed new photonic crystal polymerized crystalline colloidal array (PCCA) glucose sensing materials, which operate on the basis of formation of cross-links in the hydrogel. These materials are composed of hydrogels that embed an array of approximately 100-nm-diameter monodisperse polystyrene colloids that Bragg diffract light in the visible spectral region. The hydrogels change volume as the glucose concentration varies. This changes the lattice spacing, which changes the wavelength of the diffracted light. In contrast to our previous glucose sensing photonic crystal materials, we no longer require Na+ chelating agents. These photonic crystal materials are being designed for use in glucose sensing contact lens for people with diabetes mellitus. We describe methods to speed up the response kinetics of these PCCA sensing materials. Rapid-response kinetics is achieved by controlling the elasticity and the hydrophilic-hydrophobic balance of the hydrogel system. A more hydrophobic hydrogel composition is obtained by copolymerizing n-hexylacrylate into an acrylamide-bisacrylamide hydrogel. The response rate significantly increases to where it fully responds within 90 s to the average glucose concentrations found in blood (5 mM) and within 300 s to the average glucose concentrations found in tear fluid (0.15 mM). We find unusual temperature-dependent kinetics, which derive from glucose mutarotation in solution. It is shown that alpha-d-glucose is the glucose anomer binding to the boronic acid derivative. Care must be taken in any glucose determination to ensure that the glucose mutarotation equilibrium has been established. We have demonstrated that the sensor is responsive to approximately 0.15 mM glucose concentrations in artificial tear fluid solution.

Summary: Two types of ink‐jet inks are presented: ink containing an aqueous dispersion of silver nanoparticles and an oil‐in‐water microemulsion‐based ink. The metallic ink contains nanoparticles of silver, which are formed in the presence of an ionic polymeric stabilizer. Sintering of the printed image obtained with the use of such silver‐based inks at temperatures as low as 300 °C results in formation of patterns possessing noticeable conductivity. The microemulsion inks are based on a thermodynamically stable microemulsion, in which the dispersed oil phase is a volatile solvent containing a water‐insoluble colorant. After contact of the jetted ink droplets with a substrate, nanodroplets of the microemulsion are converted into nanoparticles of the solubilized colorant. In some cases, it was found that the evaporation of microemulsion ink droplets leads to formation of rings composed of ordered nanoparticles.Scheme of ink‐jet printing of an oil‐in‐water microemulsion followed by conversion of the nanodroplets into nanoparticles, caused by quick evaporation of the solvent within the microemulsion droplets. Therefore, the ink behaves as a dye‐based ink prior to printing, but after printing it behaves like a pigment‐based ink.magnified imageScheme of ink‐jet printing of an oil‐in‐water microemulsion followed by conversion of the nanodroplets into nanoparticles, caused by quick evaporation of the solvent within the microemulsion droplets. Therefore, the ink behaves as a dye‐based ink prior to printing, but after printing it behaves like a pigment‐based ink.

Evaporation of liquid drops containing nanospheres resulted in circular deposition patterns. The circularity of the patterns depended on the uniformity of the surface tension on the substrate. By employing binary suspensions, containing two differently sized nanospheres, it was possible to modulate the fine structure of such rings. Slow evaporation on mirror-polished substrates resulted in well-ordered distributions, where larger particles self-assembled in dense hexagonal packages, forming apparently an external ring, deposited around the massive inner ring. Deposition started at the air/liquid/solid-contact line. Results could inspire principles for the fabrication of optical devices and may be fruitfully used to design biomaterials with cell-selective properties. A simple model is employed to predict the radial arrangement of nanospheres in rings. Deviations from a standard order (predicted by the model) may be useful to detect biologically active nanoparticles.

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