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Commercial or clinical tissue adhesives are currently limited due to their weak bonding strength on wet biological tissue surface, low biological compatibility, and slow adhesion formation. Although catechol-modified hyaluronic acid (HA) adhesives are developed, they suffer from limitations: insufficient adhesiveness and overfast degradation, attributed to low substitution of catechol groups. In this study, we demonstrate a simple and efficient strategy to prepare mussel-inspired HA hydrogel adhesives with improved degree of substitution of catechol groups. Because of the significantly increased grafting ratio of catechol groups, dopamine-conjugated dialdehyde–HA (DAHA) hydrogels exhibit excellent tissue adhesion performance (i.e., adhesive strength of 90.0 ± 6.7 kPa), which are significantly higher than those found in dopamine-conjugated HA hydrogels (∼10 kPa), photo-cross-linkable HA hydrogels (∼13 kPa), or commercially available fibrin glues (2–40 kPa). At the same time, their maximum adhesion energy is 384.6 ± 26.0 J m–2, which also is 40–400-fold, 2–40-fold, and ∼8-fold higher than those of the mussel-based adhesive, cyanoacrylate, and fibrin glues, respectively. Moreover, the hydrogels can gel rapidly within 60 s and have a tunable degradation suitable for tissue regeneration. Together with their cytocompatibility and good cell adhesion, they are promising materials as new biological adhesives.

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However, we have no information on the stoichiometric charge number on the surface of tungstic acid colloid. Thus, we estimated the amount of free protons from the solution conductance and from the reference values of equivalent conductance of protons.The evaluated D 1 values for our system were in the range of several thousand angstroms. This correction term then became quite significant for the smaller colloids. The triangles in Figure 8 show the values of D, calculated from Perrin's equation with use of effective semiaxes including Debye-length. The dashed line indicates the rotational diffusion constant estimated by using crystallographic size. The increasing tendency of D, with concentration is clearly the same as that shown by the triangles, though the absolute values are slightly different. This deviation is believed to be due to the rough estimation of the amount of free protons.The significance of the Debye-length has often been pointed out for the solution properties of various colloids and polyelectrolytes in salt-free systems such as the ordered solution structure in monodispersed l a t i c e~,~~-~~ conformation of ionic flexible polymer^,^*-^^ and very low mobility of spherical colloids at ex-(31) Alexander, S.; Chaikin, P. M.; Grant, P.; Morales, G. J.; Pimcus, P.; Hone. D.Abstract: The one-electron reduction of Cr"'(EDTA)-at a mercury electrode was studied by an AC impedance technique in aqueous solutions of different viscosities (varied by addition of sucrose). The standard rate constant of the heterogeneous electron transfer, k",,, (corrected for diffuse double layer effects with experimentally measured parameters), showed a significant variation with solution viscosity. This viscosity dependence of k",, in the kinetically limited region was interpreted in terms of the dynamic properties of the solvent. A reasonable correlation between k",, and the solvent polarity term (nD-2e; ' ) could be obtained only when the preexponential factor was allowed to vary inversely with solution viscosity.A variation of the rate constant for heterogeneous electron transfer (et) reactions ( k S ) with solution viscosity was reported

Chemiluminescence (CL) detection is seldom used in two-dimensional solid support microarray platforms because adequate sensitivity and spatial resolution is difficult to achieve. The three-dimensional ordered microchannels of the Flow-thru Chip increase both the sensitivity and spatial resolution required for quantitative CL measurements on microarrays. Enzyme-catalyzed CL reactions for the detection of hybridizations on microchannel glass were imaged using a CCD camera. Signal uniformity, sensitivity, and dynamic range of the detection method were determined. The relative standard deviation of signal intensities across an array of 64 spots was 8.1%. A detection limit of 250 amol of target with a linear dynamic range of 3 orders of magnitude was obtained for a 3-h assay. Similar to two-color fluorescence measurements, multiple enzyme labels were employed to demonstrate two-channel chemiluminescence. A unique method for measuring the relaxation time of a chemiluminescent species is also described.

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