A Green-Emitting Luminol Analogue as the Next-Generation Chemiluminescent Substrate in Biochemical Analysis.

Luminol and its derivatives are extensively used as chemiluminogenic substrates in bioimaging and biochemical analysis. Luminol reagents can typically emit blue chemiluminescence (CL), whose wavelength is normally outside the most sensitive detection range of human naked eyes and most CL analyzers with silicon-based charge-coupled device (CCD) detectors. Development of luminol analogues with longer wavelength emission is thus attractive. Herein, four new phthalhydrazide CL probes (GL-1/2/3/4) have been prepared through the derivatization of luminol. The most promising one, 5-(4-hydroxy-1,3-dioxoisoindolin-2-yl)-2,3-dihydrophthalazine-1,4-dione (GL-1), emits bright green CL upon oxidation and shows enhanced CL performance compared to its parent luminol. Bloodstain imaging, horseradish peroxidase (HRP)-based immunoassay, and the analysis of glucose/glucose oxidase reaction have been performed using the GL-1 reagent. These results indicate that GL-1 is a new chemiluminogenic luminol analogue with great potential in real analytical applications and will be an alternative to replace luminol in practical CL analysis.

Multiregional viscoelastic characterization of the corona radiata in the sagittal plane of the porcine brain.

Detailed finite element (FE) models are used as promising tools to investigate traumatic brain injuries, although their accuracy is strongly dependent on the characterization of the mechanical behaviors of the different anatomic structures in the brain. In some cases, when the FE models require finer spatial resolution, the heterogeneous and anisotropic corona radiata cannot be taken as a homogeneous whole body. In this work, indentation experiments were conducted on the anterior, superior, and posterior regions of the corona radiata in the sagittal plane. To determine the parameters available for computational modeling purposes, a linear viscoelastic model using the Boltzmann hereditary integral was fitted to the force-time data of the three regions. In the indentation tests, the superior region appeared to be the stiffest, while no significant differences were observed between the anterior and posterior regions until the viscoelastic tissue reached equilibrium. During the period of relaxation, statistical comparisons among the different regions indicated significant differences between the superior and anterior regions, and between the superior and posterior regions. This work complements existing investigations into the anatomic heterogeneity of the brain, and contributes toward improving the spatial resolution of future computational models. Graphical abstract Relaxation functions of different regions based on the Prony series parameters and the multiregional Kolmogorov-Smirnov comparisons (*p < 0.017). The anisotropy and interregional differences of the corona radiata observed in this study are supplementary to the previous explorations of the mechanical properties of different brain anatomic structures.

Mechanical Properties of Porcine Brain Tissue in the Coronal Plane: Interregional Variations of the Corona Radiata.

Most biomechanical models that aim to investigate traumatic brain injury consider the corona radiata as a homogeneous structure. To verify this, indentation-relaxation tests using a custom-designed indentation device were performed on the anterior, superior, and posterior region of the corona radiata in the coronal plane of the porcine brain. Using Boltzmann hereditary integral, a linear viscoelastic model with a Prony series approximation was fitted to the time-dependent shear modulus for different regions of the corona radiata, and the fit parameters were generated. The posterior region was the stiffest and the anterior region was the least stiff. A statistical analysis revealed a significant difference in biomedical properties between the anterior and superior regions, as well as between the anterior and posterior regions in the short time scale. However, the results showed that these differences faded away as the tissue approached equilibrium. No significant difference was observed between the superior and posterior regions along the total time history of relaxation. This is the first demonstration of the regional biomechanical heterogeneity of the corona radiata, and these results will improve future biomedical models of the porcine brain.