Graphene active sensor arrays for long-term and wireless mapping of wide frequency band epicortical brain activity.

Graphene active sensors have demonstrated promising capabilities for the detection of electrophysiological signals in the brain. Their functional properties, together with their flexibility as well as their expected stability and biocompatibility have raised them as a promising building block for large-scale sensing neural interfaces. However, in order to provide reliable tools for neuroscience and biomedical engineering applications, the maturity of this technology must be thoroughly studied. Here, we evaluate the performance of 64-channel graphene sensor arrays in terms of homogeneity, sensitivity and stability using a wireless, quasi-commercial headstage and demonstrate the biocompatibility of epicortical graphene chronic implants. Furthermore, to illustrate the potential of the technology to detect cortical signals from infra-slow to high-gamma frequency bands, we perform proof-of-concept long-term wireless recording in a freely behaving rodent. Our work demonstrates the maturity of the graphene-based technology, which represents a promising candidate for chronic, wide frequency band neural sensing interfaces.

Hemodialysis-induced upregulation of granulocyte adhesion molecules CD11b/CD18 is independent from 5-lipoxygenase activity.

Hemodialysis with new cuprophane membranes upregulates expression of granulocyte adhesion molecules and activates 5-lipoxygenase as reflected by the enhanced generation of leukotriene B4 (LTB4). We assessed the role of 5-lipoxygenase activity in hemodialysis-induced upregulation of the granulocyte adhesion molecules, CD11b and CD18, and granulocyte adhesion to human umbilical vein endothelial cells in an ex vivo dialysis model. 5-Lipoxygenase was effectively inhibited by preincubation of human whole blood with the specific inhibitor, BAY X1005. Dialysis with new cuprophane but not with new acrylonitrile membranes significantly upregulated expression of CD11b and CD18 by 6-fold and 4-fold, respectively. Inhibition of 5-lipoxygenase did not affect the expression of CD11b and CD18 during dialysis with either of the two membranes. In contrast to the enhanced expression of CD11b and CD18, adhesion of granulocytes to human umbilical vein endothelial cells did not increase during dialysis, nor was it affected by BAY X1005. These data indicate that ex vivo dialysis with cuprophane membranes upregulates expression of CD11b and CD18 on granulocytes independent of the activation of 5-lipoxygenase.