New approach to control ischemic severity ex vivo.

Background: It is advantageous to be able to both control and define a metric for ischemia severity in ex vivo models to enable more precise comparisons to in vivo models and to facilitate more sophisticated mechanistic studies. Currently, the primary method to induce and study ischemia ex vivo is to completely deplete oxygen and glucose in the culture media; however, in vivo ischemia often involves varying degrees of severities.

New Method: In this work, we have successfully developed an approach to both control and characterize three different ischemic severities ex vivo and we define these standard condition metrics via an oxygen sensor: normoxia (control), mild ischemia (partial oxygen-glucose deprivation), and severe ischemia (complete oxygen-glucose deprivation).

Plasma-treated gold microelectrodes for subsecond detection of Zn(II) with fast-scan cyclic voltammetry.

The sensitivity of zinc (Zn(II)) detection using fast-scan cyclic voltammetry (FSCV) with carbon fiber microelectrodes (CFMEs) is low compared to other neurochemicals. We have shown previously that Zn(II) plates to the surface of CFME's and we speculate that it is because of the abundance of oxide functionality on the surface. Plating reduces sensitivity over time and causes significant disruption to detection stability.

Subsecond Codetection of Dopamine and Estradiol at a Modified Sharkfin Waveform.

17β-Estradiol (E2) is a ubiquitously expressed hormone that is active in a wide range of neuroprotective and regenerative roles throughout the brain. In particular, it is a well-known dopamine (DA) regulator and is responsible for modulating the expression of dopaminergic receptors and transporters. Recent studies point to E2 release occurring on a rapid time scale and having impacts on DA activity within seconds to minutes.

Dynamic and Rapid Detection of Guanosine during Ischemia.

Guanosine acts in both neuroprotective and neurosignaling pathways in the central nervous system; in this paper, we present the first fast voltammetric measurements of endogenous guanosine release during pre- and post-ischemic conditions. We discuss the metric of our measurements via analysis of event concentration, duration, and interevent time of rapid guanosine release. We observe changes across all three metrics from our normoxic to ischemic conditions.

Graphene-Fiber Microelectrodes for Ultrasensitive Neurochemical Detection.

Here, we have synthesized and characterized graphene-fiber microelectrodes (GFME's) for subsecond detection of neurochemicals with fast-scan cyclic voltammetry (FSCV) for the first time. GFME's exhibited extraordinary properties including faster electron transfer kinetics, significantly improved sensitivity, and ease of tunability that we anticipate will have major impacts on neurochemical detection for years to come. GF's have been used in the literature for various applications; however, scaling their size down to microelectrodes and implementing them as neurochemical microsensors is significantly less developed.