We report that vertically aligned ZnO nanowire arrays (ZnO NWAs) were fabricated on 3D graphene foam (GF) and used to selectively detect uric acid (UA), dopamine (DA), and ascorbic acid (AA) by a differential pulse voltammetry method. The optimized ZnO NWA/GF electrode provided a high surface area and high selectivity with a detection limit of 1 nM for UA and DA. The high selectivity in the oxidation potential was explained by the gap difference between the lowest unoccupied and highest occupied molecular orbitals of a biomolecule for a set of given electrodes. This method was further used to detect UA levels in the serum of patients with Parkinson's disease (PD). The UA level was 25% lower in PD patients than in healthy individuals. This finding strongly implies that UA can be used as a biomarker for PD.
Chronic in vivo imaging and electrophysiology are important for better understanding of neural functions and circuits. We introduce the new cranial window using soft, penetrable, elastic, and transparent, silicone-based polydimethylsiloxane (PDMS) as a substitute for the skull and dura in both rats and mice. The PDMS can be readily tailored to any size and shape to cover large brain area. Clear and healthy cortical vasculatures were observed up to 15 weeks post-implantation. Real-time hemodynamic responses were successfully monitored during sensory stimulation. Furthermore, the PDMS window allowed for easy insertion of microelectrodes and micropipettes into the cortical tissue for electrophysiological recording and chemical injection at any location without causing any fluid leakage. Longitudinal two-photon microscopic imaging of Cx3Cr1+/− GFP transgenic mice was comparable with imaging via a conventional glass-type cranial window, even immediately following direct intracortical injection. This cranial window will facilitate direct probing and mapping for long-term brain studies.
Recording
neural activity from the living brain is of great interest
in neuroscience for interpreting cognitive processing or neurological
disorders. Despite recent advances in neural technologies, development
of a soft neural interface that integrates with neural tissues, increases
recording sensitivity, and prevents signal dissipation still remains
a major challenge. Here, we introduce a biocompatible, conductive,
and biostable neural interface, a supramolecular β-peptide-based
hydrogel that allows signal amplification via tight neural/hydrogel
contact without neuroinflammation. The non-biodegradable β-peptide
forms a multihierarchical structure with conductive nanomaterial,
creating a three-dimensional electrical network, which can augment
brain signal efficiently. By achieving seamless integration in brain
tissue with increased contact area and tight neural tissue coupling,
the epidural and intracortical neural signals recorded with the hydrogel
were augmented, especially in the high frequency range. Overall, our
tissuelike chronic neural interface will facilitate a deeper understanding
of brain oscillation in broad brain states and further lead to more
efficient brain–computer interfaces.
The incidence of amyloid plaques, composed mainly of bamyloid peptides (Ab), does not correlate well with the severity of neurodegeneration in patients with Alzheimer's disease (AD). The effects of Ab 42 on neurons or neural stem cells (NSCs) in terms of the aggregated form remain controversial. We prepared three forms of oligomeric, fibrillar, and monomeric Ab 42 peptides and investigated their effects on the proliferation and neural differentiation of adult NSCs, according to the degree of aggregation or concentration. A low micromolar concentration (1 lmol/L) of oligomeric Ab 42 increased the proliferation of adult NSCs remarkably in a neurosphere assay. It also enhanced the neuronal differentiation of adult NSCs and their ability to migrate. These results provide us with valuable information regarding the effects of Ab 42 on NSCs in the brains of patients with AD.
Though the etiology of Parkinson's disease (PD) remains unclear, alpha-synuclein (alpha-SN) is regarded as a major causative agent of PD. Several lines of evidence indicate that immunological abnormalities are associated with PD for unknown reasons. The present study was performed to assess whether peripheral blood mononuclear cells (PBMCs) show altered alpha-SN expression in PD patients and to identify its functions, which may be related to peripheral immune abnormalities in PD. alpha-SN was found to be expressed more in 151 idiopathic PD (IPD) patients than in 101 healthy controls, who nevertheless showed as age-dependent increases. By in vitro transfection, alpha-SN expression was shown to be correlated with glucocorticoid sensitive apoptosis, possibly caused by the enhanced expression of glucocorticoid receptor (GR), caspase activations (caspase-8, caspase-9), CD95 up-regulation, and reactive oxygen species (ROS) production. An understanding of the correlation between alpha-SN levels and apoptosis in the presence of the coordinated involvement of multiple processes would provide an insight into the molecular basis of the disease. The present study provides a clue that the alpha-SN may be one of the primary causes of the immune abnormalities observed in PD and offers new targets for pharmacotherapeutic intervention.
Progressive
Alzheimer’s disease is correlated with the oligomerization
and fibrillization of the amyloid beta (Aβ) protein. We identify
the fibrillization stage of the Aβ protein through label-free
near-field THz conductance measurements in a buffer solution. Frequency-dependent
conductance was obtained by measuring the differential transmittance
of the time-domain spectroscopy in the THz range with a molar concentration
of monomer, oligomer, and fibrillar forms of the Aβ protein.
Conductance at the lower frequency limit was observed to be high in
monomers, reduced in oligomers, and dropped to an insulating state
in fibrils and increased proportionally with the Aβ protein
concentration. The monotonic decrease in the conductance at low frequency
was dominated by a simple Drude component in the monomer with concentration
and nonlinear conductance behaviors in the oligomer and fibril. By
extracting the structural localization parameter, a dimensionless
constant, with the modified Drude–Smith model, we defined a
dementia quotient (DQ) value (0 < D
e < 1) as a discrete metric for a various Aβ proteins at
a low concentration of 0.1 μmol/L; DQ = 1.0 ± 0.002 (fibril
by full localization, mainly by Smith component), DQ = 0.64 ±
0.013 (oligomer by intermixed localization), and DQ = 0.0 ± 0.000
(monomer by Drude component). DQ values were discretely preserved
independent of the molar concentration or buffer variation. This provides
plenty of room for the label-free diagnosis of Alzheimer’s
disease using the near-field THz conductance measurement.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.