Alzheimer’s disease (AD) is a neurodegenerative disorder that leads to a decline in cognitive and intellectual abilities and an irreversible mental deterioration. Based on multidisciplinary AD research, the most universally accepted hypotheses on AD pathogenesis are the intracerebral aggregate formation of beta-amyloid (Aβ ) peptides. According to medical paradigmatic transition from medical treatment to early diagnostic prevention, scientists have considered physiological body fluid as a biomarker medium, in which the promising AD biomarkers could be verified. Recently, use of saliva has been considered as one of the diagnostic fluids over the past decade with meaningful diagnostic potential. We utilized saliva as a biomarker medium to correlate the salivary Aβ levels to AD pathological aspects, especially to the mild cognitive impairment group among AD patients, and to verify our detecting system to be sensitive enough for an early diagnostic tool. The identification of the salivary AD biomarkers using a facile microarraying method would motivate this study with the assistance of magnetically assembled antibody-conjugated nanoparticles and a photomultiplier tube as an optical detector. This simple magnetoimmunoassay system measures the photointensity generated by fluorescence, enables the quantification of the Aβ peptides from AD salivary samples, and consequently classifies the salivary Aβ levels into AD pathological aspects. This method demonstrates a facile approach enabling it to simply detect salivary Aβ peptides at a concentration as low as ∼20 pg/ml . It is expected that our simple magnetoimmunoassay system may have a potential as a detector for low-level Aβ peptides with weak-fluorescence emission.
In order to detect interested matters in fields, various lab-on-a-chips where chemical, physical, or biological sensors are
loaded have been developed. eNOSE can be a representative example among them. Because animals can sense
300~1000 different chemicals by olfactory system – smell –, the olfactory system has been spotlighted as new materials
in the field of sensing. Those investigations, however, are usually focused on how to detect signals from the olfactory
neurons or receptors loaded on chips and enhance sensing efficacy of chips. Therefore, almost of those chips are
designed for only one material sensing. Multi-sensing using multi-channels will be needed when the olfactory systems
are adopted well on chips. For multiple sensing, we developed an addressable cell array. The chip has 38 cell-chambers
arranged in a circle shape and different cell types of thirty eight can be allocated with specific addresses on the chip
without any complex valve system. In order to confirm the cell addressing, we loaded EGFP-transfected and empty
vector-transfected HEK293a cells into inlets of the cell array in a planned address and those cells were positioned into
each chamber by brief aspiration. The arrayed cells were confirmed as a specific pattern through EGFP and nuclei
staining. This cell array which can generate address of sensor materials like cells with their own specification is expected
to be applied to a platform for a biosensor chip at various sensing fields.
This article describes a novel method for detection of amyloid-β (Aβ) peptide that utilizes a photo-sensitive field-effect
transistor (p-FET). According to a recent study, Aβ protein is known to play a central role in the pathogenesis of
Alzheimer’s disease (AD). Accordingly, we investigated the variation of photo current of the p-FET generated by the
magnetic beads conjugated with Aβ peptides which are placed on the p-FET sensing areas. Additionally, in order to
amplify the output signal, we used the lock-in amplifier (LIA) and confirmed the generating the photo current by a small
incident light power under 100 μW. It means that it is possible to simply detect a certain protein using magnetic beads
conjugated with Aβ peptide and fluorescent label located on the p-FET device. Therefore, in this paper, we suggest that
our method could detect tiny amounts of Aβ peptide for early diagnosis of AD using the p-FET devices.
The importance of early Alzheimer’s disease (AD) detection has been recognized to diagnose people at high risk of AD.
The existence of intra/extracellular beta-amyloid (Aβ) of brain neurons has been regarded as the most archetypal
hallmark of AD. The existing computed-image-based neuroimaging tools have limitations on accurate quantification of
nanoscale Aβ peptides due to optical diffraction during imaging processes. Therefore, we propose a new method that is
capable of evaluating a small amount of Aβ peptides by using photo-sensitive field-effect transistor (p-FET) integrated
with magnetic force-based microbead collecting platform and selenium(Se) layer (thickness ~700 nm) as an optical filter.
This method demonstrates a facile approach for the analysis of Aβ quantification using magnetic force and magnetic
silica microparticles (diameter 0.2~0.3 μm). The microbead collecting platform mainly consists of the p-FET sensing
array and the magnet (diameter ~1 mm) which are placed beneath each sensing region of the p-FET, which enables the
assembly of the Aβ antibody conjugated microbeads, captures the Aβ peptides from samples, measures the photocurrents
generated by the Q-dot tagged with Aβ peptides, and consequently results in the effective Aβ quantification.
KEYWORDS: Ferroelectric materials, Actuators, Data storage, Analog electronics, Optical storage, Sensors, Surface roughness, Mathematical modeling, Near field, Control systems
Near-field optical storage using cantilever aperture tip is a promising way for next generation optical data storage. To enhance the speed of reading and writing data, gap between tip and media should be controlled fast and precisely within near field region. In this paper, several PZT actuators are analyzed for constructing dual servo control algorithm: coarse actuators (stack PZT, bimorph PZT) for media surface inclination and fine actuator (film PZT) for media surface roughness. Dynamic analysis of stack PZT, bimorph PZT, and film PZT are performed through the frequency response. Based on the frequency response and mathematical model, fast analog controller is designed and experimented. From experimental results, analog control of film PZT is 50 times faster than conventional stage. We get the 0.1 msec over 800nm step.
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