Bolus tracking with nanofilter-based multispectral videography for capturing microvasculature hemodynamics

Multispectral imaging is a highly desirable modality for material-based analysis in diverse areas such as food production and processing, satellite-based reconnaissance, and biomedical imaging. Here, we present nanofilter-based multispectral videography (nMSV) in the 700 to 950â €...nm range made possible by the tunable extraordinary-optical- transmission properties of 3D metallic nanostructures. Measurements made with nMSV during a bolus injection of an intravascular tracer in the ear of a piglet resulted in spectral videos of the microvasculature. Analysis of the multispectral videos generated contrast measurements representative of arterial pulsation, the distribution of microvascular transit times, as well as a separation of the venous and arterial signals arising from within the tissue. Therefore, nMSV is capable of acquiring serial multispectral images relevant to tissue hemodynamics, which may have application to the detection and identification of skin cancer

Surface Plasmon Resonance Sensing Properties of a 3D Nanostructure Consisting of Aligned Nanohole and Nanocone Arrays

Molecular surface plasmon resonance (SPR) sensing is one of the most common applications of an array of periodic nanoholes in a metal film. However, metallic nanohole arrays (NHAs) with low-hole count have lower resolution and SPR sensing performance compared to NHAs with high-hole count. In this paper, we present a compact three-dimensional (3D) plasmonic nanostructure with extraordinary optical transmission properties benefiting from surface plasmon matching and enhanced localized surface plasmon coupling. The 3D nanostructure consisted of a gold film containing a NHA with an underlying cavity and a gold nanocone array (NCA) at the bottom of the cavity. Each nanocone was aligned with the nanohole above and the truncated apex of each nanocone was in close proximity (100 nm) to the gold film. The NHA-NCA structures outperformed conventional NHA structures in terms of bulk sensitivity and Figure of Merit (FOM). Furthermore, the NHA-NCA structure with 525-nm periodicity was capable of sensing streptavidin down to 2 nM exhibiting a 10-fold increase in streptavidin sensitivity compared to conventional NHA structures. The sensitivity and performance of the 3D nanostructure can be further improved by exploiting multiplexing methods in combination with stable light sources and detection systems

Potential for photoacoustic imaging of the neonatal brain

Photoacoustic imaging (PAI) has been proposed as a non-invasive technique for imaging neonatal brain injury. Since PAI combines many of the merits of both optical and ultrasound imaging, images with high contrast, high resolution, and a greater penetration depth can be obtained when compared to more traditional optical methods. However, due to the strong attenuation and reflection of photoacoustic pressure waves at the skull bone, PAI of the brain is much more challenging than traditional methods (e.g. near infrared spectroscopy) for optical interrogation of the neonatal brain. To evaluate the potential limits the skull places on 3D PAI of the neonatal brain, we constructed a neonatal skull phantom (1.4-mm thick) with a mixture of epoxy and titanium dioxide powder that provided acoustic insertion loss (1-5MHz) similar to human infant skull bone. The phantom was molded into a realistic infant skull shape by means of a CNCmachined mold that was based upon a 3D CAD model. To evaluate the effect of the skull bone on PAI, a photoacoustic point source was raster scanned within the phantom brain cavity to capture the imaging operator of the 3D PAI system (128 ultrasound transducers in a hemispherical arrangement) with and without the intervening skull phantom. The resultant imaging operators were compared to determine the effect of the skull layer on the PA signals in terms of amplitude loss and time delay. © 2013 Copyright SPIE

The involvement of aβ in the neuroinflammatory response

In the same year as Alzheimer described the case of Auguste D. as a peculiar disease of the cerebral cortex, Fischer published his classic paper about miliary plaque formation in a large number of brains from patients with senile dementia [1]. In this paper and a following one from 1910, Fischer stated that plaque formation is the result of the deposition of a peculiar foreign substance in the cortex that induces a regenerative response of the surrounding nerve fibers [2]. He described spindle-shaped thickening of nerve fibers terminating with club forms in the corona of plaques (Fig. 4.1). These altered nerve fibers were considered as axonal sprouting, and the terminal club forms showed a strong similarity with the clubshaped buddings of axons found in developing nerve fibers and after transections of peripheral nerves as described by Cajal some years earlier. According to Fischer, the crucial step of the plaque formation is the deposition of a foreign substance that provokes a local inflammatory response step followed by a regenerative response of the surrounding nerve fibers. However, Fischer could not find morphological characteristics of an inflammatory process around the plaques after extensive histopathological observations including complement binding studies. The only tissue reaction appeared to be an overgrowth of club-formed neurites