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maintain than the opto-acoustic geometry of conventional PA microscopy techniques. This results in a system capable of high resolution and sensitivity, imaging at real-time rates. The authors believe this work represents a vital step towards a clinical high-resolution reflection-mode video-rate PA imaging system.

In summary, we present a method that has a small computational overhead for image rendering, resulting in a live display capable of real-time frame rates. selleck products We also report the first 3D imaging with a non-contact label-free reflection-mode PA technique. The all-optical confocal geometry required by PARS is significantly easier to implement and maintain than the opto-acoustic geometry of conventional PA microscopy techniques. This results in a system capable of high resolution and sensitivity, imaging at real-time rates. The authors believe this work represents a vital step towards a clinical high-resolution reflection-mode video-rate PA imaging system.

Optical fiber probe spectroscopy can characterize the blood content, hemoglobin oxygen saturation, water content, and scattering properties of a tissue. A narrow probe using closely spaced fibers can access and characterize a local tissue site, but analysis requires the proper light transport theory.

Monte Carlo simulations of photon transport specified the response of a two-fiber probe as a function of optical properties in a homogeneous tissue. The simulations used the dimensions of a commercial fiber probe (400-micron-diameter fibers separated by 80-microns of cladding) to calculate the response to a range of 20 absorption and 20 reduced scattering values. The 400 simulations yielded an analysis grid (lookup table) to interpolate the probe response to any given pair of absorption and scattering properties.

The probe in contact with tissue is not sensitive to low absorption but sensitive to scattering, as occurs for red to near-infrared spectra. The probe is sensitive to both absorption and scattering the dimensions of a commercial probe (Ocean Insight), but the method can be applied to any probe design. A closely spaced fiber probe can document blood in the shorter visible wavelengths, but has difficulty detecting red and near-infra-red absorption. Hence detection of hydration is difficult. The strength of the closely spaced fiber probe is detecting scattering that depends on tissue structure at the micron to sub-micron scale.

Near infrared (NIR) environment-sensitive fluorophores are highly desired for many biomedical applications because of its non-invasive operation, high sensitivity and specificity, non-ionizing radiation and deep penetration in biological tissue. When the fluorophores are appropriately encapsulated in or conjugated with some thermal-sensitive polymers, they could work as excellent temperature-sensing probes.

In this study, we synthesized and characterized a series of NIR temperature-switchable nanoparticles based on two series of NIR fluorophores aza-BODIPY (ADP is used for abbreviation in this work) and Zinc phthalocyanine (ZnPc) and four pluronic polymers (F127, F98, F68 and F38). Encapsulating the fluorophores in the polymers by sonication, we synthesized the nanoparticles that showed switch-like functions of the fluorescence intensity (and/or lifetime) as the temperature, with high switch on-to-off ratio. We also investigated various factors that might change the temperature thresholds (T

) of the switch functions, in order to control T

during synthesis.

These nanoparticles showed excellent temperature-switchable properties of fluorescence intensity and/or lifetime. Meanwhile, some factors (i.e., pluronic categories and nanoparticles’ concentration) significantly affected the nanoparticles’ T

s while other (i.e., fluorophore categories) that weakly affected T

s.

By selecting appropriate pluronic categories and adjusting the nanoparticle’s concentration, we can synthesize the nanoparticles with a wide range of T

s. These temperature-switchable fluorescence nanoparticles can be used for biomedical imaging and

tissue temperature sensing/imaging.

By selecting appropriate pluronic categories and adjusting the nanoparticle’s concentration, we can synthesize the nanoparticles with a wide range of Tths. These temperature-switchable fluorescence nanoparticles can be used for biomedical imaging and in vivo tissue temperature sensing/imaging.

Genetically encoded calcium indicators (GECIs), especially the GCaMP-based green fluorescence GECIs have been widely used for

detection of neuronal activity in rodents by measuring intracellular neuronal Ca

changes. More recently, jRGECO1a, a red shifted GECI, has been reported to detect neuronal Ca

activation. This opens the possibility of using dual-color GECIs for simultaneous interrogation of different cell populations. However, there has been no report to compare the functional difference between these two GECIs for

imaging. Here, a comparative study is reported on neuronal responses to sensory stimulation using GCaMP6f and jRGECO1a that were virally delivered into the neurons in the somatosensory cortex of two different groups of animals, respectively.

GCaMP6f and jRGECO1a GECI were virally delivered to sensory cortex. After 3-4 weeks, the animals were imaged to capture the spatiotemporal changes of neuronal Ca

and the hemodynamic responses to forepaw electrical stimulation (0.3 mA, 0.3 types (e.g., neurons and astrocytes) to study brain activation and brain functional changes in normal or diseased brains.

Conventional light sheet fluorescence microscopy (LSFM), or selective plane illumination microscopy (SPIM), enables high-resolution 3D imaging over a large volume by using two orthogonally aligned objective lenses to decouple excitation and emission. The recent development of oblique plane microscopy (OPM) simplifies LSFM design with only one single objective lens, by using off-axis excitation and remote focusing. However, most reports on OPM have a limited microscopic field of view (FOV), typically within 1×1 mm

. Our goal is to overcome the limitation with a new variant of OPM to achieve a mesoscopic FOV.

We implemented an optical design of mesoscopic scanning OPM to allow the use of low numerical aperture (NA) objective lenses. The angle of the intermediate image before the remote focusing system was increased by a demagnification under Scheimpflug condition such that the light collecting efficiency in the remote focusing system was significantly improved. A telescope composed of cylindrical lenses was used to correct the distorted image caused by the demagnification design.