Optoacoustic monitoring of water content in tissue phantoms and human skin.

Skin water content monitoring is important for diagnostics and management of edema, dehydration, and other skin conditions as well as for cosmetic applications. Because optoacoustic (OA) technique has high (optical) contrast and (ultrasound) resolution and significant probing depth, it may be suitable for accurate, noninvasive water content monitoring in the skin. In this work we studied OA response from skin tissue phantoms and human wrist skin in the wavelength range from 1370 nm to 1650 nm using a novel, tunable OPO OA system.

Ultrafast, Ultrasensitive Detection and Imaging of Single Cardiac Troponin-T Molecules.

The fluorescence-based methods of single-molecule optical detection have opened up unprecedented possibilities for imaging, monitoring, and sensing at a single-molecule level. However, single-molecule detection methods are very slow, making them practically inapplicable. In this paper, we show how to overcome this key limitation using the expanded laser spot, laser excitation in a nonfluorescent spectral window of biomolecules, and more binding fluorescent molecules on a biomolecule that increases the detection volume and the number of collected photons.

Adipose-derived stem cells improve grafted burn wound healing by promoting wound bed blood flow.

Background: Researchers have explored the use of adipose-derived stem cells (ASCs) as a cell-based therapy to cover wounds in burn patients; however, underlying mechanistic aspects are not completely understood. We hypothesized that ASCs would improve post-burn wound healing after eschar excision and grafting by increasing wound blood flow via induction of angiogenesis-related pathways.

Methods: To test the hypothesis, we used an ovine burn model.

Non-Invasive Transcranial Nano-Pulsed Laser Therapy Ameliorates Cognitive Function and Prevents Aberrant Migration of Neural Progenitor Cells in the Hippocampus of Rats Subjected to Traumatic Brain Injury.

Traumatic brain injury (TBI) can lead to chronic diseases, including neurodegenerative disorders and epilepsy. The hippocampus, one of the most affected brain region after TBI, plays a critical role in learning and memory and is one of the only two regions in the brain in which new neurons are generated throughout life from neural stem cells (NSC) in the dentate gyrus (DG). These cells migrate into the granular layer where they integrate into the hippocampus circuitry.

Nano-Pulsed Laser Therapy Is Neuroprotective in a Rat Model of Blast-Induced Neurotrauma.

We have developed a novel, non-invasive nano-pulsed laser therapy (NPLT) system that combines the benefits of near-infrared laser light (808 nm) and ultrasound (optoacoustic) waves, which are generated with each short laser pulse within the tissue. We tested NPLT in a rat model of blast-induced neurotrauma (BINT) to determine whether transcranial application of NPLT provides neuroprotective effects. The laser pulses were applied on the intact rat head 1 h after injury using a specially developed fiber-optic system.

Optoacoustic Monitoring of Physiologic Variables.

Optoacoustic (photoacoustic) technique is a novel diagnostic platform that can be used for noninvasive measurements of physiologic variables, functional imaging, and hemodynamic monitoring. This technique is based on generation and time-resolved detection of optoacoustic (thermoelastic) waves generated in tissue by short optical pulses. This provides probing of tissues and individual blood vessels with high optical contrast and ultrasound spatial resolution.

Optoacoustic diagnostic modality: from idea to clinical studies with highly compact laser diode-based systems.

Optoacoustic (photoacoustic) diagnostic modality is a technique that combines high optical contrast and ultrasound spatial resolution. We proposed using the optoacoustic technique for a number of applications, including cancer detection, monitoring of thermotherapy (hyperthermia, coagulation, and freezing), monitoring of cerebral blood oxygenation in patients with traumatic brain injury, neonatal patients, fetuses during late-stage labor, central venous oxygenation monitoring, and total hemoglobin concentration monitoring as well as hematoma detection and characterization. We developed and built optical parametric oscillator-based systems and multiwavelength, fiber-coupled highly compact, laser diode-based systems for optoacoustic imaging, monitoring, and sensing.

Split Hole Resonator: A Nanoscale UV Light Source.

Because of strong light absorption by metals, it is believed that plasmonic nanostructures cannot be used for generating intensive radiation harmonics in the ultraviolet (UV) spectral range. This work presents results of investigation of nonlinear optical interaction with a single gold nanostructure, the split-hole resonator (SHR) under the state-of-the-art experimentally realized conditions. To realize interaction with all spectral components of a 6 fs laser pulse several multipole plasmon resonances were simultaneously excited in the SHR nanostructure.

Optoacoustic detection of intra- and extracranial hematomas in rats after blast injury.

Surgical drainage of intracranial hematomas is often required within the first four hours after traumatic brain injury (TBI) to avoid death or severe disability. Although CT and MRI permit hematoma diagnosis, they can be used only at a major health-care facility. This delays hematoma diagnosis and therapy.

Effect on blood glucose monitoring of skin pressure exerted by an optical coherence tomography probe.

We proposed to use optical coherence tomography (OCT) for continuous noninvasive blood glucose monitoring, and recently we significantly improved the sensitivity of this technique. The accuracy of OCT glucose monitoring is limited by several factors, including variation of tissue pressure exerted by the OCT probe. We studied the influence of high (>10 kPa) and low (<1 kPa) pressure levels on OCT blood glucose monitoring.

Composition of PLGA and PEI/DNA nanoparticles improves ultrasound-mediated gene delivery in solid tumors in vivo.

The goal of this study was to enhance gene delivery and tumor cell transfection in vivo by using a combination of ultrasonication with complex nanoparticles consisting of two types of nanoparticles: PEI/DNA beta-gal plasmid with highly positive zeta-potential and air-filled poly (lactic-co-glycolic acid) (PLGA) particles (with negative zeta-potential) manufactured in our laboratory. The PLGA/PEI/DNA nanoparticles were a colloid with positive zeta-potential and injected i.v.

Monte Carlo modeling of optoacoustic signals from human internal jugular veins.

Monitoring of blood oxygenation, in particular, cerebral venous oxygenation, is necessary for management of a variety of life-threatening conditions. An optoacoustic technique can be used for noninvasive monitoring of blood oxygenation in blood vessels, including large veins. We calculated optoacoustic signals from a cylinder mimicking a blood vessel using a modified Monte Carlo code and analyzed their temporal profiles.

Prediction capability of optical coherence tomography for blood glucose concentration monitoring.

Background: Optical coherence tomography (OCT) has been shown to be a promising optical approach to noninvasive monitoring of blood glucose concentration because of its capability of probing optical properties at different depths in tissue with high resolution. This article investigates the capability of OCT to predict changes in blood glucose concentration.

Methods: We varied blood glucose concentration in the physiological range in three sets of experiments.

Influence of osmolytes on in vivo glucose monitoring using optical coherence tomography.

Diabetes mellitus and its complications are the third leading cause of death in the world, exceeded only by cardiovascular disease and cancer. Tighter monitoring and control of blood glucose could minimize complications associated with diabetes. Recently, optical coherence tomography (OCT) for noninvasive glucose monitoring was proposed and tested in vivo.

In vivo study of glucose-induced changes in skin properties assessed with optical coherence tomography.

Recently, our in vivo studies demonstrated a strong correlation between blood glucose concentration and the slope of the optical coherence tomography (OCT) signal when the probing beam was scanned over a straight line. To improve the sensitivity of OCT for blood glucose monitoring, two-dimensional (2D) lateral scanning of the OCT probing beam was proposed. Depth-dependent changes in pig skin properties with variation of blood glucose concentration were revealed due to significant suppression of speckle noise and motion artefacts in 2D scanning mode.

Multiwavelength optoacoustic system for noninvasive monitoring of cerebral venous oxygenation: a pilot clinical test in the internal jugular vein.

A noninvasive, high-resolution optoacoustic technique is a promising alternative to currently used invasive methods of brain oxygenation monitoring. We present the results of our pilot clinical test of this technique in healthy volunteers. Multiwavelength optoacoustic measurements (with nanosecond optical parametric oscillator as a source of radiation) were performed on the area of the neck overlying the internal jugular vein, a deeply located large vein that drains blood from the brain and from extracranial tissues.

Effect of 5-fluorouracil, Optison and ultrasound on MCF-7 cell viability.

The aim of this study was to analyze cell viability and expression of apoptotic-related signaling proteins in MCF-7 breast cancer cells induced by combinations of ultrasound, the anticancer drug 5-fluorouracil (5-FU) and the ultrasound contrast agent Optison. MCF-7 cells were treated with 5-FU and sonicated at the frequency of 3.0 MHz and intensity of 3.

Optoacoustic monitoring of blood hemoglobin concentration: a pilot clinical study.

The optoacoustic technique is noninvasive, has high spatial resolution, and potentially can be used to measure the total hemoglobin concentration ([THb]) continuously and accurately. We performed in vitro measurements in blood and in vivo tests in healthy volunteers. Our clinical protocol included rapid infusion of intravenous saline to simulate rapid change in the [THb] during fluid therapy or surgery.

Optimal drug and gene delivery in cancer cells by ultrasound-induced cavitation.

Background: Lack of efficient drug and gene delivery is one of the major problems of cancer chemo- and bio-therapy. This work is focused on optimization of ultrasound-induced delivery of model macromolecular anti-cancer drugs and DNA in human cancer cells.

Materials And Methods: FITC dextrans simulated antisense oligonucleotides (10 kDa), antibodies (70 kDa), and genes (2000 kDa).

Enhancement of drug delivery in tumors by using interaction of nanoparticles with ultrasound radiation.

Efficacy and safety of cancer chemo- and biotherapy are limited by poor penetration of anti-cancer drugs from blood into tumor cells. Tumor blood vessel wall, slow diffusion in the interstitium, and cancer cell membrane create physiological barriers for anti-cancer drugs, in particular promising macromolecular agents. Recently, we proposed to use selective accumulation of exogenous nano- and microparticles in tumors followed by ultrasound-induced cavitation for safe and efficient drug and gene delivery.

Optoacoustic, noninvasive, real-time, continuous monitoring of cerebral blood oxygenation: an in vivo study in sheep.

Background: Current, invasive cerebral oxygenation monitors require either retrograde jugular venous bulb cannulation or intraparenchymal probe insertion. There is no accurate, noninvasive, continuous monitor of cerebral blood oxygenation.

Methods: The authors designed, built, and tested novel optoacoustic instrumentation that continuously measures blood oxygenation in the superior sagittal sinus (SSS) in vivo in 12 anesthetized sheep.

Monitoring of rabbit cornea response to dehydration stress by optical coherence tomography.

Purpose: To evaluate the application of optical coherence tomography (OCT) for continuous noninvasive monitoring and quantification of the dynamics of corneal response after exposure of the cornea to dehydrating stress.

Methods: The changes in central corneal thickness (CCT) and scattering properties of the cornea were monitored with OCT in rabbit cornea in vivo after topical application of a glycerin-based hypertonic agent (HA) or prolonged surface evaporation of the cornea. The observed changes in backscatter were correlated with the changes in corneal hydration.

Phase-sensitive optical low-coherence reflectometry for the detection of analyte concentrations.

Optical techniques may potentially be used for noninvasive glucose sensing. We investigated the application of phase-sensitive optical low-coherence reflectometry (PS-OLCR) to the measurement of analyte concentrations. The dependence of the PS-OLCR signal on the concentration of various analytes, including aqueous solutions of glucose, calcium chloride, magnesium chloride, sodium chloride, potassium chloride, potassium bicarbonate, urea, bovine serum albumin, and bovine globulin, were determined in clear and turbid media.

Continuous, noninvasive monitoring of total hemoglobin concentration by an optoacoustic technique.

Measurement of total hemoglobin concentration [Hgb] is a blood test that is widely used to evaluate outpatients, hospital inpatients, and surgical patients, especially those undergoing surgery associated with extensive blood loss, rapid fluid administration, and transfusion of packed red blood cells. Current techniques for measurement of [Hgb] are invasive (requiring blood sampling) and cannot provide real-time, continuous monitoring. We propose to use an optoacoustic technique for noninvasive and continuous monitoring of [Hgb].