Size matters: Micro- versus nanobubbles in ultrasound imaging and therapy.

This study investigates the reported ability of nanobubbles (<500 nanometers in diameter) to exhibit a comparable or superior acoustic response to microbubbles (>1 micrometer in diameter). Eight hypotheses were examined. Both the theoretical and experimental results supported only one hypothesis: The apparent echogenicity of nanobubbles under both linear and nonlinear imaging is due to the presence of preexisting microbubbles, which are not reliably detected by available nanoparticle sizing methods.

Effect of Anesthetic Carrier Gas on In Vivo Circulation Times of Intravenously Administered Phospholipid Oxygen Microbubbles in Rats.

Objective: For the treatment of tumor hypoxia, microbubbles comprising oxygen as a majority component of the gas core with a stabilizing shell may be used to deliver and release oxygen locally at the tumor site through ultrasound destruction. Previous work has revealed differences in circulation half-life in vivo for perfluorocarbon-filled microbubbles, typically used as ultrasound imaging contrast agents, as a function of anesthetic carrier gas. These differences in circulation time in vivo were likely due to gas diffusion as a function of anesthetic carrier gas, among other variables.

Stepwise approach for fundus imaging in the diagnosis and management of posterior uveitis.

An array of retinochoroid imaging modalities aid in comprehensive evaluation of the immunopathological changes in the retina and choroid, forming the core component for the diagnosis and management of inflammatory disorders such as uveitis. The recent technological breakthroughs have led to the development of imaging platforms that can evaluate the layers of retina and choroid and the structural and functional alteration in these tissues. Ophthalmologists heavily rely on imaging modalities such as dye-based angiographies (fluorescein angiography and indocyanine green angiography), optical coherence tomography, fundus autofluorescence, as well as dye-less angiography such as optical coherence tomography angiograph,y for establishing a precise diagnosis and understanding the pathophysiology of the diseases.

Photoacoustic Vaporization of Endoskeletal Droplets Loaded with Zinc Naphthalocyanine.

Vaporizable endoskeletal droplets are solid hydrocarbons in liquid fluorocarbon droplets in which melting of the hydrocarbon phase leads to the vaporization of the fluorocarbon phase. In prior work, vaporization of the endoskeletal droplets was achieved thermally by heating the surrounding aqueous medium. In this work, we introduce a near-infrared (NIR) optically absorbing naphthalocyanine dye (zinc 2,11,20,29-tetra--butyl-2,3-naphthalocynanine) into the solid hydrocarbon (eicosane, -CH) core of liquid fluorocarbon (CF) drops suspended in an aqueous medium.

Ultrasonic fragmentation for removing thick organized clots during diabetic vitrectomy - A novel technique.

A 65-year-old male with proliferative diabetic retinopathy (PDR) and non-clearing vitreous hemorrhage underwent 25G pars plana vitrectomy (PPV). A large disk of thick organized blood of 5 disk diameter (DD) size was encountered in subhyaloid space. All attempts including lower cut rates to remove this disk using a 25G cutter turned futile.

Epiretinal Membrane from Uncontrolled Gliosis After Inverted ILM Flap Technique for Idiopathic Macular Hole.

We describe two cases with epiretinal membrane (ERM) from uncontrolled gliosis seen after multilayered inverted internal limiting membrane (ILM) flap technique for full thickness macular hole (FTMH). Two patients with FTMH who had undergone surgery with inverted ILM flap technique were examined by serial optical coherence tomography scans to evaluate the course of multilayered ILM flaps seen as foveal hyperreflective lesions postoperatively. We observed excessive uncontrolled gliosis over these hyperreflective ILM flaps with ERM formation, along with worsening metamorphopsia and best-corrected visual acuity.

Detecting insulitis in type 1 diabetes with ultrasound phase-change contrast agents.

Type 1 diabetes (T1D) results from immune infiltration and destruction of insulin-producing β cells within the pancreatic islets of Langerhans (insulitis). Early diagnosis during presymptomatic T1D would allow for therapeutic intervention prior to substantial β-cell loss at onset. There are limited methods to track the progression of insulitis and β-cell mass decline.

Contrast-Enhanced Sonography with Biomimetic Lung Surfactant Nanodrops.

Nanodrops comprising a perfluorocarbon liquid core can be acoustically vaporized into echogenic microbubbles for ultrasound imaging. Packaging the microbubble in its condensed liquid state provides some advantages, including activation of the acoustic signal, longer circulation persistence, and the advent of expanded diagnostic and therapeutic applications in pathologies which exhibit compromised vasculature. One obstacle to clinical translation is the inability of the limited surfactant present on the nanodrop to encapsulate the greatly expanded microbubble interface, resulting in ephemeral microbubbles with limited utility.

Acoustic Nanodrops for Biomedical Applications.

Acoustic nanodrops are designed to vaporize into ultrasound-responsive microbubbles, which presents certain challenges nonexistent for conventional nano-emulsions. The requirements of biocompatibility, vaporizability and colloidal stability has focused research on perfluorocarbons (PFCs). Shorter PFCs yield better vaporizability via their lower critical temperature, but they also dissolve more easily owing to their higher vapor pressure and solubility.

The effect of size range on ultrasound-induced translations in microbubble populations.

Microbubble translations driven by ultrasound-induced radiation forces can be beneficial for applications in ultrasound molecular imaging and drug delivery. Here, the effect of size range in microbubble populations on their translations is investigated experimentally and theoretically. The displacements within five distinct size-isolated microbubble populations are driven by a standard ultrasound-imaging probe at frequencies ranging from 3 to 7 MHz, and measured using the multi-gate spectral Doppler approach.

Microbubble Radiation Force-Induced Translation in Plane-Wave Versus Focused Transmission Modes.

Due to the primary radiation force, microbubble displacement has been observed previously in the focal region of single-element and array ultrasound probes. This effect has been harnessed to increase the contact between the microbubbles and targeted endothelium for drug delivery and ultrasound molecular imaging. In this study, microbubble displacements associated with plane-wave (PW) transmission are thoroughly investigated and compared to those obtained in focused-wave (FW) transmission over a range of pulse repetition frequencies, burst lengths (BLs), peak negative pressures, and transmission frequencies.

Hyperacute spontaneous closure of a traumatic macular hole in a colobomatous eye.

A 12 year old boy presented to us with complaints of diminution of vision following blunt injury to his left eye. Examination revealed a grade 5 retina-choroidal coloboma in left eye with haemorrhage at its inferior border. A macular hole was seen clinically which was confirmed on ocular coherence tomography (OCT).

Microbubble Formulations: Synthesis, Stability, Modeling and Biomedical Applications.

Microbubbles are increasingly being used in biomedical applications such as ultrasonic imaging and targeted drug delivery. Microbubbles typically range from 0.1 to 10 µm in size and consist of a protective shell made of lipids or proteins.

Microbubble-Mediated Enhanced Delivery of Curcumin to Cervical Cancer Cells.

The major bottleneck in the current chemotherapy treatment of cancer is the low bioavailability and high cytotoxicity. Targeted delivery of drug to the cancer cells can reduce the cytotoxicity and increase the bioavailability. In this context, microbubbles are currently being explored as drug-delivery vehicles to effectively deliver drug to the tumors or cancerous cells.

Effect of PEGylation on performance of protein microbubbles and its comparison with lipid microbubbles.

Aqueous suspensions of microbubbles are being used in various biomedical applications such as contrast imaging, targeted drug and gene delivery, delivery of drugs through blood brain barrier (BBB) and IV O delivery etc. Major microbubble formulations use either proteins or lipids as their shell material. Protein microbubble formulations mainly consist of serum albumin, lysozyme etc.