Ultrasound Detection of Regional Oxidative Stress in Deep Tissues Using Novel Enzyme Loaded Nanoparticles.

Oxidative stress is a powerful tool that is critical to immune mediated responses in healthy individuals, yet additionally plays a crucial role in development of cancer, inflammatory pathologies, and tissue ischemia. Despite this, there remain relatively few molecular tools to study oxidative stress, particularly in living mammals. To develop an intravenously injectable probe capable of labeling sites of oxidative stress in vivo, 200 nm catalase synthetic hollow enzyme loaded nanospheres (catSHELS) are designed and fabricated using a versatile enzyme nanoencapsulation method. catSHELS catalyze H2 O2 to water and oxygen producing microbubbles that can be detected and imaged using a clinical ultrasound system. catSHELS are optimized in vitro to maximize ultrasound signal and their functionality is demonstrated in rat ischemic renal injury model. Ischemic oxidative injury is induced in a single kidney of normal rats by clamping the renal artery for 1 h followed by 2 h of reperfusion. Imaging of both kidneys is performed following the intravenous bolus injection of 1012 catSHELS of the optimized formulation. There is significant increase in ultrasound signal of the injured kidney relative to controls. This method offers a novel intravenous approach to detect oxidative stress in deep tissues in living animals.

Recovery of Drug Delivery Nanoparticles from Human Plasma Using an Electrokinetic Platform Technology.

The effect of complex biological fluids on the surface and structure of nanoparticles is a rapidly expanding field of study. One of the challenges holding back this research is the difficulty of recovering therapeutic nanoparticles from biological samples due to their small size, low density, and stealth surface coatings. Here, the first demonstration of the recovery and analysis of drug delivery nanoparticles from undiluted human plasma samples through the use of a new electrokinetic platform technology is presented. The particles are recovered from plasma through a dielectrophoresis separation force that is created by innate differences in the dielectric properties between the unaltered nanoparticles and the surrounding plasma. It is shown that this can be applied to a wide range of drug delivery nanoparticles of different morphologies and materials, including low-density nanoliposomes. These recovered particles can then be analyzed using different methods including scanning electron microscopy to monitor surface and structural changes that result from plasma exposure. This new recovery technique can be broadly applied to the recovery of nanoparticles from high conductance fluids in a wide range of applications.

Dual-porosity hollow nanoparticles for the immunoprotection and delivery of nonhuman enzymes.

Although enzymes of nonhuman origin have been studied for a variety of therapeutic and diagnostic applications, their use has been limited by the immune responses generated against them. The described dual-porosity hollow nanoparticle platform obviates immune attack on nonhuman enzymes paving the way to in vivo applications including enzyme-prodrug therapies and enzymatic depletion of tumor nutrients. This platform is manufactured with a versatile, scalable, and robust fabrication method. It efficiently encapsulates macromolecular cargos filled through mesopores into a hollow interior, shielding them from antibodies and proteases once the mesopores are sealed with nanoporous material. The nanoporous shell allows small molecule diffusion allowing interaction with the large macromolecular payload in the hollow center. The approach has been validated in vivo using l-asparaginase to achieve l-asparagine depletion in the presence of neutralizing antibodies.