Tag Archives: UC San Diego Jacobs School of Engineering

Plant Viruses Used to Ward Off Pests

Imagine a technology that could target pesticides to treat specific spots deep within the soil, making them more effective at controlling infestations while limiting their toxicity to the environment.

Researchers at the University of California San Diego and Case Western Reserve University have taken a step toward that goal. They discovered that a biological nanoparticle—a plant virus—is capable of delivering pesticide molecules deeper below the ground, to places that are normally beyond their reach.

The work could help farmers better manage difficult pests, like parasitic nematodes that wreak havoc on plant roots deep in the soil, with less pesticide. The work is published May 20 in the journal Nature Nanotechnology.

It sounds counterintuitive that we can use a plant virus to treat plant health,” said Nicole Steinmetz, a professor of nanoengineering at the UC San Diego Jacobs School of Engineering and senior author of the study. “This is an emerging field of research in nanotechnology showing that we can use plant viruses as pesticide delivery systems. It’s similar to how we’re using nanoparticles in medicine to target drugs towards sites of disease and reduce their side effects in patients.

Pesticides are very sticky molecules when applied in the field, Steinmetz explained. They bind strongly to organic matter in the soil, making it difficult to get enough to penetrate deep down into the root level where pests like nematodes reside and cause damage. To compensate, farmers end up applying large amounts of pesticides, which cause harmful residues to build up in the soil and leach into groundwater.

Steinmetz and her team are working to address this problem. In a new study, they discovered that a particular plant virus, Tobacco mild green mosaic virus, can transport small amounts of pesticide deep through the soil with ease.

Source: https://ucsdnews.ucsd.edu/

Micromotors Deliver Oral Vaccines

Researchers are working on new generations of oral vaccines for infectious diseases. But to be effective, oral vaccines must survive digestion and reach immune cells within the intestinal wall. As a step in this direction, UC San Diego nanoengineering researchers have developed oral vaccines powered by micromotors that target the mucus layer of the intestine.

The work appears in the ACS journal Nano Letters. It’s a collaboration between the labs of nanoengineering professors Joseph Wang and Liangfang Zhang at the UC San Diego Jacobs School of Engineering.

CLICK ON THE IMAGE TO ENJOY THE VIDEO

The lack of needles is one reason oral vaccines are attractive. Another reason: oral vaccines can generate a broad immune response by stimulating immune cells within the mucus layer of the intestine to produce a special class of antibody called immunoglobulin A (IgA). The NanoLetters paper documents the team’s efforts to use magnesium particles as tiny motors to deliver an oral vaccine against the bacterial pathogen Staphylococcus aureus. When coated over most of their surfaces with titanium dioxide, magnesium microparticles use water as fuel to generate hydrogen bubbles that power their propulsion.

To develop the oral vaccine, the researchers coated magnesium micromotors with red blood cell membranes that displayed the Staphylococcal α-toxin, along with a layer of chitosan to help them stick to the intestinal mucus. Then, they added an enteric coating that protects drugs from the acidic conditions of the stomach.

The micromotors safely passed through the stomach to the intestine, at which point the enteric coating dissolved, activating the motors. Imaging of mice that had been given the vaccine showed that the micromotors accumulated in the intestinal wall much better than non-motorized particles. The micromotors also stimulated the production of about ten times more IgA antibodies against the Staphylococcal α-toxin than the static particles.

Source: http://jacobsschool.ucsd.edu/

Nanorobots Clear Bacteria From Blood

Engineers at the University of California San Diego have developed tiny ultrasound-powered robots that can swim through blood, removing harmful bacteria along with the toxins they produce. These proof-of-concept nanorobots could one day offer a safe and efficient way to detoxify and decontaminate biological fluids.

Researchers built the nanorobots by coating gold nanowires with a hybrid of platelet and red blood cell membranes. This hybrid cell membrane coating allows the nanorobots to perform the tasks of two different cells at once—platelets, which bind pathogens like MRSA bacteria (an antibiotic-resistant strain of Staphylococcus aureus), and red blood cells, which absorb and neutralize the toxins produced by these bacteria. The gold body of the nanorobots responds to ultrasound, which gives them the ability to swim around rapidly without chemical fuel. This mobility helps the nanorobots efficiently mix with their targets (bacteria and toxins) in blood and speed up detoxification.

The work, published May 30 in Science Robotics, combines technologies pioneered by Joseph Wang and Liangfang Zhang, professors in the Department of NanoEngineering at the UC San Diego Jacobs School of Engineering. Wang’s team developed the ultrasound-powered nanorobots, and Zhang’s team invented the technology to coat nanoparticles in natural cell membranes.

SEM image of a MRSA bacterium attached to a hybrid cell membrane coated nanorobot

By integrating natural cell coatings onto synthetic nanomachines, we can impart new capabilities on tiny robots such as removal of pathogens and toxins from the body and from other matrices,” said Wang. “This is a proof-of-concept platform for diverse therapeutic and biodetoxification applications.”

The idea is to create multifunctional nanorobots that can perform as many different tasks at once,” adds co-first author Berta Esteban-Fernández de Ávila, a postdoctoral scholar in Wang’s research group at UC San Diego. “Combining platelet and red blood cell membranes into each nanorobot coating is synergistic—platelets target bacteria, while red blood cells target and neutralize the toxins those bacteria produce.

Source: http://jacobsschool.ucsd.edu/