Tag Archives: infectious diseases

Self-Sterilizing Microneedles

Vaccinations are the world’s frontline defence against infectious diseases yet despite decades of interventions, unsafe injection practices continue to expose billions of people to serious infection and disease.

Now, new technology from the University of South Australia is revolutionising safe vaccination practices through antibacterial, silver-loaded dissolvable microneedle patches, which not only sterilise the injection site to inhibit the growth of bacteria, but also physically dissolve after administration.

These first generation microneedles have the potential to transform the safe administration of transdermal vaccinations and drug delivery”, explains Lead researcher, Professor Krasimir Vasilev .

Injections are one of the most common health care procedures used for vaccinations and curative care around the world,” Prof Vasilev adds. “But up to 40 per cent of injections are given with improperly sterilised syringes and needles, placing millions of people at risk of contracting a range of illnesses or diseases. “Our silver-loaded microneedles have inherently potent antibacterial properties which inhibit the growth of pathogenic bacteria and reduce the chance of infection.”

The UniSA study tested the antibacterial efficacy of silver-loaded microneedles against bacteria associated with common skin infections – Golden staph, staphylococcus epidermis, escherichia coli and pseudomonas aeruginosa – and found that the silver-loaded microneedle patches created a 24-hour bacteria-free zone around the patch administration site, a feature unique to the new technology.

The silver-loaded microneedles comprise an array of 15 x 15 needles each 700 micron in length, which pierce only the top layer of the skin without reaching the underlying nerves, making them 100 per cent painless.

The microneedles are made from a safe, biocompatible and highly water-soluble polymer that completely dissolve within one minute of application, leaving behind no sharp waste.

Source: http://www.unisa.edu.au/

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.

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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/