Nanotechnology Fights Infection

Infection Resistance makes new Infection-Fighting Methods Critical

Only a small number of effective oral antibiotic types, such as penicillin, exist. Most other drugs are simply derivatives, or small variations, in these same drugs. Over the next ten years, over 388 million people will die due to infection. Unfortunately, many dangerous bacteria that cause these infections are growing resistant to antibiotics. In 2011, over 440,000 cases of multidrug-resistant tuberculosis, multi-drug resistant malaria, and—the most dangerous because it often is passed between hospital patients—methicillin-resistant Staphylococcus aureus (MRSA) (pronounced “merr-sa”) were diagnosed.

Nanotechnology: The Future of Infection Prevention

Nanoparticles important for fighting bacteria in the biotechnology and medical industries are of three main types:

1. Free Nanoparticles with antibacterial activity
2. Drug Delivery Nanoparticles
3. Nanoparticle films and coatings

Nanotechnology is the study of materials with sizes that range from 1 to 100 nanometers, the size of only a few atoms. When combined with biological agents, such as medicines, nanotechnology is considered to be one of the most important areas of biotechnology. At these small sizes, normal Newtonian principles (i.e. equal and opposite reactions) do not apply. Instead, Quantum mechanical theories govern how these materials act.

Because these particles are so small, nanomaterials have a much larger ratio of surface area to mass than normal sized objects, giving them special properties that can be used for a variety of tasks, including fighting infection. Because of these special properties, nanoparticles can be attached to surfaces to create antibacterial materials, combined with antibiotics as medicines, or engineered to attack bacteria directly.

Classes of Infection-Fighting Nanomaterials

Free Nanoparticles

Very small particles of different shapes that include spheres, cubes, crystal-shapes, tubes, and rods are generally called nanoparticles. These particles are small enough to move freely in and out of many cells and tissues to reach dangerous bacteria that cause infection. Examples of nanoparticles that fight bacteria include:

• Silver colloids – Very tiny silver particles in solution, known as colloids, can be used as a topical antibiotic. Silver, which has long been used in silverware due to its mild ability to ward off bacteria, serves as a natural antibacterial when the silver particle sizes are very small.
• IBM’s MRSA Fighter – Based on the principles of semiconductor and computer part creation, IBM has announced a new nanoparticle combined with a polymer (or plastic). These tiny particles are attracted to infection-resistant MRSA cells like magnets. They mechanically poke holes in the bacteria’s walls, causing immediate death. Unlike antibiotics, bacteria cannot develop resistance to these mechanical attacks. These nanoparticles are also biodegradable, so after they do their job they are naturally broken down by the body.

Drug Delivery Nanoparticles

Some nanoparticles can be specially engineered to be attracted, like magnets, to infection-causing bacteria cells. While some, such as free nanoparticles, act to kill the cells themselves, others act as carriers to deliver antibiotics or other bacteria-killing compounds. Drugs can be bound to nanoparticles by physical encapsulation, adsorption, or chemical conjugation. Examples of nanoparticles used in drug delivery include:

• Lipid vesicles (“fatty sacs”) – The most common type of infection-fighting nanoparticle is the lipid vesicle, first discovered in the 1970s. It acts as a balloon of fatty compounds, similar to the wall around bacterial cells, that contains and protects antibiotics. These balloons can join with bacterial cells, releasing the toxic compounds and killing bacteria.
• Polymeric nanoparticles (“plastic-coated”) – The nanoparticles are the largest growing field in nanoparticle biotechnology used for medical applications. Nanoparticles and other bacteria-killing compounds are coated in a polymer (or plastic) shell, allowing them to move into the body to fight infection without being broken down before reaching their targets.
• Solid Lipid nanoparticles (“fat balls”) – Fatty balls, much similar to cell membranes can be used to encapsulate bacteria-fighting antibiotics and other materials.
• Dendrimers (“large molecules”) – Dendrimers are macromolecules, or large molecules, with many branches attached to nanoparticles and antibiotics.

Nanoparticle films and Coatings

When millions of antibacterial nanoparticles are mixed with other substances, most commonly polymers, they can form antibacterial plastics, paints, and coatings that can be used in many different products. The medical industry uses these commonly, to create antibacterial devices such as medical tubing and needles that resist bacteria buildup. Commercial products, such as antibacterial clothing and writing pens are also becoming available, forming an important new consumer-driven biotechnology sector.

• Antibacterial Textiles and Fabrics – Many compounds can be used to create antibacterial fabrics, primarily through binding fibers with nanoparticle or nanotube coatings. TiO₂ nano-particles, metallic and non-metallic TiO₂ nano-composites, titania nanotubes (TNTs), silver nano-particles, silver-based nano-structured materials, gold nano-particles, zinc oxide nano-particles and nano-rods, copper nano-particles, carbon nanotubes (CNTs), nano-clay and its modified forms, gallium, liposomes loaded nano-particles, metallic and inorganic dendrimers nano-composite, nano-capsules, and cyclodextrins containing nano-particles are all used in fabrics.
• Inorganic-compound coatings – Coatings are thin layers of inorganic nanoparticles on the surface of a device. The most common material used in these coatings is silver (Ag); however, gold and titanium are also used to resist bacteria. These can be used to coat devices, such as medical instruments and household appliances to prevent bacterial buildup.

Nanoparticles that prevent bacteria growth, and nanoparticles that hunt down and kill infection-causing bacteria have already improved medical care and sanitation in office, homes, and hospitals. In the future, these nanoparticle treatments will play an important role in fighting antibiotic resistant infection.

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