Jovana Grbic
Jul 24, 2012

Nano-surface modifications with anti-bacterial potential

Polymicrobic biofilm grown on a stainless steel surface in a laboratory potable water biofilm reactor for 14 days, then stained and examined by epifluorescence microscopy. Scale bar represents 20 µm.Researchers at the Institute for Agrobiotechnology at the University of Navarre, Spain, are reporting exciting results that might have implications for fighting bacterial resistance.  Utilizing a laser set to nanoscale accuracy, researchers demonstrated that nanostructures drawn on the surfaces of various materials show significant resistance to the formation of bacterial biofilms. The research team worked with two bacterial strains ubiquitously found across materials, organic living beings and common places—Staphylococcus aureus and Salmonella. In both instances, surfaces were pre-treated with the laser, exposed to the bacteria and allowed to form bacterial matrices. The bacteria were then harvested off the surfaces, grown in culture and quantified by colony formation. In both cases, the laser nanostructures were able to disrupt biofilm formation by up to 65-70%. The researchers anticipate that applications could be limitless, from surgical materials such as prosthetics and catheters, to the lining of water tanks.

Bacterial biofilms are created when bacteria adhere to a surface and create a matrix that attracts even more bacteria, and subsequently makes them more resistant.  "Bacteria," according to the head study researcher Jaione Valle-Turrillas, "stick to any surface; it can be the skin, internal organs, surfaces of materials, etc. and they produce this biofilm, a kind of film that makes them more resistant to antibiotic treatments and disinfectants."  They are virtually ubiquitous, with virtually every species or organism having a mechanism by which it can adhere to surfaces and each other. Bacterial biofilms can be found on everything from dental plaque to everyday surfaces to the bottoms of rocks and the bottoms of rivers and streams and even extreme surfaces. To date, disruption methods have included laser generated shockwaves, lauroyl glucose, enzymes, and surface-engineered quantum dots used to label hydrophobic microdomains on bacterial films.Staff remove rubbish while disinfecting the operating theatre after a procedure on a patient with MRSA, a drug-resistant "superbug."

Even in developed Western countries, a long history of improper antibiotic use and prescription, coupled with little development of effective new antibiotics, is causing the emergence of ‘superbugs,’ resistant to all front-line treatment. Some scientists posit that deaths due to these superbugs may surpass AIDS in the US alone. Worse yet, hospitals, which were once a haven for the sick, are now one of the biggest sources of superbugs such as MRSA and Clostridium difficile, killing at least one hundred thousand people each year in the US. The development of effective, economical and mobile technology to kill common bacteria is, therefore, a pressing global urgency.

The result described in this paper is only an initial aspect of the project, which is slated to run for 3 years, in collaboration with the German Research and Development Centre Institut Fraunhofer for Material and Beam Technology, which provided all the lasers used in the experiments. Future efforts of the research team will include elucidating the mechanism by which bacterial films adhere to their surfaces, in the hope of improving laser anti-microbial efficacy. Furthermore, the team wants to incorporate their findings with resistance to current antibiotics, behavior on an even more varied assortment of biofilms and retaining properties after prolonged use.

Extrapolation of this technology into the biomedical and general technology sectors could have enormous impact on public health. Beyond surgical tools and any hospital equipment being attached directly to patients, hospitals could forego expensive and meticulous cleaning rituals in battling superbugs and simply treat surfaces with anti-microbial nanowires. To that extent, UCLA has already begun investigating whether copper surfaces installed throughout lower infection rates. Virtually any large public area, such as bus and transportation depots, sports arenas, restaurants and commercial establishments, could ensure cleaner, more bacteria-resistant surfaces for the general public.  Foodborne illness is another major area that could be impacted by this technology. Statistics show that salmonella is now estimated to cause more than a million illnesses and 378 deaths annually, with E. coli toxins a close second 176,000 illnesses and 20 fatalities a year, among other deadly bacterial pathogens. The social cost of these illnesses is $1.4 trillion. Not only could this technology be applied to the surfaces where meat is butchered and other fruits and vegetables are processed, but restaurant kitchens could also be more effective in preventing bacterial film growth in storage areas and cooking and preparation surfaces.

This new result absolutely holds enormous potential, as bacterial resistance continues to grow and a lack of new, effective antibiotics continues to plague the medical field.