3D-printed anti-bacterial smartphone cases could help to stop the spread of superbugs like MRSA, scientists claim

  • UK scientists made 3D printed parts that show resistance to common bacteria
  • The technology could stop spread of difficult-to-treat infections such as MRSA 
  • The material can also be used in medical devices, denstures, or children’s toys

A new anti-bacterial material that can be used to make smartphone cases could hep to stop the spread of deadly superbugs.

British scientists have created 3D-printed parts that kill bacteria which have become resistant to antibiotics, such as the dreaded MRSA. 

The material could be used in general parts for hospitals, door handles, children’s toys, dentures and everyday consumer products.

It promises to halt outbreaks of serious illnesses in wards and care homes – potentially saving the lives of vulnerable patients.

Individual bacteria on a Nylon-12 surface. The bacteria is Pseudomonas aeruginosa, which can cause disease in plants, animals and humans

‘Managing the spread of harmful bacteria, infection and the increasing resistance to antibiotics is a global concern,’ said Dr Candice Majewski, a mechanical engineering at the University of Sheffield. 

‘Most current 3D printed products don’t have additional functionality. 

WHAT IS MRSA? 

Methicillin-resistant Staphylococcus aureus (MRSA) is a type of bacteria that is resistant to several widely-used antibiotics, which makes it particularly hard to treat.

Catching the infection early could prevent it spreading and infecting others.

Approximately 30 per cent of people carry the Staphylococcus aureus bacteria even in their nose, armpits, groin or buttocks without realising it.

This can invade the body’s bloodstream and release poisonous toxins that kill up to one-fifth of infected patients.

MRSA is most commonly associated with hospitals. 

As well as being highly drug resistant, current screening methods are fairly inaccurate, which allows the infection to spread as a patient moves around both within and outside hospitals.

Even when the infection is successfully treated, it doubles the average length of a patient’s hospital stay, as well as increasing healthcare costs.

‘Introducing antibacterial protection to products and devices at the point of manufacture could be an essential tool in this fight.’

The World Health Organisation says resistance to antibiotics poses a ‘major global threat’ to public health.

It has described a ‘post antibiotic era’, where people die from simple infections that have been treatable for decades.

To fight this threat, University of Sheffield researchers created a technique that combines 3D-printing with a silver-based anti-bacterial compound.

‘We have adopted a commercially available antimicrobial additive (Biocote B65003) and combined this with a widely used Laser Sintering powder (polyamide 12, EOS PA2200) to create an antimicrobial material suitable for a range of potential uses,’ the researchers say in their paper, published in Scientific Reports.   

Results showed the chemical can be successfully incorporated into existing 3D printing materials without any negative impact on production or strength.

Under the right conditions, the parts are effective against potentially harmful bugs without being toxic to human cells.

Tests on human cells grown in the lab found there were no toxic effects.  

More experiments are being planned in the manufacture of a range of products with the aim of working with leaders in industry to bring them to market. 

Photograph of a selection of parts made from PA2200 (left) alongside the 1% B65003 composite material (right) 

Medical devices are often already coated with an anti-bacterial compound and are subject to strict and rigorous cleaning or sterilisation procedures.

AMR: A PRIMER 

Antibiotics have been doled out unnecessarily by GPs and hospital staff for decades, fueling once harmless bacteria to become superbugs. 

The World Health Organization (WHO) has previously warned if nothing is done the world is heading for a ‘post-antibiotic’ era.

It claimed common infections, such as chlamydia, will become killers without immediate solutions to the growing crisis.

Bacteria can become drug resistant when people take incorrect doses of antibiotics or if they are given out unnecessarily. 

Former chief medical officer Dame Sally Davies claimed in 2016 that the threat of antibiotic resistance is as severe as terrorism.

Figures estimate that superbugs will kill 10 million people each year by 2050, with patients succumbing to once harmless bugs

While this provides some protection from microbes, human error in cleaning or damage occurring to the covering can still lead to bacteria spreading. 

Rigorous testing and imaging techniques were carried out to establish the effect of the additive, such as its mechanical properties and whether it survived the manufacturing process.

Parts with and without the antibacterial compound were submerged in various solutions to test how many bugs remained after 24 hours.

Those containing the compound were effective against examples of the two main groups of bacteria, Gram positive (Staphylococcus aureus) and Gram negative (Pseudomonas aeruginosa), both of which can cause different infections.

The number of bacteria stuck to the part surfaces in the form of difficult-to-remove biofilms was also reduced. 

Researchers observed an ‘anti-biofilm’ effect where bacteria died before they could stick to the parts. 

3D-printed parts worked less well in liquid containing lots of nutrients – these were found to interfere with the silver before it could do its job.

This will help people decide what environments to use this technology in, the team says, meaning users would be best advised to keep their anti-bacterial smartphone case away from liquids if the material is commercialised. 

Further work is ongoing to investigate the full extent of the material’s capability before this happens, however. 

‘Our interactions with microbes are complex and contradictory,’ said Dr Bob Turner, of Sheffield’s department of computer science. 

‘They are essential to our survival and they can knock us dead.

‘Technology like this will be key to informed and sustainable management of this crucial relationship with nature.’  

WHAT IS 3D PRINTING AND HOW DOES IT WORK?

First invented in the 1980s by Chuck Hull, an engineer and physicist, 3D printing technology – also called additive manufacturing – is the process of making an object by depositing material, one layer at a time.

Similarly to how an inkjet printer adds individual dots of ink to form an image, a 3D printer adds material where it is needed, based on a digital file.

Many conventional manufacturing processes involved cutting away excess materials to make a part, and this can lead to wastage of up to 30 pounds (13.6 kilograms) for every one pound of useful material, according to the Energy Department’s Oak Ridge National Laboratory in Tennessee.

By contrast, with some 3D printing processes about 98 per cent of the raw material is used in the finished part, and the method can be used to make small components using plastics and metal powders, with some experimenting with chocolate and other food, as well as biomaterials similar to human cells.

3D printers have been used to manufacture everything from prosthetic limbs to robots, and the process follows these basic steps:

· Creating a 3D blueprint using computer-aided design (CAD) software

· Preparing the printer, including refilling the raw materials such as plastics, metal powders and binding solutions.

· Initiating the printing process via the machine, which builds the object.

· 3D printing processes can vary, but material extrusion is the most common, and it works like a glue gun: the printing material is heated until it liquefies and is extruded through the print nozzle

· Using information from the digital file, the design is split into two-dimensional cross-sections so the printers knows where to put the material

· The nozzle deposits the polymer in thin layers, often 0.1 millimetre (0.004 inches) thick.

· The polymer rapidly solidifies, bonding to the layer below before the build platform lowers and the print head adds another layer (depending on the object, the entire process can take anywhere from minutes to days.)

· After the printing is finished, every object requires some post-processing, ranging from unsticking the object from the build platform to removing support, to removing excess powders. 

 

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