Nanoparticles take a bite out of infections

July 11, 2017, King Abdullah University of Science and Technology
A rapid test under UV light reveals if dental imaging plates are contaminated with bacteria, thanks to polymers embedded with multi-functional nanoparticles. Credit: Reproduced with permission from ref 1.© 2016 Wiley-VCH

Antibiotic-resistant bacteria that colonize surfaces and medical equipment are causing alarming annual rises in the number of patients becoming infected in hospitals and clinics. A KAUST team is working to reduce these numbers with a smart polymer that changes color and activates natural antimicrobial enzymes when bacterial contamination is detected.

Constant exposure to salivary bacteria makes dental tools, such as reusable X-ray imaging plates, ideal environments for virulent biofilms. One solution to this problem is to coat devices with polymers embedded with nanoscale crystals that slowly release silver ions, a broad-spectrum biocide agent. However, challenges with nanoparticle leaching, have thwarted advancement of this technology.

Associate Professor Niveen Khashab, her Ph.D. student Shahad Alsaiari and colleagues from the University's Advanced Membranes and Porous Materials Center realized that switching to gold nanoparticles could give antimicrobial coatings detection capabilities—these tiny crystals have sensitive optical properties that can be tuned to spot specific biomolecular interactions. But incorporating them safely into polymers required new types of nanofillers.

"Nanofillers are small chemical agents distributed in the matrix of a polymer composite," explained Khashab. "They're dopants, so they improve on the regular material and introduce new properties—in our case, making the coating antibacterial."

The team's approach uses treated with lysozyme enzymes that have innate defenses against pathogens, such as Escherichia coli, commonly known as E. coli. They attached these colloids to the surface of slightly larger, porous silica nanoparticles stuffed with antibiotic drug molecules.

Normally, this gold-silica complex emits glowing, red fluorescent light. But when the lysozyme units encounter bacteria, a strong attraction for cell walls rips the gold nanoclusters from their silica partners—an action that simultaneously switches off fluorescence and releases the antibiotic cargo.

Blending experiments revealed the gold-based nanofillers integrated thoroughly into polymer composites and exhibited minimal leaching during trials with E. coli. Khashab attributes these favorable polymer interactions to the sharp exposed edges of gold clusters on the silica spheres

The researchers tested their concept by comparing X-ray dental plates with and without the smart coating. Both samples yielded the same high-resolution images of teeth and bone structure. However, only the coated plate enabled rapid visual assessment of , simply by illuminating the device with a UV-lamp and looking for color change. Successful release of the antibacterial agent also drastically decreased biofilm buildup.

"The process of coating is easy," noted Khashab. "We are looking at improving this technology to include other medical devices of different sizes and shapes."

Explore further: Nanoparticles coated with antibiotic eliminate drug-resistant bacteria

More information: Shahad K. Alsaiari et al. Colloidal Gold Nanoclusters Spiked Silica Fillers in Mixed Matrix Coatings: Simultaneous Detection and Inhibition of Healthcare-Associated Infections, Advanced Healthcare Materials (2017). DOI: 10.1002/adhm.201601135

Related Stories

Nanosilver and the future of antibiotics

May 27, 2015

Precious metals like silver and gold have biomedical properties that have been used for centuries, but how do these materials effectively combat the likes of cancer and bacteria without contaminating the patient and the environment?

Nanocages for gold particles—What is happening inside?

March 16, 2017

Scientists at Tokyo Institute of Technology have used high-resolution crystallography to uncover the mechanism behind protein-assisted synthesis of gold nanoparticles, providing a platform for designing nanomaterials tailored ...

Dental implants with antibacterial activity

December 28, 2016

The quest for surfaces capable of preventing bacterial colonisation and adhesion around dental implants is a subject of research interest, according to Beatriz Palla, a researcher in the Biomaterials Group of the UPV/EHU's ...

Surface-patterned colloidal particles

September 21, 2016

(Phys.org)—A group of researchers from several institutions have attached thiol-terminated polymers to gold nanoparticles and created surface micelles by changing the solvent from one that is favorable for the polymer to ...

Recommended for you

Engineers develop first method for controlling nanomotors

September 19, 2018

In a breakthrough for nanotechnology, engineers at The University of Texas at Austin have developed the first method for selecting and switching the mechanical motion of nanomotors among multiple modes with simple visible ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.