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Decorated gel bead 'doughnuts' with activity against drug-resistant bacteria

Posted on 16 April 2020

Core shell gel beads can be decorated with silver nanoparticles and show antimicrobial activity against drug-resistant bacteria.

Antibiotic-resistant bacteria are a major problem in modern healthcare, and can cause significant complications in hospitals for bone and wound healing. With problems such as these in mind, the development of antibacterial gels that can be used to help wound healing and bone regrowth is a vital.

Professor David Smith and his research group have expertise in developing soft biocompatible gels that self-assemble from simple molecular-scale building blocks. In recent studies they used one of their self-assembled gels as the 'filling' in a natural alginate polymer gel shell to create innovative core-shell gel beads that could be compared to jam-filled doughnuts.

They reasoned that these gel beads, which can be easily made, handled and manipulated could potentially be useful for preventing infections in orthopaedic and wound-healing applications, where gel bead systems are already in clinical use.


In the same way that doughnuts can be decorated with other ingredients, Dr Carmen Piras, working in Professor Smith’s team, reasoned that her gel beads could also be 'decorated' with other components to give them the required antibacterial properties. As the additional ingredient, she selected silver nanoparticles, which are known to be active against multiple drug-resistant bacterial strains and can promote bone growth. The use of silver nanoparticles on orthopaedic implants to avoid infections has recently gained some interest as an alternative to the administration of antibiotics.

In order to decorate the gel beads, Dr Piras made use of the unique properties of the self-assembled gel bead filling, which is able to reduce precious metals such as silver, to form metal nanoparticles. In this way, the gel beads could be effectively loaded up with the active ingredient.


Working with Dr Clare Mahon, Dr Piras demonstrated that the decorated gel bead doughnuts had antimicrobial activity against drug-resistant bacteria, in particular, vancomycin-resistant enterococci and pseudomonas aeruginosa, both of which are highly problematic hospital-acquired infections.

Dr Piras explained: "These gel beads are very easy to make and manipulate. They would be straightforward for surgeons to apply into wounds during orthopaedic surgery, and their antibacterial properties could potentially make them valuable for patients during the healing process."

The research was funded by EPSRC and the European Commission and is published in Chemistry—A European Journal.