his global health crisis has caused many people to become seriously ill that have to be hospitalized and connected to artificial respirators, treatments that save lives but are also highly invasive and can lead to hospital infections. At UDT we are developing antimicrobial materials, specially designed for the health sector allowing to avoid bacteria and fungi.
One of the greatest dangers of Covid-19 is that it manifests with pneumonia that requires mechanical ventilation, an invasive life support treatment that basically consists of the introduction of an endotracheal tube connected to a machine that performs respiratory work for the person. And not only is the tube down the throat, catheters are also inserted into the veins to deliver medications, nutrients or fluids, directly through the blood. Both elements are potential open doors to the dreaded hospital infections.
The surface of tubes and catheters acts as a substrate, facilitating the adhesion of bacteria and, with it, the formation of a dangerous biofilm, their main defense mechanism. Endotracheal tubes are usually made of PVC or silicone, the first material is cheaper, but favors the adherence of the biofilm, due to its porous surface. The catheters are made of polyurethane and at this point, where the incision is made in the skin, an infection by bacteria or fungi can arise.
In order to find a solution to the first problem, the Technological Development Unit (UDT) of the Universidad de Concepción executed the FONDEF project “Development of antimicrobial polymeric materials with core-shell type nanostructures (Copper-Silver) as active agent for the prevention of hospital infections”, with the aim of creating an antibacterial polymeric material that reduces the formation of biofilms on its surface and that can be used to manufacture medical material.
Following this line of bioactive materials, UDT applied for the CORFO I+D Empresarial project, currently underway, “Antibacterial central venous catheter (CVC) as a method of prevention against hospital infections associated with the use of CVCs”, to develop, characterize and validate a prototype of an antibacterial catheter based on polyurethane with copper micro/nanoparticles.
Copper and Silver
The design of the antibacterial polymeric material is not a simple mixture of its components, but an innovative process that managed to incorporate, in a homogeneous way and preserving their properties, active antimicrobial metallic nanostructures in polymeric matrices.
The material for the endotracheal tubes was designed from PVC, to which core-shell nanoparticles were incorporated. “These nanostructures are composed of a copper core covered by a thin outer layer of silver. This makes the compound to have antimicrobial activity, both by contact and sustained release of the active agents. The silver shell provides immediate contact activity and the copper core, which is less exposed, offers sustained activity over time”, explains Dr. Cristian Miranda, from the Biomaterials Department of UDT and one of the project researchers.
Antimicrobial tests of the new material showed that it inhibited bacterial growth and, consequently, the formation of biofilms, “in addition, it was achieved that the copper and silver nanoparticles were homogeneously distributed in the PVC polymer matrix, which allowed obtaining a composite material that can be transformed by injection or extrusion, the usual techniques of thermoplastic processing, that is, that the material can be converted into different products, in addition to the endotracheal tubes”, says Dr. Miranda.
In the case of CVC catheters, polyurethane was used to which micro and nanoparticles of copper were added. It was shown that the material reached 100% bacterial death after 4 hours of exposure.
Technical tests of the materials were carried out, confirming that the addition of the nanoparticles did not affect the rheological (deformation), mechanical or thermal properties of PVC or polyurethane. Both projects have the participation of the company Sylex Chile Ltda. where functional prototypes of endotracheal tubes and intravenous catheters have been manufactured.
Additionally, this initiative gave rise to an application for an invention patent and work is being done on submitting an application to the FONDEF IT contest, to scale these technologies so that they can soon reach mass production.