Periodic Reporting for period 1 - PHOTO-IASIS (Nanoengineered coatings for visible-light photocatalytic disinfection of medical devices)
Periodo di rendicontazione: 2020-05-01 al 2022-04-30
The aim of PHOTO-IASIS project is to exploit the potential anti-biofilm capacity of visible light photocatalytic nanoparticles to develop a novel concept of “smart” catheters, that consists of the polymer catheter tube and nanoparticles deposited on them. The engineered nanocoating devices were produced by flame spray pyrolysis that is a nanomanufacturing process with proven scalability and reproducibility. The anti-biofilm performance of the nanodevices has been studied in the absence of any antibiotics against model pathogen microorganisms related to catheter-associated nosocomial infections, both gram-negative (e.g. Pseudomonas aeruginosa) and gram-positive bacteria (e.g. Staphylococcus aureus) along with their corresponding strains that exhibit antibiotic resistance. Overall, this project contributes decisively to the development of sophisticated and novel, nanoscale revolutionary medical devices for the prevention of biofilms on catheters and aiding the fight against antimicrobial drug resistance, the most prevalent public health threat today.
The method used results in a composite layer comprising a percolating network of photocatalytic nanoparticles in a polymer matrix, wherein the composite layer has enhanced durability and maintains activity after several cycles of irradiation, which is an improvement over currently known coatings.
Method of Production
A method for the production of a composite layer in which photocatalytic nanoparticles are embedded in a polymer matrix, wherein the method comprises the steps of:
a. providing a substrate;
b. producing photocatalytic nanoparticles in situ by flame spray pyrolysis and depositing the nanoparticles on a surface of the substrate via aerosol deposition to produce a photocatalytic nanoparticle film on the surface of the substrate; and
c. immersing the photocatalytic nanoparticle film with a polymer solution, or a liquid polymer precursor material, to form the composite layer,
wherein, the photocatalytic nanoparticle film has a thickness of from about 200 to about 1200nm.
The result is the production of a composite layer comprising a percolating network of photocatalytic nanoparticles in a polymer matrix.
In particular the nanoparticles are photocatalytically active in the visible light spectrum range, and the nanoparticles have a broad absorption band starting at about 400 nm (visible-light range) and extending into the near-infrared region of the spectrum. Such nanoparticles that can achieve this absorption/activation range include silver-titanium nanoparticles, which material is commonly referred to as “black titania”. By the term “silver-titanium nanoparticles” we refer to TiO2 nanoparticles which have been doped with silver (Ag) atoms, thus arriving at visible-light-active Ag/TiOx nanoparticles, with TiOx often being given the term “suboxide”, and shifts the peak absorption of the nanoparticles from the UV into the visible-light activation range.
The use of the composite layer has been studied as an antimicrobial coating, to provide antimicrobial properties towards gram-positive and gram-negative bacteria.
The method of treatment and prevention comprised a step of irradiating the coated surface of the catheter with visible light to thus produce ROS from the photocatalytic nanoparticles, which impart an anti-bacterial effect. The power of the light used was about 5 to about 75 mW cm-2. Irradiation took place for from about 15 to about 90 minutes.