Periodic Reporting for period 1 - PHOTO-IASIS (Nanoengineered coatings for visible-light photocatalytic disinfection of medical devices)
Berichtszeitraum: 2020-05-01 bis 2022-04-30
Catheter-associated infections from biofilms constitutes the most common nosocomial treat posing an enormous emotional and financial burden to society and healthcare sector. The continuous use and abuse of antibiotics to fight infections lead to antimicrobial resistance in some bacterial strains (the so-called “superbugs”) and constitutes the most serious public health threat termed as “slow-motion catastrophe” with minimal or none essential contribution of antibiotics in treating bacterial diseases. Current therapeutic approaches to fight these infections enables nanotechnology based-strategies including catheter surface design and engineering. The target of these strategies is to eradicate biofilm formation without the use of antibiotics via mostly physical modes of antibacterial action. Photocatalytic metal oxide nanoparticles (NPs), present antimicrobial and antibiofilm efficacy via generated electrons Reactive Oxygen Species ([superoxide anion radicals (O2-●) and hydroxyl radical (OH●)] upon UV irradiation, which are the active species contributing to the mineralization of microorganism cells and inhibiting, therefore, bacterial growth. This concept is quite successful and, in fact, is already applied in outdoor paints, or even surgical instruments for fast sterilization by UV irradiation. However, the use of such nanoparticles for treatments in humans needs to be avoided because UV irradiation, even at low doses, may be harmful for healthy tissues. Therefore, there is an important societal and clinical need to re-engineer polymer-based catheters in order to avoid the formation of biofilms on their surface.
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 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.
We found a method that utilises a process of producing photocatalytic nanoparticles in situ by flame spray pyrolysis (FSP) and depositing the nanoparticles on the substrate via aerosol deposition to produce a photocatalytic nanoparticle film on the substrate, followed by immersing the photocatalytic nanoparticle film with a polymer solution, or a liquid polymer precursor material, to form a composite layer.
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.
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.
In PHOTO-IASIS project, we developed a visible-light-responsive coating that can be easily applied on medical devices and can destroy established biofilms in a triggered manner. The coating was made through direct deposition of flame aerosol nanoparticles on substrates, resulting in nanoparticle generation and film fabrication in a single step. The developed coating consists of a porous Ag/TiOx particle film that is photocatalytically active in the visible-light range and can generate superoxide radicals to destroy biofilms. This porous particle film is subsequently infused with a PDMS solution, resulting in a highly stable polymer nanocomposite film with superior photocatalytic properties and triggered eradication of established biofilms. The increased mechanical stability makes these coatings durable and active over several cycles. This makes the films attractive for medical devices as coating suitable for repeating treatments. The biocompatible PDMS surface of the developed coatings do not trigger any toxic response to mammalian cells. This further strengthens the potential of such a coating for the antibiotic-free treatments of bacterial biofilms, aiding the fight against antibiotic drug resistance.