Home Framework Antibacterial films based on metallo-organic composites (MOF)

Antibacterial films based on metallo-organic composites (MOF)

February 12, 2022

(News from Nanowerk) Nosocomial infections are a major problem for modern medicine, with pathogens like methicillin resistance Staphylococcus aureus (MRSA) and Clostridium difficile (C difference.) widely publicized.

One in 10 hospitalized patients is affected by what is called Nosocomial infectionsor hospital-acquired infections – an infection you get while you are in hospital.

In modern healthcare, invasive procedures and surgeries, indwelling medical devices and prosthetics are associated with these infections. Patients and healthcare professionals bring germs inside hospitals and pass them on to each other. Among other mechanisms, viruses and bacteria can spread when a person touches a site where germs have taken up residence, such as a door frame, handrail, or medical device. A healthy person can often fight off these insects, but hospitalized patients may be more susceptible to infection.

The result is an extension of hospital stays of more than 10 million patient days per year in Europe alone. And a staggering 3 million deaths are caused by hospital-acquired infections.

Although medical facilities have strict cleaning policies, insist on frequent hand washing by staff, and have potent medications, it is difficult to eliminate these infections unless the hospital environment is made more hostile to germs. Chemical disinfectants or coatings containing hydrophobic compounds, silver or copper ions can reduce infectious contaminants on surfaces, but these treatments do not last.

This makes antimicrobial coatings of hospital surfaces and medical equipment merely a prophylactic strategy. Such coatings prevent the arrival and growth of microorganisms on surfaces and maintain their inhibitory or destructive activity against transient microorganisms after each use, thereby reducing the likelihood of future infections resulting from surface contact. .

Among the most effective topical biocides is iodine, which is widely available, inexpensive, and has broad-spectrum antimicrobial activity. Iodine acts by causing irreversible and non-specific damage to the cells of microorganisms; thus, unlike antibiotics, it does not cause resistance.

However, the low aqueous solubility of iodine limits its use in many applications. Additionally, although iodine is much more soluble in alcohols, these solvents penetrate tissues too quickly, causing over-delivery of iodine, which in turn leads to irritation and other undesirable side effects.

Reflecting on approaches to circumvent the limitations of the direct use of iodine solutions in antimicrobial surface applications, the authors of a recent article in Advanced functional materials (“Antibacterial Films Based on MOF Composites that Release Iodine Passively or Upon Triggering by Near-Infrared Light”) predicted that the adsorption of iodine into porous materials could allow both its storage and subsequent release, while preventing direct contact with human skin.

ac) Field emission scanning electron microscopy (FE-SEM) of the cross-section of the films containing [email protected]2@ UiO-66 microbeads at 25% (w/w). In (c), the microbeads are highlighted in pale green to better illustrate their encapsulation. d,e) FE-SEM of the cross section of films containing [email protected]2Microbeads @UiO-66 at 8% (d) or 46% (e) (w/w). f) X-ray powder diffraction (PXRD) of a blank polyvinylidene difluoride (PVDF) film (black), [email protected]2Microbeads @UiO-66 (violet) and films containing [email protected]2@UiO-66 microbeads at 8% (red), 25% (blue) or 46% (green) (w/w). Scale bars: 200 µm (a), 50 µm (b), 5 µm (c), 50 µm (d) and 50 µm (e). (Reproduced with permission from Wiley-VCH Verlag)

Additionally, they imagined that the resulting porous material could then be incorporated into polymer matrices to produce antimicrobial films or coatings. Of the different types of porous materials available to store iodine, the researchers felt that metal-organic structures (MOFs) would be ideal.

In their article, the team from the Universitat Autònoma de Barcelona reports the design, synthesis and in vitro validation of the antibacterial activity of composite films based on MOF which adsorb and store iodine at very high concentration, and can release it in two ways: slow and passive at low concentration; or, when triggered by NIR light, rapidly and actively at high concentration.

This MOF composite consists of a spherical microbead of UiO-66 MOF that encapsulates gold nanorods covered with a silica shell ([email protected]2). The microporous UiO-66 adsorbs and stores iodine, while the photoactive [email protected]2 activates active NIR triggered release.

The team also demonstrates that these [email protected]2@UiO-66 microbead composites can be incorporated into organic polymers to develop iodine-based antimicrobial films that retain iodine adsorption capacity and both release mechanisms.

The researchers validated the antibacterial activity of their light-sensitive films against gram-positive and gram-negative bacteria.