A Thin Film with a Strong Promise

The lifestyle of bacteria has been extensively studied over the past few years, with biofilm biology turning tables. With this collective mode of existence in bacteria, which confers higher tolerance to antimicrobials, prevention and treatment of biofilms has become important. Biofilms grow on varied surfaces and environments, leading to a lot of complications in  various sectors, ranging from industries to hospitals. An added issue is antimicrobial resistance, due to which, we cannot go with the conventional approach to treating and eradicating biofilms.


Bacterial biofilms play a pivotal role in Urinary Tract Infections (UTI), causing the infection by growing on the catheters and leading to recurrence in infection. They are difficult to eradicate, and various methods of coating with antibiotics, nanoparticles, biofilm enzyme inhibitors, liposomes, bacterial interference, bacteriophages, quorum sensing inhibitors, low-energy surface acoustic waves, and anti-adhesion agents have been used, but haven’t been completely effective. This brings up a necessity for new approaches to eradicating biofilm growth by organisms such as Uro-pathogenic E. coli (UPEC).

A group of researchers from SASTRA University have come up with a possible solution for this issue, by developing an antibacterial thin Film from renewable resources such as cardanol and linseed oil. Dr.Srinandan.C,S, Dr. Subbiah Nagarajan and their colleagues at SASTRA University have developed a self-assembling hydrophobic thin film which has antibacterial properties and inhibits the growth of UPEC, which can be used to develop urinary catheters to prevent infection.

“Uro-pathogenic E. coli is the major cause of urinary tract infections worldwide, including the catheter associated UTI. The organism forms cell clusters enmeshed in a matrix that is called as biofilm on the surface of catheters. The biofilm lifestyle makes them recalcitrant to antibacterial compounds, therefore making it a difficult task to kill them by using antibiotics.  In this study, we developed a derivative of naturally available compound to coat catheters, and this wonderfully showed to inhibit biofilm formation by E. coli on the coated surface”-Dr.Srinandan


With the use of inexpensive Cardanol, the main component of cashew nut shell liquid, which is a phenolic lipid frequently used in making coatings and resins, and linseed oil, a vegetable oil, which has drying properties that allow it to polymerise into a solid form, the group has synthesised cardanol based metal complexes and acrylated epoxidized linseed oil (AELO), which form a self-assembling thin film, with thermal stability and intrinsic hydrophobicity.


A Cashewnut tree with Fruits (Source: balconygardenweb.com)


These compounds were tested for their antimicrobial activity and their effect on biofilm formation. They show antimicrobial activity against a variety of microorganisms, with effectiveness increasing linearly with concentration. Most importantly, the bio-based thin film coating could inhibit the growth of UPEC biofilms on urinary catheters! The group tested a urinary catheter made of PVC, by coating it with the thin film, and used scanning electron microscopy to observe biofilm growth on the catheter. The results showed no biofilm formation! Further experiments where the catheter was submerged in media were also performed, and showed promising results.

“Intrinsic hydrophobic antibacterial thin film coating material derived from cashew nut shell liquid and linseed oil holds promise in the development of anti-biofilm urinary catheters. The developed metal enabled thin film coating material could also be used as environmental friendly, non-leachable surface coating materials for public bacterial threats, especially in hospitals, public toilets, railway stations, schools and other sanitary facilities.” -Dr. S.Nagarajan

This thin film sure shows strong promise! Since Indwelling Catheter Associated Urinary Tract Infections’ (CAUTI) root cause is UPEC, using such a coating will help decrease the incidence of the infection. The race between microbes and humans may be never ending, but this surely puts us a step ahead!

The paper can be found here: http://pubs.acs.org/doi/abs/10.1021/acssuschemeng.6b01806



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