Introduction:
Today, most of the microbial diseases spread via surface transmission. We all are well aware of the SARS-CoV-2 which transmits via aerosol droplets that can remain viable up to 1 week, resulting in millions of deaths worldwide. But what if we could have an antimicrobial coating on fabrics with self-disinfecting properties that can destroy the microbes within few hours? This can prevent the transmission to a great extent. Let’s delve deeper to explore the likelihood and efficacy of this idea.
The latest research conducted by the team of Taylor Wright at The University of British Columbia gives insight about this process. In their research article titled “Photodynamic and Contact Killing Polymeric Fabric Coating for Bacteria and SARS-CoV‑2”, they mentioned about developing the polysiloxane textile coating which is potential of inactivating the microbes via passive contact inactivation and the active photodynamic inactivation. The efficacy of this coating was demonstrated on E. coli, MRSA and SARS-CoV‑2.
Research:
Here, the researchers followed a dual-functional approach by using a single polymer with both antimicrobial functionalities, through amines and by generation of reactive oxygen species via irradiation of covalently attached photosensitizer with green light. Antimicrobial photodynamic inactivation (aPDI) stimulates the generation of ROS from atmospheric oxygen which is effective against wide range of microbes. The fabrics were coated at room temperature using a simple soak procedure, followed by UV cross-linking to ensure that the polymer is fixed entirely. The antimicrobial polymer (PRB) was prepared by condensing (7wt % aminopropylmethylsiloxane)-dimethylsiloxane copolymer (PNH2-7) with Rose Bengal Lactone (RBL). To resolve the issue of RBL getting photobleached and thus being unavailable for further 1O2 production, tetraphenylporphyrin was added as a sacrificial source.
Firstly, the passive antimicrobial activity of these coated textiles were assessed against E. coli and MRSA in the dark. Up to 31% and 99% decrease in E. coli CFUs was observed for 4 cm² and 18 cm² respectively, thus signifying that larger surface area decreases the CFUs to a greater extent. On coating the cotton with PNH2-23, 98% decrease in CFUs was observed for a 4 cm² sample, 3 times greater than PNH2-7. For MRSA, 99% decrease in CFUs was observed for 18 cm² samples for PNH2-7. In aPDI activity, it was observed that after 30 minutes, the remaining CFUs of E. coli were 85% (dark) and 3% (light). For MRSA, it was 95% (dark) and 35% (light), and no CFUs were observed for both the irradiated samples at 2 h. Similarly, the antiviral properties were tested against SARS-CoV-2 and 90% reduction was observed in just 2 h.
Conclusion:
To conclude, the passive antimicrobial activity increases with the weight % of amine functionality in the polymer. The antibacterial activity greatly increases in light conditions but the antiviral activity was observed in light conditions only. The researchers successfully developed a low-cost and non-toxic antimicrobial textile which can be widely used in combating the transmission of various microbes. For pandemic situations, say COVID-19, the antimicrobial masks along with the vaccination drive can greatly reduce the transmission rate. These treated fabrics can also prove beneficial against influenza A virus and other coronaviruses because of the non-specific antiviral mechanism of 1O2.
Reference:
Taylor Wright et al, Photodynamic and Contact Killing Polymeric Fabric Coating for Bacteria and SARS-CoV-2, ACS Applied Materials & Interfaces (2022).
by Aditi Singh
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