Antiviral and Antibacterial 3D-Printed Products Functionalised with Poly(hexamethylene biguanide)

Abstract

Infection prevention and public health are a vital concern worldwide, especially during pandemics such as COVID-19 and seasonal influenza. Frequent manual disinfection and use of chemical spray coatings at public facilities are the typical measures taken to protect people from coronaviruses and other pathogens. However, limitations of human resources and coating durability, as well as the safety of disinfectants used are the major concerns in society during a pandemic. Non-leachable antimicrobial agent poly(hexamethylene biguanide) (PHMB) was mixed into photocurable liquid resins to produce novel and tailor-made covers for public facilities via digital light processing, which is a popular 3D printing technique for satisfactory printing resolution. Potent efficacies of the 3D-printed plastics were achieved in standard antibacterial assessments against S. aureus, E. coli and K. pneumoniae. A total of 99.9% of Human coronavirus 229E was killed after being in contact with the 3D-printed samples (containing the promising PHMB formulation) for two hours. In an eight-week field test in Hong Kong Wetland Park, antibacterial performances of the specially designed 3D-printed covers analysed by environmental swabbing were also found to be satisfactory. With these remarkable outcomes, antimicrobial products prepared by digital light processing 3D printing can be regarded as a reliable solution to long-term infection prevention and control.

Keywords: 3D-printed plastics; additive manufacturing; antibacterial; antiviral; digital light processing; poly(hexamethylene biguanide).

Figure 1

Chemical structure of poly(hexamethylene biguanide).

Figure 2

Comparison of antimicrobial plastic products prepared by chemical coating and DLP 3D printing by the cross-sectional views of the plastic products.

Figure 3

Photos of facilities covered with 3D printing products prepared with PHMB formulations installed in Hong Kong Wetland Park (indicated by red arrows); (a) door’s pulling handles of exhibition hall on the 1/F; (b) push button of faucet at the park entrance; (c) surface of stainless-steel tray at ticket counter; (d) door lock of toilet cubicle in males’ toilet on the G/F; and (e) ventilation window in toilet cubicle in men’s toilet on the G/F.

Figure 4

Decolourisation of BPB solution (31.3 mg/L) by 3D-printed ERF-A sample plates doped with different % contents of PHMB (presented with error bars of standard deviations).

Figure 5

Images of S. aureus and E. coli streak cultures after 24 h incubation with ERF-A samples loaded with 0% to 4% PHMB without post-treatment.

Figure 6

Images of S. aureus and E. coli streak cultures after 24 h incubation with ERF-A samples loaded with 0% to 4% PHMB abraded with sandpaper.

Figure 7

Images of S. aureus and E. coli streak cultures after 24 h incubation with ERF-A samples loaded with 0% to 4% PHMB cleaned with 1:49 household bleach solution.

Figure 8

Images of S. aureus and E. coli streak cultures after 24 h incubation with ERF-A samples loaded with 0% to 4% PHMB cleaned with 1:49 household bleach solution, followed by being abraded with sandpaper.

Figure 9

Formation of inhibition widths of various ERF-A samples loaded with 0% to 4% against S. aureus and E. coli streak cultures after incubation: samples (a) without post-treatment; (b) abraded with sandpaper; (c) cleaned with 1:49 household bleach solution and (d) cleaned with 1:49 household bleach solution, followed by being abraded with sandpaper.

Figure 10

Images of K. pneumoniae and S. aureus streak cultures after incubation with ERF-C samples loaded with 0% and 3% PHMB contents under different post-treatment conditions.