Investigation of Bio-interfaces of Common Paediatric Virus Human Parainfluenza Virus Type3 with Synthetic Nanospike Silicon Surfaces
Creators: name: Mah, Wai Liong (Samson)
Publisher: name: RMIT University
Year: 2024
Subjects: classificationCode: 510501
subject: Biological physics
classificationCode: 400302
subject: Biomaterials
classificationCode: 310607
subject: Nanobiotechnology

description: Respiratory viruses have been a significant cause of illness and death throughout human history (e.g., Spanish flu, Swine flu, SARS, MERS) and continue to pose a threat to public health. The primary transmission mode for most respiratory viruses is airborne transmission via an infected person's expelled respiratory secretions (via coughing, sneezing, talking, or singing). However, indirect contact through contaminated surfaces (inadvertently deposited by viral-laden expelled respiratory droplets) is also possible, as the virus can survive on common surfaces for varying periods depending on the specific virus and environmental conditions. When a person touches a contaminated surface and then touches their eyes, nose, or mouth, the virus can enter their body and causes infection. This phenomenon is also known as hidden transmission or fomites (contaminated surfaces) transmission and can happen not just with respiratory viruses but with many enteric viruses as well. 

The development of antiviral surfaces has become an area of significant research interest in recent years. Current antiviral surfaces incorporate materials that release active agents, such as heavy metal ions or nanoparticles (NPs), antimicrobial peptides, and quaternary ammonium compounds (QACs) that can inactivate the virus. While these technologies show promise in reducing the spread of viruses, they do have some disadvantages. For example, the active agents used in antiviral coatings, such as heavy metal-based NPs and QACs, can be toxic at high doses, and prolonged exposure to these materials and bioaccumulation could cause adverse health effects. Additionally, some of these materials may interact with other chemicals or drugs in the body, potentially altering their effectiveness or causing adverse reactions. The durability of active agents can also degrade over time and there are exorbitant costs involved in incorporating heavy metal materials in the coatings. 

A novel approach toward developing antiviral surfaces is to modify the physical properties of the surface to make it less hospitable to virus attachment. This approach was inspired by the nanoscale topography found on insect wings that was found to physically rupture attaching bacterial cells. Biomimetic nanofabricated surfaces, such as nanospike silicon (Si) surfaces (also known as black Si), have been reported to exhibit excellent bactericidal activity and anti-biofouling behaviour. However, it was still unclear whether the same physico-mechanical means of microbial inactivation could be achieved for viruses; there is a lack of studies reporting the virucidal activity of such nanofabricated surfaces. There is also no clear understanding of the mechanisms of the antiviral effect of the inert nanofabricated surfaces. 

In this research project, I investigated the effect of biomimetic nanostructured surfaces, namely nanospike silicon (Si), against human parainfluenza virus type-3 (HPIV3), a common paediatric respiratory virus with a reported size range of 150 – 250 nm. Nanospike Si surfaces were fabricated by inductively coupled plasma (ICP) assisted reactive ion etching (RIE). This resulted in an irregular array of surface nanospikes with an average height of 289 nm, an average density (spacing) of 62.1 nm, and a tip diameter of 3 nm. HPIV3-laden droplets were incubated on nanospike Si and non-structured Si control surfaces for 1, 3, and 6 h in an ambient environment in the dark. Nanospike Si caused a significant (p &lt; 0.005) 1.4 log reduction in infectious HPIV3 particles after 6 h. In addition, analysis of the electron microscopy images depicted changes in the morphology of the HPIV-3 particles attached on nanospike Si. In comparison, for smooth Si, after 1 h, there was a 0.4 log reduction of infectious HPIV3 particles, after 3 h, a 0.5 log reduction, and after 6 h, a 0.6 log reduction. Notably, scanning electron microscopy (SEM) revealed irreversible physical damage to the viral particles, while transmission electron microscopy (TEM) and focused-ion beam (FIB) milling SEM images revealed the piercing effect of the viral particles by the nanospikes. Moreover, reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) showed no significant differences in the number of viral copies between the control and nanospike Si surfaces, demonstrating no disruption of the viral nucleic acid by either chemical or physical disruption. Together, these results suggest that the physical disruption of the virus envelope by the nanospike topography is vital to the virucidal mechanism. 
Furthermore, I share some of the key technical challenges encountered during the experimental procedures involved in studying antiviral surfaces. The improvements made in cell culture techniques, viral propagation, plaque assays, and direct visualization using electron microscopy have set a reliable foundation for future research in the field of antiviral surfaces. The findings presented also contribute to a better understanding of virus-surface interactions.

Overall, these findings will help set a precedent for further developing antiviral surfaces to combat indirect contact transmission of respiratory viruses and other viruses. Moreover, the nanospikes pattern used in this study demonstrated a promising key design feature for the fabrication of low toxicity, low cost, and durable antimicrobial surfaces, particularly for application in medical devices, orthopaedic implants, and food packaging that would require the advantages.