ABSTRACT
The development of simple, cost-effective, rapid, and quantitative diagnostic tools remains critical to monitor infectious COVID-19 disease. Although numerous diagnostic platforms, including rapid antigen tests, are developed and used, they suffer from limited accuracy, especially when tested with asymptomatic patients. Here, a unique approach to fabricate a nanochannel-based electrochemical biosensor that can detect the entire virion instead of virus fragments, is demonstrated. The sensing platform has uniform nanoscale channels created by the convective assembly of polystyrene (PS) beads on gold electrodes. The PS beads are then functionalized with bioreceptors while the gold surface is endowed with anti-fouling properties. When added to the biosensor, SARS-CoV-2 virus particles block the nanochannels by specific binding to the bioreceptors. The nanochannel blockage hinders the diffusion of a redox probe; and thus, allows quantification of the viral load by measuring the changes in the oxidation current before and after virus incubation. The biosensor shows a low limit of detection of ≈1.0 viral particle mL-1 with a wide detection range up to 108 particles mL-1 in cell culture media. Moreover, the biosensor is able to differentiate saliva samples with SARS-CoV-2 from those without, demonstrating the potential of this technology for translation into a point-of-care biosensor product.
ABSTRACT
A variety of coating techniques are available for medical devices to be tailored with surface properties aimed at optimizing their performance in biological environments. Cold spray, as a member of the thermal spray family, is now being exploited to efficiently deposit micro- to nanometer sized metallic or non-metallic particles on surgical implants, medical devices and surfaces in the healthcare environment to create functional coatings. Cold spray has attracted attention in the context of biomedical applications due to the fact that multiple materials can be combined easily at the surface of these devices, and that oxygen-sensitive and heat-sensitive organic molecules, including bioactive compounds, can be incorporated in these coatings due to the relatively low temperatures used in the process. The ability to maintain material and chemical properties and the ability to create functional coatings make the cold spray process particularly suitable for applications in the MedTech industry sector. This review explores the fabrication of cold spray coatings including the types of materials that have been used for biomedical purposes, provides a detailed analysis of the factors affecting cold spray coating performance, and gives an overview over the most recent developments related to the technology. Cold spray coatings that have been used until this point in time in biomedical applications can be broadly classified as biocompatible coatings, anti-infective coatings, anti-corrosive coatings, and wear-resistant coatings. In addition, this review discusses how these applications can be broadened, for example by providing antiviral effect against coronavirus (COVID-19). While we highlight examples for multifunctional cold spray coatings, we also explore the current challenges and opportunities for cold spray coatings in the biomedical field and predict likely future developments.