Nano-Immune Magnetic Beads Developed To Bind to SARS-CoV-2, Provides Rapid and Effective Method of Testing COVID-19 Virus

The highly contagious SARS-CoV-2 virus causes pneumonia, which has significantly affected public health, especially during the COVID-19 pandemic. Because of this, health experts needed a fast and convenient method for virus separation.

One effective approach to carry this out is utilizing immune magnetic beads (IMBs), where magnetic microspheres with specific probes are used to bind to target substances. However, applying IMBs in biological separation techniques involves challenges which need to be addressed, including low target substance concentration and complex biological environments. One suggested way to solve this problem is using small-sized magnetic beads, which can enter the impurities and decrease nonspecific binding.

A Better Approach to Testing COVID-19 Virus

A group of researchers led by Professor Wang Junfeng from the Hefei Institutes of Physical Science (HFIPS) of the Chinese Academy of Science (CAS) developed a more efficient method of testing the SARS-CoV-2 virus. They designed a novel nano-immune magnetic bead (Mal-IMB) that can efficiently bind to SARS-CoV-2 pseudovirus as they study protein biomimetic mineralization and synthesize it into magnetic nanoparticles.

This research was based on a previous study on biomimetic mineralization synthesis. In this experiment, the researchers altered the surface of ultra-small cluster magnetic beads. They united them with ultra-small single-chain antibody fragments (RBD-scFv), which target the RBD region of the S protein. This approach allowed the scientists to gain highly efficient nano-immune magnetic beads to identify RBD antigens and join them to the SARS-CoV-2 pseudovirus.

The cluster magnetic beads possess magnetic properties, chemical stability, and high homogeneity. Since they exist as nanoparticles, they demonstrate strength in capture capacity with superior binding efficiency. This makes them a potential key for quick and efficient enrichment and separation of the SARS-CoV-2 virus.

According to research member Ma Kun, the innovative bead they developed is intended to solve the problems of enriching and detecting novel coronavirus in complex biological settings. MaI-IMB exhibits a maximum virus loading capacity of 83 μg/mg in complex biological settings and can effectively enhance pseudoviruses as low as 70 copies/mL compared to commercially available beads.

When immunofluorescence and transmission electron microscopy were involved in the experiments, the nano-immune magnetic bead enhancement mechanism in complex biological settings was further revealed. This means that the novel immune magnetic beads are not only practical but also have the potential to provide significant insights for their improved performance in biological environments.

What is a Pseudovirus?

A pseudovirus is a virus artificially created to contain envelop proteins from a different virus. It was first documented in 1967 when researchers studied a particle developed from cultured mouse cells infected by polyomavirus.

Also known as a 'fake' virus, the pseudovirus contains backbone and surface proteins derived from different viruses. Their genes are altered to eliminate any native surface protein expression and to maintain functional elements of the virus that make them important research tools.

When SARS-CoV-2 began spreading globally during the COVID-19 pandemic, scientists tried to adapt existing tools to understand the nature of coronavirus better. The pseudoviruses served as invaluable models of pathogens that can safely be studied in laboratories with lower biosafety levels (BSL) requirements that the wild-type version.