Toward Community Surveillance: Detecting Intact SARS-CoV-2 Using Exogeneous Oligonucleotide Labels

DNA-Directed Patterning for Versatile Validation and Characterization of a Lipid-Based Nanoparticle Model of SARS-CoV-2

Lipid-based nanoparticles have been applied extensively in drug delivery and vaccine strategies and are finding diverse applications in the coronavirus disease 2019 (COVID-19) pandemic-from vaccine-component encapsulation to modeling the virus, itself. High-throughput, highly flexible methods for characterization are of great benefit to the development of liposomes featuring surface proteins. DNA-directed patterning is one such method that offers versatility in immobilizing and segregating lipid-based nanoparticles for subsequent analysis. Here, oligonucleotides are selectively conjugated onto a glass substrate and then hybridized to complementary oligonucleotides tagged to liposomes, patterning them with great control and precision. The power of DNA-directed patterning is demonstrated by characterizing a novel recapitulative lipid-based nanoparticle model of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-S-liposomes-that presents the SARS-CoV-2 spike (S) protein on its surface. Patterning a mixture of S-liposomes and liposomes that display the tetraspanin CD63 to discrete regions of a substrate shows that angiotensin-converting enzyme 2 (ACE2) specifically binds to S-liposomes. Subsequent introduction of S-liposomes to ACE2-expressing cells tests the biological function of S-liposomes and shows agreement with DNA-directed patterning-based assays. Finally, multiplexed patterning of S-liposomes verifies the performance of commercially available neutralizing antibodies against the two S variants. Overall, DNA-directed patterning enables a wide variety of custom assays for the characterization of any lipid-based nanoparticle.