Surface Engineering of Graphene through Heterobifunctional Supramolecular-Covalent Scaffolds for Rapid COVID-19 Biomarker Detection

PICCININI, ESTEBAN; CANTILLO, AGUSTIN L.; AZZARONI, OMAR; SCOTTO, JULIANA; MARMISOLLÉ, WALDEMAR A.; ALLEGRETTO, JUAN A.; FENOY, GONZALO E.

ACS APPLIED MATERIALS & INTERFACES

AMER CHEMICAL SOC

Lugar: Washington; Año: 2021

1944-8244

Graphene is a two-dimensional semiconductingmaterial whose application for diagnostics has been a real gamechanger in terms of sensitivity and response time, variables ofparamount importance to stop the COVID-19 spreading. Nevertheless, strategies for the modification of docking recognition andantifouling elements to obtain covalent-like stability without thedisruption of the graphene band structure are still needed. In thiswork, we conducted surface engineering of graphene throughheterofunctional supramolecular-covalent scaffolds based on vinylsulfonated-polyamines (PA-VS). In these scaffolds, one side bindsgraphene through multivalent π−π interactions with pyrenegroups, and the other side presents vinylsulfonated pending groupsthat can be used for covalent binding. The construction of PA-VSscaffolds was demonstrated by spectroscopic ellipsometry, Raman spectroscopy, and contact angle measurements. The covalentbinding of −SH, −NH2, or −OH groups was confirmed, and it evidenced great chemical versatility. After field-effect studies, wefound that the PA-VS-based scaffolds do not disrupt the semiconducting properties of graphene. Moreover, the scaffolds werecovalently modified with poly(ethylene glycol) (PEG), which improved the resistance to nonspecific proteins by almost 7-foldcompared to the widely used PEG-monopyrene approach. The attachment of recognition elements to PA-VS was optimized forconcanavalin A (ConA), a model lectin with a high affinity to glycans. Lastly, the platform was implemented for the rapid, sensitive,and regenerable recognition of SARS-CoV-2 spike protein and human ferritin in lab-made samples. Those two are the targetmolecules of major importance for the rapid detection and monitoring of COVID-19-positive patients. For that purpose, monoclonalantibodies (mAbs) were bound to the scaffolds, resulting in a surface coverage of 436 ± 30 ng/cm2. KD affinity constants of 48.4 and2.54 nM were obtained by surface plasmon resonance (SPR) spectroscopy for SARS-CoV-2 spike protein and human ferritinbinding on these supramolecular scaffolds, respectively.