Facile Determination of COVID-19 Seroconversion via Nonradiative Energy Transfer

Abstract

Serological tests are crucial in a pandemic scenario, since they are a valuable tool to spot those citizens with potential immunity, specific regions with herd immunity or particular at-risk populations, as well as acquired immunity after vaccination. Hence, high-throughput, fast, cost-effective, and straightforward technologies facilitating interrogation of COVID-19 seroconversion are an existing need. Herein, we developed an innovative assay for the determination of COVID-19 seroconversion. Fluorophore-labeled SARS-CoV-2 spike receptor-binding domain recombinant protein (F-RBD) was discovered to operate as a bioprobe that emits a strong fluorescence upon COVID-19 antibody detection; however, F-RBD fluorescence was deactivated by graphene oxide-decorated surfaces when COVID-19 antibodies are absent in the sample. With a cost of less than 0.5 USD per test (at laboratory scale), the biosensing system offers optimum results within 42 min. To demonstrate that this technology is technically sound in a relevant environment, 34 human serum samples were analyzed and clearly differentiated, requiring a tiny amount of serum (1 μL to be later diluted in saline buffer).

Ultrasensitive Detection of SARS-CoV-2 Antibody by Graphene Field-Effect Transistors

“…In terms of SARS-CoV-2 antibody detection (Table ), g-FETs have a response time of ∼80 s in serum at 10 –15 M level, comparable to that of 3D-printed electrochemical test chip in PBS at the same level of concentration. The response time of g-FETs is <2 min upon 5 × 10 –18 ∼ 5 × 10 –12 M antibody, faster than paper-based electrochemical biosensor (30 min for 6.4 × 10 –12 M) and nonradiative energy transfer assay (42 min for 2 × 10 –14 M). The fast response is attributed to the large association rate ( K on ), which is calculated by where t 1 and t 2 are the time of adding the sample and after a while; Δ I % 1 and Δ I % 2 are |Δ I DS / I 0 | values at t 1 and t 2 , respectively.…”

Measurement of Protein Kinetics Using a Liquid Phase-Based Biosensing Platform

“…The resulting quenching signals employed to calculate the kinetic constants were obtained following previous procedures. 14,17 with the real-time biosensing platform, particularly for the interaction between H-IgG and F-anti-H-IgG, which is included in the Supporting Information. The characteristic one-phase association curves were then plotted.…”

“…Besides, unlike the SPR method in which instrumentation and sensor chips are expensive, our approach is relatively cost-effective as the assay is around 0.47 USD per test, at a laboratory scale. 17 Microplate readers are available in the market for approximately 28 000 USD (e.g., from Molecular Devices). We foresee a new generation of diagnostics based on our affordable protein kinetics analysis.…”

“…Indeed, the quenching signal R is modulated by the direct association between the fluorescent probe and its respective analyte. The resulting quenching signals employed to calculate the kinetic constants were obtained following previous procedures. , Figure S1 displays an example of the raw data obtained with the real-time biosensing platform, particularly for the interaction between H-IgG and F-anti-H-IgG, which is included in the Supporting Information. The characteristic one-phase association curves were then plotted.…”

Multifunctional carbon nanomaterials for diagnostic applications in infectious diseases and tumors

“…In addition, the use of aptamer-like recognition sensors based on CNs has been reported by several studies. Avila-Huerta et al constructed a novel FRET-based fluorescent sensor with FITC-labeled SARS-CoV-2 spike RBD recombinant protein (F-RBD) as a signal probe for SARS-CoV-2 antibodies detection [ 117 ]. F-RBD can emit an intense fluorescence upon SARS-CoV-2 antibody detection; however, the fluorescence of F-RBD can be quenched by GO in the absence of RBD antibody.…”