Electrochemical investigation of hydroxyapatite–lanthanum strontium cobalt ferrite composites (HA–LSCF) for SARS-CoV-2 aptasensors

The hydroxyapatite–lanthanum strontium cobalt ferrite (HA–LSCF) composite showed a good response on a screen-printed carbon electrode (SPCE) electrochemical aptasensor to detect SARS-CoV-2. SPCE/HA–LSCF with a thiolated aptamer has a strong affinity for the SARS-CoV-2 spike RBD protein. This occurs due to the binding of –SH to the HA-positive region. In the presence of LSCF, which is conductive, an increase in electron transfer from the redox system [Fe(CN)(6)](3−/4−) occurs. The interaction of the aptamer with the RBD protein can be observed based on the decrease in the electron transfer process. As a result, the developed biosensor is highly sensitive to the SARS-CoV-2 spike RBD protein with a linear range of 0.125 to 2.0 ng mL(−1), a detection limit of 0.012 ng mL(−1), and a quantification limit of 0.040 ng mL(−1). The analytical application of the aptasensor demonstrates its feasibility in the analysis of saliva or swab samples.