Additive manufacturing of carbon black immunosensors based on covalent immobilization for portable electrochemical detection of SARS-CoV-2 spike S1 protein

Abstract

The global pandemic of the COVID-19 disease has emphasized the need to develop clinical tests which are simple, fast and inexpensive. In this aspect, electrochemical biosensors are alternatives capable to attend such requirements and providing reliable results, highly required in clinical analysis. Associating the quality of electrochemical biosensors with additive manufacturing technology (3D printing) ensures the production of sensors on a large scale, at a reduced cost, and in an automated way. In this regard, the present work proposes the development of an additive-manufactured electrochemical immunosensor, based on the covalent immobilization of antibodies on electrodes obtained from lab-made conductive filaments, composed of carbon black and polylactic acid, for the detection of the spike S1 protein of the SARS-CoV-2 virus. Due to the readily available carboxylic groups on the surface of the additive-manufactured sensor, it was possible to produce an immunosensor without the need for modification steps with metallic particles. Therefore, the proposed immunosensor showed satisfactory results, with a linear range varying from 0.01 to 4.5 nmol L−1 and a detection limit of 2.7 pmol L−1, with a sensitivity of 7.606 µA nmol−1 L. The 3D-printed immunosensor was fully designed for in loco application and all results were obtained from portable equipment, making it a highly viable alternative to be applied as a point-of-care device.