*Article* **Carbon Nanotube-Based Electrochemical Biosensor for Label-Free Protein Detection**

**Jesslyn Janssen 1,\*, Mike Lambeta 2,3, Paul White 3 and Ahmad Byagowi 3**


Received: 3 October 2019; Accepted: 9 December 2019; Published: 17 December 2019

**Abstract:** There is a growing need for biosensors that are capable of efficiently and rapidly quantifying protein biomarkers, both in the biological research and clinical setting. While accurate methods for protein quantification exist, the current assays involve sophisticated techniques, take long to administer and often require highly trained personnel for execution and analysis. Herein, we explore the development of a label-free biosensor for the detection and quantification of a standard protein. The developed biosensors comprise carbon nanotubes (CNTs), a specific antibody and cellulose filtration paper. The change in electrical resistance of the CNT-based biosensor system was used to sense a standard protein, bovine serum albumin (BSA) as a proof-of-concept. The developed biosensors were found to have a limit of detection of 2.89 ng/mL, which is comparable to the performance of the typical ELISA method for BSA quantification. Additionally, the newly developed method takes no longer than 10 min to perform, greatly reducing the time of analysis compared to the traditional ELISA technique. Overall, we present a versatile, affordable, simplified and rapid biosensor device capable of providing grea<sup>t</sup> benefit to both biological research and clinical diagnostics.

**Keywords:** electrochemical biosensors; SWCNT; point-of-care diagnostics; label-free biosensors; ELISA; carbon nanotubes; bovine serum albumin
