3D printed skyscraper electrochemical biosensor for the detection of tumour necrosis factor alpha (TNFα) in faeces

Tumour necrosis factor alpha (TNFα) is an important inflammatory mediator in the body and and thus, is considered an important biomarker in a host of inflammatory disorders such as ulcerative colitis. Many biosensing strategies are expensive and use complex fabrication approaches. Therefore, this study aimed to develop a simple yet robust TNFα sensor, which could conduct measurement within biological environments. 3D printing was utilised to fabricate an electrode with skyscraper structures to provide increased surface area for the sensor. The sensor was made by covalent immobilization of anti-TNFα onto carboxylic acid bearing conducting polymer thiophene-2-carboxylic (Th2CA) after electrodeposition of gold nanoparticles (AuNPs) onto the SS electrode. The development of the biosensor was characterised using field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). The linear range for TNFα was from 160 to 1820 pg/ml with a limit of detection of 44.5 pg/ml on the skyscraper (SS) immunosensor. The sensor was selective for the detection of TNFα when compared to other commonly found extracellular biological molecules. The sensor was able to monitor levels of TNFα from faecal pellets, where an increase in TNFα was observed with increasing age. These findings highlight that 3D printing could be used to make a simple yet robust immunosensor for the detection of a host of key biomolecules providing the potential for vital diagnostic tools.