Determination of Interleukin-23 in Whole Blood Using a Stochastic Sensor Based upon the Physical Immobilization of Protoporphyrin IX in Multiwalled Carbon Nanotubes/Graphite Paste Decorated with Titanium (IV) Oxide

Interleukins play an important role as biomarkers, helping in the diagnosis of cancer, obesity, and influenza. Interleukin-23 (IL-23) is a very important biomarker for colorectal cancer diagnosis. This paper proposed a stochastic sensor based on physical immobilization of protoporphyrin IX in a multiwalled carbon nanotubes/graphite paste decorated with TiO2 (PIX@TiO2MWCNT/Gr) for fast and ultrasensitive determination of IL-23. The signature of IL-23 is 0.3 s. A linear concentration range between 2.5 × 10–15 g mL−1 and 25.0 × 10−9 g mL−1 was recorded, while the sensitivity was high (2.37 × 107 s−1 g−1 mL). The limit of detection was 2.5 × 10–15 g mL−1. The validation of the sensor and screening method for whole blood was done using ten samples collected from the patients confirmed with colorectal cancer. High recoveries of IL-23 in whole blood were recorded (98.76%) with a low relative standard deviation (0.09%). Student’s t test demonstrated that there is no significant difference between the proposed screening method and an enzyme-linked immunosorbent assay (ELISA), the standard protocol in accredited clinical laboratories.