Synthesis of a Functionalized Carbon Nanotube Graphene Composite Enabling pH-Responsive Electrochemical Sensing for Biomedical Applications

Sensing of pH value plays an important role in many fields of studies including biology, chemistry, and biomedicine. In recent years, nanomaterials have emerged as a promising sensing element for a variety of applications. In this study, we report a high-sensitivity pH sensor synthesized by a functionalized single-wall carbon nanotube graphene (FSWCNT/G) composite. This sensor was constructed with Cr/Au electrodes and FSWCNT/G sealed in a PDMS microchannel on a glass substrate. The experiments of a field-effect transistor (FET), linear sweep voltammetry (LSV), and response time measurement all proved the superiority of the fabricated composite sensor over a pristine graphene sensor. A high potentiometric gradient of 98.75 mV/pH within the operating pH range of 4-10 was obtained in direct potentiometric measurements. The composite nanosensor can be used to monitor the pH value in cancer cell solution. Moreover, the composite nanosensor was tested for cancer cell detection, and the range of the concentration detection was from 5 x 106 to 2.5 x 105 cells/mL, showing a potential way to achieve label-free cell detection.

Automated summary

In this study, a high-sensitivity pH sensor was developed using a functionalized single-wall carbon nanotube graphene (FSWCNT/G) composite. The sensor consisted of Cr/Au electrodes and FSWCNT/G sealed in a PDMS microchannel on a glass substrate. The fabricated composite sensor exhibited superior performance compared to a pristine graphene sensor, as confirmed by field-effect transistor (FET), linear sweep voltammetry (LSV), and response time measurements. The composite nanosensor demonstrated a high potentiometric gradient of 98.75 mV/pH within the pH range of 4-10 and showed potential for label-free cancer cell detection with a concentration detection range of 5 x 106 to 2.5 x 105 cells/mL.