# Electrochemical and colorimetric sensing of P-xylene using doped C60 fullerenes: a dual approach to medical and environmental applications

## TL;DR

This paper explores using doped fullerenes to detect p-xylene, a potential prostate cancer biomarker, and for environmental cleanup due to its toxicity.

## Contribution

The study introduces doped fullerene-based sensors with dual medical and environmental applications for p-xylene detection and removal.

## Key findings

- BC59 shows the strongest adsorption of p-xylene, making it ideal for environmental removal.
- NC59 exhibits ultrafast recovery and high conductivity modulation, suitable for medical sensing.
- Dipole moment and NCI analysis reveal interaction differences between doped and undoped fullerenes.

## Abstract

P-xylene is a type of aromatic hydrocarbon that has growing biomedical and environmental importance. It has been identified as a putative biomarker for prostate cancer and its fast and selective detection in biological fluids (especially urine and blood) is critical in the diagnosis and monitoring of the disease. Similarly, removal of p-xylene from industrial effluents and wastewater is an important environmental consideration due to its toxicity and persistence. These reasons emphasize the importance of developing and calculating the performance of efficient adsorbent and electrochemical sensors for p-xylene. Here, the adsorption and sensing performance of three fullerene-based nanostructures (C60, BC59, NC59) were computationally studied for p-xylene using electronic structure calculations, charge transport analysis, dipole moment calculations, and non-covalent interaction (NCI/RDG) maps. There were significant changes in electrical conductivity induced by adsorption and transduction was strongly analyte-dependent: C60 from 1.92 × 10− 5 to 2.93 × 10− 4 S/m (C60 @ p-xylene), BC59 from 1.18 × 10− 2 to 1.81 × 10− 1 S/m (BC59 @ p-xylene), NC59 from 3.68 × 10− 3 to 2.07 × 10− 3 S/m (NC59@ p-xylene). Recovery times were ultrafast for all three complexes with the fastest recovery time being for NC59 @ p-xylene (3.5 × 10− 7 s), C60 = 9.8 × 10− 7, and BC59@ p-xylene (1.9 × 10− 5 s). Dipole-moment analysis showed significant polarization upon adsorption for the doped systems. The dipole moment increased from 1.50 to 3.91 D in BC59 and from 1.39 to 3.05 D in NC59. NCI and RDG analyses found that C60@p-xylene is mainly affected by weak van der Waals forces. BC59@p-xylene shows stronger π-π interactions. NC59@p-xylene has intermediate but improved attractive interactions because of nitrogen doping. These trends are consistent with the adsorption energy ranking BC59 > C60 > NC59 and highlight the changes in sensor response and recovery behavior. This study shows that BC59 has the strongest adsorption and is suitable for environmental adsorption and removal of p-xylene. NC59, on the other hand, has extremely high conductivity modulation and ultrafast recovery, along with reasonable adsorption. This makes NC59 the most promising candidate for detecting p-xylene in early prostate cancer detection.