Highly sensitive detection of Campylobacter jejuni using a carbon dot-embedded nanoMIPs fluorescent sensor

Abstract

Campylobacter jejuni, a leading cause of gastroenteritis worldwide, poses significant detection challenges due to the labor-intensive and insufficiently sensitive current methods. Developing efficient, rapid diagnostics is vital for clinical and food industry applications; yet the vulnerability of biological elements in creating bacterial sensors remains a major obstacle. This study introduces an innovative fluorescence-based sensor employing fully synthetic carbon dot (CDs) functionalized molecularly imprinted polymer (CDs@nanoMIPs) receptors to detect this foodborne pathogenic bacterium. The CDs@nanoMIPs synthesis was accomplished using a solid-phase approach, with an immunodominant epitope of C. jejuni serving as a guiding template. During the polymerization process, nitrogen-doped CDs were synthesized in situ and incorporated into nanoMIPs as a fluorescent tag, constituting approximately 19 % of the composite. The synthesized nanomaterials were characterized by employing transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS), Fourier-transform infrared spectroscopy (FT-IR), fluorescence microscopy, UV–Vis spectrophotometry, and fluorescence spectrometry. CDs@nanoMIPs demonstrated a notable blue fluorescence when excited at 350 nm, along with excellent photostability and a negative zeta potential. These nanostructured particles (59 nm) exhibited moderate polydispersity and a spherical morphology. The FT-IR spectrum deviated from that of conventional CDs, aligning more closely with the template epitope. When in contact with C. jejuni, CDs@nanoMIPs induced a significant increase in fluorescence intensity, enabling the efficient bacterial detection. This interaction showed exceptional affinity and sensitivity towards C. jejuni, featuring a linear range of 1 × 10¹–1 × 10⁸ CFU mL⁻¹ (R² = 0.98) and a low detection limit of 4.6 CFU mL⁻¹. CDs@nanoMIPs-based C. jejuni sensors marked a novel approach to pathogen detection.