The sensitive detection of inflammatory biomarkers in gingival crevicular fluid (GCF) is highly desirable for the evaluation of periodontal disease. Luminol-based electrochemiluminescence (ECL) immunosensors offer a promising approach for the fast and convenient detection of biomarkers. However, luminol’s low ECL efficiency under neutral conditions remains a challenge. This study developed an immunosensor by engineering an immunorecognition interface on the outer surface of mesoporous silica nanochannel film (SNF) and confining a Co3O4nanocatalyst within the SNF nanochannels to improve the luminol ECL efficiency. The SNF was grown on an indium tin oxide (ITO) electrode using the simple Stöber solution growth method. A Co3O4nanocatalyst was successfully confined within the SNF nanochannels through in situ electrodeposition, confirmed by X-ray photoelectron spectroscopy (XPS) and electrochemical measurements. The confined Co3O4demonstrated excellent electrocatalytic activity, effectively enhancing luminol and H2O2oxidation and boosting the ECL signal under neutral conditions. Using interleukin-6 (IL-6) as a proof-of-concept demonstration, the epoxy functionalization of the SNF outer surface enabled the covalent immobilization of capture antibodies, forming a specific immunorecognition interface. IL-6 binding induced immunocomplex formation, which reduced the ECL signal and allowed for quantitative detection. The immunosensor showed a linear detection range for IL-6 from 1 fg mL−1to 10 ng mL−1, with a limit of detection (LOD) of 0.64 fg mL−1. It also demonstrated good selectivity and anti-interference capabilities, enabling the successful detection of IL-6 in artificial GCF samples.
In clinical practice, hydrogen peroxide (H 2 O 2 ) concentration in the gingival crevicular fluid (GCF) has been regarded as a straightforward biochemical indicator for nonintrusive early periodontitis diagnosis. However, the complex composition of the GCF samples from periodontitis patients presents significant challenges for achieving highly sensitive and accurate H 2 O 2 detection. Here, we synthesized cobalt-based metal–organic framework nanofibers (Co-MOF NFs) with ultrahigh surface area to construct a highly sensitive electrochemical sensor, achieving a low H 2 O 2 detection limit in the real GCF samples. Benefitting from large surface area (1704.2 m 2 ·g −1 ) and high H 2 O 2 redox ability of Co-MOF NFs, the prepared electrochemical sensor exhibited a wide detection range (0.5 μM–5 mM), low detection limit (0.05 μM), and high sensitivity (273.07 μA·mM −1 ·cm −2 ). Moreover, the synthesized electrochemical sensor exhibited excellent accuracy and anti-interference ability in the real GCF samples. After periodontitis treatment, the concentration of H 2 O 2 in real GCF samples detected by a fabricated sensor is significantly reduced, which is highly consistent with diagnostic results of periodontitis patients, including intraoral scanning photos and dental panoramic radiographs. The results of this study highlight the potential of synthesized Co-MOF NFs-based electrochemical sensors as an alternative with clinical value in the early diagnosis of periodontitis.
As an important inflammatory cytokine, interleukin-6 (IL-6) can mediate the entire pathological process of periodontitis and is closely associated with the degree of inflammation. Therefore, it is critical to develop convenient quantitative methods for monitoring IL-6 quantity in gingival crevicular fluid. In this study, methylene blue (MB)-decorated reduced graphene oxide (rGO) is employed as signal probe to further support the antibody-enabling specific recognition of IL-6. Due to π–π stacking and electrostatic interactions, rGO-MB nanocomposites can be stably obtained. rGO with good conductivity and large surface area characteristics promotes the redox signals of MB on the glassy carbon electrode (GCE). In addition, through the simple in situ self-polymerization of dopamine, the polydopamine (PDA) obtained can be not only directly used as a biological crosslinking agent for covalent immobilization of anti-IL-6 antibody but can also be regarded as a protective layer to enhance the stability of rGO-MB on the GCE surface. Such a designed PDA/rGO-MB/GCE-based immunosensor enables specific binding with IL-6 and produces a decreased electrochemical signal for MB, realizing the selective and sensitive quantitative measurement of IL-6. Consequently, our fabricated PDA/rGO-MB/GCE-based electrochemical immunosensor has an excellent linear relationship with IL-6 ranging from 1 pg/mL to 100 ng/mL, with a limit of detection as low as 0.48 pg/mL. Moreover, our as-prepared sensing strategy shows accurate monitoring of the IL-6 quantity in gingival crevicular fluid samples.
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