Biosensor based on hybrid composite and Concanavalin a lectin for microorganisms differentiation

For the treatment of candidemia, especially in critical care settings, rapid identification of Candida species remains essential. Hybrid compounds have emerged as a powerful strategy to address challenges in microbiological detection and control. By integrating organic and inorganic components within a single architecture, these materials exhibit synergistic physicochemical and biological properties that are useful for sensor platform strategies. Lectins can act as bioreceptors due to their affinity for carbohydrates, and the addition of nanomaterials increases the platform's surface area and sensitivity. This work developed an electrochemical biosensor using a self-assembling monolayer of 4-mercaptobenzoic acid (MBA) and a hybrid nanocomposite composed of chitosan-coated magnetite nanoparticles capped with gold (Fe₃O₄@Chit@Au) and the lectin Concanavalin A (ConA) as the biorecognition element. The hybrid architecture was designed to enhance the microorganism-sensor interface by increasing surface area and improving lectin immobilization. Topographic analysis confirmed the effective assembly of the sensing layer on gold electrodes. Selective responses to Candida albicans and Candida tropicalis were observed by electrochemical analysis, whereas bacterial species such as Staphylococcus aureus, Klebsiella pneumoniae, and Bacillus subtilis exhibited reduced signals. The stronger response for Candida species is consistent with the high affinity of ConA for mannan residues present in fungal cell walls. The biosensor demonstrated a limit of detection of 0.71 CFU.mL⁻¹ and a limit of quantification of 2.39 CFU.mL⁻¹ for C. albicans within a working range of 10¹-10⁵ CFU.mL⁻¹. These findings demonstrate how lectin-based electrochemical platforms can identify and distinguish clinically significant microorganisms.