Nancy Fabiana Ferreyra

Glycans and glycoproteins encode biologically and clinically relevant information that influences molecular stability, immune recognition, disease‐associated signaling, and biotherapeutic quality. Their analysis is therefore important for diagnostics, biomarker discovery, pathogen detection, and biopharmaceutical characterization. Electrochemical impedance spectroscopy (EIS) provides a label‐free, miniaturization‐compatible approach for converting glycan‐mediated recognition events into electrical responses using small sample volumes and simple instrumentation. This review critically examines impedimetric biosensing strategies for targeted detection of glycans, glycoproteins, and disease‐relevant glycoforms, as well as comparative glycoprofiling. We discuss the mechanistic foundations of Faradaic and non‐Faradaic EIS, emphasizing equivalent circuit selection, frequency domain analysis, signal interpretation, and experimental artifacts. Lectin‐ and glycan‐based interfaces, immobilization chemistries, antifouling layers, and nanomaterial‐enabled architectures are evaluated for their effects on charge‐transfer resistance, interfacial capacitance, receptor accessibility, interfacial stability, and reproducibility. Representative platforms are compared according to sample matrix, validation strategy, selectivity, matrix effects, and performance in clinical, biopharmaceutical, and pathogen‐detection settings. EIS is positioned alongside quartz crystal microbalance and surface plasmon resonance as a complementary, fit‐for‐purpose technique rather than a replacement for structural glycomics. Key barriers to translation include lectin cross‐reactivity, uncontrolled multivalent recognition, interfacial instability, inadequate real‐matrix validation, and nonstandardized EIS acquisition and analysis, all of which hinder robust glycoform profiling and targeted glycoanalysis.

Glucosamine–chitosan synthesized by the Maillard reaction was combined with montmorillonite to obtain a nanohybrid composite to immobilize horseradish peroxidase. The material combines the advantageous properties of clay with those of the chitosan derivative; has improved water solubility and reduced molecular weight and viscosity; involves an eco-friendly synthesis; and exhibits ion exchange capacity, good adhesiveness, and a large specific surface area for enzyme adsorption. The physicochemical characteristics of the composite were analyzed by infrared spectroscopy and X-ray diffraction to determine clay–polycation interactions. The electrochemical response of the different polyphenols to glassy carbon electrodes modified with the composite was evaluated by cyclic voltammetry. The sensitivity and detection limit values obtained with the biosensor toward hydroquinone, chlorogenic acid, catechol, and resorcinol are (1.6 ± 0.2) × 10² µA mM⁻¹ and (74 ± 8) nM; (1.2 ± 0.1) × 10² µA mM⁻¹ and (26 ± 3) nM; (16 ± 2) µA mM⁻¹ and (0.74 ± 0.09) μM; and (3.7± 0.3) µA mM⁻¹ and (3.3 ± 0.2) μM, respectively. The biosensor was applied to quantify polyphenols in pennyroyal and lemon verbena extracts.