Selective Adsorption of Trace Biomolecules by Amino Acid‐Functionalized Ti ₃ C ₂ T _x MXene

Abstract Accurate detection and enrichment of trace‐level biomolecules are essential for early disease diagnosis, environmental monitoring, and biotechnological research. However, conventional adsorbents often lack the sensitivity and selectivity required at ultralow analyte concentrations. Here, a systematic study is conducted on dopamine adsorption on amino‐acid‐surface‐modified Ti ₃ C ₂ T _x MXene nanosheets covalently grafted onto glass wool via silane linkers. Comprehensive characterization confirms the stability of the MXene lattice and successful functionalization. Continuous‐flow columns packed with amino acid‐MXene–coated glass wool are fabricated, enabling preconcentration and recovery from real samples. Adsorption follows the Langmuir isotherm and pseudo–second‐order kinetics, indicative of chemisorption. Thermodynamic analysis (ΔG⁰ < 0, ΔH⁰ > 0, ΔS⁰ > 0) reveals a spontaneous, endothermic process accompanied by increased interfacial disorder. Among the tested modifiers, the cystine‐modified MXene exhibits nearly complete uptake (10 ppm analyte) through synergistic effects of electrostatic attraction, hydrogen bonding, and thiol–catechol interactions. Under optimized conditions, >99% desorption is achieved using ultrasonic‐assisted ethanol–acetic acid elution, with stable performance over ten adsorption–desorption cycles. Compared with activated carbon and silica gel, the amino acid–MXene adsorbents demonstrate markedly superior capacity, selectivity, and cycling stability, establishing a versatile platform for trace biomolecule capture and enrichment.