Beyond Equilibrium Refractive-Index Shifts: Dynamical Information Encoded in Sensorgrams

Disordered Ag-nanowire localized surface plasmon resonance sensorgrams for glycated hemoglobin (HbA1c) detection exhibit reproducible multi-component temporal structures that cannot be fully explained within conventional equilibrium refractive-index models; in particular, the quantification of the molecular target escapes from the classical theory. The HbA1c-associated contribution emerges at earlier times while displaying slower relaxation dynamics compared with naïve hemoglobin-associated kinetics, revealing the coexistence of distinct activation and interfacial relaxation pathways. Analysis of temporal derivatives, phase-space trajectories, characteristic peak times, and relaxation times aims to suggest that the plasmonic response originates from multiple competing nonequilibrium processes evolving on different timescales. The description of the structured temporal response relies on a phenomenological framework incorporating activation and relaxation dynamics. Dynamical redistribution pathways associated with heterogeneous adsorption, hydration-shell relaxation, and plasmonic coupling within spatially non-uniform electromagnetic environments, along with resonance shift, support molecular fingerprint. The findings suggest that sensorgrams contain molecular information hidden beyond conventional equilibrium optical observables, motivating a transition toward dynamical and time-resolved approaches in plasmonic biosensing.