Correlating Molecular Recognition With Dynamic Light Scattering: Swelling of Molecularly Imprinted Polymers As a Quantitative Signal Publisher

Summary: Can polymer swelling detect amphetamine? A molecularly imprinted sensor measured binding directly and matched HPLC in urine tests. #Biosensors #AnalyticalChemistry

Asafari S ; Alizadeh T ; Abdi K M
Source: Microchemical Journal Published:2026

Abstract

Swelling of molecularly imprinted polymers (MIPs) resulting from selective analyte binding was employed as a direct and self-reporting analytical signal. A molecularly imprinted polymer holding amphetamine selective sites was synthesized, and the interaction between the MIP and amphetamine produced a measurable hydrodynamic expansion, which was monitored using dynamic light scattering (DLS). It was demonstrated that the recognition event led to considerable expansion in the MIP particles, which subsequently resulted in increased laser light scattering intensity. The phenomenon was not observed in the case of the non-imprinted polymer involved in the similar experiment. The imprinting factor obtained by DLS signal was 9.01, whereas that obtained by a traditional method was 2.22, which showed that the proposed method may reduce the influence of nonspecific adsorption on the analytical signal. This difference highlights the potential of swelling-based detection to more selectively reflect the contribution of specific molecular recognition to the analytical response. Within the concentration range of 5 × 10−9 to 5 × 10−5 mol L−1, the swelling response exhibited a strong linear relationship with amphetamine concentration. The method achieved a low detection limit of 0.98 × 10−10 mol L−1. High selectivity of the method was also demonstrated by comparing the swelling signal of the MIP to the target molecule, amphetamine, with those of some structurally related interferents like ephedrine and methamphetamine. Real sample analysis (urine) demonstrated recoveries (93.8–103.6%) and low RSD values (2.51–3.53), with no significant difference compared to HPLC results at the 95% confidence level. These findings highlight polymer swelling as a transduction mechanism that directly links molecular recognition to a measurable physical signal. © 2026 Elsevier B.V.