Micromolar-level glucose detection using a colorimetric sensor based on imprinted polymer-coated Fe3O4 nanoparticles

초록

The glucose concentration in the blood, commonly referred to as blood sugar level, typically ranges from 3.9 to 5.6 mmol/L. It is one of the most critical physiological parameters in the human body, requiring strict regulation to maintain proper bodily function. There is a strong demand for glucose sensors that are highly sensitive, userfriendly, and exhibit high selectivity towards glucose molecules, even in challenging environments. In this study, a colorimetric sensor based on imprinted polymer and Fe3O4 nanoparticles (NPs) was developed, enabling the detection of glucose at micromolar levels, observable by the naked eye. Fe3O4 NPs were prepared using a sol-gel method and served as cores for the deposition of polydopamine (PDA) via in situ polymerization. An imprinting process created glucose-imprinted PDA, resulting in molecular cavities on the PDA surface, with the polymeric layer approximately 25 nm thick. The surface of the Fe3O4 NPs facilitated the degradation reaction of H2O2 to produce hydroxyl radicals (center dot OH), which subsequently oxidized 3,3 ',5,5 '-Tetramethylbenzidine (TMB) to its oxidized form (TMB & thorn;), causing a color change from colorless to blue. The cavities played a crucial role in the sensing mechanism, connecting the catalytic surface of the Fe3O4 NPs to the surrounding environment. When glucose molecules occupied the cavities, the catalytic activity decreased, leading to a corresponding variation in color change depending on glucose concentration. Leveraging these advantages, the imprinted PDA was applied to detect glucose in aqueous solutions and human plasma with a limit of detection as low as 10 mu M. The sensor exhibited high selectivity towards glucose over other common analytes in human blood, such as lysine, Ca2+, and K+, along with reproducibility, maintaining approximately 73 % of its sensing signal after six cycles of reuse. This study demonstrates the detection of glucose by the naked eye at micromolar levels. The detection procedure can be conducted outside of laboratory settings, presenting a highly promising approach for glucose detection in realworld applications, particularly in remote areas.

키워드