3D paper-based analytical platform decorated with ZIF-8/CuFe2O4 nanozyme for simultaneous determination of glutathione, ascorbic acid, and dopamine

A 3D μPAD featuring physical isolation has been designed for crosstalk-free triplex detection. • A ZIF-8/CuFe 2 O 4 nanozyme, which exhibits broad-spectrum POD-like activity and generates three distinct color signals, has been synthesized. • A low-cost POCT platform that integrates functional materials, devices, and intelligent readout for GSH, AA, and DA has been developed. This work addresses the challenge of synchronous and rapid on-site detection of multiple metabolic small molecules in serum, and has constructed a point-of-care testing (POCT) platform based on broad-spectrum catalytic nanoenzyme and anti-interference three-dimensional (3D) paper chip. The ZIF-8/CuFe 2 O 4 composite nanoenzyme, prepared by a simple method, utilizes its interface synergy effect and exhibits excellent broad-spectrum peroxidase-like (POD-like) activity, capable of simultaneously and efficiently catalyzing the production of three-color contrasting chromogenic signals with 3,3′,5,5′-tetramethylbenzidine (TMB), 4-aminoantipyrine (4-AAP)/phenol, and o -phenylenediamine (OPD). On this basis, a 3D microfluidic paper-based analytical device (μPAD) with vertically isolated flow channels is constructed, which fundamentally eliminates signal crosstalk in multi-channel detection from the physical architecture level. During the detection, the target substances glutathione (GSH), ascorbic acid (AA), and dopamine (DA) quantitatively regulate the chromogenic reaction through competitive inhibition mechanisms. Combined with smartphone imaging and image analysis, synchronous and rapid quantification of the three substances can be achieved. The limit of detection (LOD) of this platform for GSH, AA, and DA is 0.072 μM, 0.44 μM, and 0.29 μM, respectively. Additionally, it shows a good recovery rate and reliability in diluted human serum samples. The integrated strategy of “functional materials–device design–intelligent reading” proposed in this work offers a new solution that is low-cost, easy-to-operate, and resistant to interference for on-site immediate detection of multiple indicators. Download: Download high-res image (131KB) Download: Download full-size image