Label-free and highly selective MOFs-based dopamine detection in urine of Parkinson's patients

The amount of dopamine (DA) in the body is closely related to the occurrence and development of Parkinson's disease. However, DA detection in real body fluids is still challenging. Here, we developed a high-selectivity and high-sensitivity label-free lanthanide metal organic frameworks (MOFs) to monitor DA in urine samples from Parkinson's patients. The fluorescent MOF Eu-alpha-cyclodextrin (CD), prepared by biomineralization under mild conditions, exhibited DA concentration-dependent fluorescence intensity via host-guest complexation. Furthermore, molecular dynamics (MD) simulation analyses quantitatively dissect thermodynamic interactions of cyclodextrin and guest molecules, which systematically reveals the specific recognition mechanism of cyclodextrin and dopamine molecules. A good response for DA in the range of 10(-9) to 10(-4) M and a limit of detection (LOD) of 0.65 nM were obtained, consistent with the detection range of DA in a variety of biological fluids. Because of the good anti-interference properties of this complex, visual test strips were prepared by the in-situ growth of Eu-alpha CD nanoparticles on a nitrocellulose (NC) membrane at room temperature, owing to the protein absorbability of NC membranes. The resultant test strips possess the potential for semiquantitative detection of DA by the naked eye. Moreover, we applied Eu-alpha CD nanoparticles to analyze clinical urine samples from Parkinson's patients, and achieved a low relative error compared with those of commercial HPLC methods. Our work offers an efficient strategy for visual and on-site detection of DA in the clinic, which can assist in early diagnosis of Parkinson's disease.