Aptamer-functionalized metal-organic framework-coated nanofibers with multi-affinity sites for highly sensitive, selective recognition of ultra-trace microcystin-LR

A novel aptamer-functionalized metal-organic framework nanofibrous composite (viz. PAN/UiO@UiO(2)-N-3-aptamer) with a high aptamer coverage density was proposed based on the electrospinning and seeded growth method, and used for specific affinity recognition of trace Microcystin-LR (MC-LR). Heterobifunctional ligand was used to modify the metal-organic framework nanoparticles (MOF NPs) surface, which could passivate the MOF surface with respect to unmodified DNA, followed by coupling massive aptamers on MOF of the solid-phase microextraction (SPME) fiber using click chemistry. Characterizations including morphology, spectra analysis, mechanical stability, binding capacity and specificity were fulfilled. Applied to the analysis of MC-LR, the good selective and sensitive recognition were obtained with the detection limit as low as 0.003 ng/mL, which was better than most non-specific SPME or solid-phase extraction (SPE) protocols. The stability and reproducibility were acceptable, and the intra-day, inter-day and column-to-column relative standard deviations (RSDs) for the recovery of MC-LR were gained in the range from 2.5% to 14.3%, respectively. Satisfactory recoveries of MC-LR in environmental water samples were measured as 96.3 +/- 4.7% - 98.9 +/- 2.7% (n = 3) in tap water, 94.4 +/- 2.5% 96.1 +/- 3.5% (n = 3) in pond water, and 97.0 +/- 2.1% - 97.9 +/- 3.1% (n = 3) in river water, respectively. This work demonstrated that the electrospun nanofibrous composite with massive aptamers would be a better alternative for ultra-trace MC-LR detection with good selectivity, matrix-resistance ability and high resolution.

Automated summary

A novel aptamer-functionalized metal-organic framework nanofibrous composite was proposed for the specific affinity recognition of trace Microcystin-LR (MC-LR), achieving good selective and sensitive recognition with a low detection limit. The composite demonstrated satisfactory stability, reproducibility, and recovery rates for MC-LR in environmental water samples, showing promise for ultra-trace MC-LR detection with good selectivity and resolution.