Pristine NiMOF\nSandwiched between 1D and 3D Engineered\nAu Particles and Dendrites for Ultraswift Folic Acid Sensing in Cellular\nMicroenvironment

Catalytic metal-organic frameworks\n(MOFs)-based sensor\nmatrices\ncan act synergistically with Au metallic nanostructures to generate\namplified signal readouts by causing the electro-oxidation of the\ntarget analyte. Folic acid (FA), an essential water-soluble vitamin\nand a precursor for enzymes, requires timely and precise monitoring\nin the serum of individuals with varying clinical diagnoses. An attempt\nhas been made in this direction through our work, where the rapid\ndetection of FA through its oxidation at metal centers from hybrid\nnanomaterials is deployed for signal generation. A nonenzymatic, nonimmunometric\napproach involving a sandwich model, comprising NiMOF layered between\ngold nanoparticles (AuNPs) and gold nanodendrites (AuNDs) incorporated\nwithin a sensor matrix, has been deployed for this purpose. The probe\ndisplayed great analytical performance with a linear dynamic range\n(LDR) from 1 × 10<sup>–11</sup> M to 1 × 10<sup>–3</sup> M and a limit of detection (LOD) of 0.43 × 10<sup>–11</sup> M. The probe’s average response time with respect to changes\nin FA concentration was recorded as less than 2.1 s, making it a rapid\nsensing platform for FA detection. The real-life applicability of\nthe developed sensor was tested in serum, followed by analysis in\na breast cancer cellular microenvironment, which yielded a current\nrecovery between 95.11 and 98.17%. The <i>in vitro</i> analysis\nwas further validated through live-cell imaging using the standard\nmethod of fluorescence. The shorter fabrication time of the developed\nsensor compared to existing ones makes it a facile and efficient sensing\nplatform for FA detection in clinical settings. This study represents\nthe first report on the conjunction of 1D, 2D, and 3D materials as\na sensing matrix for molecular detection applications.