Uniformly mesocaged cubic Fd3m monoliths as modal carriers for optical chemosensors

With recent advances in materials science and nanotechnology, development of optical chemosensors with uniformly shaped three-dimensional (3D) nanostructures applicable for large-scale sensing systems of toxic pollutants can forge new frontiers in materials. Here, highly ordered cubic Fd3m silica monoliths that had nanopore-like cages were fabricated, for the first time, by direct templating of cationic surfactant phases. This simple strategy offered significant control over the pore connectivity and structural regularity of the cubic Fd3m geometry. The potential functionalities of these uniformly sized cage cubic Fd3m materials show promise as the primary component in efficient sensing systems that can satisfy analytical needs as well, such as simplicity in fabrication design and sensing functionality in terms of selectivity and sensitivity with a fast response time of the recognition of pollutant cations. However, successful immobilization of chromophore probe molecules into the 3D network matrixes enabled manipulation of optically defined chemosensors into new shapes and functionality for visual detection of toxic analytes. Here, 3D cubic Fd3m chemosensors were developed and fabricated and successfully enabled highly revisable, selective and sensitive detection of Bi-(III) target ions down to nanomolar concentrations (∼10¹⁰ mol/dm³) with rapid response assessment (≤25 s). Significantly, the HOM nanosensors not only worked under standardized conditions but also could be used for reliable sensing of the Bi(III) ion in a real-life sample such as wastewater.