Luminescent Ultralong Microfibers Prepared through Supramolecular Self-Assembly of Lanthanide Ions and Thymidine in Water

In vitro selection and application of lanthanide-dependent DNAzymes

Highly sensitive and selective detection of lanthanide ions is a major analytical challenge. In recent years, the use of DNA for this purpose has been pursued. For such highly charged cations, it is difficult to select their aptamers due to strong nonspecific binding. On the other hand, the use of catalytic DNA or DNAzymes has an advantage to overcome this problem, especially DNAzymes with RNA-cleaving activity. In this chapter, a few such DNAzymes are introduced and methods for in vitro selection of lanthanide-dependent RNA-cleaving DNAzymes are described in detail, including the selection protocols, the DNA sequences used, the characterization of selected DNAzymes and their conversion into biosensors. All of the experiments use only fluorophore-labeled DNA, and radioisotope labeling is completely avoided. The resulting DNAzymes can distinguish lanthanides from non-lanthanide metals, tell the difference between light and heavy lanthanides, and can be used together to discriminate individual lanthanides.

A high local DNA concentration for nucleating a DNA/Fe coordination shell on gold nanoparticles

Preparing DNA/Fe coordination nanoparticles in solution requires a high concentration of DNA. Herein we grew a DNA/Fe shell on DNA-functionalized gold nanoparticles. Taking advantage of the high local DNA density, the required DNA concentration decreased 60-fold, and the size can be controlled. This hybrid material allowed drug loading and colorimetric sensing.

Multiresponsive Supramolecular Luminescent Hydrogels Based on a Nucleoside/Lanthanide Complex

Supramolecular luminescent hydrogels based on natural molecules have shown high potential for a variety of applications because of unique optical properties and biocompatibility, particularly serving as advanced biomaterials for bioimaging, biosensing, cell engineering, and so forth. A lanthanide complex-based system provides a promising way to prepare supramolecular luminescent hydrogels. Herein, we realize the creation of a luminescent hydrogel assembled from lanthanides and nucleosides. Nucleosides, the essential components of nucleic acids, functioning as the ligands, successfully chelate with lanthanides and form complexes in water. The complexes subsequently serve as building-blocks to form supramolecular hydrogels, which exhibit characteristic luminescent emission of lanthanides. The coordination modes and forming mechanism are studied by electrospray ionization time-of-flight mass spectrometry, matrix-assisted laser desorption/ionization time of flight mass spectrometry, ¹H NMR spectroscopy, and Fourier transform infrared spectroscopy; the corresponding molecular simulations are presented, and macro-/micro-morphologies, mechanical properties, and luminescent performances of hydrogels are systemically studied. Remarkably, these luminescent hydrogels show fluorochromic properties in response to external stimuli, including pH, temperature, anions, and cations, which are thus adopted to design smart luminescent switches and detect specific species such as Cu²⁺. Our work provides a feasible strategy to prepare stimuli-responsive luminescent hydrogels, reveals the diverse potential of nucleoside-based hydrogels, and exhibits a novel pathway for the preparation of smart optical materials.