A ratiometric nanosensor based on lanthanide-functionalized attapulgite nanoparticle for rapid and sensitive detection of bacterial spore biomarker

Since the 2001 anthrax attacks, researchers have focused on the development of a bacterial spore biomarker detector with rapid response time and high sensitivity and selectivity. Hence, a ratiometric fluorescent nanosensor based on lanthanide-functionalized attapulgite (Atta) was designed and prepared using dye-doped Atta as an internal reference. Atta, which is famous because of Maya Blue, is a hydrated magnesium aluminum silicate present in nature, with pronounced adsorption and a large specific surface area rich in silicon hydroxyl. The adsorption of dye molecules benefits the formation of an internal reference with orange fluorescence. Meanwhile, silicon hydroxyl would be available for terbium (Tb3+) complex grafting, which favors the sensitization of the bacterial spore biomarker. With increasing dipicolinic acid (DPA) concentrations, energy transfer from DPA to Tb3+ gradually enhanced, thereby resulting in strong and predominant green fluorescence. The ratiometric fluorescence intensity is highly sensitive. It has a limit of detection of 9.8 nM, which is much lower than the infectious dosage of Bacillus anthracis spores (60 μM) for humans. The rapid response time (10s), high selectivity, and reliable and practical performances in actual applications make this ratiometric fluorescent nanosensor useful in the detection of biomarkers for various bacterial spores. Moreover, the reported construction of visual ratiometric detection system follows the sustainable development idea of ‘‘from nature, for nature, into the nature’’ and promotes the use of naturally renewable resources to produce promising and eco-friendly functional materials for various applications.