Dual-emission of silicon nanoparticles encapsulated lanthanide-based metal-organic frameworks for ratiometric fluorescence detection of bacterial spores.

Dipicolinic acid (DPA) is employed as a significant biomarker to detect Bacillus anthracis, which can do serious damages to the health of human beings. Hence, it is crucial to develop a fast and highly efficient strategy for DPA monitoring. In this work, based on silicon nanoparticles (Si NPs) and terbium metal-organic frameworks (Tb-MOFs), a hybrid structure (Si NPs/Tb-MOFs) as a novel dual-emitting fluorescence probe was fabricated for ratiometric detection of DPA, where blue light-emitting Si NPs (Ex: 280 nm; Em: 422 nm) are encapsulated into green light-emitting Tb-MOFs (Ex: 280 nm; Em: 547 nm). The optical properties and chemical composition of the as-obtained Si NPs/Tb-MOFs were characterized in detail. The Si NPs/Tb-MOFs probe not merely possesses the merits of a facile synthesis method but also is an excellent fluorescence probe. The response time towards DPA is less than 30 s, revealing that the process of detecting DPA can be completed in such a short time. The limit of detection for DPA is 5.3 nM, which is four orders of magnitude lower than an infectious dosage of anthrax spores for human beings (60 μM). This dual-emitting Si NPs/Tb-MOFs probe with interference-free and self-calibrating properties may be a potential candidate for further development in medical diagnosis. Graphical abstract.