The efficient detection of tumor markers is crucial to early cancer diagnosis and monitoring. Here, we propose a unique “two birds with one stone” dissolution-enhanced afterglow bioassay based on amino-functionalized mesoporous SiO₂ nanoparticles (MSNs-NH₂) encapsulated Eu(OH)CO₃ nanoprobes. These nanoprobes (i) stably conjugate to the antibody and (ii) are highly soluble in the acidic enhancer solution, and provide a high Eu³⁺ concentration. The released Eu³⁺ ions further activate the photochemical afterglow system to determine the alpha-fetoprotein (AFP) levels in clinical serum samples. Without the use of a real-time excitation source, the interference of autofluorescence and scattering from blood can be avoided. The demonstrated limit of detection (LOD) for AFP was as low as 0.12 ng·mL⁻¹. This covalently connected dissolution-enhanced luminescent bioassay (DELBA) and novel afterglow system shows tremendous potential for ultrasensitive and rapid clinical diagnosis.

Upconversion nanophosphors (UCNPs) have been widely used in bioscience and bioimaging, but the effect of UCNPs on plants and on animals after subsequent oral ingestion of the plants has not been studied previously. Herein, we investigate the effects of UCNPs on plant development using mung beans as a model. Incubation at a high UCNP concentration of 100 μg/mL led to growth inhibition, while a low concentration of 10 μg/mL promoted their development. Confocal imaging showed that UCNPs accumulated in the seeds and were transferred from seeds and roots to stems and leaves through the vascular system. Quantitative study by radioanalysis showed the distribution of UCNPs in the plant on the 5th day after incubation decreased in the order (root > seed > leaf > stem). After UCNP-treated bean sprouts were orally ingested by mice, UCNPs were completely excreted with feces, without absorption of residual amounts. Histology and hematology results showed no detectable toxic effects of UCNP-treated mung beans on exposed mice.

Photoswitchable polymer nanoparticles (ps-PNPs) have been constructed by emulsion polymerization through embedding an iridium(Ⅲ) complex, [Ir(bt)₂(pic)] (bt = phenylbenzothiazole, pic = picolinate), as a fluorophore and a diarylethene derivative (DTE) as a photochrome. The ps-PNPs show reversible luminescence modulation with DTE switching using UV light in aqueous solution and even in living cells. Such luminescent modulation only occurred in polymer nanoparticles and not in a simple mixed solution with low concentrations of [Ir(bt)₂(pic)] and DTE. The ps-PNPs displayed good cellular uptake and fast intracellular luminescence modulation by photoswitching, indicating the nanoparticles could be developed as photoswitchable luminescent probes for a diversity of bioimaging applications.