Lanthanide-doped nanoparticles exhibit unique optical properties, such as a long luminescence lifetime (up to several milliseconds), sharp emission peaks, and upconversion luminescence over the range of wavelengths from near-infrared to visible. Exploiting these optical properties, lanthanide-doped nanoparticles have been widely utilized for cellular and small animal imaging with the absence of background autofluorescence. In addition, these nanoparticles have advantages of high signal-to-noise ratio for highly sensitive and selective diagnostic detection. In this review, we summarize and discuss recent progress in the development of highly sensitive diagnostic methods using lanthanide-doped nanoparticles. Combined with a smartphone, portable luminescence detecting platforms could be widely applied in point-of-care tests.

Crystalline red phosphorus has very recently emerged as a stable and cost-effective semiconductor material. However, despite its potentiality in electronics and optoelectronics, the widespread application of this material is still hampered by the limited synthetic route of the ampoule-based chemical vapor deposition that critically requires mineralizing agents. To address this issue, we report the chemical synthesis of soluble polyphosphide precursors that serve as inks for the solutionprocessed fabrication of crystalline fibrous phosphorus thin films. The purified polyphosphide precursor formed crystalline fibrous phosphorus via thermal annealing at a temperature as low as 250 °C without any mineralizing agents. This anionic polyphosphide functioned as a surface-capping ligand for nanoparticles including metals, semiconductors, and magnets. Therefore, the study investigates the possibility of solution-processed fibrous phosphorus thin films as active channel layers in fieldeffect transistors as well as photodetectors and demonstrates their initial performances on the charge-transport and photoresponsive characteristics of these devices. The effect of semiconducting PbS nanoparticles embedded in the fibrous phosphorus thin films on device performance was also studied. The synthesized polyphosphide precursor offers a vast opportunity for the facile preparation of crystalline red phosphorus and chemical design of nanoparticles.

No abstract

Raman spectroscopy provides excellent specificity for in vivo preclinical imaging through a readout of fingerprint-like spectra. To achieve sufficient sensitivity for in vivo Raman imaging, metallic gold nanoparticles larger than 10 nm were employed to amplify Raman signals via surface-enhanced Raman scattering (SERS). However, the inability to excrete such large gold nanoparticles has restricted the translation of Raman imaging. Here we present Raman-active metallic gold supraclusters that are biodegradable and excretable as nanoclusters. Although the small size of the gold nanocluster building blocks compromises the electromagnetic field enhancement effect, the supraclusters exhibit bright and prominent Raman scattering comparable to that of large gold nanoparticle-based SERS nanotags due to high loading of NIR-resonant Raman dyes and much suppressed fluorescence background by metallic supraclusters. The bright Raman scattering of the supraclusters was pH-responsive, and we successfully performed in vivo Raman imaging of acidic tumors in mice. Furthermore, in contrast to large gold nanoparticles that remain in the liver and spleen over 4 months, the supraclusters dissociated into small nanoclusters, and 73% of the administered dose to mice was excreted during the same period. The highly excretable Raman supraclusters demonstrated here offer great potential for clinical applications of in vivo Raman imaging.

No abstract