Luminescent nanomaterials, with wide applications in biosensing, bioimaging, illumination and display techniques, have been consistently garnering enormous research attention. In particular, those with wavelength-controllable emissions could be highly beneficial. Carbon nanostructures, including graphene quantum dots (GQDs) and other graphene oxide derivates (GODs), with excitation-dependent photoluminescence (PL), which means their fluorescence color could be tuned simply by changing the excitation wavelength, have attracted lots of interest. However the intrinsic mechanism for the excitation-dependent PL is still obscure and fiercely debated presently. In this review, we attempt to summarize the latest efforts to explore the mechanism, including the quantum confinement effect, surface traps model, giant red-edge effect, edge states model and electronegativity of heteroatom model, as well as the newly developed synergistic model, to seek some clues to unravel the mechanism. Meanwhile the controversial difficulties for each model are further discussed. Besides this, the challenges and potential influences of the synthetic methodology and development of the materials are illustrated extensively to elicit more thought and constructive attempts toward their application.

The spread of SARS-CoV-2 virus in the ongoing global pandemic has led to infections of millions of people and losses of many lives. The rapid, accurate and convenient SARS-CoV-2 virus detection is crucial for controlling and stopping the pandemic. Diagnosis of patients in the early stage infection are so far limited to viral nucleic acid or antigen detection in human nasopharyngeal swab or saliva samples. Here we developed a method for rapid and direct optical measurement of SARS-CoV-2 virus particles in one step nearly without any sample preparation using a spike protein specific nanoplasmonic resonance sensor. As low as 370 vp/mL were detected in one step within 15 min and the virus concentration can be quantified linearly in the range of 0 to 10 7 vp/mL. Measurements shown on both generic microplate reader and a handheld smartphone connected device suggest that our low-cost and rapid detection method may be adopted quickly under both regular clinical environment and resource-limited settings.

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Rational design of solar absorption, heat conversion and water supply for efficient solar steam generation.

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Breast cancer (BC) is a heterogeneous tumor, and better understanding of its heterogeneity is essential to improving treatment effect. Quantum dot (QD)-based immunofluorescent nanotechnology (QD-IHC) for molecular pathology has potential advantages in delineating tumor heterogeneity. This potential is explored in this paper by QD-IHC imaging of HER2 and ER. BC heterogeneity can be displayed more clearly and sensitively by QD-IHC than conventional IHC in BC tissue microarrays. Furthermore, the simultaneous imaging of ER and HER2 might help understand their interactions during the process of evolution of heterogeneous BC.

The rate and mechanism of diffusion by anionic sulforhodamine B (SRB) dye molecules within organic nanotubes self-assembled from bolaamphiphile surfactants were investigated by imaging fluorescence correlation spectroscopy (imaging-FCS). The inner and outer surfaces of the nanotubes are terminated with amine and glucose groups, respectively; the former allow for pH-dependent manipulation of nanotube surface charge while the latter enhance their biocompatibility. Wide-field fluorescence video microscopy was used to locate and image dye-doped nanotubes dispersed on a glass surface. Imaging-FCS was then used to spatially resolve the SRB transport dynamics. Mobilization of the dye molecules was achieved by immersion of the nanotubes in buffer solution. Experiments were performed in pH 6.4, 7.4 and 8.4 buffers, at ionic strengths ranging from 1.73 mM to 520 mM. The results show that coulombic interactions between cationic ammonium ions on the inner nanotube surface and the anionic SRB molecules play a critical role in governing mass transport of the dye. The apparent dye diffusion coefficient, D, was found to generally increase with increasing ionic strength and with increasing pH. The D values obtained were found to be invariant along the nanotube length. Mass transport of the SRB molecules within the nanotubes is concluded to occur by a desorption-mediated Fickian diffusion mechanism in which dye motion is slowed by its coulombic interactions with the inner surfaces of the nanotubes. The results of these studies afford information essential to the use of organic nanotubes in controlled drug release applications.