Here, we report a visible-light-induced deboronative alkynylation reaction, which is redox-neutral and works with primary, secondary and tertiary alkyl trifluoroborates or boronic acids to generate aryl, alkyl and silyl substituted alkynes. This reaction is highly chemoselective and performs well on substrates containing alkenes, alkynes, aldehydes, ketones, esters, nitriles, azides, aryl halides, alkyl halides, alcohols, and indoles, with no detectable occurrence of side reactions. The mechanism of this novel C(sp(3))-C(sp) bond coupling reaction was investigated by luminescence quenching, radical trapping, on-off light, and (13)C-isotopic-labeling experiments. This reaction can be performed in neutral aqueous conditions, and it is compatible with amino acids, nucleosides, oligosaccharides, nucleic acids, proteins, and cell lysates.

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Amyloid β-peptide oligomer (AβO) is widely acknowledged as the promising biomarker for the diagnosis of Alzheimer's disease (AD). In this work, we designed a three-dimensional (3D) DNA walker nanoprobe for AβO detection and real-time imaging in living cells and in vivo. The presence of AβO triggered the DNAzyme walking strand to cleave the fluorophore (TAMRA)-labeled substrate strand modified on the gold nanoparticle (AuNP) surface and release TAMRA-labeled DNA fragment, resulting in the recovery of fluorescent signal. The entire process was autonomous and continuous, without external fuel strands or protease, and finally produced plenty of TAMRA fluorescence, achieving signal amplification effect. The nanoprobe enabled the quantitative detection of AβO in vitro, and the limit of detection was 22.3 pM. Given the good biocompatibility of 3D DNA walker nanoprobe, we extended this enzyme-free signal amplification method to real-time imaging of AβO. Under the microscope, nanoprobe accurately located and visualized the distribution of AβO in living cells. Moreover, in vivo imaging results showed that our nanoprobe could be used to effectively distinguish the AD mice from the wild-type mice. This nanoprobe with the advantages of great sensitivity, high specificity, and convenience, provides an outstanding prospect for AD's early diagnosis development.

The hydrogenation process of the layered α-MoO3 crystal was investigated on a nanoscale. At low hydrogen concentration, the hydrogenation can lead to formation of HxMoO3 without breaking the MoO3 atomic flat surface. For hydrogenation with high hydrogen concentration, hydrogen atoms accumulated along the <101> direction on the MoO3, which induced the formation of oxygen vacancy line defects. The injected hydrogen atoms acted as electron donors to increase electrical conductivity of the MoO3. Near-field optical measurements indicated that both of the HxMoO3 and oxygen vacancies were responsible for the coloration of the hydrogenated MoO3, with the latter contributing dominantly. On the other hand, diffusion of hydrogen atoms from the surface into the body of the MoO3 will encounter a surface diffusion energy barrier, which was for the first time measured to be around 80 meV. The energy barrier also sets an upper limit for the amount of hydrogen atoms that can be bound locally inside the MoO3 via hydrogenation. We believe that our findings has provided a clear picture of the hydrogenation mechanisms in layered transition-metal oxides, which will be helpful for control of their optoelectronic properties via hydrogenation.