2,3-bis(4-(phenyl(4-(1,2,2-triphenylvinyl)phenyl)amino)phenyl)fumaronitrile (TTF) shows unique aggregation-induced emission (AIE) characteristics. Under the excitation of a 1560 nm femtosecond laser, simultaneous three-photon-excited luminescence (3PL) and third-harmonic-generation signals can be observed from its nanoaggregate and the solid state. TTF is further encapsulated with DSPE-mPEG (a type of amphiphilic polymer) to form AIE-active nanoparticles. 3PL brain imaging of mice is achieved based on the nanoparticles.
Near-infrared (NIR) imaging technology has been widely used for biomedical research and applications, since it can achieve deep penetration in biological tissues due to less absorption and scattering of NIR light. In our research, polymer nanoparticles with NIR fluorophores doped were synthesized. The morphology, absorption/emission features and chemical stability of the fluorescent nanoparticles were characterized, separately. NIR fluorescent nanoparticles were then utilized as bright optical probes for macro in vivo imaging of mice, including sentinel lymph node (SLN) mapping, as well as distribution and excretion monitoring of nanoparticles in animal body. Furthermore, we applied the NIR fluorescent nanoparticles in in vivo microscopic bioimaging via a confocal microscope. Under the 635 nm-CW excitation, the blood vessel architecture in the ear and the brain of mice, which were administered with nanoparticles, was visualized very clearly. The imaging depth of our one-photon microscopy, which was assisted with NIR fluorescent nanoprobes, can reach as deep as 500 μm. Our experiments show that NIR fluorescent nanoparticles have great potentials in various deep-tissue imaging applications.
Optically pure lactams have a wide diversity of applications, one of which is serving as important intermediates in the synthesis of agricultural bioactive compounds or pharmaceuticals. Efficient stereoselective synthesis of chiral lactams with low‐cost amine donors under mild conditions is desired for manufacturing of these important chemicals. Herein, a two‐step chemo‐enzymatic strategy has been designed to produce (S)‐lactams by engineering a natural amine dehydrogenase from Thermoanaerobacter thermohydrosulfuricus (TtherAmDH). TtherAmDH was subjected to eight cycles of directed evolution to enhance its reductive amination activity toward keto acid substrates. The variants showed improved specific activity toward 6 tested substrates and gave high stereoselectivities of up to 99% in the asymmetric synthesis of γ‐ and δ‐ lactams. In particular, TtherAmDHV8 showed a 237‐fold higher specific activity toward the model substrate levulinic acid and gave (S)‐5‐methyl‐2‐pyrrolidone in 99% ee with a space‐time yield of 75.3 g L−1 d−1. These results indicate that the engineered amine dehydrogenase TtherAmDH can serve as an efficient biocatalyst for the manufacture of highly valued chiral lactams.
We synthesize Au/Ag alloyed nanoboxes (ANBs) with different LSPR (localized surface plasmon resonance) peak wavelengths and observe their various nonlinear optical properties.
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