Protein Nanotubes as Advanced Material Platforms and Delivery Systems.

Protein nanotubes (PNTs) as state-of-the-art nanocarriers are promising for various potential applications both in the food and pharmaceutical industries. Derived from edible starting sources like α-lactalbumin, lysozyme, and ovalbumin, PNTs bear properties of biocompatibility and biodegradability. Their large specific surface area and hydrophobic core facilitate chemical modification and loading of bioactive substances, respectively. Moreover, their enhanced permeability and penetration ability across biological barriers such as intestinal mucus, extracellular matrix, and thrombus clot, make it promising platforms for health-related applications. Most importantly, their simple preparation processes enable large-scale production, supporting applications in the biomedical and nanotechnological fields. Understanding the self-assembly principles is crucial for controlling their morphology, size, and shape, and thus provides the ground to a multitude of applications. Here, the current state-of-the-art of PNTs including their building materials, physicochemical properties, and self-assembly mechanisms are comprehensively reviewed. The advantages and limitations, as well as challenges and prospects for their successful applications in biomaterial and pharmaceutical sectors are then discussed and highlighted. Potential cytotoxicity of PNTs and the need of regulations as critical factors for enabling in vivo applications are also highlighted. In the end, a brief summary and future prospects for PNTs as advanced platforms and delivery systems are included.

Iridium-catalyzed asymmetric hydrogenation of cyclic enamines.

The first highly enantioselective iridium-catalyzed hydrogenation of cyclic enamines has been developed. This new reaction provided an efficient method for the synthesis of optically active cyclic tertiary amines including natural product crispine A.

Highly efficient Rh(I)-catalyzed asymmetric hydrogenation of enamines using monodente spiro phosphonite ligands.

A highly enantioselective hydrogenation of nonfunctionalized enamines has been developed by using rhodium complexes of chiral spiro phosphonite ligands, providing chiral tertiary amines in excellent enantioselectivities.

Highly enantioselective hydrovinylation of alpha-alkyl vinylarenes. an approach to the construction of all-carbon quaternary stereocenters.

The highly enantioselective hydrovinylation of alpha-alkyl vinylarenes was realized by using nickel complexes of chiral spiro phosphoramidite ligands. The method provided a new approach to the construction of chiral all-carbon quaternary centers.

Synthesis of monodentate chiral spiro phosphonites and the electronic effect of ligand in asymmetric hydrogenation.

New monodentate chiral phosphonites were synthesized from enantiomerically pure 1,1'-spirobiindane-7,7'-diol. The phosphonites 2 were efficient ligands for the Rh-catalyzed asymmetric hydrogenation of alpha- and beta-dehydroamino acid derivatives, providing the amino acids in high enantioselectivities. The study of electronic effect showed that the electron-withdrawing substitutent on the P-phenyl ring of the phosphonite ligand dramatically decreased both the reactivity and enantioselectivity of the ligand.

Synthesis and optical resolution of 9,9'-spirobifluorene-1,1'-diol.

[reaction: see text] 9,9'-Spirobifluorene-1,1'-diol (SBIFOL) was conveniently synthesized from 1,2-dibromobenzene and 3-bromoanisole in high yield. Both enantiomers of SBIFOL were obtained in 99% ee by inclusion resolution with 2,3-dimethoxy-N,N,N',N'-tetracyclohexylsuccinamide. The absolute configurations were determined by X-ray analysis of a single crystal of molecular complex.