Facile assembly of bifunctional, magnetically retrievable mesoporous silica for enantioselective cascade reactions

Resin-Immobilized Palladium Acetate and Alcohol Dehydrogenase for Chemoenzymatic Enantioselective Synthesis of Chiral Diarylmethanols

The enantioselective synthesis of chiral diarylmethanols is highly desirable in synthetic chemistry and the pharmaceutical industry, but it remains challenging, especially in terms of green and sustainable production. Herein, a resin-immobilized palladium acetate catalyst was fabricated with high activity, stability, and reusability in Suzuki cross-coupling reaction of acyl halides with boronic acids, and the coimmobilization of alcohol dehydrogenase and glucose dehydrogenase on resin supports was also conducted for asymmetric bioreduction of diaryl ketones. Experimental results revealed that the physicochemical properties of the resins and the immobilization modes played important roles in affecting their catalytic performances. These two catalysts enabled the construction of a chemoenzymatic cascade for the enantioselective synthesis of a series of chiral diarylmethanols in high yields (83-90%) and enantioselectivities (87-98% ee). In addition, the asymmetric synthesis of the antihistaminic and anticholinergic drugs (S)-neobenodine and (S)-carbinoxamine was also achieved from the chiral diarylmethanol precursors, demonstrating the synthetic utility of the chemoenzymatic cascade.

Mesoporous Silica Hybridized With Gadolinium(III) Nanoplatform for Targeted Magnetic Imaging-Guided Photothermal Breast Cancer Therapy

Achieving drug target accumulation in antitumor tissue, simultaneous diagnostic imaging, and optimal release behavior with treatment needs a best chemotherapy procedure involving receptive switch of drug delivery. Constructed on mesoporous silica nanoparticles, which are crossed with multiscale charming nanoparticles for magnetic resonance imaging (MRI)-aided and alternate magnetic field (AMF) response chemotherapy for breast cancer, we report in this work the assembly of a new theranostics drug conveyance process. Hydrothermal processes (gadolinium(III) oxide nanoparticles [Gd-NPs]) and heat decomposition process (radical size uFe-NPs) were used to prepare superparamagnetic Gd-NPs with multiscale sizes. Gadolinium(III) oxide nanoparticles act as an AMF-responsive heat mediator, while ultra-Fe nanoparticles (uFe-NPs) act as an MRI T₂ contrast mediator. Nanoparticles of the mesoporous silica with radially oriented mesochannels were further grown in situ on the surfaces of the Gd-NPs, and the uFe-NPs anticancer drug doxorubicin can be easily incorporated in the mesochannels. To provide better targeting capabilities for the as-synthesized biotin-loaded nanohybrids, the particle surfaces are updated with biotin (Bt). This optimized drug conveyance method based on nanocomposites of SiO₂ demonstrated great efficiency of medication charging and receptive properties of AMF stimulus release. However, tests of MRI in vitro showed an outstanding contrast effect in MRI with a high stimulation quality (299 mM⁻¹ s⁻¹). In contrast, the study of in vitro cytotoxicity assessment revealed that an MRI-directed stimulus-mediated theranostics tool can be used as a drug conveyance device to efficiently treat breast cancer.