Diverse Morphologies of Self‐Assemblies from Homoditopic 1,18‐Nucleotide‐Appended Bolaamphiphiles: Effects of Nucleobases and Complementary Oligonucleotides

The synthesis of 1,18‐nucleotide‐appended bolaamphiphiles (1 , 2 , 4 , and 6) is reported, in which a 3′‐phosphorylated guanidine, adenosine, thymidine, or cytidine is connected to each end of an octadecamethylene chain. Single‐component self‐assemblies and binary self‐assemblies with the complementary oligonucleotides dC ₂₀ , dT ₂₀ , dA ₂₀ , and dG ₂₀ are studied by atomic force microscopy, powder X‐ray diffraction analysis, temperature‐dependent UV absorption, circular dichroism, and attenuated total‐reflection Fourier‐transform infrared spectroscopy. The single‐component self‐assembly of 1 forms a two‐dimensional sheet, whereas the binary self‐assembly 1 / dC ₂₀ gives helical nanofibers. Non‐helical nanofibers are observed for the single‐component self‐assemblies of 2 and 4 , and helical nanofibers form from the binary self‐assembly 2 / dT ₂₀ . Interestingly, helical nanorod structures are obtained from the binary self‐assembly 4 / dA ₂₀ , and the aligned nanorods form a nematic phase. The single‐component and binary self‐assemblies from 6 give unilamellar vesicles owing to a lack of stacking interaction between the cytosine moieties.     

Smart Probe for Tracing Cancer Therapy: Selective Cancer Cell Detection,Image‐Guided Ablation,and Prediction of Therapeutic Response In Situ

Integrated diagnosis and therapy systems that can offer traceable cancer therapy are in high demand for personalized medicine. Herein, a pH‐responsive polymeric probe containing tetraphenylsilole (TPS) with aggregation‐induced emission characteristics and pheophorbide A (PheA) photosensitizer (PS) with aggregation‐caused quenching property for tracing the whole process of cancer therapy is reported. At physiological conditions (pH 7.4), the probe self‐assembles into nanoparticles (NPs), which show weak fluorescence of PheA with low phototoxicity, but strong green fluorescence from TPS for probe self‐tracking. Upon uptake by cancer cells and entrapment in lysosomes (pH 5.0), the NPs disassemble to yield weak emission of TPS but strong red fluorescence of PheA with restored phototoxicity for PS activation monitoring. Upon light irradiation, the generated reactive oxygen species can cause lysosomal disruption to trigger cell apoptosis. Meanwhile, the probe leaks to the cytoplasm (pH 7.2), where the TPS fluorescence is restored for in situ visualization of the therapeutic response. The probe design thus represents a novel strategy for traceable cancer therapy.