Latest ArticlesOver the past few decades, supramolecular chemistry has entered the field of scientific research and attracted extensive attention. Among supramolecular macrocycles, cyclodextrins (CDs) are widely applied in the field of adsorption due to their unique structure and properties. This review focuses on the important role of cyclodextrin polymers (CDPs) as adsorbents in the adsorption of different substances. It covers the category of CDPs adsorbents (including crosslinked CDPs, grafted CDPs, CD-based polyrotaxanes/pseudo-polyrotaxanes, and imprinted CDPs), their adsorption mechanism and applications in the adsorption of inorganic metal ions, organic pollutants, and biomacromolecules. Finally, the challenges and future perspectives in relative research fields are discussed.
Five hybrid tetrapeptides, each consisting a central dipeptide segment of α-amino acid residues flanked by two aromatic γ-amino acid residues, are found to fold into well-defined β-hairpin conformations as shown by NMR, computational study, and X-ray structures. The turn loop of this β-hairpin motif accommodates different two-residue α-amino acid sequences from the highly flexible Gly-Gly, to the more restricted d-Pro-Gly. The presence of α-amino acid side chains enhances the stabilities of the β-hairpins with the exception of d-Pro-Gly-which results in destabilization. Based on this hairpin/turn motif, a variety of different dipeptide sequences of α-amino acids which rarely occur in β-turns can be introduced and presented as two-residue loops.
We describe a janusarene derivative PyJ, which forms micrometer-scale one-dimensional metallo-supramolecular polymer through coordination driven self-assembly. PyJ is a well-preorganized dodecatopic pyridyl ligand built on a hexaphenylbenzene platform. The two-face structural feature of PyJ allows for a delicate control over multiple Py-Ag+-Py coordination interactions, leading to assembled structure of PyJ-Ag, which was characterized by dynamic light scattering, atomic force microscopy, and transmission electron microscopy.
The rational design of nanozymes with superior activities is essential for improving bioassay performances. Herein, nitrogen and boron co-doped graphene nanoribbons (NB-GNRs) are prepared by a hydrothermal method using urea as the nitrogen source and boric acid as the boron source, respectively. The introduction of co-doped and edge structures provides high defects and active sites. The resultant NB-GNRs nanozymes show superior peroxidase-like activities to nitrogen-doped and boron-doped counterparts due to the synergistic effects. By taking advantage of their peroxidase-like activities, NB-GNRs are used for the first time to develop enzyme-linked immunosorbent assay for the detection of interleukin-6. The biosensors exhibit a high performance with a linear range from 0.001 ng/mL to 1000 ng/mL and a detection limit of 0.3 pg/mL. Due to their low cost and high stability, the proposed nanomaterials show great promise in biocatalysis, immunoassay development and environmental monitoring.
Early and precise diagnosis are propitious to timely treatment and simultaneously increase the chance of successful treatments. It is of critical importance to develop rapid, sensitive, and reliable sensing techniques of physiological biomarkers for disease diagnosis. Due to the advantages of structural designability and property tunability, nanoscale metal-organic frameworks (nMOFs) have been widely applied in the field of biomedicine in recent years. Particularly, enhanced stability, more modification sites and improved distribution make nMOFs more suitable as biosensors for detection of biomarkers. This review article will summarize the recent advancements of nMOFs-based biosensors for detection of biomarkers, classified into four sections via different sensing modes: fluorescent sensing, colorimetric sensing, electrochemical sensing and surface-enhanced Raman scattering (SERS) sensing within the latest years. Except introducing and comparing the role of nMOFs in different sensing modes, designing strategies of nMOFs-based biosensors are involved as well. At last, a brief conclusion and outlook for further applications are provided, which is helpful for exploring multi-functional biologic nano-platforms with nMOFs. We expect that this review can inspire the interest on this promising research area of nMOFs-based biosensors for detection of biomarker and early diagnosis.
Herein, the nanoscaled ATP-responsive upconversion metal-organic frameworks (UCMOFs) are aqueous-phase synthesized for co-delivery of therapeutic protein cytochrome c (Cyt c) and chemodrugs doxorubicin (DOX), achieving targeted combinational therapy of human cervical cancer. The UCMOFs are rationally fabricated by growing ZIF-90 on mesoporous silica-coated upconversion nanoparticles (UCNPs), in which the ZIF-90 layer attenuates the upconversion luminescence (UCL) and the rigid frameworks increase the stability of encapsulated proteins. Once the UCMOF@DOX/Cyt c are internalized into HeLa cells via specific recognition of sgc8 aptamers, the intracellular ATP triggers the dissolution of ZIF-90 into Zn2+, which facilitates not only the release of Cyt c and DOX but also the restoration of UCL for real-time monitoring of drug release. It has been demonstrated that the therapeutic efficacy is greatly improved by the combination of caspase-mediated apoptosis activated by Cyt c (protein therapeutics), DNA fragmentation induced by DOX (chemotherapy), and Zn2+-promoted generation of reactive oxygen species (ROS) (oxidative stress). Overall, our proposed multifunctional UCMOFs provide an effective platform for targeted combinational cancer therapy and in situ imaging, which hold great promise in biomedical and clinical applications.
Electronic tuning by para substitutions was explored to achieve a highly active manganese N-heterocyclic carbene pincer complex for the selective electrocatalytic reduction of CO2 to CO. [MnCNCOMe]BF4 (L2-Mn) bearing an electron-donating group (-OMe) showed high activity with 63×catalytic current enhancement, average Faradaic efficiency of 104%, and a TOFmax value of 26, 127 s-1, which is 127 times higher than that of unsubstituted [MnCNCH]Br (L1-Mn) reported previously. In contrast, the electron-withdrawing group (-COOMe) in [MnCNCCOOMe]PF6 (L3-Mn) inhibited the electrocatalytic activity. Ambient Brønstic acid, however, suppressed the activity of L2-Mn probably due to the protonation of the -OMe group. These findings indicate a potential electronic tuning strategy to improved manganese N-heterocyclic carbene catalysts for CO2 reduction.
A new micro-spherical conjugated macrocycle polymer (P[5]-TFB-CMP) was prepared by the condensation reaction between dihydrazide functionalized pillar[5]arene and 1, 3, 5-triformylbenzene under ambient conditions. P[5]-TFB-CMP exhibits large surface area with excellent thermal stability and has been used as additive to prepare composite PMMA film of photochromic naphthopyrans. The results showed that the addition of P[5]-TFB-CMP could dramatically accelerate the thermal fading rate of the photochromic composite film by up to 12 times. This is a new strategy to overcome the drawback of the matrix effect.
A new electrochemical strategy for trifluoromethylation/cyclization using TfNHNHBoc as a CF3 source was established. This approach was realized by the direct electrolysis of TfNHNHBoc under external oxidant-free and catalyst-free conditions, and afforded various trifluoromethylated oxindoles with good functional group compatibility and broad substrate scope. Preliminary mechanistic studies show that the reaction proceeds by a radical process.
A facile access to mono-C-alkynyl-o-carboranes from o-carboranes and arylsulfonylacetylenes was developed. This facile process tolerates a wide variety of functional groups, occurs at mild conditions in one-pot procedure with short reaction time. The obtained mono-C-alkynyl-o-carboranes can be easily derivatized to synthesize 1, 2-difunctionalized o-carboranes. This work provides a useful tool for the functionalization of o-carboranes.