This article reports a convenient supramolecular strategy to construct fluorescent photoswitchable molecular assemblies between a macrocyclic host, cucurbit[8]uril (CB8), and a fluorogenic dye, thiazole orange (TO). The interaction mechanism and the stable stoichiometric host-guest arrangements have been claimed on the basis of the optical absorption, steady-state and time-resolved fluorescence lifetime and anisotropy measurements, and also the geometry optimization studies. The CB8 recognized TO in its 2:2 stoichiometry exhibited spectacular fluorescence enhancement of the order of 1700 fold, which is the largest directly determined value so far reported for a dye in an organic macrocyclic system. This prospective 2CB8:2TO assembly responded to selected chemical stimuli such as metal ions, adamantylamine, and tryptophan, providing different dissociation mechanisms and demonstrating a controlled exchange and release action desired with such noncovalently linked assemblies. Positively, considering the aqueous solubility and biocompatibility of the host-guest constituents, this methodology can evolve into a general approach to deliver and operate intracellularly functional molecular components under chemical/thermal/optical trigger control, especially for therapeutic applications.

extracted with the help of patterned hydrophilic/hydrophobic regions present on its back. [3][4][5] Cotula fallax, a plant from South Africa efficiently collects water from fog using its hierarchical 3D layout present on its leaves. [6] Pinus radiata and Casuarina equisetifolia, the tree canopies, are also capable of extracting water from air with the help of structures present on their leaves. [7][8][9] Researchers have also demonstrated that spider silk of certain species of spider has directional water collecting ability. This is attributed to the presence of periodic spindle knots on its fibers. [10][11][12][13][14] These mechanisms of harvesting water from humid air have inspired the researchers to mimic the structural design as well as geometry of natural materials. [15][16][17][18][19] Electrostatic spinning (electrospinning) has received a great deal of attention in the last two decades for its ability to fabricate ultrafine fibers that are useful for various applications. [20][21][22][23][24][25][26] Researchers have demonstrated that electrospinning can be used to fabricate fibers that resemble the structural geometry of natural materials. [27][28][29][30] For example, electrospinning is used to Quest for efficient fog harvesting methods has drawn immense attention in recent times. In this study, electrospinning is used to fabricate three different sets of membranes that are based on pristine poly(N-isopropylacrylamide) (PNIPAM) fibers, pristine polyvinylidene fluoride (PVDF) fibers, and PNIPAM-PVDF bead-on-string fibers. The wettability of these membranes is investigated as a function of temperature and the effect of their wettability on the fog collection efficiency is determined. Membranes based on pristine PNIPAM and pristine PVDF fibers are fabricated using conventional electrospinning and are shown to have a smooth surface morphology. On the other hand, PNIPAM-PVDF bead-on-string fibers are fabricated using core-shell electrospinning. Water collection efficiency of the membranes is compared to investigate the influence of microstructures and wettability gradient on fog harvesting ability of the samples. Among the three samples, the bead-on-string hierarchical fibrous membrane demonstrates the highest fog harvesting rate of 1150 ± 28 mg cm −2 h −1 at 25 °C and 909 ± 31 mg cm −2 h −1 at 40 °C. Furthermore, the results demonstrate that the presence of microstructures on the nanofibers improve the fog harvesting efficiency of PNIPAM-PVDF bead-on-string fibers.

The ultimate aim in developing controlled drug delivery systems is to derive formulations to achieve drug release at a constant rate over a long duration. The drug release profile that follows zero-order kinetics is crucial for reduction in the drug administration frequency, reduced cytotoxicity, and improved convenience and compliance of patients. Designed drug delivery systems for achieving zero-order release are often complex, expensive, and difficult to manufacture. Herein, we demonstrate that a supramolecular hydrogel formed through the self-assembly of guanosine monophosphate (GMP) into highly ordered G-quadruplex structure and cross-linked through Fe3+ and Ca2+ ions exhibits potential for the pH-responsive controlled zero-order drug release of doxorubicin, a model chemotherapeutic drug. The fibril formation is initiated by the self-assembly of GMP into a quadruplex complex, which is cross-linked through the complexation of the phosphate groups with Fe­(III) ions, resulting in a spontaneous hydrogel formation. The Ca2+ ions facilitate the improvement in the mechanical integrity of the fibril network in the Fe-GMP hydrogel via cross-linking of sugar moieties. The hydrogel showed a high loading capacity for drug molecules and a pH-responsive sustained zero-order drug release over several days owing to the lowered degradability of the cross-linked hydrogel in acidic buffer stimulant. In vitro drug-release studies further established a controlled pH-triggered drug release profile. The Ca2+ cross-linking of the Fe-GMP hydrogel also resulted in significant enhancement in the biocompatibility of the drug delivery system. The fabrication of biocompatible, low-cost, and efficient Ca2+ cross-linked metal–organic hydrogels may present promising applications in biological fields.

A novel sandwich polyoxometalate (POM) Na12[WCo3(H2O)2(CoW9O34)2] and poly(vinylimidazolium) cation [PVIM+] in combination with nitrogen-doped carbon nanotubes (NCNTs) was developed for a highly selective and ultrasensitive detection of dopamine. Conductively efficient heterogenization of Co5POM catalyst by PVIM over NCNTs provides the synergy between PVIM–POM catalyst and NCNTs as a conductive support which enhances the electron transport at the electrode/electrolyte interface and eliminates the interference of ascorbic acid (AA) at physiological pH (7.4). The novel PVIM–Co5POM/NCNT composite demonstrates a superior selectivity and sensitivity with a lowest detection limit of 500 pM (0.0005 μM) and a wide linear detection range of 0.0005–600 μM even in the presence of higher concentration of AA (500 μM).

Development of nanozymes with intrinsic multienzyme mimetic activity has attracted tremendous research attention as nanozymes offer several advantages over multimodal natural enzymes and are a key toward multifunctional biomedical applications. Shape-selective ternary metal oxides with multicatalytic sites can be developed as potential multienzyme mimetic nanomaterials taking advantage of the variable valence states of the metal constituents and their synergy along with the added advantage offered by the exposed surface for enhanced catalytic activity. Herein, we have explored the multicatalytic activity of Cu 3 V 2 O 7 (OH) 2 •2H 2 O nanoribbons for peroxidase, oxidase, and laccase mimicking activity. The fabrication of Cu 3 V 2 O 7 (OH) 2 nanoribbons was performed using the polyol-based hydrothermal pathway, and the choice of precursor metal salts and their molar ratio was found to be instrumental in the shape, size, and phase selective evolution of copper pyrovanadates. The as-synthesized nanoribbons showed excellent peroxidase-like activity with K m value of 0.004 mM for H 2 O 2 , which is considerably smaller than those reported for HRP and other nanozymes. The efficient oxidase mimicking behavior of these Cu 3 V 2 O 7 (OH) 2 nanoribbons could be used for the colorimetric detection of glutathione with a limit of detection of 0.08 μM. Further, the nanoribbons also showed laccase-mimetic behavior and were used for the colorimetric detection of epinephrine, which is a useful hormone and neurotransmitter.