An In Situ One‐Pot Synthetic Approach towards Multivariate Zirconium MOFs

Chemically highly stable MOFs incorporating multiple functionalities are of great interest for applications under harsh environments. Herein, we presented a facile one‐pot synthetic strategy to incorporate multiple functionalities into stable Zr‐MOFs from mixed ligands of different geometry and connectivity. Via our strategy, tetratopic tetrakis(4‐carboxyphenyl)porphyrin (TCPP) ligands were successfully integrated into UiO‐66 while maintaining the crystal structure, morphology, and ultrahigh chemical stability of UiO‐66. The amount of incorporated TCPP is controllable. Through various combinations of BDC derivatives and TCPP, 49 MOFs with multiple functionalities were obtained. Among them, MOFs modified with FeTCPPCl were demonstrated to be catalytically active for the oxidation of ABTS. We anticipate our strategy to provide a facile route to introduce multiple functionalities into stable Zr‐MOFs for a wide variety of potential applications.     

Carbon Dots: Bottom‐Up Syntheses,Properties, and Light‐Harvesting Applications

The development of cost‐effective and environmentally friendly photocatalysts and photosensitizers has received tremendous attention because of their potential utilization in solar‐light‐harvesting applications. In this respect, carbon dots (CDs) prepared by bottom‐up methods have been considered to be promising light‐harvesting materials. Through their preparation from various molecular precursors and synthetic methods, CDs exhibit excellent optical and charge‐transfer properties. Furthermore, their photophysical properties can be readily optimized and enhanced by means of doping, functionalization, and post‐synthetic treatment. In this review, we summarize the recent progress in CDs synthesized using bottom‐up approaches. These CDs exhibit strong light absorption and unique electron donor/acceptor capabilities for light‐harvesting applications. We anticipate that this review will provide new insights into novel types of photosensitizers and photocatalysts for a wide range of applications.     

A Solvent‐Free Hot‐Pressing Method for Preparing Metal–Organic‐Framework Coatings

Metal–organic frameworks (MOFs), with their well‐defined pores and rich structural diversity and functionality, have drawn a great deal of attention from across the scientific community. However, industrial applications are hampered by their intrinsic fragility and poor processability. Stable and resilient MOF devices with tunable flexibility are highly desirable. Herein, we present a solvent‐ and binder‐free approach for producing stable MOF coatings by a unique hot‐pressing (HoP) method, in which temperature and pressure are applied simultaneously to facilitate the rapid growth of MOF nanocrystals onto desired substrates. This strategy was proven to be applicable to carboxylate‐based, imidazolate‐based, and mixed‐metal MOFs. We further successfully obtained superhydrophobic and “Janus” MOF films through layer‐by‐layer pressing. This HoP method can be scaled up in the form of roll‐to‐roll production and may push MOFs into unexplored industrial applications.     

Acid Exfoliation of Imine‐linked Covalent Organic Frameworks Enables Solution Processing into Crystalline Thin Films

Covalent organic frameworks (COFs) are highly modular porous crystalline polymers that are of interest for applications such as charge‐storage devices, nanofiltration membranes, and optoelectronic devices. COFs are typically synthesized as microcrystalline powders, which limits their performance in these applications, and their limited solubility precludes large‐scale processing into more useful morphologies and devices. We report a general, scalable method to exfoliate two‐dimensional imine‐linked COF powders by temporarily protonating their linkages. The resulting suspensions were cast into continuous crystalline COF films up to 10 cm in diameter, with thicknesses ranging from 50 nm to 20 μm depending on the suspension composition, concentration, and casting protocol. Furthermore, we demonstrate that the film fabrication process proceeds through a partial depolymerization/repolymerization mechanism, providing mechanically robust films that can be easily separated from their substrates.     

Thermo‐Responsive MOF/Polymer Composites for Temperature‐Mediated Water Capture and Release

We report an in situ polymerization strategy to incorporate a thermo‐responsive polymer, poly(N‐isopropylacrylamide) (PNIPAM), with controlled loadings into the cavity of a mesoporous metal–organic framework (MOF), MIL‐101(Cr). The resulting MOF/polymer composites exhibit an unprecedented temperature‐triggered water capture and release behavior originating from the thermo‐responsive phase transition of the PNIPAM component. This result sheds light on the development of stimuli‐responsive porous adsorbent materials for water capture and heat transfer applications under relatively mild operating conditions.     

Highly Fluorescent Pyridinium Betaines for Light Harvesting

We report the findings of our experimental and theoretical investigations into the properties of pyridinium enolates and their potential utility in light‐harvesting applications, such as in luminescent solar concentrators (LSCs). We present the synthesis, structures, photophysical characterization, and wavefunction‐based quantum‐chemical studies of five cyclobetaines. The performance of an LSC device incorporating one of these cyclobetaines is shown to be comparable to state‐of‐the‐art devices.     

Stable Encapsulated Air Nanobubbles in Water

The dispersion into water of nanocapsules bearing a highly hydrophobic fluorinated internal lining yielded encapsulated air nanobubbles. These bubbles, like their micrometer‐sized counterparts (microbubbles), effectively reflected ultrasound. More importantly, the nanobubbles survived under ultrasonication 100‐times longer than a commercial microbubble sample that is currently in clinical use. We justify this unprecedented stability theoretically. These nanobubbles, owing to their small size and potential ability to permeate the capillary networks of tissues, may expand the applications of microbubbles in diagnostic ultrasonography and find new applications in ultrasound‐regulated drug delivery.     

Topotecan‐Loaded Mesoporous Silica Nanoparticles for Reversing Multi‐Drug Resistance by Synergetic Chemoradiotherapy

Multi‐drug resistance (MDR) has become a major challenge for the further improvement of chemotherapy. Thus, more effective strategies for further enhancing the treatment against cancer by overcoming MDR are warranted. In this study, by the encapsulation of the radiosensitizing drug TPT into mesoporous silica nanoparticles (MSNs), the combined use of drug‐delivered chemotherapy and high‐energy X‐ray induced radiotherapy could produce synergetic chemoradiotherapeutic effects to kill multi‐drug resistant cells through significant DNA damage, thus leading to an efficient circumvention of MDR. We hope that this synergetic dual‐mode treatment strategy may achieve higher oncolytic efficacy and find use in future clinical anti‐MDR applications.     

Free‐Radical‐Promoted Conversion of Graphite Oxide into Chemically Modified Graphene

The preparation of chemically modified graphene (CMG) generally involves the reduction of graphite oxide (GO) by using various reducing reagents. Herein, we report a free‐radical‐promoted synthesis of CMG, which does not require any conventional reductant. We demonstrated that the phenyl free radical can efficiently promote the conversion of GO into CMG under mild conditions and produces phenyl‐functionalized CMG. This pseudo‐“reduction” process is attributed to a free‐radical‐mediated elimination of the surface‐attached oxygen‐containing functionalities. This work illustrates a new strategy for preparing CMG that is alternative to the conventional means of chemical reduction. Furthermore, the phenyl‐functionalized graphene shows an excellent performance as an electrode material for lithium‐battery applications.     

Ultra Flexible Paper Based Electrochemical Sensors: Effect of Mechanical Contortion upon Electrochemical Performance

The influence of mechanical contortion upon the electrochemical performance of screen‐printed graphite paper‐based electroanalytical sensing platforms is evaluated and contrasted with traditionally employed polymeric based screen‐printed graphite sensors. Such a situation of implementation can be envisaged for the potential sensing of analytes on the skin where such sensors are based, for example in clothing where mechanical contortion, viz, bending will occur, and as such, its effect upon electrochemical sensors is of both fundamental and applied importance. The effect of mechanical contortion or stress upon electrochemical behaviour and performance is of screen printed sensors is explored. Comparisons are made between both paper‐ and polymeric‐ based sensing platforms that are evaluated towards the sensing of the well characterised electrochemical probes potassium ferrocyanide(II), hexaammine‐ruthenium(III) chloride and nicotinamide adenine dinucleotide (NADH). It is determined that the paper‐based sensors offer greater resilience in terms of electrochemical performance after mechanical stress. We gain insights into the role played by both the effect of the time of mechanical contortion and additionally the potentially detrimental effects of repeated contortion are explored. These unique paper‐based sensors hold promise for widespread applications where flexible and ultra‐low cost sensors are required such as applications into medical devices were ultra‐low cost sensors are a pre‐requisite, but also for utilisation within applications which require the implementation of ultra‐flexible electroanalytical sensing platforms such as in the case of wearable sensors, whilst maintaining useful electrochemical performances.     

Flexible Broad‐Range Pressure Sensors Enabled by Deformation‐Induced Conductive Channels in 3D Graphene Foam@Polydimethylsiloxane Composite for Precise Vibrational Signal Detection

Here we report the design and fabrication of high‐performance pressure sensors based on three‐ dimensional (3D) graphene foam filled polydimethylsiloxane (GF@PDMS) composite with a broad sensing range spaning from 0.05 kPa to 130 kPa. The interpretation of device functioning mechanism can be classified into low and high pressure sensing regions. In the low pressure region (<15 kPa), the pressure loading leads to the temporal connection of micro‐cracks in GF scaffold and forming conductive channels. In the high pressure region (15 kPa to 130 kPa), the pressure induced deformation of GF results in the better connections among micro‐cracks and the shortening of conductive pathway to further decrease the electrical resistance. The GF@PDMS sensors exhibited accuracy, sensibility and reproducibility to detect pressure signals with remarkable stability for over 16000 loading‐unloading cycles, indicating its great potential for practical applications. Moreover, the GF@PDMS sensors also showed high performances in the detection of dynamic pressures, such as subtle mechanical vibration signals, as well as physiology vibrational signals generated by human throats. We expect this technology could be integrated into different sensing systems for the applications in wearable smart electronics and human‐machine communications.     

Nanostructure Synthesis at the Solid–Water Interface: Spontaneous Assembly and Chemical Transformations of Tellurium Nanorods

Bottom‐up synthesis offers novel routes to obtain nanostructures for nanotechnology applications. Most self‐assembly processes are carried out in three dimensions (i.e. solutions); however, the large majority of nanostructure‐based devices function in two dimensions (i.e. on surfaces). Accordingly, an essential and often cumbersome step in bottom‐up applications involves harvesting and transferring the synthesized nanostructures from the solution onto target surfaces. We demonstrate a simple strategy for the synthesis and chemical transformation of tellurium nanorods, which is carried out directly at the solid–solution interface. The technique involves binding the nanorod precursors onto amine‐functionalized surfaces, followed by in situ crystallization/oxidation. We show that the surface‐anchored tellurium nanorods can be further transformed in situ into Ag₂Te, Cu₂Te, and SERS‐active Au–Te nanorods. This new approach offers a way to construct functional nanostructures directly on surfaces.     

Biomolecular DNP‐Supported NMR Spectroscopy using Site‐Directed Spin Labeling

Dynamic nuclear polarization (DNP) has been shown to greatly enhance spectroscopic sensitivity, creating novel opportunities for NMR studies on complex and large molecular assemblies in life and material sciences. In such applications, however, site‐specificity and spectroscopic resolution become critical factors that are usually difficult to control by current DNP‐based approaches. We have examined in detail the effect of directly attaching mono‐ or biradicals to induce local paramagnetic relaxation effects and, at the same time, to produce sizable DNP enhancements. Using a membrane‐embedded ion channel as an example, we varied the degree of paramagnetic labeling and the location of the DNP probes. Our results show that the creation of local spin clusters can generate sizable DNP enhancements while preserving the intrinsic benefits of paramagnetic relaxation enhancement (PRE)‐based NMR approaches. DNP using chemical labeling may hence provide an attractive route to introduce molecular specificity into DNP studies in life science applications and beyond.     

Integrated Antimicrobial and Nonfouling Zwitterionic Polymers

Zwitterionic polymers are generally viewed as a new class of nonfouling materials. Unlike their poly(ethylene glycol) (PEG) counterparts, zwitterionic polymers have a broader chemical diversity and greater freedom for molecular design. In this Minireview, we highlight recent microbiological applications of zwitterionic polymers and their derivatives, with an emphasis on several unique molecular strategies to integrate antimicrobial and nonfouling properties. We will also discuss our insights into the bacterial nonfouling performance of zwitterionic polymers and one example of engineering zwitterionic polymer derivatives for antimicrobial wound‐dressing applications.     

A “Schizophotonic” All‐In‐One Nanoparticle Coating for Multiplexed SE(R)RS Biomedical Imaging

SERS nanoprobes for in vivo biomedical applications require high quantum yield, long circulation times, and maximum colloidal stability. Traditional synthetic routes require high metal–dye affinities and are challenged by unfavorable electrostatic interactions and limited scalability. We report the synthesis of a new near‐IR active poly(N‐(2‐hydroxypropyl) methacrylamide) (pHPMA). The integration of various SERS reporters into a biocompatible polymeric surface coating allows for controlled dye incorporation, high colloidal stability, and optimized in vivo circulation times. This technique allows the synthesis of very small (<20 nm) SERS probes, which is crucial for the design of excretable and thus highly translatable imaging agents. Depending on their size, the “schizophotonic” nanoparticles can emit both SERS and fluorescence. We demonstrate the capability of this all‐in‐one gold surface coating and SERS reporter for multiplexed lymph‐node imaging.     

Organized Aggregation of Porphyrins in Lipid Bilayers for Third Harmonic Generation Microscopy

Nonlinear optical microscopy has become a powerful tool for high‐resolution imaging of cellular and subcellular composition, morphology, and interactions because of its high spatial resolution, deep penetration, and low photo‐damage to tissue. Developing specific harmonic probes is essential for exploiting nonlinear microscopic imaging for biomedical applications. We report an organized aggregate of porphyrins (OAP) that formed within lipidic nanoparticles showing fingerprint spectroscopic properties, structure‐associated second harmonic generation, and superradiant third harmonic generation. The OAP facilitated harmonic microscopic imaging of living cells with significantly enhanced contrast. The structure‐dependent switch between harmonic (OAP‐intact) and fluorescence (OAP‐disrupted) generation enabled real‐time multi‐modality imaging of the cellular fate of nanoparticles. Robustly produced under various conditions and easily incorporated into pre‐formed lipid nanovesicles, OAP provides a biocompatible nanoplatform for harmonic imaging.     

Near‐Infrared Photoinduced Coupling Reactions Assisted by Upconversion Nanoparticles

We introduce nitrile imine‐mediated tetrazole–ene cycloadditions (NITEC) in the presence of upconversion nanoparticles (UCNPs) as a powerful covalent coupling tool. When a pyrene aryl tetrazole derivative (λ_{abs, max}=346 nm) and UCNPs are irradiated with near‐infrared light at 974 nm, rapid conversion of the tetrazole into a reactive nitrile imine occurs. In the presence of an electron‐deficient double bond, quantitative conversion into a pyrazoline cycloadduct is observed under ambient conditions. The combination of NITEC and UCNP technology is used for small‐molecule cycloadditions, polymer end‐group modification, and the formation of block copolymers from functional macromolecular precursors, constituting the first example of a NIR‐induced cycloaddition. To show the potential for in vivo applications, through‐tissue experiments with a biologically relevant biotin species were carried out. Quantitative cycloadditions and retention of the biological activity of the biotin units are possible at 974 nm irradiation.     

Biocompatible and fluorescent polycaprolactone/silk electrospun nanofiber yarns loaded with carbon quantum dots for biotextiles

Carbon quantum dots (CDs) are attractive nanoparticles for several applications, due to inherent properties such as excitation dependent photoluminescence emission and chemical stability. In the present work, we synthesized CDs from silk (Bombyx Mori) by a microwave‐assisted method. The resultant spherical nanoparticles with high fluorescence under UV light were incorporated into PCL/silk matrix and electrospun into continuous nanofiber yarns (NF‐Ys) by a one‐step method. Besides granting yarns fluorescence, CD inclusion contributed to a decrease in fiber diameter and an increase in strength by 2.7‐fold. Cell viability studies with mammalian lung cell lines show viability above 80%, suggesting good biocompatibilty. Such yarns show the potential to be assembled into larger structures such as biotextiles, with possible multifunctionalities such as antiviral, antibacterial, and biosensing applications.