Graphene oxide (GO) is emerging as a potential adsorbent for environmental cleanup due to its attractive attributes associated with high removal efficiency toward water pollutants. However, it is difficult to separate GO from water after adsorption. Until now, the development of an effective approach that can simultaneously take advantage of the adsorption feature of GO and overcome the separation problem is still a challenge. Herein, we demonstrate a simple one-step approach to fabricate magnetic GO/poly(vinyl alcohol) (PVA) composite gels (mGO/PVA CGs), which not only exhibit convenient magnetic separation capability but also show remarkably enhanced adsorption capacity for cationic methylene blue (MB) and methyl violet (MV) dyes as compared with the one without GO (e.g., the adsorption capacities of mGO/PVA-50% and mGO/PVA-0% for MB are 231.12 and 85.64 mg/g, respectively). Detailed adsorption studies reveal that the adsorption kinetics and isotherms can be well-described by pseudo-second-order model and Langmuir isotherm model, respectively. Moreover, the adsorbent could be well regenerated in an acid solution without obvious compromise of removal efficiency. Considering the facile fabrication process and robust adsorption performance of the mGO/PVA CG, this work opens up enormous opportunities to bring GO from experimental research to practical water treatment applications. In addition, the mGO/PVA CG can act as a magnetic support for in situ growth of noble metal nanocatalyst with excellent catalytic performance, as exemplified by the synthesis of mGO/PVA-Pt catalyst in this paper.

Herein, we report a class of molecular spherical nucleic acid (SNA) nanostructures. These nano-sized single molecules are synthesized from T polyoctahedral silsesquioxane and buckminsterfullerene C scaffolds, modified with 8 and 12 pendant DNA strands, respectively. These conjugates have different DNA surface densities and thus exhibit different levels of nuclease resistance, cellular uptake, and gene regulation capabilities; the properties displayed by the C SNA conjugate are closer to those of conventional and prototypical gold nanoparticle SNAs. Importantly, the C SNA can serve as a single entity (no transfection agent required) antisense agent to efficiently regulate gene expression. The realization of molecularly pure forms of SNAs will open the door for studying the interactions of such structures with ligands and living cells with a much greater degree of control than the conventional polydisperse forms of SNAs.

Fluorescent carbon dots (CDs) hold great promise for a myriad applications due to their fascinating attributes. However, the development of CDs with high fluorescence quantum yield (QY) and unique surface property is still in its infancy. Herein, we report a simple and green strategy to produce water-soluble nitrogen-doped CDs (N-CDs) via the one-pot hydrothermal carbonization of the mixture of natural peach gum polysaccharide (PGP) and ethylenediamine. The resulting N-CDs exhibit a remarkably enhanced QY (28.46%) as compared with that of undoped CDs (5.31%). In addition, the N-CDs show stable fluorescence against ionic strength variation and pH change. Preliminary biological studies reveal that N-CDs possess low cytotoxicity and high fluorescent contrast in cells. Moreover, we present here for the first time that the obtained N-CDs can exhibit a fast and highly sensitive and selective fluorescence quenching effect toward Au3+ ions. The detection limit can reach 6.4 × 10–8 M, which compares favorably to other reported fluorescent probes. We have also demonstrated that the N-CDs can be employed to sense Au3+ ions in real river water. Considering the easy synthetic process and excellent performance of the N-CDs, this investigation opens up new opportunities for preparing high-quality fluorescent CDs to meet the requirement of many applications.

Two dimensional MoS 2 nanosheets decorated with inorganic nanoparticles (INPs) are emerging as novel MoS 2 -based nanohybrids for tuning the intrinsic attributes of both components for fundamental research and technological applications. However, the design and fabrication of MoS 2 -INP nanohybrids with a tailor-made structure and functions remain a significant challenge. Herein we report a general and controllable protocol for the one-step synthesis of various MoS 2 -INP nanohybrids by employing carboxylic MoS 2 (MoS 2 -COOH) nanosheets as a versatile support. The obtained MoS 2 -INP nanohybrids exhibit good dispersibility, high reactivity and excellent processability. The size, morphology and coverage density of INPs on the surface of MoS 2 -COOH can be readily controlled by tuning the feed ratio. Control experiments reveal that the presence of carboxylic functional groups plays a key role in controlling the structure and properties of the resulting MoS 2 -INP nanohybrids. In addition, ternary MoS 2 -based nanohybrids can also be readily prepared by this approach, as exemplified by the synthesis of MoS 2 -Fe 3 O 4 /Pt nanohybrids, which simultaneously exhibit excellent catalytic performance toward the reduction of 4-nitrophenol and favorable magnetic separation capability. Considering the simple fabrication process, high controllability of this protocol and excellent performance of the product, the present work opens up enormous opportunities for the large-scale production of diverse MoS 2 -based nanohybrids for many technological applications.

Upconversion nanoparticle (UCNP) as a new class of imaging agent is gaining prominence because of its unique optical properties. An ideal UCNP for bioimaging should simultaneously possess fine water dispersibility and favorable functional groups. In this paper, we present a simple but effective method to the synthesis of a UCNP-based nanohybrid bearing a multihydroxy hyperbranched polyglycerol (HPG) shell by the combination of a "grafting from" strategy with a ring-opening polymerization technique. The structure and morphology of the resulting UCNP-g-HPG nanohybrid were characterized in detail by Fourier transform infrared, (1)H NMR, thermogravimetric analysis, and transmission electron microscopy measurements. The results reveal that the amount of grafted HPG associated with the thickness of the HPG shell can be well tuned. UCNP-g-HPG shows high water dispersibility and strong and stable upconversion luminescence. On the basis of its numerous surface hydroxyl groups, UCNP-g-HPG can be tailored by a representative fluorescent dye rhodamine B to afford a UCNP-g-HPG-RB nanohybrid that simultaneously presents upconversion and downconversion luminescence. Preliminary biological studies demonstrate that UCNP-g-HPG shows low cytotoxicity, high luminescent contrast, and deep light penetration depth, posing promising potential for bioimaging applications.

We have synthesized a series of stimuli-responsive brush polymers by grafting azide-terminated side chains onto a self-immolative, alkyne-bearing poly(benzyl ether) backbone, which is prepared by anionic polymerization of quinone methide-based monomers. Upon exposure to a decapping reagent (Pd(0) or F−), these brush polymers undergo an irreversible degradation cascade from head to tail to yield individual side chains. It is observed that several factors affect the depolymerization kinetics, including solvent polarity, type of counterion, the rate of the decapping chemistry, and interestingly, the rigidity of the side chains.

No abstract

Herein, we report a poly­(benzyl ether)-based self-immolative polymer (SIP) with pendant pyridine disulfide groups. Cleavage of the side-chain disulfides leads to the formation of phenolates, which initiate depolymerization from the side chain. Due to the higher density of the disulfide groups compared to that of the chain-end-capping group, which normally is responsible for initiating depolymerization of SIPs, the side chain-immolative polymer (ScIP) can be readily degraded in the solid state where the mobility of polymer chains is substantially limited. The ScIP was also further modified through the thiol–disulfide exchange reaction to prepare ScIP-g-poly­(ethylene glycol) graft polymers and organogels, which were also able to undergo complete reductive self-immolative degradation.