Dynamic biointerfaces: from recognition to function.

The transformation of recognition signals into regulating macroscopic behaviors of biological entities (e.g., biomolecules and cells) is an extraordinarily challenging task in engineering interfacial properties of artificial materials. Recently, there has been extensive research for dynamic biointerfaces driven by biomimetic techniques. Weak interactions and chirality are two crucial routes that nature uses to achieve its functions, including protein folding, the DNA double helix, phospholipid membranes, photosystems, and shell and tooth growths. Learning from nature inspires us to design dynamic biointerfaces, which usually take advantage of highly selective weak interactions (e.g., synergetic chiral H-bonding interactions) to tailor their molecular assemblies on external stimuli. Biomolecules can induce the conformational transitions of dynamic biointerfaces, then drive a switching of surface characteristics (topographic structure, wettability, etc.), and eventually achieve macroscopic functions. The emerging progresses of dynamic biointerfaces are reviewed and its role from molecular recognitions to biological functions highlighted. Finally, a discussion is presented of the integration of dynamic biointerfaces with the basic biochemical processes, possibly solving the big challenges in life science.

A stable, reusable, and highly active photosynthetic bioreactor by bio-interfacing an individual cyanobacterium with a mesoporous bilayer nanoshell.

An individual cyanobacterium cell is interfaced with a nanoporous biohybrid layer within a mesoporous silica layer. The bio-interface acts as an egg membrane for cell protection and growth of outer shell. The resulting bilayer shell provides efficient functions to create a single cell photosynthetic bioreactor with high stability, reusability, and activity.

Polymer-based stimuli-responsive recyclable catalytic systems for organic synthesis.

The introduction of stimuli-responsive polymers into the study of organic catalysis leads to the generation of a new kind of polymer-based stimuli-responsive recyclable catalytic system. Owing to their reversible switching properties in response to external stimuli, these systems are capable of improving the mass transports of reactants/products in aqueous solution, modulating the chemical reaction rates, and switching the catalytic process on and off. Furthermore, their stimuli-responsive properties facilitate the separation and recovery of the active catalysts from the reaction mixtures. As a fascinating approach of the controllable catalysis, these stimuli-responsive catalytic systems including thermoresponsive, pH-responsive, chemo-mechano-chemical, ionic strength-responsive, and dual-responsive, are reviewed in terms of their nanoreactors and mechanisms.

Chiral biointerface materials.

Chiral phenomena are ubiquitous in nature from macroscopic to microscopic, including the high chirality preference of small biomolecules, special steric conformations of biomacromolecules induced by it, as well as chirality-triggered biological and physiological processes. The introduction of chirality into the study of interface interactions between materials and biological systems leads to the generation of chiral biointerface materials, which provides a new platform for understanding the chiral phenomena in biological system, as well as the development of novel biomaterials and devices. This critical review gives a brief introduction to the recent advances in this field. We start from the fabrication of chiral biointerface materials, and further investigate the stereo-selective interaction between biological systems and chiral interface materials to find out key factors governing the performance of such materials in given conditions, then introduce some special functionalities and potential applications of chiral biointerface materials, and finally present our own thinking about the future development of this area (108 references).

Modulating cell behaviors on chiral polymer brush films with different hydrophobic side groups.

Chirality is one of the significant biochemical signatures of life. Nearly all biological polymers are homochiral as they usually show high preference toward one specific enantiomer. This phenomenon inspires us to design biomaterials with chiral units and study their interactions with cells and other biological entities. In this article, through adopting three pairs of aliphatic amino acids with different hydrophobic side groups as chiral species, and using two adhesive cell lines as examples, we show that the chirality of polymer brushes can trigger differential cell behaviors on the enantiomorphous surfaces, and more interestingly, such chiral effect on cellular behaviors can be modulated in a certain extent by varying the hydrophobic side groups of the chiral moieties composing the polymers. This work not only proves the versatility of the chiral effect at the cell level but also demonstrates a method to bridge the gap between organic signal molecules and biomaterials. It thus points out a promising approach for designing novel biomaterials based on the chiral effect, which will be an important complement for conventional strategies in the study of biomaterials.

Enhanced delivery of theranostic liposomes through NO-mediated tumor microenvironment remodeling.

Highly efficient delivery of nanoagents to the tumor region remains the primary challenge for cancer nanomedicine. Herein, we propose a NO-mediated tumor microenvironment (TME) remodeling strategy for the high-efficient delivery of nanoagents into tumor. Quantum dots (QDs) with bright fluorescence in the near-infrared IIb (NIR-IIb, 1500-1700 nm) window and high photothermal conversion efficiency were encapsulated into liposomes for the imaging-guided photothermal therapy (PTT) of tumor. The fabrication of PEG and arginine-glycine-aspartate (RGD) peptide on liposomes ensured the prolonged circulation in vivo and active targeting to tumor. Moreover, the loading of a natural NO generator L-arginine in liposomes realized the continuous generation of NO in the acidic TME. By co-localization fluorescence imaging and western blot of tumor tissue, we confirmed that the release of NO activated the expression of metalloproteinases in TME and further degraded Collagen I in the peripheral region of the tumor, thus removing the barrier for the permeation of liposomes. Attributed to the enhanced accumulation of liposomes inside the tumor, NIR IIb imaging-guided PTT was achieved with remarkable therapeutic efficacy.

An Ultra-Stable, Oxygen-Supply Nanoprobe Emitting in Near-Infrared-II Window to Guide and Enhance Radiotherapy by Promoting Anti-Tumor Immunity.

Currently, radiotherapy (RT) is the main method for cancer treatment. However, the hypoxic environment of solid tumors is likely to cause resistance or failure of RT. Moreover, high-dose radiation may cause side effects to surrounding normal tissues. In this study, a new type of nanozyme is developed by doping Mn (II) ions into Ag2 Se quantum dots (QDs) emitting in the second near-infrared window (NIR-II, 1000-1700 nm). Through the catalysis of Mn (II) ions, the nanozymes can trigger the rapid decomposition of H2 O2 and produce O2 . Conjugated with tumor-targeting arginine-glycine-aspartate (RGD) tripeptides and polyethylene glycol (PEG) molecules, the nanozymes are then constructed into in vivo nanoprobes for NIR-II imaging-guided RT of tumors. Owing to the radiosensitive activity of the element Ag, the nanoprobes can promote radiation energy deposition. The specific tumor-targeting and NIR-II emitting abilities of the nanoprobes facilitate the precise tumor localization, which enables precise RT with low side effects. Moreover, their ultra-stability in the living body ensures that the nanoprobes continuously produce oxygen and relieve the hypoxia of tumors to enhance RT efficacy. Guided by real-time and high-clarity imaging, the nanoprobe-mediated RT promotes anti-tumor immunity, which significantly inhibits the growth of tumors or even cures them completely.

Clickable gold nanoparticles as the building block of nanobioprobes.

A new method of fabricating "clickable" gold nanoparticles that could be used as the building block of nanobioprobes was described. On the basis of a well-developed strategy of encapsulating hydrophobic nanoparticles with a layer of amphiphilic polymers, cheap, easily prepared graft polymer was used as a modifier to prepare monodisperse azide-functionalized gold nanoparticles (AuNPs), which showed good stability in physiological solution. By conjugation with alkyne functional horseradish peroxidase (HRP) via click chemistry under mild conditions, the azide-AuNPs have demonstrated their potential in the fabrication of stable, bioactive nanobioprobes. Some critical problems in the fabrication of nanobioprobes, such as how to detect the number of bound biomolecules on nanoparticles and evaluate the bioactivities of nanobioprobes, are discussed in detail.

Microcrystalline cellulose (MCC) based materials as emerging adsorbents for the removal of dyes and heavy metals - A review.

In an attempt to overcome such threats posed by water pollution, various processes ranging from physical, chemical as well as biological were applied to get rid of wastewater pollutants. The simplicity, high efficiency and cheapness of an adsorption process make it the most widely used among various other processes. Adsorbents with different properties were used in the adsorption process but this paper was focused on reviewing various articles published by numerous researchers on the isolation of microcrystalline cellulose (MCC), a popular carbohydrate polymer from lignocellulosic biomass and utilization of MCC based materials as effective adsorbents for the successful removal of dyes and heavy metals from synthetic wastewater. The sudden interest on MCC and MCC-based materials as adsorbents cannot be separated from their excellent properties such as renewability, biodegradability, biocompatibility, economic value, non-toxicity, high mechanical properties and surface area. Upon comparison with established adsorbents reported from literature, MCC-based materials performed excellently well in the adsorption of dyes and heavy metals with Langmuir isotherm and pseudo-second order reported mostly as the best fit models for the generated equilibrium and kinetic data, respectively pointing at the distribution of adsorption sites to be homogeneous as well as the formation of monolayer adsorbate on their surfaces. The various thermodynamic studies reported further revealed the adsorption processes of both dyes and heavy metals onto MCC-based materials to be entropy driven processes, spontaneous, and endothermic. Finally, future research was suggested to focus on optimization to enhance the performance of the MCC-based adsorbents, carrying out the adsorption on real wastewater instead of synthetic ones as well as expanding the range of adsorbates to include other contaminants such as chlorophenols, herbicides, pesticides and others in addition to dyes and heavy metals.

Kinetic study of Aß(1-42) amyloidosis in the presence of ganglioside-containing vesicles.

Alzheimer's disease (AD) is characterized by the amyloid-beta peptide (Aß) misfolding to form aberrant amyloid aggregates in the brain. Although recent evidence implicates that amyloid deposition in vivo is highly related to biomembranes, how the characteristic lipid components of neuronal membranes mediate this process remains to be fully elucidated. Herein, we established vesicle models to mimic exosomes and investigated their influence on the kinetics of Aß(1-42) amyloidosis. By using ternary vesicles composed of three brain lipids monosialoganglioside GM1, cholesterol and sphingomyelin, we found that GM1 could regulate peptide fibrillation by facilitating the conformational transition of Aß(1-42), and further quantitatively analyzed the influence of GM1-containing vesicles on the kinetics of Aß(1-42) fibrillation. In addition, GM1-containing vesicles induced the formation of Aß(1-42) fibrils at low concentrations, and these fibrils were toxic to PC12 cells. By analyzing the role of GM1 in this ternary mixture of membranes at the molecular level, we confirmed that GM1 clusters are presented as attachment sites for peptides, thus promoting the fibrillation of Aß(1-42).

Multiplexed NIR-II Probes for Lymph Node-Invaded Cancer Detection and Imaging-Guided Surgery.

Tumor-lymph node (LN) metastasis is the dominant prognostic factor for tumor staging and therapeutic decision-making. However, concurrently visualizing metastasis and performing imaging-guided lymph node surgery is challenging. Here, a multiplexed-near-infrared-II (NIR-II) in vivo imaging system using nonoverlapping NIR-II probes with markedly suppressed photon scattering and zero-autofluorescence is reported, which enables visualization of the metastatic tumor and the tumor metastatic proximal LNs resection. A bright and tumor-seeking donor-acceptor-donor (D-A-D) dye, IR-FD, is screened for primary/metastatic tumor imaging in the NIR-IIa (1100-1300 nm) window. This optimized D-A-D dye exhibits greatly improved quantum yield of organic D-A-D fluorophores in aqueous solutions (≈6.0%) and good in vivo performance. Ultrabright PbS/CdS core/shell quantum dots (QDs) with dense polymer coating are used to visualize cancer-invaded sentinel LNs in the NIR-IIb (>1500 nm) window. Compared to clinically used indocyanine green, the QDs show superior brightness and photostability (no obvious bleaching even after continuous laser irradiation for 5 h); thus, only a picomolar dose is required for sentinel LNs detection. This combination of dual-NIR-II image-guided surgery can be performed under bright light, adding to its convenience and appeal in clinical use.

Core/shell quantum-dot-photosensitized nano-TiO2 films: fabrication and application to the damage of cells and DNA.

Through the use of monodisperse core/shell quantum dots (QDs) as photosensitizers for the first time, a novel strategy for the fabrication of QD-photosensitized nano-TiO2 films was demonstrated. Core/shell QDs were self-assembled on nano-TiO2 films through carboxyls as anchoring groups to metal oxides. Atomic force microscopy and some other experiments showed the fabrication strategy is successful. Reactive oxygen species detection experiments indicated that such films have photosensitization ability. The results of bactericidal and DNA damage experiments demonstrate that such films have excellent photoactivity.

Gating of responsive multiple nanochannels by ultra-low concentration of saccharides.

We report a saccharide recognition system by modifying responsive copolymers on the solid-based multiple nanochannels. The ion transport through nanochannels can be regulated by ultra-low concentration of saccharides, which can switch nanochannels between the "on" and "off" states.

Synthesis, crystal structures, luminescence and catalytic properties of two d¹° metal coordination polymers constructed from mixed ligands.

Two new coordination polymers [Cd(bmb)(hmph)]n (1), {[Ag(bmb)]·H2btc}n (2) (bmb=1,4-bis(2-methylbenzimidazol-1-ylmethyl)benzene, H2hmph=homophthalic acid, H3btc=1,3,5-benzenetetracarboxylic acid) were synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction methods, IR spectroscopy, TGA, XRPD and elemental analysis. Complex 1 features a 3D threefold interpenetrating dia array with a 4-connected 6(6) topology. Complex 2 shows a 1D helix chain structure connected by L1 ligands, which is finally extended into a rarely 2D 4L2 supramolecular network via C-H⋯O hydrogen bond interactions. In addition, the luminescence and catalytic properties of the two complexes for the degradation of the methyl orange azo dye in a Fenton-like process were presented. The degradation efficiency of the methyl orange azo dye for 1 and 2 are 56% and 96%, respectively.

Intermediate-dominated controllable biomimetic synthesis of gold nanoparticles in a quasi-biological system.

A new biomimetic strategy of creating a quasi-biological system (an aqueous solution containing electrolytes, peptide, enzyme and coenzyme) for the preparation of gold nanoparticles with uniform and tunable sizes has been put forward and validated, adopting environmentally-friendly reducing agents and a biocompatible capping ligand in aqueous solution at room temperature. The biomimetic synthetic route has the characteristics for good stability of the resulting AuNPs capped with glutathione via strong Au-S bond in aqueous solution, an appropriate composition of the intermediate with a redox potential favorable for the biomimetic reduction under mild conditions, suitable pH values to adjust the rate of the reduction, and the addition of enzyme catalyzing the reduction. By only adjusting the concentration of the reducing agent NADPH, a series of AuNPs with narrow size-distribution could be controllably synthesized. This method of rational utilization of biological processes could provide a new way for the sustainable development of nanotechnology.