Hierarchically Porous Composite Scaffold Composed of SBA-15 Microrods and Reduced Graphene Oxide Functionalized with Cyclodextrin for Water Purification.

Large-scale decontamination of bisphenol A (BPA) from wastewater under field conditions is an urgent need because of the harmful toxic effects of BPA on living organisms. In this study, we report the fabrication of a three-dimensional (3D) hierarchically porous composite scaffold composed of mesoporous SBA-15 silica microrods and reduced graphene oxide (rGO-CD) functionalized with ß-cyclodextrin (CD) and its application for BPA separation from contaminated water. The macroporous structure was achieved by sacrificial salt leaching, and the mesoporous structure was derived from the interparticle pores between compressed SBA-15 particles and intrinsic mesopores in SBA-15. The 3D hierarchical macroporous and mesoporous architecture of the scaffold enhances mass transport without any external forces, and the rGO-CD component provides good capture sites for BPA in solution via inclusion complexation between CD and BPA. The inorganic SBA-15 component of the scaffold also allows long-term operation of filters by increasing the mechanical strength of the scaffold. The hierarchically porous SBA-15/rGO-CD composite scaffold could separate BPA from contaminated water significantly better than the scaffold without rGO-CD in both batch and filter systems. Our study indicates that the functional hierarchically porous composite scaffold can be a potential material in wastewater treatment technology.

A 3D Macroporous Alginate Graphene Scaffold with an Extremely Slow Release of a Loaded Cargo for In Situ Long-Term Activation of Dendritic Cells.

Ex vivo manipulation of autologous antigen-presenting cells and their subsequent infusion back into the patient to dictate immune response is one of the promising strategies in cancer immunotherapy. Here, a 3D alginate scaffold embedded with reduced graphene oxide (rGO) is proposed as a vaccine delivery platform for in situ long-term activation of antigen-presenting dendritic cells (DCs). High surface area and hydrophobic surface of the rGO component of the scaffold provide high loading and a very slow release of a loaded antigen, danger signal, and/or chemoattractant from the scaffold. This approach offers long-term bioavailability of the loaded cargo inside the scaffold for manipulation of recruited DCs. After mice are subcutaneously vaccinated with the macroporous alginate graphene scaffold (MAGS) loaded with ovalbumin (OVA) and granulocyte-macrophage colony-stimulating factor (GM-CSF), this scaffold recruits a significantly high number of DCs, which present antigenic information via major histocompatibility complex class I for a long period. Furthermore, an MAGS loaded with OVA, GM-CSF, and CpG promotes production of activated T cells and memory T cells, leading to the suppression of OVA-expressing B16 melanoma tumor growth in a prophylactic vaccination experiment. This study indicates that an MAGS can be a strong candidate for long-term programming and modulating immune cells in vivo.

Direct Chemical Synthesis of Plasmonic Black Colloidal Gold Superparticles with Broadband Absorption Properties.

Self-assembly of plasmonic metal nanoparticles can provide an opportunity of creating colloidal superparticles with fascinating optical properties arising from interparticle plasmonic coupling, but typically requires multiple steps involving solvent and/or ligand exchange. We developed a direct, one-step chemical synthesis of plasmonic black colloidal Au superparticles with broadband absorption in visible and near-infrared regions. During the synthesis, the Au superparticles were formed through self-assembly of in-situ-formed Au nanoparticles driven by solvophobic interactions between nanoparticles and solvent. These superparticles could be solution-processed to fabricate a thin film, which exhibited near-perfect absorption over a broad range from 400 nm to 2.5 µm as well as the excellent antireflective property. Thanks to their broadband absorption property, the Au superparticles showed good performances for near-infrared surface-enhanced Raman spectroscopy and light-to-heat conversion.

Separation of Microcystin-LR by Cyclodextrin-Functionalized Magnetic Composite of Colloidal Graphene and Porous Silica.

Microcystin-LR belongs to the family of microcystins produced by cyanobacteria and known to be the most toxic of this family. Existence of cyanobacteria in water bodies leads to the contamination of drinking water with microcystin-LR and thus their separation is essential for an advanced water purification system. Here we report functional nanocomposite-based selective separation of microcystin-LR from contaminated water. We have synthesized cyclodextrin-functionalized magnetic composite of colloidal graphene and porous silica where the cyclodextrin component offers host-guest interaction with microcystin-LR and the magnetic component offers easier separation of microcystin-LR from water. High surface area and large extent of chemical functional groups offer high loading (up to 18 wt %) of cyclodextrin with these nanocomposites, and the dispersible form of the nanocomposite offers easier accessibility of cyclodextrin to microcystin-LR. We have shown that microcystin-LR separation efficiency is significantly enhanced after functionalization with cyclodextrin, and among all the tested cyclodextrins, γ-cyclodextrin offers the best performance. We have also found that graphene-based nanocomposite offers better performance over porous silica-based nanocomposite due to better accessibility of cyclodextrins for interaction with microcystin-LR. The proposed graphene-based functional nanocomposite is environment friendly, reusable, and applicable for advanced water purification.

ß-Cyclodextrin functionalized magnetic mesoporous silica colloid for cholesterol separation.

Although cholesterol plays significant biochemical function in the human body, excess of it leads to various disorders, and thus, its control/separation is important in medical science and food industries. However, efficient and selective separation of cholesterol is challenging because cholesterol often exists in microheterogeneous or insoluble forms in remote organ and exists with other chemicals/biochemicals. Here, we have described a colloidal magnetic mesoporous silica (MMS)-based approach for efficient separation of cholesterol in different forms. MMS is functionalized with ß-cyclodextrin for selective binding with cholesterol via host-guest interaction. The colloidal form of MMS offers effective interaction with cholesterol of any form, and magnetic property of MMS offers easier separation of bound cholesterol. Functionalized MMS is efficient in separating cholesterol crystals, water-insoluble cholesterol, and the microheterogeneous form of cholesterol from milk or a cellular environment. Developed material can be used to remove cholesterol from a complex bioenvironment and extended for large-scale cholesterol separation from food.

Dextran-gated, multifunctional mesoporous nanoparticle for glucose-responsive and targeted drug delivery.

Design of drug delivery nanocarrier having targeted recognition followed by bioresponsive controlled release, especially via glucose-responsive release, is a challenging issue. Here, we report magnetic mesoporous silica (MMS)-based drug delivery nanocarrier that can target specific cell and release drug via glucose-responsive gate. The design involves synthesis of MMS functionalized with phenylboronic acid and folate. After drug loading inside the pores of MMS, outside of the pores are closed by dextran via binding with phenylboronic acid. Dextran-gated pores are opened for drug release in the presence of glucose that competes binding with phenylboronic acid. We found that tolbutamide and camptothecin loaded MMS can target beta cells and cancer cells, respectively, release drugs depending on bulk glucose concentration and offers glucose concentration dependent cytotoxicity. Developed functional MMS can be used for advanced drug delivery applications for diabetes and cancers with more efficient therapy.

Graphene-based composite with γ-Fe2O3 nanoparticle for the high-performance removal of endocrine-disrupting compounds from water.

Graphene is a 2D sp(2)-hybridized carbon sheet and an ideal material for the adsorption-based separation of organic pollutants. However, such potential applications of graphene are largely limited, owing to their poor solubility and extensive aggregation properties through graphene-graphene interactions. Herein, we report the synthesis of graphene-based composites with γ-Fe2O3 nanoparticle for the high-performance removal of endocrine-disrupting compounds (EDC) from water. The γ-Fe2O3 nanoparticles partially inhibit these graphene-graphene interactions and offer water dispersibility of the composite without compromising much of the high surface area of graphene. In their dispersed form, the graphene component offers the efficient adsorption of EDC, whilst the magnetic iron-oxide component offers easier magnetic separation of adsorbed EDC.

Tunable catalytic performance and selectivity of a nanoparticle-graphene composite through finely controlled nanoparticle loading.

Graphene-based composites offer enhanced catalytic performance of metal and semiconductor nanoparticles, but their development is challenging because catalytic performance strongly depends on the structure and composition of the composite. Herein we show that the catalytic performance of a nanoparticle-graphene composite is very dependent on catalyst loading, which can be optimized for simultaneous enhancement of activity and selectivity. A glassy carbon working electrode has been modified with a gold nanoparticle-graphene (Au-G) composite with a varied number of gold nanoparticles per graphene, so that the conducting property of graphene and the electrocatalytic property of the metal were effectively coupled to give the best catalytic activity and selectivity. The modified electrode was used for simultaneous electrochemical detection of a mixture of electroactive species with high sensitivity. This result shows that the catalytic performance of a graphene-based composite is sensitive to the catalyst loading and should be optimized for the best performance.

Functional, mesoporous, superparamagnetic colloidal sorbents for efficient removal of toxic metals.

γ-Fe(2)O(3) incorporated mesoporous silica particles of 50-100 nm size have been synthesized which are functionalized with chelating agents of metal ions. These particles are water dispersible but aggregate in response to the external magnetic field and have been used for high performance and selective removal of Cd, Pb, Hg and As.