There has been considerable interest in recent years in using metal, semiconductor, and magnetic nanoparticles in biological applications. [1][2][3][4][5][6][7] A wide range of ligation and encapsulation methods have been developed to render the nanoparticles soluble in aqueous solution, to prevent aggregation, and to provide means by which functional molecules can be attached. Among these methods, encapsulation of nanoparticles by a polymer, [8,9] phospholipid, [10] or inorganic [11,12] shell is of particular interest to us, since these stable shells prevent dissociation of surface ligands and provide anchor points where biomolecules are unlikely to be lost once attached. This is a significant advantage over direct conjugation through surface ligands, since even strong thiol ligands can dissociate from or undergo exchange on gold surfaces, [13] let alone weaker ligands on the surfaces of quantum dots or magnetic nanoparticles. Stable attachment of biomolecules would be particularly important where only a few biomolecules are selectively attached to a nanoparticle, or when multiple types of singly functionalized nanoparticles are mixed.Stable functionalization of quantum dots remains a challenge. While biomolecules have been attached to quantum dots and used for biological studies, [4,5] a nondissociable ligand shell would be required for attachment of biomolecules selectively and with controlled valency. Recently, Taton et al. reported encapsulation of gold nanoparticles (AuNPs) [14,15] and magnetic nanoparticles (MagNPs) [16,17] by amphiphilic diblock copolymers. The resulting nanoparticles have a stable, well-defined core/shell structure impermeable to ionic species in aqueous solution. Such a polymer shell would be ideal for functionalization of quantum dots if a similar encapsulation methodology could be adopted. However, it was found that in this system small (d < 10 nm) AuNPs and MagNPs act as solutes in polymer micelles and are therefore prone to multiple inclusion on encapsulation. [14] In contrast, large AuNPs act as surface templates on which polymer molecules assemble into micellar shells that each encapsulate a single AuNP. Since most nanoparticles used for biological studies, particularly quantum dots, have diameters in the range of 2-9 nm, it is necessary that we develop new methods that can encapsulate single nanoparticles of sizes similar to quantum dots.Herein we report the encapsulation of single small AuNPs, in preparation for future work on quantum dots, since AuNPs are easier to handle and characterize. Diblock copolymers such as PS 108 PGA 108 , PS 132 PAA 72 , and PS 159 PAA 62 [PS: polystyrene, PGA: poly(glutamic acid), PAA: poly(acrylic acid)] were used to encapsulate AuNPs in "hairy" micelles (Figure 1 B); the resulting core/shell nanoparticles are stable in solution without chemical crosslinking. The long hydrophilic blocks of the polymers were initially chosen to help stabilize attached biomolecules, but were later found to allow encapsulation of single small AuNPs. The use of such po...

Oil/water separation has been of great interest worldwide because of the increasingly serious environmental pollution caused by the abundant discharge of industrial wastewater, oil spill accidents, and odors. Here, we describe simple and economical superhydrophobic hybrid membranes for effective oil/water separation. Eco-friendly, antifouling membranes were fabricated for oil/water separation, waste particle filtration, the blocking of thiol-based odor materials, etc., by using a cellulose membrane (CM) filter. The CM was modified from its original superhydrophilic nature into a superhydrophobic surface via a reversible addition-fragmentation chain transfer technique. The block copolymer poly{[3-(trimethoxysilyl)propyl acrylate]-block-myrcene} was synthesized using a "grafting-from" approach on the CM. The surface contact angle that we obtained was >160°, and absorption tests of several organic contaminants (oils and solvents) exhibited superior levels of extractive activity and excellent reusability. These properties rendered this membrane a promising surface for oil/water separation. Interestingly, myrcene blocks thiol (through "-ene-" chemistry) contaminants, thereby bestowing a pleasant odor to polluted water by acting as an antifouling material. We exploited the structural properties of cellulose networks and simple chemical manipulations to fabricate an original material that proved to be effective in separating water from organic and nano/microparticulate contaminants. These characteristics allowed our material to effectively separate water from oily/particulate phases as well as embed antifouling materials for water purification, thus making it an appropriate absorber for chemical processes and environmental protection.

Biomaterials generally suffer from rapid nonspecific protein adsorption, which initiates many deleterious host responses, and complex chemistries that are employed to facilitate cellular interactions. A chemical approach that, based upon current literature, combines a nonfouling architecture with a biomemtic cell-adhesive end-group, is presented. Namely, surface-initiated polymerization of zwitterionic [poly (carboxybetaine methacrylamide)] brushes, with controlled charge densities and phosphonate head groups. Nitroxide mediated free radical polymerization (NMFRP) was employed for various reasons: reduces presence of potentially cytotoxic organometallic catalysts common in atom transfer radical polymerization (ATRP); and it allows a phosphonate end-group instead of the common brominated end-group. Thermally oxidized silicon wafers were covalently functionalized with diethyl-(1-(N-(1-(3-(trimethoxysilyl)propylcarbamoyl)ethoxy)-Ntert-butylamino)ethyl)phosphonate. NMFRP was used to graft zwitterionic carboxybetaine methacrylamide monomers of varying inter-charge separation. The resulting thin films were characterized using Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) and X-ray photoelectron (XPS) spectroscopy, ellipsometry, water contact angle analysis, and thermo gravimetric analysis (TGA). The effect of spacer group on the surface charge density was determined using zeta potential techniques. It is thought that this stratagem will facilitate the ability to tailor systematically both the interior and terminal polymer properties, providing a platform for further understanding how these conditions affect protein adsorption as well as cell-surface interactions. V