journal covers

An article to Biomaterials Science entitled Sequestering survivin to functionalized nanoparticles: a strategy to enhance apoptosis in cancer cells was selected for the cover art.

Abstract: Surviving belongs to the family of inhibitor of apoptosis proteins (IAP) and is present in most cancers while being below detection limits in most terminally differentiated adult tissues, making it an attractive protein to target for diagnostic and, potentially, therapeutic roles. Sub-100 nm poly(propargyl acrylate) (PA) particles were surface modified through the copper-catalyzed azide/alkyne cycloaddition of an azide-terminated survivin ligand derivative (azTM) originally proposed by Abbott Laboratories and speculated to bind directly to survivin (protein) at its dimer interface. Using affinity pull-down studies, it was determined that the PA/azTM nanoparticles selectively bind survivin and the particles can enhance apoptotic cell death in glioblastoma cell lines and other survivin over-expressing cell lines such as A549 and MCF7 relative to cells incubated with the original Abbott-derived small molecule inhibitor.

An article to Advanced Functional Materials entitled Rapid and Continuous Hydrodynamically Controlled Fabrication of Biohybrid Microfibers was selected for the cover art.

Cell encapsulation is critical for many biotechnology applications including environmental remediation, bioreactors, and regenerative medicine. Here, the development of biohybrid microfi bers comprised of encapsulated bacteria in hydrogel matrices produced on-chip using microfl uidics is reported. The fiber production process utilizes hydrodynamic shaping of a cell-laden core fluid by a miscible sheath fluid. Production of the fibers containing viable bacteria was continuous in contrast to the more typical methods in which cells infiltrated or were attached to prepared fi bers. The biohybrid fibers were composed of poly (ethylene glycol dimethacrylate) matrices and individually both E. coli and B. cereus were explored as model cellular payloads. Post processing growth curves (24 h) of bacteria within fi bers were in excellent agreement with that of controls suggesting minimal impact. Finally, the biohybrid fibers showed even distribution of encapsulated cells and > 90% cell viability.

An article to Small entitled Substrate-Baited Nanoparticles: A Catch and Release Strategy for Enzyme Recognition and Harvesting was selected for the cover art.

The isolation of a single type of protein from a complex mixture is vital for the characterization of the function, structure, and interactions of the protein of interest and is typically the most laborious aspect of the protein purifi cation process. In this work, a model system is utilized to show the effi cacy of synthesizing a “baited” nanoparticle to capture and recycle enzymes (proteins that catalyze chemical reactions) from crude cell lysate. Enzyme trapping and recycling is illustrated with the carbazole 1,9a-dioxygenase (CARDO) system, an enzyme important in bioremediation and natural product synthesis. The enzymes are baited with azide modified carbazolyl moieties attached to poly(propargyl acrylate) nanoparticles through a click transformation. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis indicates the single-step procedure to immobilize the enzymes on the particles is capable of signifi cantly concentrating the protein from raw lysate and sequestering all required components of the protein to maintain bioactivity. These results establish a universal model applicable to concentrating and extracting known substrate–protein pairs, but it can be an invaluable tool in recognizing unknown protein–ligand affinities.

An article to Soft Matter entitled Designing fluoroprobes through Förster resonance energy transfer: surface modification of nanoparticles through “click” chemistry.

Abstract: Aqueous-phase 83 nm poly(propargyl acrylate) (PA) nanoparticles were surface-functionalized with sparingly water soluble fluorescent moieties through a copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC) (i.e., “click” transformation) to produce fluoroprobes with a large Stokes shift. For moieties which could not achieve extensive surface coverage on the particles utilizing a standard click transformation procedure, the presence of β-cyclodextrin (β-CD) during the transformation enhanced the grafting density onto the particles. Moieties containing oxadiazolyl groups exhibited an 84% increase in grafting density when the transformation was performed in the presence of the oligosaccharide, going from 1.04 oxadiazolyl groups/nm2 to 1.91 oxadiazolyl groups/nm2. Similarly, an azide-modified coumarin 6 (AD1) underwent a 17% enhancement in grafting density from 1.56 AD1 groups/nm2 to 1.82 AD1 groups/nm2 when the transformation was done in the presence of β-CD. A polyethylene glycol modified naphthalimide-based emitter (AD2) was less sensitive to the presence of β-CD due to its elevated water solubility and exhibited a 5% increase in grafting density. In contrast, a carbazolyl-containing moiety which could achieve 100% surface coverage of the particles without the use of β-CD exhibited a slight retardation in the incorporation rate (and final grafting density) onto the particle when the oligosaccharide was employed. Photoluminescence studies of the particles modified singly or with multiple moieties indicated that when oxadiazolyl and carbazolyl groups were attached to the particles, an exciplex was formed that had a peak emission at ca. 400 nm. The absorption of the surface attached naphthalimide-based dye exhibited a complete spectral overlap with the carbazole/oxadiazole exciplex emission and photoluminescence excitation studies indicated an efficient energy transfer process from the carbazolyl and oxadiazolyl groups to the dye, resulting in an emission maxima at 510 nm for the modified particles and a total Stokes shift of 180 nm. This large Stokes shift is an important determinant of the ultimate sensitivity of a fluoroprobe, where scattering and background fluorescence can interfere with the detection of low concentrations of an analyte and the ability to manipulate the separation between the excitation and emission wavelengths is a critical parameter for optimal detection.

An article to Advanced Materials entitled Functionalization of Crystalline Colloidal Arrays through Click Chemistry was selected for the cover art.

The preparation of well-defined and regioselectively functionalized ordered colloidal particles through the exploitation of ‘click' transformations is presented; specifically, the copper(I)-catalyzed Huisgen 1,3-dipolar cycloaddition between azides and terminal alkynes to form 1,2,3-triazoles is utilized. This approach is demonstrated through the attachment of 9-azidomethylanthracene to post-hydrogel stabilized, ordered poly(propargyl acrylate) colloidal particles.

An article to Advanced Materials entitled Multicolor Pattern Generation in Photonic Bandgap Composites was selected for the cover art.

The generation of complex, permanent, multicolor patterns in photonic bandgap films is demonstrated. The procedure allows for the overall spatial control of the reflected color on the surface of a photonic crystal, as well as the ability to define the visible or near-IR response of a patterned region through control of the stop-band wavelength. For example, the attached image presents a 10 mm wide, orange, “tiger paw” insignia templated on a green background.