Analysis of Fluorescent Proteins with a Nanoparticle Probe

This Letter presents the first application of high-energy, single nanoparticle probes (e.g., 520 keV Au₄₀₀ 2 nm NP) in the characterization of surfaces containing fluorescent proteins (e.g., GFP variants) by their coemitted photon, electron and secondary ion signals. NP-induced protein luminescence increases with the NP incident energy, is originated by the NP impact, and is transferred to the protein fluorophor via electronic energy transfer. Multielectron emission is observed per single NP impacts, and their distributions are specific to the target morphology and composition. Fragment ions of protein subunits consisting of 2–7 amino acid peptides are observed under individual NP impacts that can be correlated to the random protein orientation relative to the impact site (e.g., outer layer or “skin” of the protein)

Noradrenaline-Functionalized Hyperbranched Fluoropolymer–Poly(ethylene glycol) Cross-Linked Networks As Dual-Mode, Anti-Biofouling Coatings

The strategy of decorating antibiofouling hyperbranched fluoropolymer–poly(ethylene glycol) (HBFP-PEG) networks with a settlement sensory deterrent, noradrenaline (NA), and the results of biofouling assays are presented. This example of a dual-mode surface, which combines both passive and active modes of antibiofouling, works in synergy to improve the overall antibiofouling efficiency against barnacle cyprids. The HBFP-PEG polymer surface, prior to modification with NA, was analyzed by atomic force microscopy, and a significant distribution of topographical features was observed, with a nanoscopic roughness measurement of 110 ± 8 nm. NA attachment to the surface was probed by secondary ion mass spectrometry to quantify the extent of polymer chain-end substitution with NA, where a 3- to 4-fold increase in intensity for a fragment ion associated with NA was observed and 39% of the available sites for attachment were substituted. Cytoskeletal assays confirmed the activity of tethered NA on adhering oyster hemocytes. Settlement assays showed deterrence toward barnacle cyprid settlement, while not compromising the passive biofouling resistance of the surface. This robust strategy demonstrates a methodology for the incorporation of actively antibiofouling moieties onto a passively antibiofouling network

Nanoscopic Cylindrical Dual Concentric and Lengthwise Block Brush Terpolymers as Covalent Preassembled High-Resolution and High-Sensitivity Negative-Tone Photoresist Materials

We describe a high-resolution, high-sensitivity negative-tone photoresist technique that relies on bottom-up preassembly of differential polymer components within cylindrical polymer brush architectures that are designed to align vertically on a substrate and allow for top-down single-molecule line-width imaging. By applying cylindrical diblock brush terpolymers (DBTs) with a high degree of control over the synthetic chemistry, we achieved large areas of vertical alignment of the polymers within thin films without the need for supramolecular assembly processes, as required for linear block copolymer lithography. The specially designed chemical compositions and tuned concentric and lengthwise dimensions of the DBTs enabled high-sensitivity electron-beam lithography of patterns with widths of only a few DBTs (sub-30 nm line-width resolution). The high sensitivity of the brush polymer resists further facilitated the generation of latent images without postexposure baking, providing a practical approach for controlling acid reaction/diffusion processes in photolithography