Applied Natural Sciences

Spin coating is introduced as a simplified method to prepare model surfaces of cellulose. Prior to spin coating, trimethylsilyl cellulose (TMSC), a nonpolar derivative of cellulose, is synthesized in order to dissolve the otherwise immiscible cellulose. After the spin coating deposition of TMSC on an untreated silicon or gold substrate, the TMSC layer is subjected to vapor phase acid hydrolysis, which regenerates it back to cellulose. X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance infrared spectroscopy (ATR-IR) revealed the films' chemical structure to be similar to pure cellulose. Spin coating parameters such as spinning speed, concentration of the coating solution, and nature of the solvent were varied to obtain diversity in morphology and thickness of the films. The optimal spin coating parameters resulted in a cellulose film with 20 nm thickness and 10% roughness, determined by atomic force microscopy (AFM). Preliminary experiments with modifying the chemistry and varying the ...

A very mild method was developed for the attachment of high-quality organic monolayers on crystalline silicon surfaces. By using visible light sources, from 447 to 658 nm, a variety of 1-alkenes and 1-alkynes were attached to hydrogen-terminated Si (100) and Si (111) ...

ABSTRACT In this paper we present an experimental protocol for protein immobilization on polydimethylsiloxane (PDMS) polymer surfaces and the subsequent application of a chromatographic PDMS microfluidic chip to measure protein–protein interactions. The PDMS surface modification steps are quantitatively and qualitatively experimentally analyzed using an array of techniques (water contact angle measurement, fluorescence spectroscopy and X-ray photoelectron spectroscopy). The protocol involves PDMS acidic surface activation using a potassium disulfite/potassium peroxidisulfate/acrylic acid mixture, followed by amination with 3-aminopropyl diethoxymethylsilane, followed by glutaraldehyde grafting and subsequent covalent protein binding. The applicability of such a miniaturized PDMS-based microfluidic system has been exemplified by measuring protein–protein interactions in a fast and accurate fashion for three model proteins, namely: hen egg white lysozyme, bovine ribonuclease-A and α-chymotrypsinogen. The protein interaction results align well with existing literature data using different materials and techniques. As the fabrication process for PDMS-based microstructures is relatively cheap, quick and requires limited lab expertise/access to specialized equipments, we consider that the implementation of such a flexible, easy to fabricate, PDMS-based microfluidic system for estimating protein interactions an important step toward quickly mapping protein phase behavior and measuring protein (self/cross) interactions in complex biological systems.

Monodisperse iron oxide particles were deposited on a planar silica transmission electron microscope (TEM) grid and from TEM and Energy Filtered TEM analyses it is confirmed that the particles are involved in a series of re-arrangements during the pretreatment and initial carbon nanotube (CNT) growth. It is also shown that CNT growth occurs in two stages; an initial disordered growth, followed by a more aligned growth underneath. The planar silica TEM grid serves the dual purpose of being the catalytic support, and the tool which facilitates TEM analysis on a planar model system. The particle re-arrangements and the two modes of CNT growth may offer an explanation as to why we find no correlation between primary particle size and final CNT diameter.

ABSTRACT Polyethylene films were grown on a flat silica surface modified by the bis(imino)pyridyl iron(II) catalyst during ethylene polymerization in an organic solvent. The resulting films show under certain polymerization conditions superhydrophobic properties. The development of the nascent polymer morphology which leads to the superhydrophobic behavior depends strongly on the polymerization conditions, especially the solvent and the polymerization temperature. Advancing water contact angle as high as 169° and sliding angles as low as 2° for a 10 μl droplet are obtained on these films. SEM images reveal special surface structures of these films containing micrometer-sized islands, submicrometer particles on the islands, and stress nanofibers between the islands, which — in combination — render superhydrophobicity to the polyethylene surfaces.