Acetylene plasma polymerized surfaces for covalent immobilization of dense bioactive protein monolayers

Smooth polymerized surfaces, suitable for biochemical and biomedical applications, were deposited using a modified plasma enhanced chemical vapour deposition method with acetylene as a reaction precursor. Horseradish peroxidase (HRP) activity assays showed that the protein immobilized on the plasma polymerized surfaces maintained its biological function for a much longer period of time compared to that on uncoated surfaces. The kinetics of HRP attachment to the plasma polymerized surfaces were analyzed using quartz crystal microbalance with dissipation analysis. Spectroscopic ellipsometry and attenuated total reflection Fourier transform infrared spectroscopy were used to determine the thickness and the quantity of the attached protein. The results showed that the plasma polymerized surfaces provided a high density of attachment sites to covalently immobilize a dense monolayer of proteins.

Synthesis of Al3BC from mechanically milled and spark plasma sintered Al-MgB2 composite materials

The aluminium-rich ternary aluminium borocarbide, Al₃BC was synthesised for the first time by solid-state reactions occurring during heat treatments after mechanical milling (MM) of pure aluminium with 15 or 50 at% MgB₂ powder mixtures in the presence of the process control agent (PCA).

The solid-state reactions in the Al–15 and 50 at% MgB₂ composite materials occurred between the MMed powders and process control agent (PCA) after heating at 773–873 K for 24 h. The products of the solid-state reaction induced Al₃BC, AlB₂, γ-Al₂O₃ and spinel MgAl₂O₄. MM processing time and heating temperatures in the Al–15 and 50 at% MgB₂ composite materials affected the selection of those intermetallic compounds. When MM processing time was increased for a given composition, the formation of the Al₃BC compound started at lower heat treatment temperatures. However, when the amount of MgB₂ was increased in the 4 h MM processing regime, the formation of the Al₃BC compound during heating was suppressed. As a result of the solid-state reactions in MMed powders the hardness was observed to increase after heating at 573–873 K for 24 h.

The fully dense bulk nano-composite materials have been successfully obtained through the combination of the MM and spark plasma sintering (SPS) processes for the 4 h or 8 h MMed powders of the Al–15 at% MgB₂ composite materials sintered under an applied pressure of 49 MPa at 873 K for 1 h.