Broad immobilization

In this chapter we describe the basic principles involved in the controlled production and modification of two-dimensional protein crystals. These are synthesized in nature as the outermost cell surface layer (S-layer) of prokaryotic organisms and have been successfully applied as basic building blocks in a biomolecular construction kit. Most importantly, the constituent subunits of the S-layer lattices have the capability to recrystallize into iso-porous closed monolayers in suspension, at liquid-surface interfaces, on lipid films, on liposomes, and on solid supports (e.g., silicon wafers, metals, and polymers). The self-assembled monomolecular lattices have been utilized for the immobilization of functional biomolecules in an ordered fashion and for their controlled confinement in defined areas of nanometer dimension. Thus, S-layers fulfill key requirements for the development of new supramolecular materials and enable the design of a broad spectrum of nanoscale devices, as required in molecular nanotechnology, nanobiotechnology, and biomimetics [1-3]. 

BB-SFG, we have investigated CO adsorption on smooth polycrystaHine and singlecrystal electrodes that could be considered model surfaces to those apphed in fuel cell research and development. Representative data are shown in Fig. 12.16 the Pt nanoparticles were about 7 nm of Pt black, and were immobilized on a smooth Au disk. The electrolyte was CO-saturated 0.1 M H2SO4, and the potential was scanned from 0.19 V up to 0.64 V at 1 mV/s. The BB-SFG spectra (Fig. 12.16a) at about 2085 cm at 0.19 V correspond to atop CO [Arenz et al., 2005], with a Stark tuning slope of about 24 cm / V (Fig. 12.16b). Note that the Stark slope is lower than that obtained with Pt(l 11) (Fig. 12.9), for reasons to be further investigated. The shoulder near 2120 cm is associated with CO adsorbed on the Au sites [Bhzanac et al., 2004], and the broad background (seen clearly at 0.64 V) is from nomesonant SFG. The data shown in Figs. 12.4, 12.1 la, and 12.16 represent a hnk between smooth and nanostructure catalyst surfaces, and will be of use in our further studies of fuel cell catalysts in the BB-SFG IR perspective. 

Precipitation is the most promising method for immobilizing dissolvable metals such as lead, cadmium, zinc, and iron.15 Some forms of arsenic, chromium, mercury, and some fatty acids can also be treated by precipitation.47 The common precipitating chemicals for metal cations are sulfide, phosphate, hydroxide, or carbonate. Among them, sulfide is the most promising, because sulfides have low solubility over a broad pH range. Precipitation is most applicable to sites with sand or coarse silt strata. 

NMR Measurement of The Residual Water. The residual water obtained in Experiments No. 5 and No. 6 was measured with a broadline NMR spectrometer, in which, proton signal of the water gives a very broad line. The full width at half height of the NMR signal is 15750 Hz and 18000 Hz for samples obtained in Experiments No. 5 and No. 6, respectively. The line width for liquid water is normally less than 5 Hz while the line width for polycrystalline ice is 56000 Hz (39). Therefore, the residual water is expected to have a mobility closer to ice than to liquid water. The wider line given by sample obtained in Experiment No. 6 seems to agree with the expectation that the water is more immobile at higher electrolyte concentration. 

In order to extend the biocatalytic activities of the biotransformation processes and reduce the frequency of producing cell mass and undesirable side products, immobilized-cell technology has been successfully applied to the whole-cell biotransformation processes. In addition to the three commercial immobilized whole-cell biotransformation processes shown in Table 10.1, examples of immobilization of three different microorganisms for whole-cell biotransformations are shown below to demonstrate the broad application of the immobilized whole-cell biotransformation processes. 

The ssDNA-PEG-lipid provides versatility in cell surface modifications. It enables the immobilization of a broad spectrum of proteins and low molecular... 

Capture array Non-protein molecules that interact with proteins are immobilized on the surface. These may be broad capture agents based on surface chemistries such as the Ciphergen Protein Chip, or may be highly specific such as molecular imprinted polymers or oligonucleotide aptamers... 

The physical adsorption of protein onto the surface of an electrode is a simple immobilization method. The adsorption is obtained by volatilizing the buffers containing proteins. The physical adsorption needs no chemical reagent, seldom activation and rinse, so that the bioactivities of the immobilized proteins can be retained well. However, the immobilized proteins are easy to break off from the electrode, which restrict broad applications of this method. Below are some examples of the physical adsorption of proteins immobilized on electrodes. 

In model studies involving Fe(n) species, three broad approaches have been used to mitigate the problem of autoxidation of the iron (Hay, 1984). These are (i) the use of low temperatures so that the rate of oxidation becomes very slow (ii) the synthesis of ligands containing steric barriers such that dimerization of the iron complex is inhibited, and (iii) immobilization of the iron complex on a solid surface such that dimerization once again will not be possible. 

The biomimetic protocol was invented by Julia and Colonna, and involves the use of polyamino acids (such as poly-(L)-leucine) as the catalysts for peroxide oxidation of chalcones, styryl alkyl ketones and conjugated alkenones. The substrate range is broad, especially when using immobilized catalysts and an organic solvent containing the substrate, urea-hydrogen peroxide and an organic base (Scheme 22)[101]. 

---