Glutaraldehyde protein immobilization

The first enzymatically coupled FET is sensitive to penicillin (1). It is composed of two separate FET chips and a silver/silver chloride reference electrode (see Fig. 4). Penicillinase, which produces protons during catalysis, is immobilized on one of the FET chips by utilizing the glutaraldehyde protein cross-linking reaction. The membrane of the reference FET chip contains immobilized bovine serum albumin. 

Walt DR and Agayn VI. The chemistry of enzyme and protein immobilization with glutaraldehyde. Trends Anal. Chem. 1994 13 425 30. 

Fig. 3. Immobilization of antibody on the PZ resonator. Gold modified with cysteamine SAM was activated with glutaraldehyde, protein A was covalently attached and captured Ab.

PAMAM dendrimer modified magnetite nanoparticles were tested as supports for GpdQ and a biomimetic complex. Previous studies have shown that a G3-PA-MAM dendrimer has a beneficial effect for protein immobilization opposed to unsubstituted MNP [1]. The dendrimer was build up stepwise by alternating additions of methanofic methyl acrylate and ethylenediamine solutions. The pendant amine functions were then further functionalized with glutaraldehyde. 

In another investigation, ELP[V5L2G3-90] with three lysines in the N-terminal region was immobihzed on a glass surface in a microreactor to enable temperature-controlled positioning of ELP fusion proteins. For this purpose, the glass surface was first functionalized with A -2-(aminoethyl)-3-aminopropyltrimethoxysilane, followed by glutaraldehyde treatment and reductive amination to immobilize the biopolymer on the surface (Fig. 17b) [132]. 

Affinity microparticles (AMPs) were obtained by cross-linking the S-layer lattice on S-layer-carrying cell wall fragments with glutaraldehyde, reducing Schiff bases with sodium borohydride, and immobilizing protein A as an IgG-specific ligand [92]. Thus, AMPs rep-... 

Purified MeHNL was crystallized by the sitting-drop vapor-diffusion method. The 10-20 mm bipyramidal crystals formed were cross-linked with glutaraldehyde and used as biocatalyst for the synthesis of optically active cyanohydrins. The cross-linked crystals were more stable than Celite-immobilized enzymes when incubated in organic solvents, especially in polar solvents. After six consecutive batch reactions in dibutyl ether, the remaining activity of the cross-linked crystals was more than 70 times higher than for the immobilized enzymes. Nevertheless, the specific activity of the cross-linked crystals per milligram protein was reduced compared with the activity of Celite-immobilized enzymes [53],... 

A simple, one-step immobilization technique is bulk cross-linking of the functional protein with bovine serum albumin (BSA) using glutaraldehyde as the cross-linking agent (Fig. 2.19). It is popular because of its simplicity, but it usually leads to reduction of the biological activity of the biomolecule. A cleaner and preferable approach is the two-step carbodiimide route. A partial summary of the various immobilization options was shown in Table 2.3. 

AOD was immobilized on aminopropyl glass beads that were first treated with 2.5% glutaraldehyde, staying in contact with the enzyme for 24 h at 30°C in a rotatory shaker incubator at 50 rpm. The protein concentration in buffer solution was quantified before (PCBI) and after (PCAI) the immobilization proceeding, using the Lowry method. The retention efficiency was calculated using Eq. 1. 

Arenkov et al. prepared poly(acrylamide) gel pads for use in protein microarrays [199], The gels were prepared by photopolymerization of acrylamide and crosslinkers. Capture probes were immobilized, either by use of glutaraldehyde or by converting some of the acrylamide groups into hydrazides and subsequent coupling of aldehyde-modified antibodies to the pending hydrazide groups. Then, immunoassays were performed on the pads, either assays with directly labeled analytes or sandwich assays. Furthermore, the gel pads were used for enzyme activity studies. 

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