Cross linking, BSA

These data indicate that the membrane became more compact and less ion-permeable at lower pH and this permeability decreased even more as a result of atrazine binding. These results can be explained by protein conformation changes upon interaction with herbicide. It is noteworthy that the responses to atrazine were noticeable in the acid media only and that these responses were irreversible. Because of poorly controllable properties and disordered structure of the cross-linked BSA matrix, reproducibility of sensor performance was insufficient. 

Fig. 13 (A) Chemical structure of 45 and schematic illustration of glutaraldehyde-cross-linked BSA dot incorporating aggregates of 45 and (B) their SEM image, (C) Confocal image of MCF-7 breast cancer cells after incubation with the dots, (D) In vivo noninvasive fluorescence imaging of H22 tumor-bearing mice after intravenous injection of the dots. The white circle marks the tumor site. Reproduced with permission from ref, 85 ( 2013, American Chemical Society), and ref, 86 ( 2011, Wiley-VCH),...

We have observed that such proteins as CaM and bovine serum albumin (BSA) can be developed at the air-water interface to form monolayer protein films. In previous works, the developed BSA monolayer was stabilized by cross-linking with a bifunctional reagent immediately after the preparation of protein monolayer. The BSA thin film thus prepared can be employed as a passive material, e.g., an ultrathin protein film for a matrix of enzyme-linked immunosorvent assays. 

Figure 281 EDC conjugation reactions can be extraordinarily consistent using the same peptide cross-linked to two carrier proteins. This figure shows the gel filtration pattern on Sephadex G-25 after completion of the cross-linking reaction. Conjugation of tyrosyl-lysine to BSA and KLH are shown. The first peaks represent eluting carrier, while the second peaks are the excess peptide. Note the consistency of conjugation using the same levels of EDC addition.

Figure 282 Conjugation to KLH often can cause precipitation due to the high molecular weight of the carrier protein. The conjugation of [Met5]-enkephalin to KLH yields a soluble immunogen if the level of EDC addition is about 0.1 times that typically used with BSA as a carrier. The figure shows the gel filtration pattern on Sephadex G-25 after completion of the cross-linking reaction. The first peak is KLH and the second peak is excess peptide. Depletion of the peptide peak correlates to hapten—carrier conjugation.

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. 

Fig. 2.19 Glutaraldehyde cross-linking of enzyme E with bovine serum albumin (BSA), followed by Li borohydride stabilization...

Agin et al. [83] Hypoxanthine Sardines Chicken Xanthine oxidase/cross-linked with glutaraldehyde and BSA Carbon paste electrode modified with electrodeposited gold nanoparticles/O V vs. Ag/ AgCl ... 

Basu et al. [85] Hypoxanthine Fish Meat Xanthine oxidase (XO)/ cross-linked with glutaraldehyde in the presence of BSA. Covered with gelatine and a membrane of cellulose acetate ... 

Cross-linked with BSA and Nafion using glutaraldehyde Prussian blue 90 2 0.1 -50 - Ricci et al. [23]... 

Cross-linked with BSA using glutaraldehyde Copper-plated SPCE 26.7 Peak in linear sweep voltammogram at 150 mV Kumar and Zen [31]... 

Balmer et al. [60] separated the two enantiomers of omeprazole on three different stationary phases with immobilized protein, viz, Chiral-AGP with a-1 acid glycoprotein, Ultron ES-OVM with ovomucoid, and BSA-DSC with BSA cross-linked into 3-aminopropyl silica using N-suc-cinimidyl carbonate. The mobile phase (1 ml/min) was phosphate buffer solution with 3—10% 2-propanol as the organic modifier. The enantiomers of omeprazole were separated on Chiralpak AD, an amylose-based chiral stationary phase, with ethanol-hexane (1 4) as mobile phase (1 ml/min). 

We report a simple and direct pre-embedding technique for processing scarce biological specimens for LM and EM. It is based on pre-embedding the samples in BSA and BA, cross-linked and polymerized. The technique is compatible with a broad range of LM and EM protocols and procedures. 

We report a simple and direct pre-embedding technique for processing scarce biological specimens for LM and EM the samples are pre-embedded in BSA and BA, cross-linked and polymerized. The technique is compatible with a broad range of LM and EM protocols and procedures. It is applicable to tissues and cells, prepared as pellet or suspension. The technique represents an improvement over others, like the ability to visualize the samples once pre-embedded and a better resistance to histological processing. It allows a more efficient and reproducible analysis of the samples by LM and EM. The technique is... 

Troupe and his coworkers reported a two-step method to electrochemically deposit GOx enzyme on a diamond film electrode (Troupe et al. 1998). In the first step, the GOx and BSA were dissolved in a buffer with pH = 7, greater than their isoelectric points. The BDD electrode was immersed into the solution and biased at 3.5 V for 2 h. Therefore, the negatively charged proteins (GOx and BSA) were drawn to the positively charged electrode. In the second step, the glutaraldehyde (GA) cross-links the protein layer forming a water insoluble barrier. 

Carbonaceous substrates (graphite and glassy carbon) are generally preferred because of their mechanical, chemical, and electrochemical properties. Excellent results are also obtained by chemically modified platinum (154,156,179) and tin(IV) oxide electrodes (155). For example, glucose oxidase has been successfully immobilized by cross-linking the enzyme with BSA and GA onto an electrochemically oxidized platinum surface, with silanization using 3-amino-propyltriethoxysilane ... 

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