Particles hydrazide-containing

Another route to the formation of a hydrazide on a surface is to use an aldehyde-containing particle (such as HEMA/acrolein copolymers) and subsequently modify the aldehydes to form hydrazone linkages with bis-hydrazide compounds, which then can be stabilized by reduction with sodium cyanoborohydride (Chapter 2, Section 5). The resulting derivative contains terminal hydrazides for immobilization of carbonyl ligands (see Figure 14.18). 

Figure 14.18 Carboxylate-particles or aldehyde-particles can be modified with the carbohydrazide in excess to create a hydrazide-particle that can be used to couple with aldehyde-containing molecules.

Figure 14.19 Aldehyde-containing molecules, such as periodate-oxidized carbohydrates or glycoproteins, can be coupled to hydrazide-particles to form a hydrazone bond. This bond can be further stabilized by reduction...

After the final wash, resuspend the particles at a concentration of 10 mg/ml in coupling buffer and add an appropriate amount of the solution from step 6, which contains the purified, oxidized antibody. The amount of oxidized antibody to add to the particles should be about 1-10 X over the amount of the calculated monolayer for the particle type used. (Note For 100 mg of 1 pm hydrazide particles, a monolayer equivalent of antibody will be about 1.5 mg, so the total amount added should be in the range of 1.5-15 mg for a 1-10 X excess). 

Aldehyde particles are spontaneously reactive with hydrazine or hydrazide derivatives, forming hydrazone linkages upon Schiff base formation. Reactions with amine-containing molecules, such as proteins, can be done through a reductive amination process using sodium cyanoborohydride (Figure 14.21). 

Hybrid dynamic proteoids, containing alternating imine and acylhydrazone linkages, have been obtained by polycondensation of amphiphilic dialdehydes with amino acid hydrazides. The polymerization displays nucleation-elongation behavior driven by hydrophobic effects, resulting in the formation of globular particles reminiscent of folded proteins (Fig. 6) [89]. 

The polymer particles contain co-polymerized carbonyl groups which, on film formation, react with hydrazide groups of the water-soluble acid dihydrazide to form hydrazone. Increased cohesion strength results due to both inter-particle and intraparticle crosslinking reactions. A similar process also occurs between corona-pre-treated polypropylene film and the emulsion adhesive thereby significantly increas-... 

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