Aldehyde Particles

Wash 10 mg of aldehyde particles 3 times with 10 mM sodium phosphate, pH 7.4 (coupling buffer). Buffers of higher pH value (i.e., carbonate buffer at pH 10) will result in more efficient Schiff base formation with amine-containing molecules than neutral pH conditions. 

After the final wash, suspend the particles at 5-10 mg/ml in coupling buffer and add a protein to be coupled to the particle suspension in an amount equal to 1-10 X molar excess over the calculated monolayer for the protein type to be coupled. (Note It takes about 18 mg of BSA or 15 mg of IgG to saturate 1 g of 1 pm particles, and more protein if the particles are smaller.) Mix thoroughly to dissolve. Low concentrations of protein may result in particle aggregation, because a single protein molecule can react and bridge more than one particle. 

Incubate with mixing for 2-4 hours at room temperature. 

Add to the particle suspension a quenching molecule (such as glycine, ethanolamine, or Tris) to give a final concentration of 0.2 M. The blocking agent will couple to any remaining aldehyde-reactive sites. 

Remove excess protein and reactants by washing with coupling buffer at least 3 times using centrifugation. Store particles in a suitable buffer containing a preservative. 

---

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 14.21 Aldehyde-particles can be reacted with amine-containing proteins or other molecules to form intermediate Schiff bases, which can be stabilized by reduction with sodium cyanoborohydride.

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). 

Whenever unvented combustion occurs iadoors or when venting systems attached to combustion units malfunction, a variety of combustion products win be released to the iadoor environment. Iadoor combustioa units include nonelectric stoves and ovens, furnaces, hot water heaters, space heaters, and wood-burning fireplaces or stoves. Products of combustion include CO, NO, NO2, fine particles, aldehydes, polynuclear aromatics, and other organic compounds. Especially dangerous sources are unvented gas and kerosene [8008-20-6] space heaters which discharge pollutants directly into the living space. The best way to prevent the accumulation of combustion products indoors is to make sure all units are properly vented and properly maintained. 

Uses of Formaldehyde. Formaldehyde is the simplest and most reactive aldehyde. Condensation polymerization of formaldehyde with phenol, urea, or melamine produces phenol-formaldehyde, urea formaldehyde, and melamine formaldehyde resins, respectively. These are important glues used in producing particle hoard and plywood. 

In the chemical industry, simple aldehydes and ketones are produced in large quantities for use as solvents and as starting materials to prepare a host of other compounds. For example, more than 1.9 million tons per year of formaldehyde, H2C=0, is produced in the United States for use in building insulation materials and in the adhesive resins that bind particle hoard and plywood. Acetone, (CH.3)2C"0, is widely used as an industrial solvent approximately 1.2 million tons per year is produced in the United States. Formaldehyde is synthesized industrial ) by catalytic oxidation of methanol, and one method of acetone preparation involves oxidation of 2-propanol. 

Interestingly, free nano-iron oxide particles are active catalysts for the selective oxidation of alcohols to yield the corresponding aldehydes/ketones [72, 73]. Different aromatic alcohols and secondary aliphatic alcohols were oxidized with high selectivity, but at low conversion. Here, further improvement should be possible (Scheme 25). 

Further indications for an additional subunit were provided by a crosslinking analysis of C Eg solubilized H,K-ATPase, which exhibited ATPase and phosphatase activities, and ligand affinities comparable to the native enzyme [70]. Glutar-aldehyde treatment of soluble protein fractions resolved on a linear glycerol gradient revealed no active fraction enriched in monomeric (A/p = 94 kDa) H,K-ATPase. Instead, K -ATPase activity was only obtained in fractions enriched in particles of Mr = 175 kDa. This size also suggested that the functional H,K-ATPase unit is a heterodimer of a catalytic subunit and an additional subunit, since the apparent molecular mass of 175 kDa is probably too small to be a homodimer of the catalytic subunit. 

Gelatin and albumin nanoparticles have been prepared through desolvation of the dissolved macromolecules by either salts (e.g., sodium sulfate or ammonium sulfate) or ethanol [179-182], This is, in principle, similar to a simple coacervation method. The particles can then be insolubilized through cross-linking with an optimum amount of aldehydes. These phase separation methods avoid the use of oils as the external phase. 

Controlling fluid loss loss is particularly important in the case of the expensive high density brine completion fluids. While copolymers and terpolymers of vinyl monomers such as sodium poly(2-acrylamido-2-methylpropanesulfonate-co-N,N-dimethylacrylamide-coacrylic acid) has been used (H)), hydroxyethyl cellulose is the most commonly used fluid loss additive (11). It is difficult to get most polymers to hydrate in these brines (which may contain less than 50% wt. water). The treatment of HEC particle surfaces with aldehydes such as glyoxal can delay hydration until the HEC particles are well dispersed (12). Slurries in low viscosity oils (13) and alcohols have been used to disperse HEC particles prior to their addition to high density brines. This and the use of hot brines has been found to aid HEC dissolution. Wetting agents such as sulfosuccinate diesters have been found to result in increased permeability in cores invaded by high density brines (14). 

In general, the results point to the edges and/or corners (small particles) favoring hydrogenation of the C=C bond whereas the planes (large particles) favor hydrogenation of the C=0 bond. This seems to be true for all compounds on Pt (see Table 2.6, lines 10-27, and 29-30) and for cinnamaldehyde on Ru and Rh (see Table 2.6, lines 33, 34, 37, and 38) however, citral on Ru did not exhibit this effect (see Table 2.6, lines 35 and 36), according to the authors statement. The reasons for this latter result are not clear. Why, for example should other alkyl-substituted a,P-unsaturated aldehydes exhibit this structure sensitivity and citral not Clearly, other factors are also at play. 

Interestingly, in some cases the IL itself can act as the reductive agent. Spherical metal silver NPs were prepared in a hydroxyl-functionalized IL (2) (entry 30, Table 1.1) [17]. In this case, the hydroxyl moiety of the IL plays a reductive role, being oxidized to the corresponding aldehyde. In a similar manner, for Au(III) precursors, the imidazolium cation itself can act as a reducing agent to yield prismatic particles in BMI.PF6 with a very broad size range of diameter 3-20 pm and thickness... 

---