Glutaraldehyde possesses unique characteristics that render it one of the most effective protein crosslinking reagents. It can be present in at least 13 different forms depending on solution conditions such as pH, concentration, temperature, etc. Substantial literature is found concerning the use of glutaraldehyde for protein immobilization, yet there is no agreement about the main reactive species that participates in the crosslinking process because monomeric and polymeric forms are in equilibrium. Glutaraldehyde may react with proteins by several means such as aldol condensation or Michael-type addition, and we show here 8 different reactions for various aqueous forms of this reagent. As a result of these discrepancies and the unique characteristics of each enzyme, crosslinking procedures using glutaraldehyde are largely developed through empirical observation. The choice of the enzyme-glutaraldehyde ratio, as well as their final concentration, is critical because insolubilization of the enzyme must result in minimal distortion of its structure in order to retain catalytic activity. The purpose of this paper is to give an overview of glutaraldehyde as a crosslinking reagent by describing its structure and chemical properties in aqueous solution in an attempt to explain its high reactivity toward proteins, particularly as applied to the production of insoluble enzymes.

https://www.future-science.com/doi/pdf/10.2144/04375RV01

Glutaraldehyde: behavior in aqueous solution, reaction with proteins, and application to enzyme crosslinking.

Results from photooxidation of aromatic compounds in a reaction chamber show that a substantial fraction of the organic aerosol mass is composed of polymers. This polymerization results from reactions of carbonyls and their hydrates. After aging for more than 20 hours, about 50% of the particle mass consists of polymers with a molecular mass up to 1000 daltons. This results in a lower volatility of this secondary organic aerosol and a higher aerosol yield than a model using vapor pressures of individual organic species would predict.

https://science.sciencemag.org/content/sci/303/5664/1659.full.pdf

Identification of polymers as major components of atmospheric organic aerosols.

Glutaraldehyde as a fixative in bioprostheses and drug delivery matrices.

Publisher Summary There have been many reviews and books on electron spin resonance (ESR) and several on transition metal ions. Many of these publications have been written by physicists or theoreticians and are very comprehensive. This review is aimed at inorganic chemists, who have had no experience relating to electron spin resonance and who are becoming more and more likely either to use the technique or to need to appreciate the significance of the information available from the technique. The first part of the review gives an elementary account of the relevant theory. There are many good books for further reading for the inorganic chemist, who wishes to go deeper into the subject. The second part of the review is a comprehensive survey of the results of ESR studies on compounds of transition elements. Inevitably, there has had to be some selection of material, and the criteria for inclusion or rejection has been based upon the likely interest of an inorganic chemist might have in the species. This is particularly in the areas, where there is a lot of related work, e.g., the Mn2+ host-lattice data. In the case of copper dg complexes, there has been much duplication of work and papers devoted to the spectra of complexes where a minor substitutive change has been made to a bulky organic ligand.

Electron Spin Resonance of Transition Metal Complexes

Atmospheric oxalic acid and SOA production from glyoxal: Results of aqueous photooxidation experiments

An experimental apparatus is described which allows the trapping of preferentially oriented molecules in neon and argon matrices at 4°K and the measurement of their ESR spectra at various orientations relative to the magnetic field. Application to Cu(NO3)2, vaporizing at 150°C, and CuF2, vaporizing at 925°C, demonstrates that the degree of orientation is dependent upon the temperature of the vaporizing molecule and the matrix gas used. The ESR spectra of highly oriented Cu(NO3)2 in neon at 4°K (there was essentially no orientation in argon) indicate that the molecule is planar with the four nitrate oxygen atoms surrounding the Cu++ ion in a square array. The g and A values are very similar to those found in copper chelate molecules: g∥ = 2.2489±0.003, g⊥ = 2.0522±0.0005, A∥ (63Cu) = 570±3 Mc/sec, and A⊥ (63Cu) = 50±3 Mc/sec. Computer simulation of the spectra not only confirms this assignment but provides an estimate of the degree of orientation as a function of the inclination. CuF2 isolated in argon at ...

Earl B. Whipple

Papers

ESR of Cu(NO3)2 and CuF2 Molecules Oriented in Neon and Argon Matrices at 4°K

Structure of aqueous glutaraldehyde

Structure of glyoxal in water

Electron spin resonance study of phenyl radicals isolated in an argon matrix at 4.deg.K

Deuterium isotope effects on carbon-13 NMR shifts and the tautomeric equilibrium in N-substituted pyridyl derivatives of piroxicam