Pierce Biotechnology Inc. is the ultimate origin of a number of products and product lines in the Thermo Fisher Scientific research and development division, "Thermo Scientific Pierce Protein Biology." The company from which this division originated, the Rockford, Illinois-based Pierce Chemical Company (PCC) was founded in 1948 when Alan Pierce assumed active management of a company known as Midwest Extraction, which focused on isolating chlorophyll from alfalfa (to take advantage of 1930s research arguing therapeutic uses for chlorophyll in infections, burns, and amputation).[not verified in body]In assuming leadership of the company, Pierce transitioned the company to being a manufacturer of fine organic chemicals, giving it the PCC name in 1950. Among other advances, PCC was the first commercial manufacturer of ninhydrin for use in amino acid analysis. After the first several years, the company diversified into other products and markets.[clarification needed] Roy Oliver succeeded Pierce as company president in 1965 (Pierce remaining affiliated with eponymous products and business units until his retirement in 1994). Under Oliver, PCC expanded its operations internationally, entering into agreements with European distributors. The company's focus began to shift in the 1970s from the manufacture of organic chemical products at scale, to research, development, and production, of high-purity reagents for biotechnology research at smaller scales—resulting in its name chance to Pierce Biotechnology (PBT).[when?][verification needed] PBT became a subsidiary of Perstorp Group in the Perstorp Life Science Division, was spun off as a component of this division as Perbio Science AB, which was subsequently acquired by Fisher Scientific International in 2003.Fisher merged with Thermo Electron in 2006, bringing some former PCC and PBT product lines of Perbio Science AB under Thermo Fisher Scientific management, as brands of its "Thermo Scientific Pierce Protein Biology" division.
This chapter discusses one of the most defined nanoparticle constructs, which is a unique polymeric assemblage called a dendrimer. Dendrimers are monodisperse, globular macromolecules grown by successive synthetic steps from a central core molecule. Each step, called a generation, adds a distinct layer to the previous one so that a dendrimer grows out from the core like the branches of a tree. The result is a polymeric molecule having a fractal dimensional quality with properties and shape that are determined by the types of monomers used to grow the branches. Dendrimers can have almost limitless properties depending on the methods and materials used for their synthesis. Characteristics can include hydrophilic or hydrophobic regions, the presence of functional groups or reactive groups, metal chelating properties, core/shell dissimilarity, electrical conductivity, hemispherical divergence, biospecific affinity, photoactivity, or the tendency to be selectively cleavable at particular points within their structure. Dendrimers have been used for many diverse applications within the biological, chemical, polymer, and nanotechnology fields. Some major applications include their use as multivalent bioconjugation scaffolds, for enhancement of signals in assays, to solubilize hydrophobic molecules in aqueous environments by internal entrapment, to functionalize surfaces and particles for conjugation, as transfection agents for cells, to create targeted therapeutic constructs for the treatment of disease, as carriers of affinity ligands, and as additives for other polymer mixtures.
This chapter provides an overview of the major reactions used in bioconjugation techniques. Each reaction is briefly discussed and illustrated, while providing key references from the literature or other parts of the book where they have been used for bioconjugation purposes. These reactions are further organized by the general reactivity or functional group that is involved in the associated conjugation process, such as amine reactions, thiol reactions, carboxylate reactions, hydroxyl reactions, aldehyde and ketone reactions, active hydrogen reactions, photochemical reactions, and cycloaddition reactions. Knowledge of the reactions of bioconjugation as discussed in this chapter combined with knowledge of the targets of bioconjugation and their functional groups as discussed in Chapter 2 can provide a firm foundation for making virtually any bioconjugate imaginable.
This chapter discusses the smallest available reagent systems for bioconjugation, called zero-length crosslinkers. These compounds mediate the conjugation of two molecules by forming a bond containing no additional atoms. Thus, one atom of a molecule is covalently attached to an atom of a second molecule with no intervening linker or spacer. In many conjugation schemes, the final complex is bound together by virtue of chemical components that add foreign structures to the substances being crosslinked. Zero-length cross-linking agents eliminate the potential for this type of cross-reactivity by mediating a direct linkage between two substances. The reagents described in this chapter can initiate the formation of three types of bonds: anamide linkage made by the condensation of a primary amine with a carboxylic acid, a phosphoramidate linkage made by the reaction of an organic phosphate group with a primary amine, and a secondary or tertiary amine linkage made by the reductive amination of a primary or secondary amine with an aldehyde group. Therefore, using these reagent systems, substances containing amines can be conjugated with other molecules containing phosphates or carboxylates. Alternatively, substances containing amines can be crosslinked to molecules containing formyl groups. All of the reactions are quite efficient, and depending on the reagent chosen and the desired application, they may be performed in aqueous or nonaqueous environments.
