Direct Chemical Modification

The surface of polymeric materials such as polypropylene (PP), PS, polyacrylonitrile (PAN), and nylon was oxidized by immersing them in aqueous solution of oxidizing agents such as potassium peroxy disulfate under nitrogen purging at high temperatures [ 14]. Graft polymerization of water-soluble monomers such as AAm, methacrylic acid, and 3-aminopropyl methacrylate has been frequently performed in aqueous solution with the use of ceric ion, for instance, at 

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Direct chemical modification of butirosin (ribostamycin analog with AHB at N-1) has led to the synthesis of several butirosin derivatives (Figure 4.9). These butirosin analogs manifested superior activity than butirosin A, especially... 

Other research being conducted at Case Western Reserve University under the direction of Dr. Lawrence Sayre is a study in which analogs of 2,5-hexanedione will be synthesized, studied chemically, and biologically evaluated in an effort to clarify the structural basis of toxicity, particularly in respect to the direct chemical modification of neurofilament proteins by these analogs or any of their metabolites. 

The surface modification of polymers for improvement of adhesive bonding, and altering surface properties in general without concomitant modification of bulk properties is an active area of research in both industrial and academic laboratories and has been accomplished by a variety of means ranging from Corona discharge treatment, direct chemical modification and by interaction with plasmas excited in inert gases either capacitively or inductively27. ... 

Entrapment and Encapsulation - Biological components are physically included in a compartment. No direct chemical modifications of molecules are... 

MSi and RSi). By involving these centers in the reactions with gas-phase molecules, one can conduct directional chemical modification of their structure (Table 7.3) and quantitatively convert them from one form to the other. This lies at the basis of the method for preparing the surface-stabilized PCs of the type (=Si -0)2Sia -r, where r — H(D), OH(OD), NH2, CH3(CD3), C2H5, etc. in silica [18,19]. This method amounts to generating low-molecular mobile radicals r in the reaction between the surface-stabilized paramagnetic center S and the gas-phase r1— r molecule ... 

A novel principle for accelerating the electron transfer has been the direct chemical modification of GOD by electron-mediating groups such as ferrocene derivatives (Heller and Degani, 1987). The distance between the mediator molecules was at most 1 nm and the relays had to be attached in the vicinity of the prosthetic group. The binding of ferrocene to GOD was therefore conducted in 2 mol/1 urea. After refold-... 

The first three classes involve the use of a solid matrix to support or entrap the enzyme and to confer the desirable mechanical properties of the solid carrier (Fig. 6-1 A-D). The last method entails covalent linking of the enzyme to itself with no additional support (Fig. 6-1 E). Each of the covalent methods requires one or more covalent bonds between reactive groups on the enzyme surface with complementary groups on the carrier, either directly or through the action of a multivalent cross-linking reagent. Covalent attachment methods result in direct chemical modification... 

McNiven et al. [22] first demonstrated this guest directed chemical modification strategy. In their studies, an MAA/EGDMA polymer imprinted with testosterone (Fig. 3) was partially esterified with methyl iodide (Mel) and 1,8-diazabicyclo(5.4.0) undec-7-ene (DBU) both in the presence and absence of the... 

Since the pioneering work of Updike and Hicks in developing enzyme electrodes and Lane and Hubbard in direct chemical modification of electrode surfaces, a great deal of attention has been paid to developing chemically modified electrodes. The result is that virtually every substance that is electroactive, or for which its chemical reaction can be coupled to the electrode-modifying matrix and/or electron transfer mediator, can now be detected electrocheniically. Principles, techniques, and scope of application of CMEs as sensors in analytical... 

FIGURE 17.8 Sketches of various rr-conjugated polymers having direct chemical modifications that alter the main... 

Site-directed chemical modification of enzymes using group-specific reagents was established mainly during the 1960s aiming at the elucidation of enzyme strucmres and mechanisms [458,459] rather than for the creation of biocatalysts with a better performance. In other words, enzyme modification has been developed more as... 

Enhanced activity of an immobilized lipase promoted by site-directed chemical modification with polymers. Process Biochem., 45 (4), 534-541. 

The polysaccharide synthesis via ring-opening polymerization method is an attractive method leading to structurally well-defined polysaccharides which are rarely attained by direct chemical modifications of natural polysaccharides. The synthetic polysaccharides obtained are useful tools to elucidate relations between the structure and functionality of polysaccharides and to develop new types of polysaccharides with novel properties. 

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