Heterobifunctional PEG

Fig. 6 Utility of the heterobifunctional PEG. Two different components such as drug and ligand can be introduced at the different ends of PEG...

Fig. 7 Synthesis of heterobifunctional PEG. (a) Nagasaki et al. developed a method for the polymerization of EO using an initiator containing defined functionalities [16, 17]. (b) Akiyama et al. further developed a synthetic route to prepare a series of heterobifunctional PEGs [18-21]. After the ring-opening polymerization of ethylene oxide, a second functional group was introduced at the co-end of PEG...

Fig. 8 Examples of heterobifunctional PEGs popularly used for PEGylation...

To date, a variety of heterobifunctional PEGs have been reported. Some popular derivatives are shown in Fig. 8. Several PEG derivatives are now commercially available from NOF, Japan. 

The heterobifunctional PEGs are very useful in linking two entities in cases where a hydrophilic, flexible, and biocompatible spacer is needed. Preferred end groups for heterobifunctional PEGs are maleimides, vinyl sulfones, pyridyl disulfides, amines, carboxylic acids, and /V-hydroxysuccinimide (NHS) esters. 

Chen, H., Chen, Y, Sheardown, H., Brook, M. A. Immobilization of heparin on a silicone surface through a heterobifunctional PEG spacer. Biomaterials 2005,26,7418-7424. 

Fig. 2. Preparation of heterobifunctional PEG derivatives. The abbreviation PEG for this scheme is defined with structure 1, and differs from the way this abbreviation is used in the remainder of the paper. The notation PEG(X, Y) refers to the statistical mature of X-PEG-X, X-PEG-Y, and Y-PEG-Y, created in step 1, which was intentionally carried out aiming for approximately 50% conversion of OH group to Cl groups. All subsequent chemical steps were quantitative, and ion-exchange chromatography resulted in the isolation of pure heterobifunctional species 2, of defined structure (see box). The indicated chemistry was carried out for both PEG-2000, n = 45 (see Section 2.6) and PEG-4000, n = 90 (comparable to text Experimental w/v ratios were kept constant so that reaction concentrations were halved), with comparable yields. In other work, not reported herein, alternative approaches were used to generate statistical PEG mixtures that included

This work has reported on a chemically well defined class of graft polymer resin supports combining the mechanical stability of a hydrophobic cross-linked PS matrix with the beneficial features of readily solvatable polar PEG chains. These PEG-PS supports show excellent physicochemical properties and are demonstrably useful for solid-phase peptide synthesis. The PEG/PS ratio can be controlled readily on the basis of the level of PS functionalization and/or the molecular weight of heterobifunctional PEG used. The PEG-PS supports prepared as described... 

Polymer linker can be used to conjugate nanoparticles to the surface of islets. One example is a heterofunctional PEG-mediated conjugation method by covalent-linkage [91]. The chemical conjugation was mediated by a heterobifunctional PEG polymer, maleimide-PEG-N-hydroxysuccinimide ester (NHS), which is biocompatible with blood, cell, and tissue. The maleimide group of the PEG polymer can react with the sulfhydryl group of the heparinized superparamagnetic... 

Chen, H. Chen, Y Sheardown, H. Brook, M. A., Immobilization of Heparin on a Silicone Surface Through a Heterobifunctional PEG Spacer. Biomaterials 2005, 26, 7418-7424. 

Heterobifunctional PEG with acryloyl and isocyanate end groups Determination of acryloyl groups [149]... 

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