Peptide‐polymer biotherapeutic synthesis on novel cross‐linked beads with “spatially tunable” and “isolated” functional sites

Abstract

Solid phase synthesis of polymer biotherapeutics using conventional polymers suffers from many limitations such as low synthetic yield and purity. The conventional polymers prepared by either pre- or post-functionalization strategies have no control over the point of functionalization. Hence we report a novel cross-linked polymer in which the functional groups are spatially tuned to predefined distance with optimal site isolation. This has been achieved by the design and synthesis of a tetra functional PEG, 3,3'-(PEG)bis(1-(4-vinylphenoxy)propan-2-ol) (bis(VPP)PEG). It has been incorporated at cross-linking of 1-12%, into a polystyrene network by free radical suspension polymerization. In this polymer, the distance between hydroxyl functional groups has been spatially tuned in a predefined manner by varying the length of the cross-linker backbone from ethylene glycol to PEG1000 Da and the loading capacity could be varied from 0.1 to 0.9 mmol/g. The polymer has been characterized by SEM, FTIR, and 13C NMR. The polymer exhibits excellent swelling behavior and high chemical stability. The synthetic efficiency of the polymer was demonstrated by the successful synthesis of three structural classes of PEGylated antimicrobial peptide biotherapeutics and the difficult ACP (65-74) fragment. Thus the "spatially defined" and "site isolated" synthesis within the new polymer offers a novel strategy for synthesis of difficult peptide-polymer bioconjugates. The bioassay studies shows that PEGylation of AMPs significantly reduces their hemolytic potential but the retainment of antibacterial property was dependent both on the peptide sequence and the size of PEG used.

Novel peptide therapeutics for treatment of infections

“…However, the site of attachment and size of the PEG chosen to be added to interferon a-2b is an important consideration that can have deleterious effects on biological activity if not done correctly (Grace et al, 2005). Similar data have been presented for PEGylated antimicrobial peptides where the size of the PEG moieties can negatively affect the antimicrobial properties of the peptide (Jacob et al, 2008).…”

Pegylation of Antimicrobial Peptides Maintains the Active Peptide Conformation, Model Membrane Interactions, and Antimicrobial Activity while Improving Lung Tissue Biocompatibility following Airway Delivery

“…The airway administration of the AMPs into the IPRL also provided unique information on the pulmonary residence and systemic absorption of lung-administered AMPs. Further, using cell biological and biophysical approaches, we explored the previously reported phenomenon that pegylation of AMPs has beneficial effects on the selectivity of interaction between prokaryotic and eukaryotic cell membranes (20). Using both circular dichroism (CD) and fluorescence spectroscopy, the biophysical interactions of the AMPs with artificial lipid models of eukaryotic and prokaryotic membranes were examined to explore the issues of AMP conformation and membrane selectivity.…”

Green Polymer Chemistry: Enzyme Catalysis for Polymer Functionalization

“…PEG is a non-toxic, hydrophilic polymer that is extensively used in medical science [41,42] including the applications of enhancing the circulation time and blood half-life for cell imaging, drug delivery, and antibody-based therapy [43,44,45]. However, the HO- end groups that are available for chemical derivatization are only a small fraction of the molecular mass of the polymer, and chemistries utilized for end-group modification must be high fidelity in nature and leave few or ideally no residuals [46,47]. Our group reported first the synthesis of quantitative end-functionalization of PEG catalyzed by CALB [48].…”