Polypseudorotaxane Formation of Randomly-Pegylated Insulin with Cyclodextrins: Slow Release and Resistance to Enzymatic Degradation

Abstract

NotesPegylation technology is one of the useful methods for sustained release systems, because when poly(ethylene glycol) (PEG) is covalently attached to a protein, it transfers many of the polymer's favorable characteristics to the resulting conjugate, i.e. a number of benefits such as increased circulating half-life, enhanced proteolytic resistance, reduced antigenicity and immunogenicity, reduced aggregation, and improved bioavailability, etc. There are many examples of protein conjugates that are mono-or randomly-substituted with PEG, such as adenosine deamidase, insulin, interferona2, b-lactoglobulin, a-chymotrypsin, lipase, bovine liver catalase, asparaginase, and superoxide dismutase, etc. of which the first three conjugates are on the market.1-3) Most of commercially available pegylated drugs are randomly-substituted derivatives, because of synthetic difficulty of the mono-pegylation.Supramolecular assemblies have attracted a great amount of attention, due to its intriguing topologies and its application in various fields such as nanodevices, sensors, molecular switches, and drug delivery systems, etc. Cyclodextrins (CyDs) are cyclic oligosaccharides composed of 6 (a-CyD), 7 (b-CyD), and 8 (g-CyD) glucopyranose units and can form inclusion complexes with various organic and inorganic compounds.4) Harada et al. first reported the supramolecular assemblies of PEG and a-CyD, in which a number of the cyclic molecule are spontaneously threaded onto the polymer chain.5,6) These complexes are called polypseudorotaxanes, because the CyD can be dethreaded from the polymer chain when dissolved in water. Recently, many studies on CyD polypseudorotaxanes with various polymers were reported, e.g. blanched PEG, poly(ethylene imine) and poly(lactic acid), etc. [7][8][9] In addition, a number of applications of polypseudorotaxanes as a biomaterial were reported, e.g. gene delivery carrier, 10-13) biodegradable hydrogel 11,[14][15][16][17] and galectin binding material. 18) In previous studies, 19,20) we found that the mono-substituted pegylated insulin forms polypseudorotaxanes with a-and g-CyDs in a similar manner as PEG does. However, there are no evidences if randomly-or multiply-pegylated proteins form polypseudorotaxanes with CyDs. In this study, therefore, we prepared randomly-substituted pegylated insulin and its CyD polypseudorotaxanes and evaluated it as a sustained release system. Further, proteolytic behavior of insulin in the polypseudorotaxane was investigated. ExperimentalMaterials Bovine Zn-insulin (27.5 IU/mg, approximately 0.5% Zn) was obtained from Sigma Chemicals (St. Louis, MO, U.S.A.). a-Succinimidyloxysuccinyl-w-methoxy-polyoxyethylene (MW about 2300) was obtained from NOF Co. (Tokyo, Japan). CyDs were donated by Nihon Shokuhin Kako (Tokyo, Japan). All other materials were of reagent grade, and deionized double distilled water was used.Preparation of Randomly-Pegylated Insulin Randomly-pegylated insulin was synthesized according to the modified method of Hinds et al. 3,21) Briefly, insulin (MW 5734...

Preparation of Polypseudorotaxanes Composed of Cyclodextrin and Polymers in Microspheres

“…The patterns of α-CyD MSs prepared without PEG corresponded to the α-CyD channel-type crystal structure, in which cyclodextrin molecules are stacked along an axis to form a cylinder and provide space for a long-chain molecule guest. 18,19,26) The XRD pattern of the channel structure also supported the formation of α-CyD/PPG PPRX in the MSs. At this point, it is difficult to explain the detailed structure α-CyD/PPG PPRX by using the XRD pattern because this is the first report for preparation of α-CyD/PPG PPRX, and further experimental work is needed in this respect.…”

“…Higashi et al reported PPRXs composed of CyDs and PEG-modified insulin. [17][18][19] These PPRXs showed a slow release of PEGylated insulin, which would correspond to a novel sustained-release system of PEGylated proteins.…”

“…[11][12][13][14][15][16][17][18][19] Seo et al have prepared a PRX using a ligand-modified CyD. 15) Both the rotation of CyD rings around the polymer axis and free arrangement of ligands were favorable in promoting multiple interactions between ligands and receptors on particular cell membranes.…”

Potential Use of Cyclodextrins as Drug Carriers and Active Pharmaceutical Ingredients

“…These results suggest that CyD PPRXs are useful as sustained release systems for PEGylated proteins. Higashi et al 35) also described PPRX formation of randomly-PEGylated insulin with CyDs with slow release and resistance to enzymatic degradation.…”

Potential Use of Polypseudorotaxanes of Pegylated Polyamidoamine Dendrimer with Cyclodextrins as Novel Sustained Release Systems for DNA

“…13,14) Recently, we found that pegylated insulin and lysozyme form PPRXs with a-CyD and g-CyD in a similar manner as PEG does, and the resulting PPRXs may be useful as a sustained drug delivery technique of pegylated proteins. [15][16][17][18] In spite of many studies on the formation of PPRXs reported so far, little is known about the application of PPRXs of pegylated gene delivery carriers with CyDs to a controlled release system for DNA or oligonucleotides. In the present study, we designed and evaluated CyDs PPRXs of the pegylated dendrimer/pDNA complexes as a novel sustained release system for pDNA.…”