Poly Ethylene Glycol End Groups Research Articles

Kidney functional stages influence the role of PEG end-group on the renal accumulation and distribution of PEGylated nanoparticles.

Modification with polyethylene glycol (PEG), or PEGylation, has become a popular method to improve the efficiency of drug delivery in vivo using nanoparticle-based delivery systems. The PEG end-group plays an important role in the in vivo fate of PEGylated nanoparticles through its interactions with proteins in the serum and the cell membrane. However, the effects of PEG end-groups on the renal clearance of PEGylated nanoparticles remain unclear. Kidney function may also affect the renal accumulation and distribution of nanoparticles. Herein, we demonstrate that the accumulation and distribution of PEGylated nanoparticles in kidneys are significantly affected by both the PEG end-group and kidney function damage. Interestingly, compared to PEG with an amino or methoxy end-group, PEG with maleimide as the end-group markedly enhanced the accumulation of PEGylated nanoparticles in normal kidneys, which may improve renal clearance. However, obvious enhancements in the renal accumulation and medullary distribution of PEGylated nanoparticles are detected in kidneys with functional impairment. Damage to renal function further affects how the PEG end-group influences the accumulation and distribution of PEGylated nanoparticles in kidneys in vivo. Collectively, the findings provide deep insights into the interactions between PEGylated nanoparticles and kidneys in vivo.

An efficient synthesis of low-covered polyrotaxanes grafted with poly(ε-caprolactone) and the mechanical properties of its cross-linked elastomers

Advanced polyrotaxane elastomers were fabricated by the synthesis of poly(ε-caprolactone)-grafted polyrotaxanes with significantly lower coverage than previously achieved. The time course for the complexation of α-cyclodextrin with an end-functionalized polyethylene glycol (PEG) was analyzed by subsequent end-capping and polyrotaxane isolation, which revealed that the bulkiness of the PEG end group affects the time required for complex nucleation and the resulting coverage. Low-coverage poly(ε-caprolactone)-grafted polyrotaxanes were synthesized in a facile and large-scale manner by optimizing the simultaneous hydrolysis of the end-capping groups and the solubility of the product during the ring-opening polymerization of ε-caprolactone. Cross-linking the thermoplastic graft polyrotaxanes yielded elastomers that are much more extensible than conventional elastomers with fivefold higher coverages. Elastomers with lower coverages behave as ideal elastic bodies due to chain sliding through the cross-links, which suggests that the arrangement entropy of the cyclic components, which counteracts chain sliding, is substantially decreased by reduced coverage.

Hybrid triazolium and ammonium ions-contained hyperbranched polymer with enhanced ionic conductivity

Hyperbranched poly(triazole) with tertiary amine moiety and longer flexible polyethylene glycol (PEG) terminal group (hb-PTA-PEG) was synthesized by successive Cu(I)-catalyzed azide-alkyne cycloaddition polymerization, and the corresponding hyperbranched poly(triazolium)s containing hybrid quaternary ammonium ion, [hb-PTA-PEG]+[I]− and [hb-PTA-PEG]+[TFSI]−, were obtained after N-alkylation and anion exchange reactions. These hyperbranched polymers presented broad electrochemical stability window of above 6.0 V versus Ag+/Ag and 5.3 V versus Li+/Li, and displayed low glass transition temperature in the range of −13 to −37 °C, owing to the hyperbranched structure combined with the hybrid ionic moiety and longer flexible PEG end-group. The ionic [hb-PTA-PEG]+[TFSI]− showed superior ionic conductivity, which was above 10−5 S cm−1 at 30 °C.

Controlling the Formation of Ionic-Liquid-based Aqueous Biphasic Systems by Changing the Hydrogen-Bonding Ability of Polyethylene Glycol End Groups.

The formation of aqueous biphasic systems (ABS) when mixing aqueous solutions of polyethylene glycol (PEG) and an ionic liquid (IL) can be controlled by modifying the hydrogen-bond-donating/-accepting ability of the polymer end groups. It is shown that the miscibility/immiscibility in these systems stems from both the solvation of the ether groups in the oxygen chain and the ability of the PEG terminal groups to preferably hydrogen bond with water or the anion of the salt. The removal of even one hydrogen bond in PEG can noticeably affect the phase behavior, especially in the region of the phase diagram in which all the ethylene oxide (EO) units of the polymeric chain are completely solvated. In this region, removing or weakening the hydrogen-bond-donating ability of PEG results in greater immiscibility, and thus, in a higher ability to form ABS, as a result of the much weaker interactions between the IL anion and the PEG end groups.

Endgroup analysis of polyethylene glycol polymers by matrix-assisted laser desorption/ionization Fourier-transform ion cyclotron resonance mass spectrometry.

Fourier-transform ion cyclotron resonance mass spectrometry (FTICR-MS) by external injection of matrix-assisted laser desorbed and ionized (MALDI) polymers offers good possibilities for characterization of low molecular weight homopolymers (MW range up to 10 kDa). The molecular masses of the molecular weight distribution (MWD) components of underivatized and derivatized (dimethyl, dipropyl, dibutyl and diacetyl) polyethylene glycol (PEG) 1000 and 4000 were measured by MALDI-FTICR-MS. These measurements have been performed using a commercial FTICR spectrometer with a home-built external ion source. MALDI of the samples with a 2,5-dihydroxybenzoic acid matrix in a 1000:1 matrix-to-analyte molar ratio produces sodiated molecules in a sufficient yield to trap the ions in the ICR cell. The masses of the molecular weight distribution of PEG components were measured in broad-band mode with a mass accuracy of < 5 ppm in the mass range around 1000 u and within 40 ppm accuracy around 4000 u. From these measurements, the endgroup mass of the polymer was determined by correlation of the measured component mass with the degree of polymerization. The masses of the PEG endgroups have been determined within a deviation of 3-10 millimass units for the PEG1000 derivatives and 10-100 millimass units for the PEG4000 derivatives, thus confirming the identity of the distal parts of the model compounds.