Gelation characteristics and applications of poly(ethylene glycol) end capped with hydrophobic biodegradable dipeptides

Abstract

Poly(ethylene glycol) (PEG) end capped with biodegradable hydrophobic dipeptides shows versatile gelation behavior in a wide range of aqueous and organic solvents. This gelation characteristic is attributed to the aggregation of polymer chains induced by dipeptide end groups. Both PEG molecular weight and molecular structure of end groups control this aggregation by striking a balance between two opposing molecular interactions: solubility of the PEG segment which tends to dissolve the polymer while hydrophobic and intermolecular noncovalent interactions between the end groups induce aggregation. Morphologically, this aggregated structure forms interpenetrating nano sheets with characteristic microstructural features. These gels are biodegradable and possess physicomechanical characteristics suitable for biomedical applications. Furthermore, proteins and hydrophobic model drugs can be encapsulated within the gels from aqueous and organic solvents, respectively, and can be released in a controlled fashion which indicates the applicability of the gels as drug delivery vehicles.

Hydrophilic polyurethane matrix promotes chondrogenesis of mesenchymal stem cells

“…WAXD of PEG shows the characteristic diffraction pattern and pure DTH, a viscous liquid, shows a broad peak with moderate intensity at a 2θ value of 20.75°. DTH molecules can self-assemble by H-bonding and π–π interactions leading to small crystallites oriented in all directions which results in a broad peak [21–23]. Both PUs show similar diffraction patterns but with different intensities.…”

Hybrid Cross‐Linking Characteristics of Hydrogel Control Stem Cell Fate

“…Presence of DTH unit within PEG chains can self‐assemble through π–π interactions of aromatic residues of tyrosine and H‐bonding of multiple urethane and amide linkages to physically cross‐link PEG chains. Previously, we have reported that presence of DTH as chain end to high molecular weight PEG forms stable gel due to physical cross‐links, but DTH within PEG chains remains water soluble because of free PEG chains . Thus, introduction of DTH in the middle of PEG chains followed by terminal functionalization with acrylate group enables to yield water soluble dual functionalized PEG which forms hydrogel through photopolymerization of acrylate end groups.…”

“…Previously, we have reported that presence of DTH as chain end to high molecular weight PEG forms stable gel due to physical cross-links, but DTH within PEG chains remains water soluble because of free PEG chains. [12] Thus, introduction of DTH in the middle of PEG chains followed by terminal functionalization with acrylate group enables to yield water soluble dual functionalized PEG which forms hydrogel through photopolymerization of acrylate end groups. This molecular design enables self-assembly of PEG chains within chemically cross-linkable PEG to control hydrogel morphology and, therefore, can impact cellular features.…”

“…Specifically, physical cross‐links in linear PEG chains were introduced through L‐tyrosine‐based dipeptide, desaminotyrosine tyrosyl hexyl ester (DTH), moieties using urethane chemistry to form self‐assembled structures via H‐bonds and aromatic π–π interactions, and chemical cross‐links were achieved from photopolymerizable acrylate groups. Presence of DTH‐based physical cross‐links in combination with chemical cross‐links regulated hydrogel morphology which influenced mesenchymal stem cell function and its ability to differentiate toward chondrogenic lineage.…”

A vegetable oil-based organogel for use in pH-mediated drug delivery

“…3 Despite these advantageous material qualities, the application of organogels as vehicles for controlled drug delivery has been hindered somewhat due to the cytotoxicity that is associated with numerous organic solvents. Many organogels have been reported that are formed using solvents including acetone, 4 tetrahydrofuran (THF), 5 toluene, 6 chloroform, 7 hexane, 8 benzene, 9 methanol, 10 dichloromethane, 11 acetonitrile 12 and dimethylformamide (DMF), 13 amongst others. Such solvents are either irritants, carcinogens, mutagens, teratogens or acute toxicants.…”