A polypeptide-based hydrogel system, when prepared from a diblock polymer with a ternary copolypeptide as one block, exhibited thermo-, mechano- and enzyme-responsive properties, which enabled the encapsulation of naproxen (Npx) during the sol–gel transition and its release in the gel state. Statistical terpolymerizations of l -alanine (Ala), glycine (Gly) and l -isoleucine (Ile) NCAs at a 1 : 1 : 1 feed ratio initiated by monomethoxy monoamino-terminated poly(ethylene glycol) afforded a series of methoxy poly(ethylene glycol)- block -poly( l -alanine- co -glycine- co - l -isoleucine) (mPEG- b -P(A-G-I)) block polymers. β-Sheets were the dominant secondary structures within the polypeptide segments, which facilitated a heat-induced sol-to-gel transition, resulting from the supramolecular assembly of β-sheets into nanofibrils. Deconstruction of the three-dimensional networks by mechanical force (sonication) triggered the reverse gel-to-sol transition. Certain enzymes could accelerate the breakdown of the hydrogel, as determined by in vitro gel weight loss profiles. The hydrogels were able to encapsulate and release Npx over 6 days, demonstrating the potential application of these polypeptide hydrogels as an injectable local delivery system for small molecule drugs.
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Peptide‐Reinforced Amphiphilic Polymer Conetworks
Amphiphilic polymer conetworks (APCNs) are polymer networks composed of hydrophilic and hydrophobic chain segments. Their applications range from soft contact lenses to membranes and biomaterials. APCNs based on polydimethylsiloxane (PDMS) and poly(2‐hydroxyethyl acrylate) are flexible and elastic in the dry and swollen state. However, they are not good at resisting deformation under load, i.e., their toughness is low. A bio‐inspired approach to reinforce APCNs is presented based on the incorporation of poly(β‐benzyl‐L‐aspartate) (PBLA) blocks between cross‐linking points and PDMS chain segments. The mechanical properties of the resulting peptide‐reinforced APCNs can be tailored by the secondary structure of the peptide chains (β‐sheets or a mixture of α‐helices and β‐sheets). Compared to non‐reinforced APCNs, the peptide‐reinforced networks have higher extensibility (53 vs. up to 341%), strength (0.71 ± 0.16 vs. 22.28 ± 2.81 MPa), and toughness (0.10 ± 0.04 vs. up to 4.85 ± 1.32 MJ m−3), as measured in their dry state. The PBLA peptides reversibly toughen and reinforce the APCNs, while other key material properties of APCNs are retained, such as optical transparency and swellability in water and organic solvents. This paves the way for applications of APCNs that benefit from significantly increased mechanical properties.
more » « less- NSF-PAR ID:
- 10375920
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Functional Materials
- Volume:
- 32
- Issue:
- 51
- ISSN:
- 1616-301X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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