Self-Assembling Peptide Based Double Network Hydrogels

  • Zixuan Liu

Student thesis: Phd


Hydrogels are a type of material composed of a network of hydrophilic polymer chains that can absorb and retain large amounts of water. They have several advantages, including high water content, durability and biocompatibility. Therefore, this makes them suitable for use in medical applications such as controlled drug release and matrix for tissue engineering. In the past decade, peptide (short chains of amino acids) has become to a prevalent material for preparing hydrogels. Compared to the synthetic compounds and other natural molecules, sequence designability, precise identification, structural rigidity and minimal toxicity are the advantages of peptide as blinding blocks of hydrogel. Through the physical interactions between peptide monomers, well-designed peptides self-assemble to the three-dimensional networks, resulting in the formation of the hydrogel. KF8K (sequence: KFEFKFEFKK) is an example of a self-assembling peptide hydrogel. This peptide self-assembles to β-sheet to form the fibres and network. It has several unique properties, involving biocompatibility, biodegradability, and tunable mechanical properties, which make it useful in various biomedical applications, such as tissue engineering and drug delivery. However, there are still several shortcomings in the KF8K hydrogel, including the unsatisfied mechanical stiffness for cell culture. Therefore, in this project, the KF8K self-assembly peptide was blended with other different sequence self-assembly peptides (SAPs), gelatin and oligonucleotide to produced the blending hydrogels with an improved but controllable stiffness, First, the KF8K peptide was physically mixed with the similar but different sequence peptide (F9) and same sequence but opposite chirality peptide (D-KF8K) for blending hydrogel. The blending hydrogels underwent the FITC-DABCYL fluorescent quenching reaction in order to explore how the different peptide monomers assemble. The F9 monomers were found to be homogeneously assembled with KF8K monomers while D-KF8K monomers were separated with L-KF8K monomers in the fibre. Unfortunately, there was not stiffness improvement observed in L-KF8K and F9 or D-KF8K blending hydrogel. However, a homogenous stiffness hydrogel with separately assembled monomers was accessible by blending the L-KF8K and D-KF8L. Subsequently, KF8K and gelatin blending hydrogel formed a double-network structure with an improved but controllable stiffness. The two networks were seen under microscopy. Blended hydrogels were also characterised in term of stiffness between 10 to 40 °C to prove the mixture did not significantly affect the temperature responsibility of gelatin. The blending hydrogel was observed with decrease stiffness with increased temperature. Finally, there still was stiffness improvement found in the KF8K and oligonucleotide blending hydrogel. The oligonucleotide monomers are also able to self-assemble to chains by Watson-Crick rule. The chains were connected to the KF8K fibres by the peptide-oligonucleotide conjugate. Therefore, the KF8K fibres were further linked by oligonucleotide chains for a higher stiffness.
Date of Award1 Aug 2023
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorAline Saiani (Supervisor) & Alberto Saiani (Supervisor)

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