Biogenic thermoresponsive polyelectrolyte multilayers as potential substrata for the generation of cell sheets for tissue engineering

• Applicants: Professor Dr. Thomas Groth; Professor Dr. Kai Zhang
• Subject Area: Biomaterials
• Term: from 2017 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 369505795

• Final Report Year: 2023

Final Report Abstract

The thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) is commonly used in biomedical fields, such as for controlled drug release and tissue engineering, but the lack of bioactivity restricts its use in cell-containing systems as a thermoresponsive adhesive substrate with no regulating effect on cell growth and differentiation. In this project, cellulose sulfate (CS) and chitosan (CHI) backbones are grafted with PNIPAM moieties (PCS and PCHI, respectively) to improve the bioactivity of PNIPAM coated substrata and for detachment after cell growth. Different strategies were used to prepare these compounds with variable degree of substitution ascribed to PNIPAM and sulfate groups. Resulting polymers generally show thermoresponsive properties, e.g., by exhibiting a cloud point at 31-33 °C, and can be used as a polyelectrolytes to fabricate thermoresponsive polyelectrolyte multilayers (PEM) using layer-by-layer (LbL) technique. Higher sulfated PCS2 generally forms larger aggregates than lower sulfated PCS1 at their cloud point temperatures (TCP) of around 33 °C, whereas PCS1 leads to larger aggregates at body temperature (37 °C). The in-situ investigation by surface plasmon resonance and quartz crystal microbalance with dissipation monitoring verifies the formation of PEMs at 25 °C with both polyanions. By using PCS for PEM formation in combination with poly-L-lysine or quaternized chitosan more stable PEM were formed in comparison to CHI used as polycation. Studies on toxicity and biocompatibility of these PEMs using 3T3 mouse fibroblasts showed a lower cytotoxicity of PEM with PCS2 than lower sulfated ones (CS1, PCS1). By using PNIPAM-grafted chitosan (PCHI), form particularly with the bioactive polyanion chondroitin sulfate PEMs that support adsorption of vitronectin and consequently cell adhesion shown with multipotent murine stem cells. The stability of PEM with PCH is further improved at physiological pH 7.4 by chemical crosslinking, by using 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide. Moreover, these PEMs exhibit de-swelling and swelling ability with different surface wettability in response to temperature, which triggers the adsorption and desorption of adhesive proteins vitronectin. PEMs using such thermoresponsive polysaccharides with sulfate groups hold great potential for new bioactive, thermoresponsive coatings on biomaterials for different tissue cells and application in tissue engineering.

Publications

• Recent Advances in Artificially Sulfated Polysaccharides for Applications in Cell Growth and Differentiation, Drug Delivery, and Tissue Engineering. ChemBioChem, 20(6), 737-746.
  Zeng, Kui; Groth, Thomas & Zhang, Kai
  
• Copper(I)‐catalyzed azide‐alkyne cycloaddition‐assisted polymerization of linear glucose‐derived co/polymers. Journal of Polymer Science, 58(11), 1535-1543.
  Fuchs, Pascal; Vana, Philipp & Zhang, Kai
  
• Recent Progress on Cellulose‐Based Ionic Compounds for Biomaterials. Advanced Materials, 33(28).
  Yang, Yang; Lu, Yi‐Tung; Zeng, Kui; Heinze, Thomas; Groth, Thomas & Zhang, Kai
  
• Thermoresponsive polymers and their biomedical application in tissue engineering – a review. Journal of Materials Chemistry B, 8(4), 607-628.
  Doberenz, Falko; Zeng, Kui; Willems, Christian; Zhang, Kai & Groth, Thomas
  
• Engineering of Stable Cross-Linked Multilayers Based on Thermo-Responsive PNIPAM-Grafted-Chitosan/Heparin to Tailor Their Physiochemical Properties and Biocompatibility. ACS Applied Materials & Interfaces, 14(26), 29550-29562.
  Lu, Yi-Tung; Zeng, Kui; Fuhrmann, Bodo; Woelk, Christian; Zhang, Kai & Groth, Thomas
  
• Synthesis of Thermoresponsive PNIPAM-Grafted Cellulose Sulfates for Bioactive Multilayers via Layer-by-Layer Technique. ACS Applied Materials & Interfaces, 14(43), 48384-48396.
  Zeng, Kui; Doberenz, Falko; Lu, Yi-Tung; Nong, Johanna Phuong; Fischer, Steffen; Groth, Thomas & Zhang, Kai
  
• Surface properties and bioactivity of PNIPAM-grafted-chitosan/chondroitin multilayers. Smart Materials in Medicine, 4, 356-367.
  Lu, Yi-Tung; Hung, Pei-Tzu; Zeng, Kui; Woelk, Christian; Fuhrmann, Bodo; Zhang, Kai & Groth, Thomas