Polyelectrolyte multilayers containing a tannin derivative polyphenol improve blood compatibility through interactions with platelets and serum proteins.

To develop hemocompatible surfaces, a cationic tannin derivate (TN) was used to prepare polyelectrolyte multilayers (PEMs) with the glycosaminoglycans heparin (HEP) and chondroitin sulfate (CS). The surface chemistry of the PEMs was characterized using X-ray photoelectron spectroscopy and water contact angle measurements. PEMs assembled with chitosan (CHI) and HEP or CS were used as controls. We investigate the hemocompatibility of PEMs by analyzing the adsorption of key blood serum proteins, adhesion and activation of platelets, and blood clotting kinetics. TN- and CHI-based PEMs adsorb similar amounts of albumin, whereas fibrinogen adsorption was more pronounced on TN-based PEMs, due to strong association with catechol groups. However, TN-based PEMs significantly reduce both platelet adhesion and platelet activation, while CHI-based PEMs promote platelet adhesion and activation. The whole-blood clotting kinetics assay also shows lower blood coagulation on TN-based PEMs. TN is an amphoteric, cationic, condensed tannin derivative with resonance structures. It also contains catechol groups, which are similar to those in mussel adhesive protein. These chemical features enable strong association with fibrinogen, which promotes the platelet-repelling effect. This study provides a new perspective for understanding platelet adhesion and activation on biomaterial surfaces, toward the development of new blood-compatible surfaces using a tannin derivative-based polymer.

Novel cationic tannin/glycosaminoglycan-based polyelectrolyte multilayers promote stem cells adhesion and proliferation.

Modifying materials with biocompatible surface coatings is an important method for controlling cell responses to biomaterials. In this work, tanfloc (TN), a cationic tannin-derivative polymer was assembled with heparin (HEP) and chondroitin sulfate (CS), using the layer-by-layer (LbL) approach, to build polyelectrolyte multilayers (PEMs) and to design cytocompatible coatings. LbL deposition was monitored through Fourier-transform surface plasmon resonance, and characterized by X-ray photoelectron spectroscopy, atomic force microscopy, and contact angle measurements. The response of human adipose-derived stem cells (ADSCs) was evaluated in vitro. All of the TN-containing PEMs exhibit cytocompatibility and support adhesion, proliferation, and the spreading of ADSCs after 7 days of culture. HEP-TN PEM assembly with 11 layers (HEP-TN11) supports the greatest rate of cell proliferation. When TN is the terminal layer of the PEM, the surfaces promote the spreading of ADSCs, indicating that the surface charge and PEM terminal layer are key determinants of the microenvironmental niche that control cellular response. The promotion of stem cell attachment and proliferation makes these surface coatings potentially useful for biomedical implants and regenerative medicine.

Novel poly(ε-caprolactone)/amino-functionalized tannin electrospun membranes as scaffolds for tissue engineering.

Poly(ε-caprolactone) (PCL) is a hydrophobic and cytocompatible aliphatic polyester that has been used to produce PCL-based nanofibrous for both wound healing and tissue repair. However, the high hydrophobicity and low water adsorptive have been challenges for developing PCL-based materials for use in tissue engineering field. Here, we report a new polymer (a hydrophilic amino-functionalized tannin (TN)) that is associated with PCL for developing PCL-TN blends at different PCL:TN weight ratios (100:0, 95:5, 85:15 and 78:22). PCL:TN ratio may be tuned to modulate hydrophilicity and cytocompatibility of the nanofibers. The neutralization step and surface wettability played an important role in the attachment of human adipose-derived stem cells (ADSC cells) on PCL-TN membranes. Also, fluorescence images confirmed great proliferation of ADSC cells on the PCL-TN electrospun surfaces. Yet, neutralized PCL-TN nanofibers promoted bactericidal activity against Pseudomonas aeruginosa. These membranes have potential to be used as scaffolds for tissue engineering purposes.