Surface Investigation on Biomimetic Materials to Control Cell Adhesion: The Case of RGD Conjugation on PCL

Abstract

The cell recognition of bioactive ligands immobilized on polymeric surfaces is strongly dependent on ligand presentation at the cell/material interface. While small peptide sequences such as Arg-Gly-Asp (RGD) are being widely used to obtain biomimetic interfaces, surface characteristics after immobilization as well as presentation of such ligands to cell receptors deserve more detailed investigation. Here, we immobilized an RGD-based sequence on poly(epsilon-caprolactone) (PCL), a largely widespread polymeric material used in biomedical applications, after polymer aminolysis. The surface characteristics along with the efficacy of the functionalization was monitored by surface analysis (FTIR-ATR, contact angle measurements, surface free energy determination) and spectrophotometric assays specially adapted for the analytical quantification of functional groups and/or peptides at the interface. Particular attention was paid to the evaluation of a number, morphology, and penetration depth of immobilized functional groups and/or peptides engrafted on polymeric substrates. In particular, a typical morphology in peptide distribution was evidenced on the surface raised from polymer crystallites, while a significant penetration depth of the engrafted molecules was revealed. NIH3T3 fibroblast adhesion studies verified the correct presentation of the ligand with enhanced cell attachment after peptide conjugation. Such work proposes a morphological and analytical approach in surface characterization to study the surface treatment and the distribution of ligands immobilized on polymeric substrates.

Immobilization of anti-CD31 antibody on electrospun poly(ɛ-caprolactone) scaffolds through hydrophobins for specific adhesion of endothelial cells

“…2) of native PCL film showed the characteristic carbonyl band ( , C O) at 1724 cm −1 , and the spectrum of HFBI-coated PCL film showed the characteristic bands of amide I ( , C O) and amide II (ı, NH) at 1653 cm −1 and 1539 cm −1 , respectively [18]. The amide bond is ascribed to the peptide linkages of self-assembled HFBI on the PCL fibers.…”

Engineering Cell Instructive Materials To Control Cell Fate and Functions through Material Cues and Surface Patterning

“…To this aim, we performed a systematic study to characterize the actual spatial presentation of the RGD signal on polycaprolactone (PCL) and its effect on cell adhesion. 15 In detail, we grafted RGD sequences on PCL foils through a two-step procedure: polymer aminolysis to graft functional primary amines on the material surface, followed by a chemical conjugation of the RGD motif. We found that the RGD signal was predominantly located on the boundaries of polymer crystallites at the surface.…”

“…57The demonstration that the mechanical properties of the culturing substrate can direct stem cell fate was first provided byEngler et al in 2007. 58 They cultivated human MSCs on PAM hydrogels that had a stiffness comparable to that of brain (0.1 -1 kPa), muscle(8)(9)(10)(11)(12)(13)(14)(15)(16)(17) or bone(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40) and observed that the different substrates promoted neurogenesis, myogenesis and osteogenesis, respectively. More recent studies have also demonstrated that undifferentiated cells cultivated on specific ranges of stiffness can undergo self-renewal.…”

Determinants of cell–material crosstalk at the interface: towards engineering of cell instructive materials

“…Indeed, it is generally considered that only a modification of the surface is achieved and that the reagent penetration depth is the same as the integrin accessible depth of 10 nm, treating the results in a two-dimensional manner. In the case of polymers, instead, the depth of the surface modification after treatment will depend upon the polymer crystallinity, the size of the pore and the swelling capability of the polymer at the surface [44] (figure 2a-c).…”