Bioactive compounds immobilized on Ti and TiNbHf: AFM-based investigations of biofunctionalization efficiency and cell adhesion

Abstract

Implant materials require optimal biointegration, including strong and stable cell-material interactions from the early stages of implantation. Ti-based alloys with low elastic modulus are attracting a lot of interest for avoiding stress shielding, but their osseointegration potential is still very low. In this study, we report on how cell adhesion is influenced by linear RGD, cyclic RGD, and recombinant fibronectin fragment III8-10 coated on titanium versus a novel low-modulus TiNbHf alloy. The bioactive molecules were either physisorbed or covalently coupled to the substrates and their conformation on the surfaces was investigated with atomic force microscopy (AFM). The influence of the different bioactive coatings on the adhesion of rat mesenchymal stem cells was evaluated using cell culture assays and quantitatively analyzed at the single cell level by AFM-based single-cell force spectroscopy. Our results show that bioactive moieties, particularly fibronectin fragment III8-10, improve cell adhesion on titanium and TiNbHf and that the covalent tethering of such molecules provides the most promising strategy to biofunctionalize these materials. Therefore, the use of recombinant protein fragments is of high importance for improving the osseointegration potential of implant materials

Tuning Mesenchymal Stem Cell Response onto Titanium–Niobium–Hafnium Alloy by Recombinant Fibronectin Fragments

“…49 The number and density of molecules immobilized on these surfaces with this method has been reported in a large number of previous studies. 50,51 However 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 adhesion than the whole FN, and similarly to RGDs.…”

“…48 Moreover, in a recent study we demonstrated that the use of APTES provides a more homogenous layer of biomolecule attachment in both Ti and TiNbHf alloy compared to physisorption. 49 Hence, in the present work APTES was chosen as linker molecule to immobilize the different bioactive molecules onto a recently developed low modulus TiNbHf alloy.…”

Development of a versatile procedure for the biofunctionalization of Ti-6Al-4V implants

“…Aminosilanes are used as precursors in this procedure because they are able to bond with hydroxyl groups which may be induced on the oxidized surface of metals [14,15] and, in particular, may be used to functionalize titanium and its alloys [16][17][18][19]. In turn, the resulting amino groups of the functionalized surface are capable of binding themselves to a wide range of biomolecules [20].…”

“…The difficulties associated with IS are firstly related with the need for surface activation to induce the appearance of -OH groups at the surface. Activation requires a pre-processing of the material by either immersion in acid [19,24] or with an oxygen plasma treatment [16]. Secondly, IS tends to result in a relatively low concentration of amine functional groups on the surface which, in addition, may be non-homogeneously distributed.…”

Islet Encapsulation: Physiological Possibilities and Limitations

“…An attractive approach is to take advantage of natural molecules in the human body, e.g., elastin (42,43). The elastin-like recombinamers can be decorated with growth factors or other molecules to promote islet cell survival and revascularization of the surface of the encapsulated islet after implantation (44,45). The covalent binding induced between the various layers would provide stability and longevity.…”