Addition of fibers or tubes in scaffolds reinforces the mechanical properties and alters the pore structures of scaffolds. The characteristics of fibers and tubes including their size, alignment and surface morphology impart new physiochemical properties to the reinforced scaffolds. The altered pore structures and physiochemical properties should affect the status of the adsorbed proteins on the scaffolds. Though extensive studies have been conducted about the amount or selective adsorption of proteins on the reinforced scaffolds, few studies paid attention to the conformation of the adsorbed proteins, which plays more crucial roles in protein functions. Instead, the protein conformation has been more often investigated by using some model structures, such as pure nanotubes or nanofibers or controlled pores. Understanding the collective contributions from wettability, pores, and fiber/tube size and alignment helps to purposefully control protein adsorption so that appropriate cell and tissue responses can be promised. To this end, both experimental and simulation methods should be required for this complex system. In this chapter, the summarized fundamentals on protein adsorption provide essential knowledge.
The mechanical properties of scaffolds are usually recognized to maintain the mechanical integrity of scaffolds. However, their significant roles in transmitting externally loadings and providing mechanical stimulation to cells/tissues are generally ignored in 3D scaffolds, though they have been widely studied and acknowledged in 2D systems and some 3D hydrogels. It should be reminded that one of the most important purposes for addition of fibers and tubes into scaffolds is to enhance the mechanical properties of the scaffolds. Therefore, more attentions should be paid to their contributions to cell/tissue responses. There is a large bank of literatures mentioning the enhanced mechanical properties and improved cell/tissue responses. Few of them, however, claimed their direct correlation. This chapter tried to find a certain correlation by providing several potential mechanisms for the mechanical properties to regulate cell/tissue responses. These mechanisms may be conductive to understand and utilize the mechanical properties of the fibers/tubes reinforced scaffolds. More importantly, this chapter tried to provoke concerns from biomaterials scientists for the regulation roles of mechanical properties in 3D scaffold systems to cell/tissue responses and for purposefully tailoring the mechanical properties of scaffolds to induce sound biocompatibility for specific applications.
The addition of fibers or tubes changes both the architecture and mechanical properties of scaffolds. Moreover, the latter is dependent on the former. In view of the fact that both the architecture and the mechanical properties influence cell/tissue responses, it is hard to discriminate their contributions. Fortunately, the mechanical properties and architecture seem to share common mechanics, namely focal adhesions and cytoskeletons, to transfer their effects on cell/tissue. This can be employed to harmonize them so as to induce sound biocompatibility for specific applications.