Nanomedicine for implants: a review of studies and necessary experimental tools

The response of host organisms (including at the protein and cellular level) to nanomaterials is different than that observed to conventional materials. Nanomaterials are those materials which possess constituents less than 100 nm in at least one direction. This review will first introduce the use of nanomaterials in a variety of implant applications highlighting their promise towards regenerating tissues. Such reviewed studies will emphasize interactions of nanomaterials with various proteins and subsequently cells. Moreover, such advances in the use of nanomaterials as novel implants have been largely, to date, determined by conventional methods. However, the novel structure–property relationships unique for nanosized materials reside at the nanoscale. That is, the novelty of a nanomaterial can only be fully appreciated by characterizing their interactions with biological systems (such as proteins) with nanoscale resolution analytical tools. This characterization of nanomaterials at the nanoscale is critical to understanding and, hence, further promoting increased tissue growth on nanomaterials. For this reason, while more tools are needed for this emerging field, this review will also cover currently available surface characterization techniques that emphasize nanoscale resolution pertinent for characterizing biological interactions with nanomaterials, including attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectroscopy (SIMS), colorimetric biological assays, circular dichroism (CD), and atomic force microscopy (AFM). Only through the coordination of nanoscale analytical tools with studies that highlight mechanisms of increased tissue growth on nanomaterials will we be able to design better implant materials.