Multifunctional nanomedicine with integrated imaging and therapeutic functions has received considerable attention for image-guided therapy of cancer. Compared with small molecular-based contrast agents or therapeutic drugs, this new nanomedicine paradigm holds considerable promise that allows for the molecular diagnosis of disease, simultaneous monitoring and treatment, and targeted therapy with minimal toxicity. Considerable challenge remains as how to incorporate multiple functions (e.g. cancer targeting, imaging ultrasensitivity, controlled drug release) within such a small size confinement (<100 nm). Various nanoplatforms, such as polymer conjugates, polymeric micelles, liposomes, and inorganic/organic nanocomposites have been established with synergistic integration of diagnostic and therapeutic functions.
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Bone, cartilage, tendon and ligament are all biologically constructed from self-assembling collagen molecules. This process results in fibrils with nanoscale radial dimensions. In addition, each tissue has at least one non-collagenous component which is interdigitated with the fibrils to form a nanophase composite. Recent efforts in the biomaterials community have focused on three principle aspects of these systems. First, how to synthetically recapitulate the nanophase aspects of the extracellular matrices of these tissues. Second, how the nanoscale structures in these tissues couple to the macroscale to confer organ level mechanics. Third, how the specialized cells found in these tissues repair sub-fracture and sub-rupture level damage. The microdamage found in these tissues often extends into the nanoscale regime squarely placing these efforts into the domain of nanomaterials. The combination of all three of these aspects is dovetailed with an implicit strategy that it is not necessary to exactly mimic the native tissue in order to obtain clinically useful results. Figuring out what nanoscale structural aspects are essential to obtain the mechanics and the desired response of native cells after implantation is the primary goal of most modern orthopedic nanomaterial research and development.
Nanostructures for Implants:
Nanostructured surfaces and interfaces play important roles in cell-implant and tissue-implant interactions. A variety of nanofeatures, nanopatterns, and nanocoatings have been created on the surface of current medical implants to improve clinical outcome. Translating nanostructured implants to clinical applications has attracted much attention.