5. Advantages over conventional ones:

The fact that such a high percentage of hip replacements performed every year are revision surgeries is not surprising when you consider the life expectancy of the implant versus that of the patient receiving the implant. Since the longevity of implants ranges only from about 12 to 15 years, even the majority of those who receive bone implants at the age of 65 will require at least one revision surgery before the end of their lives. For the dental community the story is not any better. Since dental implants may be necessary for the young and old alike, it is imperative that they are able to last for the duration of the patient’s life.

Nanotechnology is playing an important role in decreasing this failure. This is because, in order to improve biomaterial performance and hence extend the lifetime of bone implants, it is essential to design surface characteristics that interface optimally with select proteins and subsequently with pertinent bone cell types. That is, immediately after implantation, proteins will adsorb from plasma to biomaterial surfaces to control cell attachment and eventual tissue regeneration (Figure 2). Initial protein interactions that mediate cell function depend on many biomaterial properties, including chemistry, charge, wet ability, and topography. Of significant influence for protein interactions is surface roughness and energy, and this represents the promise of nanophase materials in bone implant applications.

The critical factor for the merging of nanotechnology with medicine is the increasingly documented, special, biologically improved material properties of nanophase implants compared to conventional formulations of the same material chemistry. This chapter will highlight a novel property of nanophase materials that makes them attractive for use as implants: increased tissue regeneration. Work is ongoing in the domains of orthopedic, dental, bladder, neurological, vascular, cartilage, and cardiovascular applications. However, only orthopedic applications, which are the closest to clinical applications, will be emphasized here. This contribution will briefly articulate the seeming revolutionary changes and the potential gains nanostructured materials can make for bone implant technology. The first report correlating increased bone cell function with decreased material grain or particulate size into the nanometer regime dates back to 1998 and involves ceramics. Such reports described how in vitro osteoblast (bone-forming cell) adhesion, proliferation, differentiation, and calcium deposition were enhanced on ceramics with particulate or grain sizes less than 100 nm.

6. Current efforts:

6.1. CURRENT RESEARCH EFFORTS TO IMPROVE BIOMEDICAL PERFORMANCE AT THE NANOSCALE

Nanoscale materials currently being investigated for bone tissue engineering applications can be placed in the following categories: ceramics, metals, polymers, and composites thereof. Each type of material has distinct properties that can be advantageous for specific bone regrowth applications. For example, HA, a ceramic mineral present in bone can also be made synthetically.

Ceramics, though, are not mechanically tough enough to be used in bulk for large-scale bone fractures. However, they have found applications for a long time as bioactive coatings due to their ionic bonding mechanisms favorable for osteoblast (or bone-forming cells) function. Owing to the numerous materials currently being used and investigated in orthopedics, this review will cover select efforts to create nanoscale surfaces in all of these categories: ceramics, metals, polymers, and composites. Several current and potential materials that have shown promise in nanotechnology for bone biomedical applications as well as needed future directions will be emphasized.

7. Disadvantages and future research directions:

Although preliminary attempts to incorporate nanotechnology into biomedical applications seem promising, numerous urgent questions still remain with regard to this new field. First and foremost, the question of safety of nanoparticles once in the human body remains largely unanswered both from a manufacturing point of view and when used in full or as a components of an implantable device. Since such particles are smaller than many pores of biological tissues, it is clear that this information will have to be obtained before further consideration of implantable nanomaterials is undertaken. Although preliminary in vitro studies highlight a less adverse influence of nanometer compared to micron particulate wear debris on bone cell viability, many more experiments are needed, especially in vivo to evaluate their efficacy.

Specifically for orthopedic applications, additional questions remain. For example, once exact optimal nanometer surface features are elucidated for increasing bone regeneration, inexpensive tools that can be used in industry will be required. In this context, if the only nanofabrication devices that can be used to synthesize desirable nanometer surface features for bone regeneration are e-beam lithography or other equally expensive techniques, industry may not participate in this boom of nanotechnology at the intersection of tissue engineering. Inexpensive but effective nanometer synthesis techniques must continually be a focus of many investigators.

The direction of the nanotechnology should be and is geared toward dealing with these issues. For example, according to the U.S. government’s research agenda, current and future broad interests in nanobiomedical activity can be categorized into three broad related fronts:

1. Development of pharmaceuticals for inside-the-body applications — such as drugs for anti-cancer and gene therapy.

2. Development of diagnostic sensors and lab-on-a-chip techniques for outside-the-body applications — such as biosensors to identify bacteriological infections in biowarfare.

3. Development of prostheses and implants for inside-the-body uses.

The biological and biomimetic nanostructures to be used as orthopedic implants involve some sort of an assembly in which smaller materials later on assume the shape of a body part, such as hip bone. These final biomimetic, bulk nanostructures can start with a predefined nanochemical (like an array of large reactive molecules attached to a surface) or nanophysical (like a small crystal) structure. It is believed that by using these fundamental nanostructured building blocks as seed molecules or crystals, a larger bulk material will self-assemble or keep growing by itself.

In summary, it is now believed that significant evidence exists that highlights the promise nanotechnology has for biological applications, particularly in the bone arena. Clearly, nanomaterials as mentioned here are at their infancy and require much more testing before their full potential can be realized.

8. Concluison:

Undoubtedly, nanoscale science and engineering has the potential to have a profound impact on medical science and technology, which will lead to improved diagnostics and enhanced therapeutic methods. The emergence of micro- and nanoscale science and engineering has provided new avenues for engineering materials with macromolecular and even down to molecular-scale precision, leading to diagnostic and therapeutic technologies that will revolutionize the way health care is administered.

Another application is the BIO-MEMS. Micro- and nanoscale devices have been fabricated using integrated circuit processing techniques and have been demonstrated to allow for strict control over the temporal release of the drug. The functions of the bone cells, osteoblasts and osteoclasts were observed to increase considerably.

On looking at the wide areas of applications of very minute nanomaterials, it seems to be very surprising. In the field of biomedicine, its applications are vast. So if a strong attempt is made towards producing these very minute things, it can prove out to be a new revolution avoiding less the efficient conventional methods hence can improve the treatment methods, because, there is nothing called impossible.