3. Applications:

3.1. NANOTECHNOLOGY IN BIOMATERIALS SCIENCE :

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.

Nanostructured tissue scaffolds and biomaterials are being applied for improved tissue design, reconstruction, and reparative medicine. Nano- and micro-arrays have been established as the preferred method for carrying out genetic and other biological (e.g., drug discovery) analysis on a massive scale. Natural nanopores and synthetic nanopores of tailored dimensions are probing, characterizing, and sequencing biological macromolecules and have demonstrated the possibility to analyze the structure of individual macromolecules faster and cheaper. Self-assembly is being applied to create new biomaterials with well-ordered structures at the nanoscale, such as nanofiber peptide and protein scaffolds. In addition, polymer networks with precisely engineered binding sites have been created via molecular imprinting, where functional monomers are preassembled with a target molecule and then the structure is locked with network formation.

In medical diagnostics, the speed and precision with which a condition is detected directly impacts the prognosis of a patient. Point-of-care (POC) diagnostic devices, which enable diagnostic testing at the site of care, can enhance patient outcomes by substantially abbreviated analysis times as a result of the intrinsic advantages of the miniature device and by eliminating the need for sample transport to an on-site or off-site laboratory for testing. The development of micro or miniaturized total analysis systems (µ-TAS), also referred to as lab-on-a-chip devices, has profoundly impacted the corresponding development of POC diagnostic devices. These µ-TAS devices integrate microvalves, micropumps, micro-separations, microsensors, and other components to create miniature systems capable of analysis that typically requires an entire laboratory of instruments. Since being introduced as a novel concept for chemical sensing devices, µ-TAS devices have been applied as innovative biological devices and POC diagnostic devices. With the further development of micro- and nanosensors, POC diagnostic devices will provide for improved medical management, leading eventually to self-regulated POC diagnostic devices that intermittently or continuously monitor the biological molecule of interest and deliver the therapeutic agents as required.

Additionally, nanoscale science and engineering have accelerated the development of novel drug delivery systems and led to enhanced control over how a given pharmaceutical is administered, helping biological potential to be transformed into medical reality . 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. Silicon microchips that can provide controlled release of single or multiple chemical substances on demand via electrochemical dissolution of the thin anode membranes covering microreservoirs have been created. The advantages of this microdevice are that it has a simple release mechanism, very accurate dosing, and ability to have complex release patterns, potential for local delivery, and possible biological drug stability enhancement by storing in a microvolume that can be precisely controlled. More recently, multi-pulse drug delivery from a resorbable polymeric microchip device was demonstrated.

In particular, the development of polymer systems that are able to interact with their environment in an “intelligent” manner has led to novel materials and applications. These intelligent materials are attractive options as functional components in micro- and nanodevices, due to the ease with which their recognition and actuation properties can be precisely tailored. In this section, neutral and intelligent polymers and networks based on environmentally responsive hydrogels and bio-mimetic polymer networks will be discussed for application as sensing/recognition elements in novel diagnostic devices, such as microsensors and microarrays, and therapeutic devices, for tailoring loading and release properties.

In addition to advances in polymer nanotechnology for sensing and recognizing changes in micro-environments, advances have been made concerning tissue regeneration on ceramic and metallic nanomaterials. Broadly speaking, nanotechnology embraces a system whose core of materials is in the range of nanometers (10−9 m). The application of nanomaterials for medical diagnosis, treatment of failing organ systems, or prevention and cure of human diseases can generally be referred to as nanomedicine. The branch of nanomedicine devoted to the development of biodegradable or nonbiodegradable prostheses fall within the purview of nanobiomedical science and engineering. Although various definitions are attached to the word “nanomaterial” by different experts, the commonly accepted concept refers nanomaterials as that material with the basic structural unit in the range 1 to 100 nm.

Since nature itself exists in the nanometer regime, especially tissues in the human body, it is clear that nanotechnology can play an integral role in tissue regeneration. Specifically, bone is composed of numerous nanostructures — like collagen and hydroxyapatite (HA) that, most importantly, provide a unique nanostructure for protein and bone cell interactions in the body (Figure 1).

FIGURE1: Nanocomponents of bone provide a high degree of nanostructured surface roughness for bone cells.

Their special surface properties compared to conventional (or micron constituent component structured) materials. In summary, nanophase material surfaces are more reactive than their conventional counterparts. In this light, it is clear that, proteins which influence cell interactions that lead to tissue regeneration will be quite different on nanophase compared with conventional implant surfaces (Figure2).

FIGURE2: Conventional grain size of currently used orthopedic implants. Bar = 10 and 1 µm for the left and right micrograph, respectively

3.2. CERAMIC NANOMATERIALS :

Perhaps slightly more mature, is the application of nanophase ceramics in bone tissue engineering applications. The next series of sections will highlight the improvement in bone regeneration that can be obtained through the use of ceramic nanotechnology.

4. AREAS OF APPLICATION:

While there has already been some effort on incorporating nanotechnology into orthopedic applications, it is clear that this is only the beginning for the incorporation of nanotechnology into biology. In the following sections some additional avenues are highlighted.

4.1. DRUG DELIVERY :

Polymers have found a significant role in the development of novel drug delivery systems. Biomaterials for muco-adhesive drug delivery applications have been improved through the addition of PEG as an adhesion promoter. Nanoporous structures have the ability to allow mass transport of desirable compounds but limit those that are undesirable.

Nanodrug delivery systems are quickly evolving in their ability to integrate biologically complex components into a functional nanodevice. Drug discovery and delivery are becoming sciences that encompass skills in nanotechnology, microtechnology, and biology to design systems effectively more capable of achieving efficient and effective therapeutic treatments. Much effort has been dedicated to engineering nanoparticulate drug delivery systems.

Surface modification allows the specific targeting of particles and enhances their ability to interact with certain types of cells. Size plays a key role in the ability of particles to participate in intracellular uptake, and biodegradable nanoparticles can be used as sustained-release delivery systems once inside the cytoplasm.

4.2. BIOLOGICAL MICRO-ELECTRO-MECHANICAL SYSTEMS (Bio MEMS) :

Most research focusing on biological micro-electro-mechanical systems (BioMEMS) is for their use in diagnostic devices and for the detection of DNA, viruses, proteins, and other biologically derived molecules. Nanoscale BioMEMS could allow for the real-time detection and analysis of signaling pathways, which would further our knowledge and understanding of the basic mechanisms and functions of the cell. While nanoscale BioMEMS is at its infancy, it is clear that nanotechnology will play an important role in its development.