ABSTRACT
Nanotechnology encompasses the creation and utilization of materials at the level of atoms, molecules, and supramolecular structures. Nanomaterials already have an impact in each and every sphere of our lives, from cosmetics to cancer research. One such material that has received wide attention in nanomaterials research is carbon nanotubes, made of atoms of carbon arranged in the form of a cylinder. Accessing the electronic properties of carbon nanotubes renders their application in biological sensing for targeting receptors in cells for ex vivo diagnosis. Constructed as a transistor, nanotubes can act as probes for detecting molecular overexpressions in cancer cells. Similarly, the small size, hollow nature, and unique optical absorption properties of nanotubes make them quite useful for therapeutic applications in the selective destruction of cancer cells. Functionalized nanotubes attached to molecular targets in cells can trigger thermal ablation using light that can be used for the surgical and selective destruction of cancer cells. 5.1 IntroductionNanotechnology encompasses the manufacturing and use of materials, devices, and systems at the level of atoms, molecules, and supramolecular structures. As a measure,
Balaji Panchapakesan,a Thomas Burkhead,a Ben King,a Peng Xu,a James Loomis,a and Eric WickstrombaSmall Systems Laboratory, Department of Mechanical Engineering, University of Louisville, 247 Belknap Research Building, Louisville, KY 40292, USAbDepartment of Biochemistry and Molecular Biology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, USA b0panc01@louisville.edu
1 nm = 1 × 10-9 m, which is about 100,000 times smaller than the diameter of the human hair. At nanometer-length scales, new physical properties emerge in these materials and, therefore, new techniques are required to make them. What makes nanotechnology interesting is that they neither behave like macroscopic systems nor behave like atoms. Size constraints often produce qualitatively new behavior at the nanometer scale. For example, when the size of the nanomaterial reaches the characteristics length scales such as Debye length, it can result in qualitatively new modes of electric current and heat transport in these materials. Similarly, mechanical properties change dramatically as the grain size approaches nanometer-length scales. The use of noble metals, such as gold, silver, and platinum, as nanoparticles lends their applications in biological imaging, sensing, and selective destruction of cancer cells. The size and unique physical properties of materials at the nanometer scale are explored for fabricating sensors to detect cancer cells and contrast agents for enhanced imaging capabilities and targeted therapeutics for treatment. 5.2 Nanotechnology for CancerIn general, nanotechnology for cancer consists of three main areas: (1) nanodetectors for sensing proteins and cancer cells, (2) nanoparticle or nanovector formulations for high-contrast imaging, and (3) nanotechnology-based drug delivery and therapeutic formulations. Figure 5.1 illustrates some examples of cancer-related nanotechnology and how it will be applied in blood vessels. Biologic nanosensors, fabricated using techniques borrowed from the integrated circuits industry, are emerging for potential use in detecting specific tumor markers. Nanosensors are precisely constructed using the top-down approach. In this process, nanoscale materials are precisely patterned on silicon substrates using lithography. UV and electron beams are focused on specific substrates to sculpt features on the nanoscale using patterned masks. Biologic entities such as antibodies, DNA, and proteins can be patterned on top of nanomaterials such as nanowires, nanoparticles, and carbon nanotubes. Examples of cancer-related nanotechnology include nanovectors [1, 2] such as liposomes for breast cancer therapy [3], nanoparticle contrast agents for high-contrast imaging of brain tumors [4], paramagnetic nanoparticles for imaging of clinically occult lymph node metastases in patients [5], nanomechanical cantilevers [6], nanowires [7], and the recent nanotube sensors for the detection of breast cancer cells [8]. The effective early detection of precancerous lesions remains an elusive goal. Clinical cancer-imaging technologies do not possess sufficient spatial resolution for early detection based on lesion anatomy. To identify malignancies based on their molecular expression profiles, all imaging technologies require contrast agents conjugated to molecular recognition and a targeting agent such as an antibody. Much of the interest in using nanoparticles for cancer detection originated with the use of semiconductor nanocrystals (quantum dots of cadmium selenide) as a tool for laboratory diagnostics of cancer [9]. These quantum dots change their optical properties with their size. When linked to an antibody or a molecule capable of binding to a substrate of interest, quantum dots act like beacons that light up when binding occurs.
