ABSTRACT
Nanotechnology has been applied to develop advanced products in a variety of industries, such as information technology, cosmetics, and clothing. Similarly, it has great potential for revolutionizing the biomedical industry. For example, it has been envisioned that a nanoscale multifunctional robota nanobot-can be developed, capable of searching damaged tissues or cells in the body and repairing them. Although truly mechanical nanobots are still merely hypothetical at this time; it should be noted that viruses operate at a nanoscale; thus, viruses represent naturally occurring “nanobots,” which can be manipulated to perform several functions for biomedical applications. For example, viruses can identify cells in the body that display a target receptor, infect these speci c cells, and modulate the cellular machinery to drive the formation of viral progeny. Each of these steps in the viral life cycle can be manipulated to perform functions required of a nanobot: identify target cells and manipulate them to change their behavior. is paradigm is most apparent in the role that viruses play as gene delivery vectors for cancer gene therapy. Examples of viruses that have gene therapy vector applications include adenovirus (Ad), adeno-associated virus (AAV), and human immunode ciency virus (HIV), among others (Saini et al. 2007). Due to their di erent biology, the use of these vectors is dependent upon the desired outcome. For example, AAV vectors have a carrying capacity for therapeutic genes of <5 kb as compared to ∼36 kb for Ad vectors (Saini et al. 2007); thus, AAV vectors are suitable for the incorporation of smaller therapeutic genes
than Ad vectors. Similarly, AAV vector-delivered genes have a prolonged expression spread out over many generations as compared to transient expression achieved using Ad vectors. us, AAV vectors are suitable for applications requiring long-term expression of the therapeutic gene, such as potential therapy for cystic brosis, whereas Ad vectors are suitable for applications requiring short-term expression of the therapeutic gene, such as tumor therapy (Saini et al. 2007).
