19-09-2012, 03:34 PM
Cancer Research - Nanoparticles, Nanobiosensors and Their Use in Cancer Research
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Abstract
Nanotechnology has shown remarkable potential to cure cancer disease. It has brought new dimension to cancer research.
University and industrial researchers have been consistently working toward numerous nanobiosensor developments, which are giving shape to new platforms for pain-free, accurate, and selectively sensitive developments of diagnostic biosensors. The biosensor industry has evolved continuously in the past few years and is expected to maintain steady growth in the future.
The ultimate goal of nanobiosensors is to identify disease at the earliest stage possible, ideally at the level of a single cell or multiple cells of cancer stages. To achieve this goal, research and
development activities in nanotechnology need to be undertaken to improve the effectiveness of in-vivo and in-vitro diagnostics. Nanobiosensors must offer diagnostic tools of better sensitivity, specificity, and reliability. In this paper, several types of nanobiosensors based on different principles along with their applications have been discussed.
Nanobiosensor technology gives new access to cancer cell's molecular processes. Nanobiosensors can provide significant potential in the early warning and detection of cancer agents such as chemical and biological pollutants, hazardous agents and pathogens.
New biosensor strategies would allow cancer testing to be performed more rapidly, inexpensively and reliably in a decentralized setting. Recent development and advances in nanotechnology has brought new insight towards the nanobiosensor. This paper provides the latest progress in the field of nanoparticles and nano-biosensors for cancer treatment.
Introduction
Nanoparticles were first developed approximately 35 years ago [1]. They were initially developed as carriers for vaccines and cancer chemotherapy agents.
In delivery of any nanoparticle inside the body pharmacokinetics and pharmacodynamics play a very important role. Pharmacokinetics deals with drug delivery inside the human body. When a drug inters the body intravenously it goes through absorption, distribution, metabolism & elimination. The result depends mainly on the physiochemical properties of the drug (Molecular weight, shape, charge, and aqueous solubility) and therefore on its chemical structure. The target of all complicated drug delivery systems, therefore, is to deliver medications to specifically targeted parts of the body through a medium that can control the therapy’s administration by means of either a physiological or chemical trigger. A successful drug carrier system needs to demonstrate optimal drug loading and release properties, long shelf-life and low toxicity. Nanoparticles are desirable for drug delivery because of a number of properties. They can be used to increase drug solubility, have lower toxicity, provide a drug direct, increase bioavailability and target drug delivery [2].
Chemotherapy via Nanoparticles
Chemotherapy using nanoparticles [6] has been studied in clinical trials for several years and lots of studies have been published in this regards. In general, nanoscale drug delivery systems for chemotherapy can be divided into two categories: Polymer and lipid based. Polymer based nanoparticles are more successful.
Nanoparticles and Their Role in Cancer
Nanoparticles play a very important role in cancer research. Due to extremely small size of nanomaterials they are more readily taken up by the human body. Nanomaterials are able to cross biological membranes and access cells, tissues and organs that larger-sized particles normally cannot. Nanoparticles are stable, solid colloidal particles consisting of biodegradable polymer [7] or lipid materials and range in size from 10 to 1,000 nm. Drugs can be absorbed onto the particle surface, entrapped inside the polymer / lipid, or dissolved within the particle matrix.
Transport of Oxygen, Nutrient & Nanoparticles Inside Tumor
Most of the ~1013 cells in the human body [9] are within a few cell diameters of a blood vessel. This remarkable feat of organization facilitates the delivery of oxygen and nutrients to the cells that form the tissue of the body. It also enables the efficient delivery of most medicines. As a result of poorly organized vasculature in solid tumors, there is limited delivery of oxygen and other nutrients to cells that are distant from functional blood vessels.
A single cancerous cell [10] enclosed by healthy tissue will replicate at a rate higher than the other cells, placing a strain on the nutrient supply and removal of metabolic waste products. Once a small tumor mass has formed, the healthy tissue will not be able to fight with the cancer cells for the inadequate supply of nutrients from the blood stream. Tumor cells will move healthy cells until the tumor reaches a diffusion- limited maximal size. While tumor cells will typically not begin apoptosis in a low nutrient environment, they do require the normal building blocks of cell function like oxygen, glucose and amino acids. The vasculature was designed to supply the now extinct healthy tissue that did not place as high a demand for nutrients due to its slower growth rate. Tumor cells will therefore continue dividing because they do so without regard to nutrient supply but also many tumor cells will die because the amount of nutrients is not enough. The tumor cells at the outer edge of a mass have the best access to nutrients while cells on the inside die creating a necrotic core within tumors that rely on diffusion to deliver nutrients and remove waste products.
Biosensor/ Nanobiosensor (Monitoring Environmental Health at the Single Cell Level)
Nanomaterials are exquisitely sensitive chemical and biological sensors. Each sensor [28] should be sensitive for one chemical or biological component of a substance. Thus, by having sensor arrays it is possible to tell the composition of an unknown substance.
The application area will be wide, encompassing food industry, detection of pollution, medical sector, brewery etc. A biosensor generally consists of a biosensitive layer that can either contain biological recognition elements or be made of biological recognition elements covalently attached to the transducer. The interaction between the target analyte and the bioreceptor is designed to produce a physicochemical perturbation that can be converted into a measurable effect such as an electrical signal. Bioreceptors are important elements providing specificity for biosensor technologies, because they allow for binding of the specific analyte of interest to the sensor for the measurement with minimum interference from other components in complex sampling mixtures. Biological sensing elements can be either a biological molecular species (eg, an antibody, an enzyme, a protein, or a nucleic acid) or a living biological system (eg, cells, tissue, or whole organisms) that uses a biochemical mechanism for recognition.
Optical Biosensor
A sensor that uses light to detect the effect of a chemical on a biological system is an optical biosensor. The construction and use of optical nanosensors was first reported by Kopelman et al. in 1992. Optical nanosensors [32], like larger sensors, can typically be classified into one of two wide categories, chemical or biological, depending on the probe used. Both types of sensor have been used to offer a reliable method of monitoring various chemicals in microscopic environments and have even been used to detect different entities within single cells.