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Nanomedicine Applications
(drug delivery, imaging and diagnostics).
are vast potential applications of nanotechnology in the field of medicine. In this section we provide examples that reflect the most intensive areas of nanomedicine research and develop hand and finger current (involving commercial products): targeted delivery of drugs, therapies, nano-enabled, and diagnostic imaging. We decided not to make an exhaustive list of possible applications (for there are hundreds) but to offer some samples of Nanomedicine applications in each area. It should be noted that the supply of drugs, imaging and diagnosis are not always distinct sectors. In cancer research, the ultimate goal is to develop multifunctional nanoscale devices that act as imaging and therapeutic agent anticancerosa.174

1. Targeted drug delivery gold nano-shells. One of the most publicized areas of research in Nanomedicine involves using gold nano-shells to detect and treat cancerous tumors. Here we have a case where the detection and therapy overlap: The nano-shells are imaging agents that also function as therapeutic agents. Although the idea of \u200b\u200bnano-shells are back in the early fifties, its creation was delayed for several decades until it was possible to design nanoscale engineered partículas.175 In the nineties, Naomi Halas, Rice University (Houston, EU), has developed nano-shells of gold. In 2002, she and her colleague, Jennifer West, Rice also formed an innovative company called Nanoespectra Biosciences Inc. Since then, the company has received more than $ 5 million in funding to develop medical applications of nano-shells Gold (including more than 3 million from federal funds) 176 data is expected to lead to human tests for early 2007,177

The Halas nano-shells are particles of silica (glass) completely covered with gold, built from a few million atoms. Can occur in a range of sizes, with diameters less than 100 nm or as large as several hundred nanometers. The manufacturing of nano-shells requires Nanomedicine engineer to finely calibrate the nanoscale thickness of gold plating, and thus exhibit the desired optical properties. When injected into the bloodstream, naturally congregate tumor sites, so no need to redirect. When tumors grow, creating sometimes very fast, many blood vessels. As such, these vessels are often poor, which allows nanoproyectiles run off between the "cracks" and reach the vascular tumor.

detect tumors and bomb making use of their surrounding vascular defects known as permeability and retention effect accented "or EPR effect. Halas describes a nano-shell as a lens nanoscale, in essence, it captures the light and then focuses itself around misma.178 When handling tamaño de los nano-proyectiles —del núcleo de vidrio y de su recubrimiento de oro—, es posible alterar la forma en que absorben la luz. En la detección y la terapia del cáncer el objetivo es “calibrar” los nano-proyectiles para que interactúen con luz cercana al infrarrojo (conocida comúnmente como NIR por sus siglas en inglés).179 Cuando se les expone a una luz NIR, los nano-proyectiles actúan como un enjambre de luciérnagas que iluminan el área donde se congregan (los sitios tumorales).
Una vez que los nano-proyectiles completaron sus tareas imagenológicas, se vuelven agentes terapéuticos. Si se alumbra con un láser near infrared to the tumor site from outside the body (the light can travel through the tissues more than 10 inches), the nano-shells absorb light and focus on the tumor. The area surrounding the nano-shells are heated and "cook" the tumor to its dissipation. This is not so different from the science experiment that we illustrated in childhood: The nano-shell works like a magnifying glass, the laser is the sun and the tumor is heated as a blade of grass.
In 2005, Halas described the shocking results of cancer treatment with nano-shells applied in mice: "Once [the nano-shells] are Instead, the infrared light is launched from outside the skin and goes to the tumor site. This involves using a laser manual, very simple to use, and only three minutes enough ... In studies with mice we have observed complete remission of tumors in the space of ten days. We used two control groups and their tumors continued to grow dramatically until the end. But mice that were treated with nano-shells survived the study and had a 100 percent survival, persisted. That test was done in 2003. Almost two years ago. So it seems that most of these mice will die of old age. "180 Halas highlights the fact that the nano-shells were leave "toxic traces in the body, while the conventional chemotherapeutic agents themselves. Nanospectra's Web site states that "long-term studies do not indicate any toxicity or effects on the immune system" .181 These statements should be inspected in great detail as it is very likely that nanoproyectiles to settle permanently in the body, and not clear, until now, how can excrete.
2. Therapeutic Nanoparticles A nanoscale silver bullet?
Medical products incorporating nanoscale silver are among the first commercial success of nanotechnology. Although the antimicrobial properties of silver are known for thousands of years, the increase in surface area of \u200b\u200bnano-particles of silver designed with engineering Nanomedicine (1 to 100 nm) makes them more chemically reactive and highlighted its therapeutic properties.
Nucryst Pharmaceuticals (a subsidiary of Westaim Corporation) manufactures coatings for wounds and burns nanometer silver impregnated to fight infection and inflammation. Silver kills bacteria and viruses by blocking the electron transport microbes and offset cell replication when in contact with DNA. Silver ions (atoms that have an electrical charge due to change in the number of electrons) can disrupt funciones.182 microbial structures and problematic side is that high levels of silver ions released by prolonged periods of time, can also kill cells, so exposure should be controlled ellos.183
Smith & Nephew, a medical equipment firms in the world's largest, sells coatings wounds with silver layer in thirty countries Nucryst with the name of Acticoat. The growing demand for antimicrobial coatings due to that very quickly, several bacteria are becoming resistant to antibiotics. Smith & Nephew Acticoat states that is effective against 150 pathogens, including some microorganisms resistentes.184
Johnson & Johnson, Bristol-Myers Squibb and Medline Industries, among other companies, marketed as medical products based on nanoscale silver. But the wound coverings are just the beginning. Since it is estimated that bacterial infections related to hospitalization are the fifth leading cause of death in the United States, the companies intend to nanoscale silver lining with the surgical instruments, bed sheets and curtains of hospitales.185 In December 2005 the FDA granted approval of a catheter (a tube for transporting liquid) coated with antimicrobial silver for implantation into the body humano.186
coatings silver nanoscale devices are also used as antimicrobials in consumer products like refrigerators finish, brushes, containers for storing food and clothing. SmartSilver antimicrobial socks are sold to soldiers in U.S. military stores, and researchers develop fabrics with nanoscale silver coatings are described as "self-cleaning" .187 A new washing machine commercially released by Samsung (called SilverCare) injects silver ions to the wash water and rinse. Samsung claims that the silver ions penetrate the fabric and kill bacteria without hot water or bleach. Specialists in water treatment at municipal level are wondering if the nanoscopic silver washing machines can cause serious problems if the silver particles are discharged into drains and kill plankton, thereby disrupting the chain alimenticia.188 A request to early 2006 by the American Association of dependencies in favor of clean water [National Association of Clean Water Agencies] Environmental Protection Agency of the U.S. government considered in June 2006 review and classification of products containing silver nano-particles such as pesticides, that is, with the ability to kill
vegetal.189 life
3. Nano-particles applied to biomedical imaging and diagnosis

The "quantum dots" are semiconductor nanoparticles that have unique optical and electrical properties. When exposed to light, clearly these nanoscale particles emit different colors depending on their size. (The smaller the quantum dot, the more the brilliance of color.) Although for decades have used fluorescent dyes the human body for biomedical imaging (to track the effects of anticancer drugs, for example), are often imprecise and are visible only for short periods of time. Biomedical researchers expect that quantum dots provide an alternative fluorescent brighter, more accurate and more durable. And fluorescent quantum dots used in the tracking or identification of biological material in vitro and in vivo in animals (not human) research purposes. Quantum dots can be injected into cells or adhere to the proteins in order to track, label or identify specific biological molecules. For biomedical researchers, the potential advantage of using quantum dots in imaging inside the human body is offering the "most advanced detection sensitivity"-a simple protein, which binds a fluorescent quantum dot, can be traced within a cell viva.190


Quantum dots Nanomedicine designed engineered and used in electronics (in computers and flat screen TVs) but have not received approval for use in therapy or diagnosis, largely because there concern that are potentially toxic. Research current evidence suggests that "under certain conditions, quantum dots can pose risks to human health or environmental" .191 The inner core of most quantum dots are made of cadmium and selenium, which are known to cause (in low concentrations) of acute and chronic poisoning in vertebrates.
In an attempt to make quantum dots are safe and biologically compatible, its core and inner shell are encapsulated within a bioactive coating that "functionalized"-and makes them suitable for molecular imaging and drug delivery , for example. However, if the outer degrades, it can expose the toxic core. Quantum dots can remain within cells for weeks or months, but we know almost nothing about how these nanoparticles are metabolized within the body or what their routes excreción.192 A recent toxicological review of quantum dots by Ron Hardman researcher at Duke University (North Carolina, USA), concludes that it is easy to identify problems involving quantum dots because, as with the nano-particles in general, even those that are chemically similar may have features physical and toxicological drastically different. Quantum dots with the size, shape and composition of metallic core and its outer shell can be a factor in determining toxicity. The result is that "each type of quantum dot must be characterized individually to determine their toxic potential" .193
"carbon points?

Researchers at Clemson University (South Carolina, USA), recently developed a new type of quantum dot from carbon, and suspect it may be more benign than the composite particles of cadmium, selenium or plomo.194 When carbon nanoparticles are covered with special polymers, flash brightly when exposed to light. Researchers believe that the photoluminescence may be due to the presence of "pockets" that trap energy or holes on its surface.

DNA detectors.

Nanosphere, Inc. (Illinois, USA) has developed an ultrasensitive detector of DNA and proteins, consisting of two instruments, each the size of a desktop computer, which the company says it has "levels sensitive than other detection techniques "and" change completely the way the world perceives the diagnosis ".195 From blood and saliva samples, the DNA detector, called Verigene, automates the identification and analysis of nucleic acids and proteins. DNA detector disclosed, for example, if a patient has a genetic mutation that predisposes to a disease or has it prone to develop blood clots during surgery process. The company asserts that its product can detect proteins at concentrations a thousand times smaller than current methods, allowing to detect a protein released in the body during a heart attack, or even, someday, the protein associated with the early stages of Alzheimer's.
Verigene system uses different techniques to detect DNA and proteins, but both systems use gold nanoparticles to create highly selective and sensitive probes. When the polls are combined with a sample, they can only go to-and link-building with additional genetic. The system is capable of identifying genetic markers in a single test.

Nano-medical sensors.
Researchers at the University of Illinois developed a tiny implantable device that would allow diabetics to monitor glucose levels sangre.196 removed without sensors are made of carbon nanotubes of pure carbon molecules shaped cylinder that naturally fluoresce when illuminated infrared light. The aim is to develop a sensor that can be implanted just under the skin and to provide an optical signal when illuminated infrared light. In essence, the more glucose there is in the body, most brilliant flash nanotubes. Implantable glucose sensors are only the first step. The researchers hope that someday develop other sensors for a wide range of biochemicals such as hormones, cholesterol, or the presence of drugs.

4. Tissue Engineering /

implants Regenerative medicine is described as "the vanguard of health care XXI century" because it offers the promise to replace or regenerate tissues and órganos.197 The researchers used nanoscale technology and engineering to drive a tissues, in order to create fully biological tissues and organs or biohybrid in vitro (ie in the laboratory) that can be implemented safely in the human body. A 2005 report prepared by the U.S. Department of Health and Human Services predicts that the global market enthusiasm for regenerative medicine will be 500 billion by 2010 (this figure is not limited to medicine nano-enabled regenerative) .198

Tissue Engineering
.
Nanotechnology plays a key role in tissue engineering because it operates on the molecular scale and is capable of integrating biological and nonbiological materials. For example, researchers are using self-replicating nanoscale structures to create artificial collagen (ie, connective tissue proteins are the main protein component of bone, skin, teeth and tendons). Because collagen protein is a major structural component of body tissues and organs, researchers hope to use artificial collagen nano-structured as three-dimensional scaffold needed to boost cell regeneration, and so grow cells, tissues and even organs específicos.199 Researchers already use this technique to grow tissue vejiga.200 About 160 thousand people in the U.S. are bladder cancer treated annually, which requires taking away portions of his body. To replace the surgically removed tissue, scientists must first create a biocompatible scaffold on which to regrow new cells of the patient's bladder. Purdue University researchers are using nanostructured polymers (chain molecules long), biocompatible, biodegradable and flexible to build a three-dimensional scaffold that cross nano bumpy surface. The nanostructured polymer scaffold is then "seeded" with cells taken from the patient's bladder. Since bladder cells from the patient to receive the transplant, the new tissue is less likely to cause rejection. It is reported that the cells grow faster when provided with a scaffold with nanoscale surface features. The hope is that, after being implanted in the human body, the scaffold dissolves slowly, leaving intact the functional tissue of the bladder.

In April 2006, researchers reported that the first urinary bladders grown in the laboratory and transplanted to seven children and young adults and worked effectively for nearly four años.201 Washington Post described the feat as the Holy Grail of medicine: "the first crop of replacements that work, bodies to remedy poor people ".202 These bladder transplants are carried out experimentally, and have not received U.S. FDA approval. The company that is commercializing the technology of transplants, Tengion has not disclosed the estimated cost of a transplant as well. Transplanted bladders grown from the patient's own cells marks the beginning of an era of "rejuvenation medicine" in which the organs that are not working properly, due to illness or age, can be replaced with models that work better. Some futurists expect to amass a collection of parts, including hearts, in anticipation of the inevitable decline of cuerpo.203
materials for bone grafting.

nanoscale materials used in the development of bone replacement grafts that have greater durability, bioactivity and strength. NanoCoatings Ltd. (Australia) is developing a technology to produce synthetic replacement of bones that could be used as a graft or as bioactive coating on artificial joints, such as dental implants and hip replacements or knee. The bone graft material, even in the early stages of development, is derived from hydroxyapatite, a calcium phosphate ceramic that naturally arises, which is also a mineral component of tooth enamel and bones, to which coated with carbonate apatite
nanoescalar.204
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