Researchers from the University of California and Harvard-MIT have developed a new type of biodegradable, non-toxic nanoparticle (NP) that break down readily and can be excreted via the kidneys after delivering a drug payload to the target site thereby avoiding a major drawback with some other nanoparticle delivery systems that may have limited biodegradability, toxicity issues or which are rejected immediately by the body’s immune system.

The novel NPs were formed by electrochemical etching of single-crystal silicon wafers followed by ultrasonication and filtration, yielding NPs with 5-10nm pore diameters. Silicon oxide grown onto the surfaces provides an intrinsic photoluminescence at 650-900nm which is a range where organs and tissues exhibit very low adsorption, thereby providing a mechanism for monitoring accumulation and degradation in-vivo.

In-vivo tests in a mouse model with the anti-cancer drug doxorubicin showed accumulation in a tumour followed by subsequent breakdown of the NPs, probably into soluble silicic acid, and elimination by renal clearance within 1-4 weeks of injection with no indications of toxicity.

Source: Nanowerk

Paper: Nature Materials

Posted: April 16th, 2009 under Chemistry, Nanomedicine.
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Researchers at New York University and Harvard University have created an autonomous, bipedal DNA “walker” that can mimic a cell’s transportation system and which marks a step toward creating more complex synthetic molecular motors.

Previous versions of walkers, which are able to move along a track of DNA, were unable to function autonomously and were liable to become uncoordinated and fall off the DNA “track”.

The New York and Harvard team overcame this problem by employing two DNA “fuel strands” which worked with the walker as a catalytic unit pushing the walker along the DNA tracks. More base pairs are formed at every step and this creates the energy necessary for movement. The fuel strands bind to the track and also release the walker’s legs allowing it to take a “step”.

The researchers hope that the research may mark a step toward creating more complex synthetic molecular motors capable of carrying a cargo from one part of a cell to another.

Video animation of walker

Science paper

Source: Nanowerk

Posted: April 6th, 2009 under Chemistry, Nanomedicine.
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While a large number of colours in nature are produced by pigments some, like the vibrant feathers of many types of birds, are instead produced by nanostructures.

An interdisciplinary team at Yale University has found that these structures, which appear sponge-like with air bubbles, form by a process of self-assembly. They compared the natural nanostructures to examples of materials undergoing phase separation in which mixtures of different materials become unstable and separate from one another. In the case of feathers, bubbles of water form in a protein-rich soup inside the living cells and are replaced by air as the feather grows forming ?-keratin and air nanostructures. The colour produced depends on the exact size and shape of the individual nanostructure.

The research provides important insights into how organisms use self-assembly of materials at the nanoscale to produce colour. The researchers are also interested in the potential technological applications of their finding to produce novel optical materials.

Publication: Soft Matter

Source: Nanowerk

Posted: April 6th, 2009 under Advanced materials, Chemistry.
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There have been a number of attempts to create artificial blood, but most so far have some drawbacks, e.g. risk of heart attacks in the patients, usually trauma cases, that receive such transfusions.

Researchers at the University of Pennsylvania have, however, now succeeded in constructing an artificial protein from scratch that is capable of carrying and delivering oxygen in the body and that is resistant to ingress by water which causes release of oxygen that can cause cellular damage.

Unlike existing blood substitutes, which are usually constructed from modified natural haemoglobin the Pennsylvania team used three amino acids to make a four-helix columnar candelabra-shaped protein structure containing a heme structure similar to the active part of haemoglobin capable of opening and closing to receive and deliver oxygen without letting water in.

While further work is required to ensure that the new protein can hold on to oxygen for long enough to be useful, and to ensure that it can work in a cellular environment and is non-toxic, the research represents a notable step in protein design

Source: MIT Technology Review

Posted: March 30th, 2009 under Chemistry, Nanomedicine.
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Using the world’s most advanced electron microscope, Eindhoven University of Technology researchers have, for the first time, captured high-resolution images of the earliest stages of bone formation. Utilizing the FEI Company’s cryoTitan microscope they imaged small clusters of calcium carbonate and showed that clusters consisting of around ten ions formed the basis for the process resulting in nucleation into larger, unstructured nanoparticles with an average diameter of around thirty nanometers through which the crystalline biominerals are formed.

The work, published in Science magazine offers increased understanding of bone, tooth and shell formation and could have important implications for creating industrial biomimetic materials.

Source: Nanowerk

Posted: March 13th, 2009 under Advanced materials, Advanced medtech, Nanomedicine.
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Researchers at the Cidetec-IK4 Research Centre at San Sebastian in Spain have developed a new type of electrochemical nanobiosensor capable of detecting mutations in DNA much more rapidly than before. The sensor technology also offers the possibility to be extended to the detection of other types of molecule.

The nanobiosensor comprises a nanotransistor, the cable of which is a carbon nanotube modified by a polymer that enables DNA to anchor. High selectivity can be achieved without the need to modify the DNA and the sensor is capable of detecting sequences, such as those implicated in particular genetic diseases directly.

Source: Basque Research

Journal reference: Nano Letters, 2009; 9 (2): 530

Cidetec-IK4

Posted: March 10th, 2009 under Advanced medtech, Nanomedicine, Nanotechnology.
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Researchers at Sandia National Laboratories, Livermore, California have succeeded in developing a device based on carbon nanotubes that can detect the entire visible spectrum of light and which may find potential uses in artificial retinas and other light gathering applications such as solar cells and miniature cameras for use in low light conditions. Earlier attempts at similar devices were only able to detect specific wavelengths.

The device utilizes carbon nanotubes decorated with three different types of chromophores, which are molecules that change shape in response to particular wavelengths of light… in the case of the Sandia research red, green and blue wavelengths. This change in shape alters the orientation of the chromophores in relation to the nanotube which, in turn, alters the conductivity of the nanotube to give a signal that can be measured. Because of their size, the nanotubes have intrinsically high resolution… around the diameter of each nanotube or 1nm.

The researchers believe that the process of manufacturing such devices could be scaled up and are also working on versions of the device that can detect infrared light, and which are more sensitive.

Source: MIT Technical Review

Posted: March 10th, 2009 under Advanced materials, Physics, Advanced medtech, Nanomedicine, Nanotechnology.
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Recent research at the US Department of Energy’s Pacific Northwest National Laboratory (PNNL) in Richland, Washington, provides further evidence to suggest that total surface area rather than size, mass or number of particles may be the most appropriate metric in relation to the toxicity of some types of nanoparticles. This supports similar conclusions reached by the EC Scientific Committee in its Opinion on the appropriateness of existing risk assessment methodologies published on 29 March 2007.

Being aware of the difficulties in agreeing on the most relevant nanoparticle dose unit to use to measure toxicity, Brian Thrall and colleagues at PNNL studied the dose of amorphous silica nanoparticles required to cause a biological response. Using particle number or mass as a dose metric their results were inconsistent but by calculating the total surface area they were able to predict a biological response which appeared also, in the study, to vary little according to the size of the nanoparticles.

Source: Pacific Northwest National Laboratory

Posted: March 4th, 2009 under Safety and risk, Nanomedicine.
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 University of Texas researchers have moved a step closer to treating melanomas using hollow gold nanospheres and near-infrared light. The work, carried out at the M.D. Anderson Cancer Center utilizes hollow gold nanospheres of 40-50nm diameter which are targeted to melanoma tumours with a peptide that binds to the melanocortin type 1 receptor expressed in melanomas. Once bound to the cancer cells, the tumours, in a mouse model, were then destroyed by thermal photoablation by near-infrared light.

The approach differs from earlier attempts using photothermal ablation in that the absorption of light by the hollow gold nanoparticles allows much greater efficiency in heating and destroying the cancer cells, some 12% of the dose required without the nanoparticles, which leads to less damage to surrounding healthy tissues. In addition, the active targeting of the gold nanoparticles means a far greater proportion bind to the cancerous cells as opposed to purely “passive” targeting through the leaky tumour vasculature.

Glucose labelling also allows the active monitoring of the tumours and the efficacy of the treatment using positron emission tomography (PET). The researchers, led by Prof. Chun Li, also hope that the new findings will be a proof in principle that other types of cancer could be targeted using peptide-linked gold nanoparticles.

News source: PhysOrg.com

Posted: February 2nd, 2009 under Nanomedicine.
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The human nervous system comprises an extremely complex network of neurons joined by synapses. When these synaptic connections fail, the nervous system does not function properly which may eventually leading to injury or disease.

Researchers at Arkansas State University have demonstrated that magnetic nanotubes coupled with nerve growth factor can help enable cells to differentiate into neurons with the possibility of repairing such damage. They noted that rat PC12 cells sent out projections called filopodia towards magnetic nanotubes incorporated with nerve growth factor and made contact with them. At the same time the nanotubes did not appear to display any toxicity. The research raises new hope for developing future treatments for neurodegenerative conditions such as Parkinson’s Disease and Alzheimer’s Disease.

Source: PhysOrg.com

Posted: January 19th, 2009 under Regenerative medicine, Nanomedicine.
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