Nanopartículas magnéticas ajudam a entender funcionamento das células-tronco

Os pesquisadores usam nanopartículas
contendo óxido de ferro, que permitem
a visualização das células às quais elas estão
anexadas por meio de um técnica de
imageamento magnético, uma
imagem que "enxerga" apenas o
magnetismo nos tecidos.
[Imagem: Wikimedia]

Células-tronco com nanopartículas

Quase todos os dias temos notícias sobre avanços em pesquisas com células-tronco em processos de regeneração de tecidos.

Contudo, apesar dos muitos progressos obtidos, algumas questões sobre o funcionamento destas células permanecem em aberto.

"Que elas funcionam nós sabemos que funcionam, mas nós queremos saber exatamente como," declara o professor Said Rabbani, do Instituto de Física (IF) da USP.

Procurando esclarecer estas dúvidas, Rabbani e seus colegas estão utilizando a marcação de células-tronco com nanopartículas supermagnéticas para realizar imagens celulares.

Nanopartículas são partículas com dimensões medidas na faixa dos nanômetros - 1 nanômetro equivale a 1 bilionésimo de metro.

Nanopartículas magnéticas

Juntando as nanopartículas às células, é possível estudar de forma muito precisa o mecanismo de funcionamento das células, acompanhando o caminho delas antes, durante e após a regeneração.

Os pesquisadores usam nanopartículas contendo óxido de ferro, que permitem a visualização das células às quais elas estão anexadas por meio de um técnica de imageamento magnético, uma imagem que "enxerga" apenas o magnetismo nos tecidos.

Verificando seu destino após terem atuado na regeneração, a marcação pode auxiliar, também, na verificação de possíveis efeitos colaterais da terapia com células-tronco.

Rastreamento de células-tronco

O rastreamento das células marcadas pelas nanopartículas é feito usando como cobaia um porco vivo.

O animal não precisa ser sacrificado, mas é-lhe induzido um infarto do miocárdio.

A seguir, os pesquisadores acompanham a regeneração do coração do animal por meio de ressonância magnética.

O primeiro objetivo da pesquisa, a visualização celular do processo, já foi alcançado.

"O próximo passo será ver para onde as células-tronco vão [após a regeneração], para tentar entender melhor seu mecanismo," diz o pesquisador.

Após o término dos estudos com os porcos, as pesquisas serão feitas com ratos, utilizando-se as nanopartículas acopladas às células-tronco para estudar o trajeto delas em casos de regeneração renal.

A ideia é verificar se o processo ocorre de forma semelhante em diferentes tipos de tecido.

Conhecimento sobre células-tronco

Said afirma que um entendimento mais completo do funcionamento das células-tronco é fundamental para que elas possam ser usadas de forma mais ampla.

O professor conta que, no início das pesquisas, por exemplo, acreditava-se que apenas as células tronco embrionárias teriam as propriedades de regeneração.

Atualmente sabe-se que as células adultas também possuem tais propriedades.

Outra questão levantada pelo professor era o desconhecimento das funções das células-tronco: "Hoje sabe-se que elas não são apenas curingas. Elas também funcionam como um sinalizador".

Isso significa que elas mostram ao corpo quando e onde o trabalho deve ser iniciado e finalizado, como por exemplo na regeneração de um corte realizado na mão.

Esta função poderia ser utilizada para realizar uma liberação mais precisa de medicações que necessitam atuar de forma direta em determinados tecidos, como no caso de um câncer.

"Pode-se encapsular o medicamento juntamente com as células-tronco e então ele atacaria diretamente o tumor, sem ser danoso aos demais tecidos", prevê.

O professor ressalta, porém, que no caso de seu trabalho, não se busca desenvolver métodos de tratamento.

"Nós apenas estudamos o comportamento das células-tronco. Mas nossa pesquisa poderá ser usada por outras áreas para gerar novas formas de diagnóstico ou terapia", conclui.

Fonte: Diário da Saúde

Nanotechnology: ‘Risk Governance’ in India

Author(s): A.P. Jayanthi, Koen Beumer, Madhulika Bhati, and Sujit Bhattacharya

A new report in Economic & Political Weekly analyzes the potential consequences of the application of nanotechnology in India, while specifically looking at the risk-related aspects of this emerging technology. 

The authors address the following questions: 

1) “What are the risks that nanotechnology may pose? 2) What does the Indian situation look like? 3) How can the risks of nanotechnology be adequately dealt with? 4) And, equally important, how can we avoid the, at times, unproductive controversies that have surrounded some of the mega-technologies in the past in order to cast a more fruitful and productive path for nanotechnology’s future?” 

The article explores the institutional arrangements for “risk governance” of nanotechnology in other countries, in an effort to illustrate possible ways for risk governance to be made operational. The authors note that while more technologically advanced countries tend to accompany technology developments with governance arrangements that ensure the responsible development of such technologies, in India attention to risks is minimal. 

They write: “Rather than explicitly taking broader societal concerns into consideration when promoting the development of a technology, it seems that any kind of measure to deal with potential adverse effects of new technologies is considered as inimical to market investment in technology sectors. By and large, the Indian state has shown a lack of anticipatory governance during the course of technology development.” 

The report concludes that the regulatory framework in India at present is not able to deal with the multifaceted dimensions and implications of nanotechnology. An effective risk governance system is urgently required, they say, arguing that a separate agency, similar to the one established for biotechnology, be implemented in order to develop human resources and infrastructure, as well as research and monitor issues and concerns in the field. “Only by creating such a well-functioning governance structure,” they conclude, “can India make nanotechnology into a success."

The original article may still be available here

Fonte: Meridian Institute

ICTA_Public interest group welcomes NRC nanomaterial report

The International Center for Technology Assessment (ICTA) welcomes the findings of a new report by an expert panel yesterday, which concluded that despite the surge of nanomaterials in the marketplace, not enough is known about their potential health and environmental risks. 

The panel was convened by the National Research Council (NRC), the research arm of the National Academy of Sciences, at the request of the Environmental Protection Agency (EPA).
"The NRC report is another indicator of the hazards posed by nanomaterials and the risk of Federal inaction on nanotechnology," said Jaydee Hanson, Policy Director for ICTA. "The public interest community continues to raise these concerns and we hope that EPA and other Federal agencies will heed yesterday's warnings."

Nanotechnology is a powerful new set of technologies for observing, taking apart and reconstructing nature at the atomic and molecular level. With $225 billion in sales in 2009, nanomaterials are used in countless other consumer products including sunscreens, face creams, baby bottles, toothbrushes, cutting boards and many others. 

Despite rise in products on the market, nano-enabled consumer products go unlabeled and largely untested for their human health and environmental effects. 

Yet as noted by the NRC's report, much of the research raises red flags on nanomaterials' ability to enter the body through contact with the skin and inhalation as well as their ability to inflict damage to the environment through multiple routes.

In December 2011, ICTA filed the first lawsuit over the health and environmental risks of nanotechnology and nanomaterials on behalf of consumer and environmental groups with the U.S. Food and Drug Administration. The lawsuit demanded FDA respond to a 2006 petition filed by ICTA requesting the FDA issue specific regulations for nanotechnology and properly regulate the use of nanoparticles in sunscreens.

In its report, the panel criticized the National Nanotechnology Initiative, the coordinator of nano-funding and priorities across Federal agencies, with failing to connect research and research findings with the creation of strategies to prevent and manage risk at the Federal level. The report also notes that, "today's exposure scenarios may not resemble those of the future," making the need for immediate action by Federal agencies all the more necessary. Mark R. Wiesner, an engineering professor at Duke University and a member of the panel, acknowledged points raised by ICTA and others that case-by-case examinations of nanomaterials are nearly impossible given the immense backlog of engineered nanomaterials needing to be assessed and the dearth of funding and resources to do so.

In 2008, ICTA and the Center for Food Safety (CFS) filed a legal petition with the EPA on behalf of a coalition of 14 public interest organizations calling on EPA to regulate nanosilver and other nano-pesticide products pursuant to its authority under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA).

In November 2009, the EPA convened a Scientific Advisory Panel (SAP) to assess and evaluate the hazards and exposure risks associated with nanosilver and other nanometal pesticide programs. The SAP concluded that data gaps on potential exposure and hazards related to nanoparticles are broad; most existing models are not appropriate for use with nanomaterials and are unable to predict accurately nanomaterial exposure scenarios; additionally, existing data on current exposure and toxicity studies vary greatly with respect to metrics, particle size, etc. Ultimately, the SAP concluded that nanoparticles are fundamentally different substances from their larger scale cousins and that nanomaterials can create new and unique health and environmental risks that need new forms of safety testing.

In November 2010, ICTA and CFS filed a similar petition with the EPA to use its FIFRA authority to halt the sale of untested nano-copper products, providing yet another blueprint for how EPA should be treating and regulating nanomaterials.
"The panel's conclusions are clear," added Hanson. "It's about time we stop speculating about the risks and start addressing them. EPA can begin with publishing its much anticipated nano-pesticide rule. "

Fonte: NanoWerk

OECD releases new publications on safety of manufactured nanomaterials

The OECD Working Party on Manufactured Nanomaterials (WPMN) has added various publications to its series on the safety of manufactured nanomaterials. 

These include National Activities on Life Cycle Assessment of Nanomaterials, which has information from Austria, Finland, Germany, Korea, Poland, the UK, the US, the European Commission, and industry, Current Developments/Activities on the Safety of Manufactured Nanomaterials and Regulated Nanomaterials:2006-2009.

• Publications

Fonte: Chemical Watch

NRDC files lawsuit blocking untested nanosilver pesticide from clothing

Jennifer Sass, 

Today we filed a federal lawsuit to block nanosilver, a potent antimicrobial pesticide, from market access.
The Environmental Protection Agency (EPA) has conditionally registered nanosilver for use in textiles including such things as clothing, baby blankets, and pillow cases.

The "conditional" part of the registration means that EPA does not have all the legally required toxicity data, but is letting the pesticide on the market anyway, on the "condition" that the manufacturer, HeiQ, provide it sometime over the next four years. Four years! (More on the registration process from my colleague Mae Wu here)

Ironically, a report of the National Academies just yesterday found that, "Despite extensive investment in nanotechnology and increasing commercialization over the last decade, insufficient understanding remains about the environmental, health, and safety aspects of nanomaterials."

Silver, a well-recognized antimicrobial, is highly toxic and kills both harmful and beneficial bacteria. Nanosilver is engineered from silver and marketed as an even stronger antimicrobial than silver. Because of its smaller size, nanosilver penetrates organs and tissues in the body that larger forms of silver cannot reach, like the brain, lung, and testes. That can't be good!

Unfortunately, while HeiQ came to EPA to have its product registered, other nanosilver manufacturers have not. 

The unregulated and untested use of nanosilver in such products as food storage containers and hair dryers continues to grow, despite potential dangerous health effects.

What can you do? 

Think twice before you purchase any products with germ-fighting or antimicrobial claims. No one needs chemical-impregnated clothing. Soap and water is all the germ-fighting we need.

Fonte: NRDC Switchboard
____________________________
Vejam:
a) Lawsuit Seeks To Block EPA’s ‘Free Pass’ on Nanosilver
b) US NGO launches lawsuit against EPA’s policy on nanosilver
c) NRDC Files Suit to Block EPA's Conditional Registration of Nanosilver

Group files first-ever suit to stop EPA approval of nanoscale chemical

Jeremy P. Jacobs, E&E reporter

Public health advocates today filed a lawsuit seeking to block U.S. EPA from allowing a nanomaterial used in clothing and baby blankets from going on the market because the health risks of the substance are unknown.

The Natural Resources Defense Council's (NRDC) petition aims to overturn EPA's decision to conditionally approve nanosilver under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA). It marks the first time ever that EPA's approval of a nanoscale chemical has been challenged in court.

Nanomaterials are approximately 100,000 times thinner than a strand of hair. They are increasingly used in consumer products, but little is known about their health effects.

Silver is a well-recognized antimicrobial, and being re-engineered in nanoform boosts its ability to kill bacteria. Consequently, companies have sought to use nanosilver in fabrics, food storage containers and hair dryers.

Last December, EPA conditionally approved a request from HeiQ Materials to sell nanosilver in fabrics, meaning the textiles could go on the market while the company conducts health and safety tests over the next four years.

"EPA gave this company a four-year free pass to sell an inadequately tested product," the NRDC's Mae Wu said in a statement. "EPA's approval of nanosilver is just the most recent example in a long line of decisions that treats humans and our environment as guinea pigs for these untested pesticides."

The NRDC petition was filed with the 9th U.S. Circuit Court of Appeals, headquartered in San Francisco, Calif.

The lawsuit unites two frequent public health criticisms of EPA: The agency's conditional approval program and the federal approach to nanomaterials. Both EPA's inspector general and a National Academy of Sciences panel have recently said that more attention needs to be paid to assessing the health risks posed by nanomaterials, and more funding and research needs to be devoted to it (E&ENews PM, Jan. 25).

Nanomaterials appear in products ranging from infant pacifiers to paint, bicycles and cosmetics. Experts project that the global market for the substances will grow to $3 trillion by 2015.

Public health advocates charge that nanosilver is particularly insidious because its makers tout its health benefits without noting any risks.

"Because of its incredibly small size, nanosilver penetrates organs and tissues in the body that larger forms of silver cannot reach, like the brain, lung and testes," said Jennifer Sass, an NRDC senior scientist.

A few years ago, Samsung tried to manufacture a washing machine that released nanosilver into the water. Green groups, including NRDC, fiercely protested it, however, and the company eventually changed its plans.

Public health groups also charge that EPA's conditional approval process under FIFRA is flawed. In addition to nanosilver, they highlight the herbicide Imprelis, which was conditionally approved in 2010 but pulled off the market last year when several cases of the chemical killing trees surfaced (E&ENews PM, Aug. 11, 2011).

Fonte: EEnews-Greenwire

Nano form of titanium dioxide can be toxic to marine organisms

The Bren School-based authors of a study published Jan. 20 in the journal PLoS ONE have observed toxicity to marine organisms resulting from exposure to a nanoparticle that had not previously been shown to be toxic under similar conditions.

Lead author and assistant research biologist Robert Miller and co-authors Arturo Keller and Hunter Lenihan – both Bren School professors and lead scientists at the UC Center for Environmental Implications of Nanotechnology (UC CEIN) – Bren Phd student Samuel Bennett, and Scott Pease, a former UCSB undergraduate and current graduate student in public health at the University of Washington, found that the nanoparticulate form of titanium dioxide (TiO₂) exposed to ultraviolet radiation (UVR) can be toxic to marine organisms.

"Application of nanomaterials in consumer products and manufacturing is quickly increasing, but there is concern that these materials, including nanoparticles, may harm the environment," says Miller. 

"The oceans could be most at risk, since wastewater and factory discharges ultimately end up there."

Nano-titanium dioxide is highly reactive to sunlight and other forms of ultraviolet radiation (UVR), the authors write, adding that TiO₂'s property of generating reactive oxygen species (ROS) when exposed to UVR makes it useful in antibacterial coatings and wastewater disinfection, and potentially valuable as an anti-cancer agent.

Until now, they say, no research has demonstrated that photoactivity causes environmental toxicity of TiO₂ under natural levels of UVR.

"Previous experiments have suggested that TiO₂ does not affect aquatic organisms, but these experiments used artificial lighting that generated much lower levels of UVR than sunlight," Miller explains. "In these new experiments, we used lights simulating natural sunlight."

But now, the authors say, "We show that relatively low levels of ultraviolet light, consistent with those found in nature, can induce toxicity of TiO₂ nanoparticles to marine phytoplankton, the most important primary producers on Earth.

"With no exposure to UVR, the TiO₂ had no effect on phytoplankton, but under low-intensity UVR, ROS in seawater increased with increasing concentrations of nano- TiO₂."

The concern is that rising concentrations of nano- TiO₂ "may lead to increased overall oxidative stress in seawater contaminated by TiO₂, and cause decreased resiliency of marine ecosystems."

The authors suggest, therefore, that UVR exposure should be considered when conducting experiments to determine the ecotoxicity of nanomaterials having photoactive potential.

Provided by University of California - Santa Barbara

Fonte: Physorg

NanoRiskCat - A conceptual decision support tool for nanomaterials

In a project funded by the Danish Environemntal Protection Agency (EPA), the Technical University of Denmark (DTU) and National Research Centre for the Working Environment have initiated the development of a screening tool called NanoRiskCat (NRC) for the evaluation of exposure and hazard of nanomaterials contained in products for professional and private use.

Authored by Steffen Foss Hansen and Anders Braun from DTU's Department of Environmental Engineering and Keld Alstrup-Jensen from the National Research Centre for the Working Environment Environmental Project, the 268-page report on the NanRiskCat screening tool can be downloaded as a PDF file from the Danish EPA's website.

The project's aim was to identify, categorize and rank the possible exposure and hazards associated with a nanomaterial in a product. NanoRiskCat is using a stepwise approach based on existing data on the conventional form of the chemical as well as the data that may exist on the nanoform. However, the tool still needs to be further validated and tested on a series of various nano products in order to adjust and optimize the concept and thereby to achieve a screening tool as informative and practical as possible.

It is the view of the Danish EPA that the traffic light ranking of the health effects may be further modified to obtain a better ranking in the various categories. Thus titanium dioxide in sunscreen is ranked as red due to lung effects of titanium dioxide, because the tool in its present form does not sufficiently take account of which type of health effects that are most relevant for the most relevant exposure route of the product. In this case the inhalational exposure of titanium dioxide from a sun screen seems less relevant.

Executive Summary

Nanomaterials are being used in a rapidly increasing number of products available for industries and private consumers. The number of nanomaterials that can be manufactured using nanotechnologies is immense and the improved material properties enable use in multiple different products. During the last decade more and more evidence has emerged in the scientific literature suggesting that some nanomaterials may have hazardous properties.

With this background, the Danish Environmental Protection Agency has identified a need for developing a new concept that can provide support to companies and regulators in regard to assessing, ranking and communicating what they know about the risks of nanomaterials in specific product uses. In this case, risk should be defined as a combination of the likelihood of exposure and adverse effects, i.e. any chance of an adverse outcome to human health, the quality of life, or the quality of environment.

Through this project, DTU Environment and the National Research Centre for the Working Environment have initiated the development of a screening tool, NanoRiskCat (NRC), that is able to identify, categorize and rank exposures and effects of nanomaterials used in consumer products based on data available in the peer-reviewed scientific literature and other regulatory relevant sources of information and data. The primary focus was on nanomaterials relevant for professional end-users and consumers as, as well as nanomaterials released into the environment.

The wider goal of NanoRiskCat is to help manufacturers, down-stream endusers, regulators and other stakeholders to evaluate, rank and communicate the potential for exposure and effects through a tiered approach in which the specific applications of a given nanomaterial are evaluated. This is done by providing detailed guidance on mapping and reporting of the:

1. Exposure potential for professional end-users 2. Exposure potential for consumers 3. Exposure potential for the environment 4. A preliminary hazard evaluation for humans 5. A preliminary hazard evaluation for the environment

A generic template for mapping and reporting these five aspects for a specific application of a given nanomaterial has been developed and can be found in Appendix 1 of the report.

In its simplest form, the final outcome of using NanoRiskCat for a nanomaterial in a given application will be communicated in the form of a short title describing the use of the nanomaterial (e.g. MeO in ship paint) and a five-color coded dots, where the first three dots always refer to potential exposure of professional end-users, consumers and the environment in that sequence and the last two colors always refer to the hazard potential for humans and the environment. The colors signify whether the indications of exposures or effects separately are high (red), medium (yellow), low (green), or unknown (grey).

Generic approach used in NanoRiskCat to assign the color-code to products with no, possible and expected exposure depending on the location of the nanomaterial in the product.

The color-coding of the dots representing the exposure potential (dost numbers one to three) is based on the generic use descriptor system established by the European Chemicals Agency (ECHA) in the current REACH Guidance on information requirements and chemical safety assessment Appendix R.124. For each use category, a color code has been assigned based on 1) the location of the nanomaterial (bulk, on the surface, liquid or airborne) and 2) a judgment of the potential for nanomaterial exposure based on the description and explanation of each process, product category, technical function, article and environmental release category provided in the REACH Guidance.

When assigning a color to the dot representing potential human health hazards (dot number four) related to the specific application of a given nanomaterial the following indicators/qualifiers should be considered:

1. Does the nanomaterial fulfil the HARN paradigm?

2. Is the bulk form of the nanomaterial known to cause or may cause serious damaging effects, i.e. is the bulk form classified according to the CLP with regard to one or more serious health hazards such as germ cell mutagenicity, carcinogenicity or reproductive toxicity in category 1A, 1B or 2?

3. Is the bulk form of the nanomaterial classified for other less severe adverse effects according to the CLP such as skin corrosion/irritation category 2 and specific target organ toxicity-single exposure category 3?

4. Is the specific nanomaterial known to be acute toxic?

5. Are there indications that the nanomaterial causes genotoxic, mutagenic, carcinogenic, respiratory, cardiovascular, neurotoxic or reproductive effects in humans and/or laboratory animals or has organ-specific accumulation been documented?

The human hazards information on the bulk form of the material may be used as a starting point in order to describe a possible minimum level of concern in regard to the toxicological profile for the nanomaterial. A guiding principle is that information about the bulk form of the material can be used under the assumption that any toxicological and ecotoxicological effects of the nanomaterial are equal to or larger than those reported on for the bulk material. Thus hazard data on the bulk material forms the basis of the lowest level of concern with regard to the nanomaterial.

In NRC, indications of the level of environmental effects (dot number five) should include considerations of whether the nanomaterial in question is reported to be:

1. Hazardous to environmental species?

2. Persistent?

3. Bioaccumulative?

4. Leading to potentially irreversible harm to the environment (e.g. ecosystem effects)?

5. Readily dispersed?

6. Novel?

It is important to note that NanoRiskCat is a stepwise and tiered approach in the sense that once a color code has been triggered this finalizes the screening process.

To help communicate the scientific reasoning behind the human health and environmental hazard categorization and the assigned color code, a number of standard sentences have been included in the framework. These sentences are primarily meant to reflect whether the categorization has been reached based on in vivo or in vitro studies and in regard to which effect or endpoint. Depending to the final categorization in regard to human health and environment, the user of NRC has to select one or more of those sentences that best reflect the scientific basis for assigning the color code.

In order to illustrate the feasibility of NanoRiskCat two nanomaterials (titanium dioxide and C60) were used as training sets in two different applications i.e. C60 used in a lubricant and TiO2 used in sunscreen. These examples were chosen order to be used in the development of the concept but they are also included in the current report in order to illustrate the applicability of NanoRiskCat.

Example of the evaluation of environmental hazard of C60 in C60 LubExtreme according to NanoRiskCat.

It is important to underline that NanoRiskCat is not a product label and NanoRiskCat is only to be used for evaluating the nanomaterial as an ingredient under the physical conditions it occurs in the product. NanoRiskCat does not evaluate exposure and effects from the other constituents and impurities in the product nor does it take into account the specific content of nanomaterial in the product. Thus, NanoRiskCat is directed towards the generic use descriptors and scenarios, which for instance are apparent in the product categories used in REACH. Although NanoRiskCat is generic in nature and can be used on all kinds of nanomaterials and applications, the NanoRiskCat color code itself is application-specific. Thus, a NanoRiskCat color code does not in itself allow for an overall evaluation of risks associated with a given nanomaterial.

A significant strength of NanoRiskCat is that it can be used even in cases where lack of data is prominent and hampers the completion of traditional risk assessment procedures. Another is that the results of NanoRiskCat can be easily communicated to interested parties. A significant weakness of NanoRiskCat is that many of the cut-off values used primarily in the environmental hazard evaluation is based on dose-by-mass which we know is probably not valid for all nanomaterials as it is an ongoing discussion on which dose-metrics will be the best to use in nano-ecotoxicology. Furthermore, the process by which the color code is assigned to human hazards associated with the nanoform of a given material is based primarily on scientific expert judgement and a holistic assessment of the evidence of mutagenicity, carcinogenicity, respiratory toxicity, etc. As expert interpretation of scientific literature vary, so can the conclusion reached and the human hazard color code assigned to nanomaterial. It is not possible to provide clear-cut guidance and rules at this point in time for how to complete holistic evaluation of the human and environmental hazards associated with the nanoform of a given material. It is crucial in this context that the users of the NRC explain what literature they have identified as relevant and explain how they interpret the reported results and assign the various color codes in the NRC template provided in Appendix 1.

The result of NRC does not lead directly to an decision in contrast to other decision-making tools available for nanomaterials, but NRC does provide a informed and structured foundation for decision-making by including a number of indicators that define whether exposure and effects are likely (or unlikely) to occur and whether the nanomaterial may have harmful properties of concern.

Decisions that could come out of using NanoRiskCat are stakeholder-dependent. Regulators could use NRC as a screening tool to identify possible uses where risk management measures may be further examined e.g. to develop guidance on controlled uses, or to evaluate whether specific restrictions would be required or to indentify data needs. Companies can use NanoRisk- Cat to communicate what they know about the exposures and effects of the nanomaterial they use, assess the need to develop guidance for safe uses that e.g. limit exposures by changing the product formulation or the use of the nanoproduct or work systematically with designing safer nanomaterials. Likewise, the company could develop guidelines for professional end-users and consumers about the safe uses of their nanomaterials and products. Down-stream users (e.g. consumers) can use NanoRiskCat to make a preliminary assessment of a range of nanomaterials as a mean to select the seemingly safest material.

Finally, independent parties such as academics and nongovernmental organizations can use the tools to learn more about what companies know about exposures and effects of their nanomaterials and they can use NanoRiskCat to do their own independent evaluation and subsequently engage in an informed dialogue about nanorisks with companies and regulators. It is finally important to stress that the color coding obtained in NanoRiskCat should not be seen as an absolute categorization. It rather serves as a step in an iterative process in which stakeholders in risk-related issues can reach a common – and guided - understanding of the level of potential exposures and effects of nanomaterials in specific products.

As decisions that could come out of using NanoRiskCat are stakeholderdependent, it is important to emphasize that it has not been possible within the framework of this project to validate the NRC concept further. To promote a wider use of the tool it is considered necessary to perform additional case studies and if relevant adjust the processes and decision criteria in order to obtain a screening tool as informative and practical as possible. Fonte: NanoWerk

Grazie alle nanoparticelle anche la vernice produce energia

Secondo quanto pubblicato sulla rivista scientifica ACS Nano, ricercatori del Dipartimento di Scienza e Nanotecnologia dell'Università di Notre Dame (in Indiana, Stati Uniti) guidati dal professor John A. Zahm hanno messo a punto una vernice che, quando esposta alla luce delle sole, grazie a nano particelle di biossido di titanio in essa contenute, riesce a produrre energia elettrica.

Sebbene l'efficienza di conversione della luce in energia raggiunta finora è appena dell'1% (valore che è ben al di sotto del 10-15% offerto dalle celle solari al silicio attualmente in commercio), si tratta di un importante passo in avanti che apre nuove strade allo sfruttamento dell'energia del sole. 

La vernice solare messa a punto dai ricercatori, infatti, non solo può essere prodotta a basso costo, dunque in grandi quantità, ma può essere applicata facilmente su qualsiasi superficie, dunque su qualsiasi tipo di edificio o costruzione, senza alcuna attrezzatura speciale.

Se gli scienziati riusciranno nei prossimi mesi a migliorare l'efficienza energetica della loro invenzione, si tratterà quindi di una vera e propria scoperta che di certo rivoluzionerà il modo di produrre energia pulita, ma che sarà anche in grado di fare la vera differenza nel soddisfare bisogni energetici dell'umanità.

Fonte: Veneto Nanotech

Nanotecnologie: arriva l'autopulitura applicata ai tessuti

Autore: Annalisa Tancredi

Se sino ad oggi avete utilizzato acqua e sapone per il lavaggio dei vostri indumenti, è possibile che in un futuro prossimo vi basterà semplicemente esporli alla luce del sole per ottenere un effetto autopulente dei tessuti. 

L’invenzione proviene da due ricercatori cinesi dell’Università di Shangai, Mingce Long e Deyong Wu, che hanno messo a punto nei laboratori accademici una nuova metodologie basata sull’applicazione delle proprietà delle nanoparticelle del biossido di titanio ai tessuti, al fine di ottenere un effetto smacchiante e disinfettante.

Il biossido di titanio è un noto catalizzatore in grado di degradare per ossidazione numerosi composti organici; quando viene esposto alla luce del sole ha la particolarità di eliminare lo sporco e disinfettare le superfici su cui viene applicato uccidendo i microbi; per queste proprietà il TiO2 è già largamente utilizzato in alcuni prodotti come vetri autopulenti, piastrelle per cucina, asfalti ma anche vernici e creme solari. 

La sperimentazione dei due ricercatori cinesi prevede l’utilizzo di un rivestimento di biossido di titanio alle fibre dei tessuti; in questo modo la molecola del titanio attiverà il processo chimico di autopulitura in seguito all’esposizione al sole; il test di sperimentazione è stato fatto sporcando i tessuti con una macchia arancione di metilarancio, un colorante chimico, e i risultati sono stati quelli prospettati: con l’esposizione alla luce, il tessuto si è autopulito senza lasciare traccia del colorante. ''Una volta esposto al sole il cotone ha eliminato il metilarancio, e anche i batteri presenti sulla superficie – si legge nell'articolo dei due chimici cinesi - e il processo è rimasto efficiente per diversi lavaggi''. 

In seguito ai lavaggi il tessuto continua a mantenere le sue proprietà nel tempo e la formula, inoltre, è perfezionabile con l’aggiunta di ioduro d’argento, un composto fotosensibile utilizzato per le pellicole fotografiche e in medicina come disinfettante o per la costruzione di protesi. 

L’uso del diossido di titanio e in generale delle nanotecnologie, in ogni caso non è stato esentato da polemiche per la presunta tossicità, soprattutto nell’ambito della cosmesi; alcune ricerche hanno riportato che le radiazioni provenienti dal Sole possono aumentare la tossicità delle nanoparticelle di TiO2 da 20 a 40 volte e che queste vengano poi assorbite dall’epidermide. 

Nel nostro corpo è presente in quantità rilevabile, non è un metallo velenoso e pare che il corpo umano sia in grado di tollerarne anche un’elevata quantità. In ogni caso le conseguenze dovute alla sovraesposizione e inalazione possono provocare leggere variazioni nei polmoni, difficoltà di respirazione e irritazioni cutanee.

Fonte: Veneto Nanotech