Yearly Archives: 2014

News Release: A new bug killer


The Center Director Dr. Phil Demokritou and the Research Fellow Georgios Pyrgiotakis are featured in the prestigious magazine “The Economist” (issue July 7) that is focus on the upcoming “Big things in Nanotechnology”. They discuss the applications of their research on the Engineered Water Nanostructures  (EWNS) in aspects of daily life. This feature is one more on the long list of recognition the research on the topic that the center has earned. You can read the entire story of on the online version of The Economist here.

The research has been featured in numerous print and on line publications:

  • Our paper has been Featured by RSC’s journal Chemistry World (link)
  • It was also featured in the German NPR radio (link)
  • It was featured on the cover of the Enviromental Science: Nano

Nano State

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The NanoCenter researchers , Phil Demokritou, Joseph Brain and Georgios Pyrgiotakis were featured in a four page special story at the Harvard School of Public Health magazine. They discussed the impact of nano in the society and the importance of the center research. Further more they talked about the Engineered Water Nanostructures a novel, chemical free method developed in the Center that is promising for the air inactivation of pathogenes.

You can read the whole story here.

Harvard School of Public Health researchers develop technique to measure the quantity of engineered nanomaterials delivered to cells

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Press Release in pdf

Boston, MA— Thousands of consumer products containing engineered nanoparticles — microscopic particles found in everyday items from cosmetics and clothing to building materials — enter the market every year. Concerns about possible environmental health and safety issues of these nano-enabled products continue to grow with scientists struggling to come up with fast, cheap, and easy-to-use cellular screening systems to determine possible hazards of vast libraries of engineered nanomaterials. However, determining how much exposure to engineered nanoparticles could be unsafe for humans requires precise knowledge of the amount (dose) of nanomaterials interacting with cells and tissues such as lungs and skin.

With chemicals, this is easy to do but when it comes to nanoparticles suspended in physiological media, this is not trivial. Engineered nanoparticles in biological media interact with serum proteins and form larger agglomerates which alter both their so called effective density and active surface area and ultimately define their delivery to cell dose and bio-interactions. This behavior has tremendous implications not only in measuring the exact amount of nanomaterials interacting with cells and tissue but also in defining hazard rankings of various engineered nanomaterials (ENMs). As a result, thousands of published cellular screening assays are difficult to interpret and use for risk assessment purposes.

Scientists at the Center for Nanotechnology and Nanotoxicology at Harvard School of Public Health (HSPH) have discovered a fast, simple, and inexpensive method to measure the effective density of engineered nanoparticles in physiological fluids, thereby making it possible to accurately determine the amount of nanomaterials that come into contact with cells and tissue in culture.

The method, referred to as the Volumetric Centrifugation Method (VCM), will be published in the March 28, 2014 Nature Communications.

The new discovery will have a major impact on the hazard assessment of engineered nanoparticles, enabling risk assessors to perform accurate hazard rankings of nanomaterials using cellular systems. Furthermore, by measuring the composition of nanomaterial agglomerates in physiologic fluids, it will allow scientists to design more effective nano-based drug delivery systems for nanomedicine applications.

“The biggest challenge we have in assessing possible health effects associated with nano exposures is deciding when something is hazardous and when it is not, based on the dose level. At low levels, the risks are probably miniscule,” said senior author Philip Demokritou, associate professor of aerosol physics in the Department of Environmental Health at HSPH. “The question is: At what dose level does nano-exposure become problematic? The same question applies to nano-based drugs when we test their efficiency using cellular systems. How much of the administered nano-drug will come in contact with cells and tissue? This will determine the effective dose needed for a given cellular response,” Demokritou said.

Federal regulatory agencies do not require manufacturers to test engineered nanoparticles, if the original form of the bulk material has already been shown to be safe. However, there is evidence that some of these materials could be more harmful in the nanoscale — a scale at which materials may penetrate cells and bypass biological barriers more easily and exhibit unique physical, chemical, and biological properties compared to larger size particles. Nanotoxicologists are struggling to develop fast and cheap toxicological screening cellular assays to cope with the influx of vast forms of engineered nanomaterials and avoid laborious and expensive animal testing. However, this effort has been held back due to the lack of a simple-to-use, fast, method to measure the dose-response relationships and possible toxicological implications. While biological responses are fairly easy to measure, scientists are struggling to develop a fast method to assess the exact amount or dose of nanomaterials coming in contact with cells in biological media.

“Dosimetric considerations are too complicated to consider in nano-bio assessments, but too important to ignore,” Demokritou said. “Comparisons of biological responses to nano-exposures usually rely on guesstimates based on properties measured in the dry powder form (e.g., mass, surface area, and density), without taking into account particle-particle and particle-fluid interactions in biological media. When suspended in fluids, nanoparticles typically form agglomerates that include large amounts of the suspending fluid, and that therefore have effective densities much lower than that of dry material. This greatly influences the particle delivery to cells, and reduces the surface area available for interactions with cells,” said Glen DeLoid, research associate in the Department of Environmental Health, one of the two lead authors of the study. “The VCM method will help nanobiologists and regulators to resolve conflicting in vitro cellular toxicity data that have been reported in the literature for various nanomaterials. These disparities likely result from lack of or inaccurate dosimetric considerations in nano-bio interactions in a cellular screening system,” said Joel Cohen, doctoral student at HSPH and one of the two lead authors of the study.

Wolfgang Kreyling, a nanotoxicologist at the German Research Center for Environmental Health who was not involved in the study, says this method should help toxicologists to understand the nano-bio interactions and address possible nano hazards for the vast libraries of engineered nanoparticles (ENPs) currently in use.

“The paper by DeLoid et al in Nature Communications is a major achievement which offers a solution to solve the pending issues of the apparent ENM density and an easy way to determine the latter by the application of the volumetric centrifugation method. Hence, this paper provides a versatile concept easy to achieve which allows for a rather precise estimate of ENM dosimetry to in vitro cell cultures which hopefully will improve the power of toxicological studies using in vitro cell cultures when comparing to in vivo studies. In this case this would be a major contribution in aiming to reduce in vivo experimental animal work,” Kreyling said.

Other authors of the study include Georgios Pyrgiotakis, research fellow at HSPH, Liying Rojanasakul, and Raymond Derk from the National Institute for Occupational Safety and Health, and Wendel Wohlleben from BASF, Germany.

This research project was supported by NIEHS grant (ES-000002), NSF grant (ID 1235806) and the Center for Nanotechnology and Nanotoxicology at HSPH. This work was performed in part at the Harvard Center for Nanoscale Systems (CNS), a member of the National Nanotechnology Infrastructure Network (NNIN), which is supported by the National Science Foundation under NSF award number ECS-0335765.

“Estimating the effective density of engineered nanomaterials for in vitro dosimetry,” Glen DeLoid, Joel M. Cohen, Tom Darrah, Raymond Derk, Liying Rojanasakul, Georgios Pyrgiotakis, Wendel Wohlleben, and Philip Demokritou, Nature Communications, online March 28, 2014.

Predicting the Impact of Engineered Nanomaterials on Lung Diseases

Title: Predicting the Impact of Engineered Nanomaterials on Lung Diseases


Speaker: Dr. James C. Bonner

Associate Professor

Department of Environmental & Molecular Toxicology,

North Carolina State University, Raleigh, NC


Date: February  27, 2014
Time: 12:30-1:30 pm
Place: 665 Huntington Ave, Building 1, Room 1302, Boston, MA 02115

Abstract:  The nanotechnology revolution offers enormous societal and economic benefits for innovation in the fields of engineering, electronics, and medicine. Nevertheless, evidence from rodent inhalation studies show that biopersistent engineered nanomaterials, including carbon nanotubes and metal nanoparticles, have the potential to stimulate immune, inflammatory, or fibroproliferative responses in the lung and pleura. These data suggest possible risks for pulmonary fibrosis or the development of pleural disease as a consequence of occupational or consumer exposure. Some engineered nanomaterials also exacerbate pre-existing allergen-induced inflammation by altering the balance of distinct T-helper cell phenotypes, suggesting that they could serve as sensitizers or adjuvants to alter the innate immune response.  These findings suggest that individuals with asthma or other pre-existing respiratory diseases would be particularly susceptible to the adverse health effects of nanomaterials. Due to their nanoscale dimensions and increased surface area per unit mass, engineered nanomaterials have a much greater potential to reach the distal regions of the lung, generate reactive oxygen species, and alter cell signaling pathways linked to disease pathogenesis. The goal of this presentation will be to discuss mechanisms through which engineered nanomaterials cause lung, airway, and pleural disease, especially in the context of susceptible individuals with pre-existing disease. Functionalization of nanomaterials through processes such as atomic layer deposition will also be discussed as a means of altering the pathogenicity of nanomaterials.

First High Throughput Genotox Assay

Protocol for the high throughput Comet Assay. (A) Assembly of macrowell comet array. Agarose gel with microwells is sandwiched between a glass substrate and a bottomless 96-well plate and sealed with mechanical force. Approximately 300 arrayed microwells comprise the bottom of each macrowell. (B) Preparation of the nanoparticle suspension according to the protocol by Cohen at al. (C) Protocol for exposing the cells to the nanoparticles. (D) Loading of the exposed cell samples in the macrowells and running the microwell assay.

Protocol for the high throughput Comet Assay. (A) Assembly of macrowell comet array. Agarose gel with microwells is sandwiched between a glass substrate and a bottomless 96-well plate and sealed with mechanical force. Approximately 300 arrayed microwells comprise the bottom of each macrowell. (B) Preparation of the nanoparticle suspension according to the protocol by Cohen at al. (C) Protocol for exposing the cells to the nanoparticles. (D) Loading of the exposed cell samples in the macrowells and running the microwell assay.

Nanomaterials are part of daily life. Although there is a wide range of methods to evaluate their potential toxic effects, there is no way to evaluate gene damage.

Scientists at Harvard University in the School of Public Health in collaboration with the research Group of Bevin P. Engelward at MIT, have developed a screening assay to detect the genotoxic potential of nanomaterials. Metal oxide nanoparticles in biological systems can generate reactive oxygen species, which can overwhelm innate antioxidant defenses and cause oxidative stress. Oxidative stress, among other factors, has been associated with DNA damage and mutations, precursors to cancer. As more and more commercial products contain nanomaterials consisting of metal oxides such as titanium dioxide and zinc oxide, screening assays such as these are crucial to reducing potential health hazards. Christa Watson, postdoctoral research fellow at HSPH, suggests that accurate toxicity assessments of nanomaterials before they are incorporated into consumer products can help us prevent similar consequences that we are currently facing from asbestos exposures such as mesothelioma. Current efforts are ongoing to understand the novel toxicities nanomaterials may pose on public safety. This research was recently published in ACS Nano February 14, 2014 DOI: 10.1021/nn404871p

Research at the HSPH NanoCenter revolutionize sunscreens!

ZnO is a widely used material in cosmetics and food applications. The ions however, that are leaching have been linked to potential adverse effects. In our center we developed a safer formulation concept to mitigate toxicity by encapsulating the materials in a thin layer of Silica.

ZnO is a widely used material in cosmetics and food applications. The ions however, that are leaching have been linked to potential adverse effects. In our center we developed a safer formulation concept to mitigate toxicity by encapsulating the materials in a thin layer of Silica.

One of the main constituents of sunscreen is the ZnO particles. ZnO nanoparticles are sought out for UV-filter applications thanks to their inherent optoelectronic properties and are, therefore, broadly used today in cosmetics and polymers. Preliminary toxicological data, however, point out that they can induce significant DNA damage and genotoxicity due to their Zn2+ ion leaching. It has become important for the nanotechnology industry, to devise scalable, safer-by-design approaches to minimize the ZnO nanoparticle dissolution and toxicity without altering their desired optoelectronic properties.

G. Sotiriou the lead author of the paper.

In their work, the researchers demonstrated a safer-by-design approach for ZnO nanorods using a scalable flame aerosol process. This technology allows for controlled synthesis of high-purity ZnO nanorods with highly crystalline core and a nanothin amorphous silica shell that improves their biocompatibility. The as-prepared nanorods exhibit high transparency in the visible range, but strong absorption in the UV rendering them suitable for use in sunscreens and polymers. Furthermore, it is demonstrated that the hermetic silica coating does not alter the desired optoelectronic properties of the core ZnO nanorods while their DNA damage potential has been 3-fold decreased.

You can read more at the Chemistry World news article or, directly the paper.

New England Nanotechnology Association Breakfast


Please join us for our next meeting of the Massachusetts chapter of the New England Nanotechnology Association (NENA) to hear about some new developments in nanotechnology and nanotoxicology.

We’ll enjoy a continental breakfast, spend a little time networking, and hear about these new developments and other topics of interest. There is no cost to attend, so please RSVP today. Thank you and we look forward to seeing you soon.

8:30 – 9:00AM:  Networking and refreshments

9:00 – 9:10AM:  Welcome and introductions – William S. Rogers, Jr., Esq., Partner, Prince Lobel Tye LLP, Boston, MA

9:10-9:20AM: Speaker – Eric S. Howard, Corporate and Outreach Manager, NSF Center for High-rate Nanomanufacturing, Northeastern University, Boston, MA

9:20-9:35AM:  Speaker – Philip Demokritou, Ph. D., Assoc. Professor and Director, Center for Nanotechnology and Nanotoxicology, Harvard School of Public Health, Cambridge, MA
9:35-9:45AM: Speaker – Joseph Brain, Ph.D., Cecil K. and Philip Drinker Professor of Environmental Physiology, Department of Environmental Health, Harvard School of Public Health, Cambridge, MA
9:45-10:00: Networking and adjourn

Click here to RSVP – deadline is 2/21/14

Can’t make the event? Join our LinkedIn Discussion Page.

We must have a complete list of attendees two days prior to the event in order to arrange visitor passes. No one can get in without a visitor’s pass.

If you have any questions, please don’t hesitate to contact me.

William S. Rogers, Jr.

Prince Lobel Tye LLP