Navigation Links
Rice eyes risks of quantum dots
Date:2/2/2009

Quantum dots have the potential to bring many good things into the world: efficient solar power, targeted gene and drug delivery, solid-state lighting and advances in biomedical imaging among them.

But they may pose hazards as well.

A team of Rice researchers has been working to discover the health risks of quantum dots, molecule-sized semiconducting nanocrystals that are generally composed of heavy metals surrounded by an organic shell.

Pedro Alvarez, Rice's George R. Brown Professor and chair of the Civil and Environmental Engineering Department, published a paper in ACS Environmental Science and Technology showing that under even mildly acidic or alkaline conditions, the shells can break down, releasing their toxic contents into the body or the environment. He coauthored the paper with colleagues Vicki Colvin, the Pitzer-Schlumberger Professor of Chemistry and in chemical and biological engineering, researcher Shaily Mahendra and postdoc Huiguang Zhu.

"We're interested in the long-term implications of nanotechnology, and we recognized quantum dots are going to be produced in large quantities," said Mahendra, who did the bulk of the research. "We thought we should be proactive in studying their effects so that we can take part in the development of safety guidelines."

The dots, 1/50,000ths the width of a human hair, were found to be safe in applications with a neutral pH environment. However, the study suggested when such products are discarded, they can eventually release their toxins into the environment.

"In that way, quantum dots resemble batteries," said Alvarez, referring to common nickel-cadmium cells that people are warned not to throw in the trash. "They're often made of coatings that are biocompatible and stable in water, but the moment we lose that coating, which can happen through a variety of mechanisms, they can release toxic compounds."

Used in solar cells, quantum dots may be quickly weathered by acid rain, he said. Another concern is that acids in the body could break down dots used in such medical applications as in vivo imaging. "If they degrade faster than they can be excreted, there's the potential for heavy metals to be released into the body," said Alvarez. "Then their impact becomes a question of dose."

The team tested its theories on common bacteria that serve as models of cell toxicity and indicators of environmental health. At near-neutral pH, bacteria exposed to quantum dots containing cadmium and selenium showed decreased rates of growth but did not die.

But in moderately acidic or alkaline conditions, quantum dot shells decomposed more rapidly, killing the bacteria in a matter of hours.

On the positive side, the study also found certain proteins and such natural organic matter as humic acids may mitigate the effects of decomposing quantum dots by coating them or by complexing the metal ions released, making them less toxic.

The researchers cautioned that short-term studies can't easily predict whether toxins released by quantum dots will build up in the body over time. "We hope our work will stimulate research by other labs into the release dynamics," said Alvarez.


'/>"/>

Contact: David Ruth
druth@rice.edu
713-348-6327
Rice University
Source:Eurekalert

Related biology news :

1. NAS report offers new tools to assess health risks from chemicals
2. Less Arctic ice means higher risks, experts warn
3. Energy drinks may pose risks for people with high blood pressure, heart disease
4. Fresh-cut produce washing practices can minimize food-borne illness risks
5. Turtle studies suggest health risks from environmental contaminants
6. Too much or too little weight gain poses risks to pregnant mothers, babies
7. Baker Institute study, conference weigh risks for global energy markets
8. Risks and benefits of antipsychotics in children and adolescents
9. African-Americans have unique lung cancer risks from chronic obstructive pulmonary disease
10. 6 environmental research studies reveal critical health risks from plastic
11. USC researchers head global effort to study genetic risks that contribute to psychiatric diseases
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:6/2/2016)... 2, 2016 The Department of Transport ... the 44 million US Dollar project, for the , ... including Personalization, Enrolment, and IT Infrastructure , to ... production and implementation of Identity Management Solutions. Numerous renowned international ... Decatur was selected for the most compliant ...
(Date:6/1/2016)... YORK , June 1, 2016 ... Technology in Election Administration and Criminal Identification to Boost ... to a recently released TechSci Research report, " Global ... By Region, Competition Forecast and Opportunities, 2011 - 2021", ... 24.8 billion by 2021, on account of growing security ...
(Date:5/16/2016)... May 16, 2016   EyeLock LLC , a ... the opening of an IoT Center of Excellence in ... expand the development of embedded iris biometric applications. ... of convenience and security with unmatched biometric accuracy, making ... aside from DNA. EyeLock,s platform uses video technology to ...
Breaking Biology News(10 mins):
(Date:6/27/2016)... ... June 27, 2016 , ... Parallel 6 , the ... today the Clinical Reach Virtual Patient Encounter CONSULT module which enables both ... physician and clinical trial team. , Using the CONSULT module, patients and physicians can ...
(Date:6/27/2016)... -- Liquid Biotech USA , Inc. ... Research Agreement with The University of Pennsylvania ("PENN") ... patients.  The funding will be used to assess ... outcomes in cancer patients undergoing a variety of ... to support the design of a therapeutic, decision-making ...
(Date:6/24/2016)... 24, 2016 Epic Sciences unveiled a ... susceptible to PARP inhibitors by targeting homologous recombination ... The new test has already been incorporated into ... cancer types. Over 230 clinical trials ... pathways, including PARP, ATM, ATR, DNA-PK and WEE-1. ...
(Date:6/23/2016)... ... June 23, 2016 , ... Mosio, a leader in ... Trials Patient Recruitment and Retention Tips.” Partnering with experienced clinical research professionals, Mosio ... practical tips, tools, and strategies for clinical researchers. , “The landscape of how ...
Breaking Biology Technology: