New method to measure insecticide on mosquito netting

Recently scientists at NC State’s Analytical Instrumentation Facility, working with researchers at the Centers for Disease Control and Prevention, published new methods to measure the amount of insecticide on mosquito netting. Using time-of-flight secondary ion mass spectrometry (ToF-SIMS), the team studied various samples of mosquito netting to determine the amount of insecticide necessary for the netting to be effective in killing mosquitoes. To learn more, visit the NC State press release or the online journal article.

“Imaging and Quantitative Analysis of Insecticide in Mosquito Net Fibers Using Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS)”

Stephen C. Smith, Centers for Disease Control and Prevention; Chuanzhen Zhou, Fred A. Stevie, and Roberto Garcia, North Carolina State University

Abstract: Time-of-flight secondary ion mass spectrometry (ToF-SIMS) analysis was used to qualitatively and quantitatively assess the distribution of permethrin insecticide on the surfaces and interiors of Olyset® long-lasting insecticidal net (LLIN) fibers. Total insecticide content in LLINs has been established using many analytical methods. However, it is important to quantify the bioavailable portion residing on the fiber surfaces for incorporated LLINs. ToF-SIMS is a very surface sensitive technique and can directly image the spatial distribution of permethrin insecticide on the surface of Olyset fibers. Surface permethrin appeared as patchy deposits which were easily removed by acetone and reappeared after several days as interior permethrin migrated (bloomed) from the fiber interior. After a wash/incubation cycle, permethrin deposits were more diffuse and less concentrated than those on the as-received fibers. ToF-SIMS is particularly sensitive to detect the Cl- ion, which is the characteristic ion of permethrin. Ion implantation and quantification of dopants using SIMS is well established in the semiconductor industry. In this study, quantitative depth profiling was carried out using 35Cl ion implantation to correlate secondary ion yield with permethrin concentration, yielding a limit of detection of 0.051 wt% for permethrin. In some cases, surface concentration differed greatly from the fiber interior (>1 µm below the surface). Two- and three-dimensional mapping of Cl at sub-micrometer resolution showed permethrin to be dissolved throughout the fiber, with about 2 vol% residing in disperse, high-concentration domains. This suggests that these fibers fall into the class of monolithic sustained-release devices. It is expected that ToF-SIMS can be a valuable tool to provide insight into the insecticide release behavior of other LLIN products, both current and future.

RTNN Honors 2018 Award Recipients

The RTNN is pleased to announce its outstanding 2018 award recipients. The awardees were all honored at a dinner reception.

Collaborative Research Award

Dr. Khara Grieger and Maryam Khazaee were co-recipients of the Collaborative Research Award. The collaborative research award seeks to identify outstanding research projects, papers, and/or presentations that leverage the resources, equipment, and/or expertise available through the RTNN. Khara is an environmental scientist at RTI, International and won for her collaborative work, “Ensuring Sustainable Innovation of Water Treatment Technologies using Engineered Nanomaterials.” This project, a collaboration with Duke and NC State, supports the development of safe and sustainable water treatment systems that rely on engineered nanomaterials. This was performed through the selection, application, and testing of risk screening tools for a select group of nanomaterials proposed for use in water treatment technologies. Maryam is a Visiting Doctoral Researcher in the Department of Mechanical Engineering and Materials Science at Duke University. (Home Institution: University of Duisburg-Essen). Her project, “Fabrication and Characterization of Multidimensional Semiconducting Bismuth Halides for Electronic Applications,” was accomplished through the collaboration and communication among five teams of scientists from Duke, NC State, UNC Chapel Hill, Dalhousie (Canada), and Duisburg-Essen (Germany). The work utilized Duke University’s Shared Materials Instrumentation Facility (SMIF), the Chapel Hill Analytical and Nanofabrication Laboratory (CHANL) (X-ray photoelectron spectroscopy (XPS)), and NC State’s Analytical Instrumentation Facility (AIF).

Student Outreach Awards

Justin Norkett (NC State), Nicole Smiddy (UNC), and Maxine Gorelick (Duke) have been awarded student outreach awards to recognize their exemplary leadership, initiative, and ongoing commitment to the mission of expanding access to RTNN nanotechnology user facilities. Justin has been involved in STEM outreach through the NCSU Department of Materials Science and Engineering for eight years. During this time, he has independently developed and documented over 100 experiments suitable for K-12 students. On average, he is interacting with over 100 students per month. For the Summer 2018 camp, he integrated his PhD research project into the student experiments, preparing a simulated failure analysis activity based on his dissertation topic, liquid metal embrittlement. He used AIF at NC State to demonstrate the power of electron microscopy for examining the nanoscale structure of materials and how that relates to their macroscopic behavior. Nicole participates in a number of activities for CHANL including doing an in lab demo for the Coursera course and helping to coordinate and execute remote SEM sessions for schools and outreach partners.  Nicole has also become an expert in taking and interpreting force measurements on cells with the CHANL AFM.  She has developed material for and led workshop sessions in the Forces in Biology workshop run by the Superfine lab at UNC.  Nicole has made a positive impact on CHANL’s outreach activities, and has done an amazing job in this role! Maxine has been an exceptionally important resource for SMIF’s K-12 outreach efforts. She has worked numerous hours with many different school groups. Maxine has a unique and valuable ability to engage and connect with students. She can explain complex scientific information is a way anyone could understand. Students loved getting the chance to talk with Maxine about what it is like to be an undergraduate at Duke. More information about the awards can be found on the RTNN Awards page.

RTNN Hosts NNCI REU Convocation

Last month, the RTNN welcomed over 50 guests to Raleigh at the annual NNCI REU Convocation. Participants came from NNCI sites across the country to share their summer research projects with their peers as well as RTNN faculty, staff, and students. The event kicked off with a scavenger hunt where students searched NC State for a variety of landmarks. Attendees also participated in professional development activities that included updates to their LinkedIn profiles and learning how to effectively communicate science to the public. Poster sessions were held on the campuses of Duke and UNC to give students a broader perspective of nanotechnology in the Research Triangle. The entire agenda can be found here and all of the event talks are posted here.      

Researchers Use Gold Nanoparticles to Unfold 3-D Structures

Researchers at NC State have developed a technique that uses nanoparticles, nanospheres and nanorods, to trigger shape changes in polymers. These differently shaped nanoparticles exhibit different surface plasmon resonances and will heat when exposed to specific wavelengths of light. When embedded in polymers, this causes the material to heat and change its shape. This work has the potential for use in soft robotics applications like biomedical implants. For more on this work, please see the NC State press release. Sequential Actuation of Shape-Memory Polymers through Wavelength-Selective Photothermal Heating of Gold Nanospheres and Nanorods Authors: Sumeet R. Mishra and Joseph B. Tracy, North Carolina State University Published: June 15, Applied Nano Materials DOI: 10.1021/acsanm.8b00394 Abstract: Photothermal triggering of shape-memory polymers is an appealing noncontact mode of actuation for responsive materials and soft robotics. Wavelength-selective photothermal triggering of shape recovery is reported in thermoplastic polyurethane shape-memory polymers with embedded gold (Au) nanospheres and nanorods. Light-emitting diodes with wavelengths of 530 and 860 nm matched to the surface plasmon resonances drive selective shape recovery. Wavelength-selective shape recovery enables sequential actuation, as demonstrated in a wavelength-controlled stage with optically controlled height and tilt angle using legs of shape-memory-polymer films with embedded Au nanospheres and nanorods.  

New Undergraduate Research Opportunity at Smart Materials Solutions

Smart Material Solutions, Inc. (SMS) is seeking two REU students for 10 week paid summer internships. SMS is a small NC State startup in Raleigh, NC that is developing an advanced nanomanufacturing process called nanocoining. The patented process can seamlessly nanopattern drum molds for roll-to-roll manufacturing hundreds of times faster than competing technologies like electron-beam lithography. Internship 1: Simulations of optical properties This student will perform finite different time domain (FDTD) simulations to model and optimize the optical properties of nanostructures. The intern will model anti-reflective coatings as well as light-extraction features for OLED displays and solid-state lighting. This student will also be trained in scanning electron microscopy (SEM) and atomic force microscopy (AFM). Students with a background in optics, modeling, physics, electrical engineering, or a related field are encouraged to apply. Internship 2: Fabrication, characterization, and lamination of nanostructured films This intern will imprint nanostructures into polymer films and characterize their optical and wetting properties. The student will also laminate nanostructures onto devices such as a solar cell and smartphone. This student will receive training on several characterization techniques including SEM, AFM, and UV-Vis spectroscopy. SMS prefers a student with a background in materials science, chemical engineering, nanotechnology, or a related field. For more information, please review this flier. To apply, send your resume to miller@smartmaterialsolutions.com and specify which internship interests you.