Tag Archives: nucleic acids

Sponges made of nanoporous gold and DNA detection

This work from the University of California at Davis seems to represent a step forward for better detection of diseases and pathogens. From a Sept. 4, 2015 news item on ScienceDaily,

Sponge-like nanoporous gold could be key to new devices to detect disease-causing agents in humans and plants, according to UC Davis researchers.

In two recent papers in Analytical Chemistry, a group from the UC Davis Department of Electrical and Computer Engineering demonstrated that they could detect nucleic acids using nanoporous gold, a novel sensor coating material, in mixtures of other biomolecules that would gum up most detectors. This method enables sensitive detection of DNA [deoxyribonucleic acid] in complex biological samples, such as serum from whole blood.

A Sept. 4, 2015 UC Davis news release on EurekAlert, which originated the news item, offers more detail,

“Nanoporous gold can be imagined as a porous metal sponge with pore sizes that are a thousand times smaller than the diameter of a human hair,” said Erkin Şeker, assistant professor of electrical and computer engineering at UC Davis and the senior author on the papers. “What happens is the debris in biological samples, such as proteins, is too large to go through those pores, but the fiber-like nucleic acids that we want to detect can actually fit through them. It’s almost like a natural sieve.”

Rapid and sensitive detection of nucleic acids plays a crucial role in early identification of pathogenic microbes and disease biomarkers. Current sensor approaches usually require nucleic acid purification that relies on multiple steps and specialized laboratory equipment, which limit the sensors’ use in the field. The researchers’ method reduces the need for purification.

“So now we hope to have largely eliminated the need for extensive sample clean-up, which makes the process conducive to use in the field,” Şeker said.

The result is a faster and more efficient process that can be applied in many settings.

The researchers hope the technology can be translated into the development of miniature point-of-care diagnostic platforms for agricultural and clinical applications.

“The applications of the sensor are quite broad ranging from detection of plant pathogens to disease biomarkers,” said Şeker.

For example, in agriculture, scientists could detect whether a certain pathogen exists on a plant without seeing any symptoms. And in sepsis cases in humans, doctors might determine bacterial contamination much more quickly than at present, preventing any unnecessary treatments.

Here are links to and citations for two recent published papers about this work,

Effect of Nanoporous Gold Thin Film Morphology on Electrochemical DNA Sensing by Pallavi Daggumati, Zimple Matharu, and Erkin Şeker. Anal. Chem., 2015, 87 (16), pp 8149–8156 DOI: 10.1021/acs.analchem.5b00846 Publication Date (Web): April 30, 2015

Copyright © 2015 American Chemical Society

Biofouling-Resilient Nanoporous Gold Electrodes for DNA Sensing by Pallavi Daggumati, Zimple Matharu, Ling Wang, and Erkin Şeker. Anal. Chem., 2015, 87 (17), pp 8618–8622 DOI: 10.1021/acs.analchem.5b02969 Publication Date (Web): August 14, 2015

Copyright © 2015 American Chemical Society

These papers are behind a paywall.

Northwestern University’s (US) International Institute for Nanotechnology (IIN) rakes in some cash

Within less than a month Northwestern University’s International Institute for Nanotechnology (IIN) has been granted awarded two grants by the US Department of Defense.

4D printing

The first grant, for 4D printing, was announced in a June 11, 2015 Northwestern news release by Megan Fellman (Note: A link has been removed),

Northwestern University’s International Institute for Nanotechnology (IIN) has received a five-year, $8.5 million grant from the U.S. Department of Defense’s competitive Multidisciplinary University Research Initiative (MURI) program to develop a “4-dimensional printer” — the next generation of printing technology for the scientific world.

Once developed, the 4-D printer, operating on the nanoscale, will be used to construct new devices for research in chemistry, materials sciences and U.S. defense-related areas that could lead to new chemical and biological sensors, catalysts, microchip designs and materials designed to respond to specific materials or signals.

“This research promises to bring transformative advancement to the development of biosensors, adaptive optics, artificially engineered tissues and more by utilizing nanotechnology,” said IIN director and chemist Chad A. Mirkin, who is leading the multi-institution project. Mirkin is the George B. Rathmann Professor of Chemistry in the Weinberg College of Arts and Sciences.

The award, issued by the Air Force Office of Scientific Research, supports a team of experts from Northwestern, the University of Miami, the University of California, San Diego, and the University of Maryland.

In science, “printing” encodes information at specific locations on a material’s surface, similar to how we print words on paper with ink. The 4-dimensional printer will consist of millions of tiny elastomeric “pens” that can be used individually and independently to create nanometer-size features composed of hard or soft materials.

The information encoded can be in the form of materials with a defined set of chemical and physical properties. The printing speed and resolution determine the amount and complexity of the information that can be encoded.

Progress in fields ranging from biology to chemical sensing to computing currently are limited by the lack of low-cost equipment that can perform high-resolution printing and 3-dimensional patterning on hard materials (e.g., metals and semiconductors) and soft materials (e.g., organic and biological materials) at nanometer resolution (approximately 1,000 times smaller than the width of a human hair).

“Ultimately, the 4-D printer will provide a foundation for a new generation of tools to develop novel architectures, wherein the hard materials that form the functional components of electronics can be merged with biological or soft materials,” said Milan Mrksich, a co-principal investigator on the grant.

Mrksich is the Henry Wade Rogers Professor of Biomedical Engineering, Chemistry and Cell and Molecular Biology, with appointments in the McCormick School of Engineering and Applied Science, Weinberg and Northwestern University Feinberg School of Medicine.

A July 10, 2015 article about the ‘4D printer’ grant  by Madeline Fox for the Daily Northwestern features a description of 4D printing from Milan Mrksich, a co-principal investigator on the grant,

Milan Mrksich, one of the project’s five senior participants, said that while most people are familiar with the three dimensions of length, width and depth, there are often misconceptions about the fourth property of a four-dimensional object. Mrksich used Legos as an analogy to describe 4D printing technology.

“If you take Lego blocks, you can basically build any structure you want by controlling which Lego is connected to which Lego and controlling all their dimensions in space,” Mrksich said. “Within an object made up of nanoparticles, we’re controlling the placement — as we use a printer to control the placement of every particle, our fourth dimension lets us choose which nanoparticle with which property would be at each position.”

Thank you Dr. Mrksich and Ms. Fox for that helpful analogy.

Designing advanced bioprogrammable nanomaterials

The second grant, announced in a July 6, 2015 Northwestern news release by Megan Fellman, is apparently the only one of its kind in the US (Note: A link has been removed),

Northwestern University’s International Institute for Nanotechnology (IIN) has been awarded a U.S. Air Force Center of Excellence grant to design advanced bioprogrammable nanomaterials for solutions to challenging problems in the areas of energy, the environment, security and defense, as well as for developing ways to monitor and mitigate human stress.

The five-year, $9.8 million grant establishes the Center of Excellence for Advanced Bioprogrammable Nanomaterials (C-ABN), the only one of its kind in the country. After the initial five years, the grant potentially could be renewed for an additional five years.

“Northwestern University was chosen to lead this Center of Excellence because of its investment in infrastructure development, including new facilities and instrumentation; its recruitment of high-caliber faculty members and students; and its track record in bio-nanotechnology and cognitive sciences,” said Timothy Bunning, chief scientist at the U.S. Air Force Research Laboratory (AFRL) Materials and Manufacturing Directorate.

Led by IIN director Chad A. Mirkin, C-ABN will support collaborative, discovery-based research projects aimed at developing bioprogrammable nanomaterials that will meet both military and civilian needs and facilitate the efficient transition of these new technologies from the laboratory to marketplace.

Bioprogrammable nanomaterials are structures that typically contain a biomolecular component, such as nucleic acids or proteins, which give the materials a variety of novel capabilities. [emphasis mine] Nanomaterials can be designed to assemble into large 3-D structures, to interface with biological structures inside cells or tissues, or to interface with existing macroscale devices, for example. These new bioprogrammable nanomaterials and the fundamental knowledge gained through their development will ultimately lead to the creation of wearable, portable and/or human-interactive devices with extraordinary capabilities that will significantly impact both civilian and Air Force needs.

In one research area, scientists will work to understand the molecular underpinnings of vulnerability and resilience to stress. They will use bioprogrammable nanomaterials to develop ultrasensitive sensors capable of detecting and quantifying biomarkers for human stress in biological fluids (e.g., saliva, perspiration or blood), providing means to easily monitor the soldier during times of extreme stress. Ultimately, these bioprogrammable materials may lead to methods to increase human cellular resilience to the effects of stress and/or to correct genetic mutations that decrease cellular resilience of susceptible individuals.

Other research projects, encompassing a wide variety of nanotechnology-enabled goals, include:

Developing hybrid wearable energy-storage devices;
Developing devices to identify chemical and biological targets in a field environment;
Developing flexible bio-electronic circuits;
Designing a new class of flat optics; and
Advancing understanding of design rules between 2-D and 3-D architectures.

The analysis of these nanostructures also will extend fundamental knowledge in the fields of materials science and engineering, human performance, chemistry, biology and physics.

The center will be housed under the IIN, providing researchers with access to IIN’s strong entrepreneurial community and its close ties with Northwestern’s renowned Kellogg School of Management.

This second news release provides an interesting contrast to a recent news release from Sweden’s Karolinska Intitute where the writer was careful to note that the enzymes and organic electronic ion pumps were not living as noted in my June 26, 2015 posting. It seems nucleic acids (as in RNA and DNA) can be mentioned without a proviso in the US. as there seems to be little worry about anti-GMO (genetically modified organisms) and similar backlashes affecting biotechnology research.