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Nanomaterials May 2017 Viewpoints

Technology Analyst: Marianne Monteforte

Scalable Graphene-Oxide Water-Filtration Membranes

Why is this topic significant?

Important research developments in graphene-oxide-based water-filtration membranes are occurring. Recent research reveals that graphene-oxide membranes can now filter out smaller common salts from water, giving the membranes potential for application in desalination plants.

Description

Graphene oxide (GO) membranes are impermeable to all gases and vapors (even helium), yet their narrow capillaries pull water vapor through with no resistance. The pores in GO membranes behave like sponges, enabling them to filter ion contaminates out of water. The unique sieving properties of GO membranes—rapid permeation and ultraprecise filtering abilities—continue to attract significant research interest from both academia and industry. Many research teams are developing GO membranes for potential application in gas-separation and water-filtration technologies (such as water pumps and desalination plants). However, until now, researchers have faced difficulties in developing the membrane to filter out common salts because the GO membrane swells in water, which increases the pore sizes.

In the April 2017 edition of Nature Nanotechnology, researchers from the University of Manchester revealed their development of a GO membrane with controllable pore size. The researchers fabricated the membrane by sandwiching the GO laminate between polymer layers to prevent swelling. The technique results in a pore size that is smaller than common salts. According to Professor Rahul Nair, one of the lead researchers on this project, the researchers "demonstrate that there are realistic possibilities to scale up the described approach and mass produce graphene-based membranes with required sieve sizes."

Implications

The University of Manchester's GO-membrane technology is an impressive breakthrough in GO-membrane research. By controlling the pore size of the membrane, the engineers can prevent swelling of the membrane and enable the filtration of common salts from seawater. This membrane technology removes the need for a second, smaller sieve during the filtration processes in desalination plants. In addition, GO has antibacterial properties. According to the researchers, their work has a scalable production methodology, making it a promising alternative to traditional polymeric membranes.

Another benefit of the GO technology is that it is not a complex system and could find use in small-scale applications—for example, in countries that do not have the financial infrastructure to fund industrial desalination plants. The GO membrane could fit to a water-pump system, enabling people access to clean drinking water.

The controllable pore size of the University of Manchester's GO membrane could open up its use in other applications. For example, manufacturers could develop the membrane to purify industrial, chemical, and pharmaceutical products. Also, because the membrane is strong and stable, it is suitable for use—such as anticorrosion coatings or chemical-protection coatings—in corrosive environments.

Impacts/Disruptions

Water shortages and technology developments are driving the desalination industry. The main players in global desalination that push developments in desalination processes include organizations such as Advanced Water Technology, smaller private players, and subsidiaries of larger water companies. Demand from countries for desalination plants will continue to grow as populations increase; the United Nations expects the world's population to grow from 7 billion to 9 billion by 2050, potentially causing global water demand to increase by 55%. Alongside unpurified natural water sources, wastewater is also likely to become a critical resource, which may drive research funding in nanotechnology-based desalination membranes.

Scale of Impact

  • Low
  • Medium
  • High
The scale of impact for this topic is: Medium

Time of Impact

  • Now
  • 5 Years
  • 10 Years
  • 15 Years
The time of impact for this topic is: 5 Years to 10 Years

Opportunities in the following industry areas:

Wastewater treatment, desalination, pharmaceutical, chemical

Relevant to the following Explorer Technology Areas:

Nanoparticle-Based Aerosol Sprays for Drug Delivery

Why is this topic significant?

Nanoparticle-based aerosol sprays are showing great promise as a noninvasive option for use in drug delivery across the blood-brain barrier. Progressive developments in such aerosol technologies could help health-care professionals to treat neurological diseases and disorders.

Description

In April 2017, engineers from Washington University in St. Louis, Missouri, unveiled their development of a noninvasive nanoparticle-based aerosol spray that has the potential to deliver a therapeutic dose of drugs to the brain rapidly. By combining aerosol science and engineering, the researchers synthesized the aerosol—consisting of 5-nanometer gold nanoparticles tagged with fluorescent markers—and tested it on an insect model that they claim is anatomically similar to humans.

In their study, the researchers revealed that the nanoparticles are small enough to permeate the blood-brain barrier passively through diffusion. They also show from their electrophysiological tests of the locust—two hours after uptake—no noticeable changes to the locust's neural activity. The researchers plan to develop a drug-loaded nanoparticle aerosol spray and use high-intensity ultrasound to guide the nanoparticles to a specific location in the brain.

Implications

Nanomaterials can encapsulate therapeutic molecules and enable delivery to site-specific cells or tissues in the body. Such delivery systems can help to reduce the dose to the patient and minimize side effects (restricting the distribution of the drug in nonspecific tissue). Typically, research teams administer nanoparticle-loaded drugs by ingestion, injection, or transdermal or implantable devices. However, researchers face challenges in developing strategies to administer drugs to the brain because of the difficulty in crossing the blood-brain barrier. The blood-brain barrier is highly selective and prevents harmful substances, such as pathogens and toxic substances, from reaching the central nervous system. As a result, the blood-brain barrier restricts membrane permeability and retention of small molecules, hindering the delivery of drugs.

The Washington University study demonstrates the feasibility of nasal-aerosol sprays for specific delivery of drugs to the brain. However, this research is at the very early developmental stage and requires extensive research before reaching clinical trials to test its use as a drug-delivery system. The research team will also need to find an effective approach to isolate and remove the nanoparticles from the patient's plasma with minimum invasion after drug delivery.

Impacts/Disruptions

Unlike other drug-delivery strategies—such as drug-loaded microbubbles—the advantage of using nanoparticles to deliver drugs to the brain is that they do not require actively opening the blood-brain barrier, which prevents damage to the membrane. Such nanoparticle-based aerosol sprays will likely attract interest from biopharmaceutical firms. Some firms, such as NanoBio, are already developing nanoemulsion technologies for use as nasal-spray vaccines.

Despite the technical limitations and public concern about the potential neurotoxicity of nanoparticles and their potential for adverse impact on human health, nanoparticle-based therapeutic delivery systems provide excellent prospects for achieving drug delivery to the brain.

Scale of Impact

  • Low
  • Medium
  • High
The scale of impact for this topic is: Medium to High

Time of Impact

  • Now
  • 5 Years
  • 10 Years
  • 15 Years
The time of impact for this topic is: 5 Years to 10 Years

Opportunities in the following industry areas:

Health care, biomedical, drug-delivery systems, nanomedicine

Relevant to the following Explorer Technology Areas: