Nanoscale Horizons blog

The sustainability issues of efficient energy storage and water purification are of vital importance to the long-term future of the planet. Researchers from Zhejiang University have developed a new nanostructured graphene material with a tuneable surface texture which can be used to for enhanced water purification and energy storage applications.

Inspired by the hierarchical structures and microscopic surface textures of the dry-climate plant Callitris endlicheri, the graphene structures use capillary effects to transport and store water in a similar way, but at much smaller length scales. Typically, tuneable surfaces such as these, require chemical surface modifications; but this Nanoscale Horizons article outlines a new method involving plasma-assisted growth of graphene ‘nano-flaps’ covalently bonded to micro-sized vertical grapheme graphene wells (termed ‘Sub-μGW’). The surfaces showed better water purification of metal nanoparticles from water and remarkable electrochemical performance in supercapacitors (2.5x higher specific capacitance of Sub-μGW electrodes). These excellent properties are attributed to enhanced solid-liquid interfacing leading to a super hydrophilic surface by reduction of air bubbles, and better device performance.

In the future, this biomimetic approach could be used to control the wettability of a range of porous microstructured surfaces, and could lead to further breakthroughs in important areas such as energy storage and conversion, water purification, and biomedical devices.

Fig. 1. SEM images of grapheme nanostructures showing the decreasing nanotexture densities from (d) to (f). (g) Schematic of the capillarity driven modification process for the adjustment of the nanotexture density in Sub-mGWs.

Read the article:
Tuneable fluidics within graphene nanogaps for water purification and energy storage
Zheng Bo, Yilei Tian, Zhao Jun Han, Shenghao Wu, Shuo Zhang, Jianhua Yan, Kefa Cena and Kostya Ostrikov
Nanoscale Horizons, 2017, Advance Article, DOI: 10.1039/C6NH00167J

Alexander Cook is a guest web writer for the RSC journal blogs. He is a PhD researcher in the Perrier group at the University of Warwick, focusing on polymer materials and their use in various applications. Follow him on twitter @alexcook222

Confocal images of a single cell under the magnetic micropen before and after turning on the external field

Single cell manipulation can provide insight into cell mechanics and adhesion, and has a crucial role in in vitro fertilization (IVF). Bartusz Grzybowski at Ulsan National Institute of Science and Technology in South Korea and his team’s new technique for this doesn’t need cells to be magnetically tagged beforehand. It also avoids the risks of heat- or stress-induced cell damage that can occur with other methods.

Grzybowski et al.’s method relies on an iron oxide nanoparticle medium in which cells are suspended. Applying an electromagnet to the magnetic medium through a micropen creates field gradients, which direct the cell to move in a certain direction. By varying how the micropen “tweezers” are positioned, cell movement can be manipulated in both 2 and 3 dimensions.

As well as controlling a single cell, the micropen can be used to pick up several cells together and guide them into regularly shaped clusters. Although it’s a long way off, this could one day be used to make IVF processes more efficient, reducing the number of potential embryos that need to be discarded. It could also be extended to manipulating bacteria and other single-celled organisms to conduct detailed studies on their behaviour.

Read the full article for free, here:
Trapping, manipulation and crystallization of live cells using magnetofluidic tweezers
J. V. I. Timonen, C. Raimondo, D. Pilans, P. P. Pillai and B. A. Grzybowski
Nanoscale Horiz., 2016, Advance Article

Susannah May is a guest web writer for the RSC Journal blogs. She currently works in the Publishing Department of the Royal Society of Chemistry, and has a keen interest in biology and biomedicine, and the frontiers of their intersection with chemistry. She can be found on Twitter using @SusannahCIMay.

Time-gated luminescence image of injured mouse brains. Dashed white circles indicate region of penetrating brain injury. Targeted and nontargeted nanoparticles are compared. Inset: Bright field image (in gray scale) under ambient light.

A novel siRNA delivery system that could pave the way for genetic treatment of cancer, neurogenerative diseases or even HIV has been described in a new HOT article published in Nanoscale Horizons.

Over the last few years siRNA (small interfering RNA) has gained increasing attention as a new way to treat genetic diseases or viruses by silencing the genes responsible – the RNA fragments prevent the proteins that cause the illness from ever being expressed in the first place, making it the ultimate preventative therapy. However, current efforts have been hampered by the difficulty of delivering the delicate siRNA to the brain in one piece, before it’s degraded or attacked by the body’s immune defences.

This new system, developed by Michael Sailor’s team at the University of California, San Diego, uses porous silica nanoparticles as a protective carrier of the siRNA – the siRNA is hidden inside the pores of the nanoparticles where it’s protected from the body’s immune responses and harsh cell environments. A graphene oxide shell around the nanoparticles ensures that the siRNA stays safely inside them until they reach the brain. They will then release the still-intact siRNA,  where it prevents sections of DNA from producing damaging proteins.  The nanoparticles, which are fluorescent and easily tracked on their journey through the body, can be targeted to specific brain cells by attaching certain peptides; when the researchers attached rabies virus glycoprotein to the nanoparticles,  their uptake by neuronal cells doubled. The system successfully silenced genes in cell cultures – even in the presence of RNA-degrading nucleases – and, promisingly, proved capable of delivering siRNA to the brains of live mice who had suffered brain injuries. Significantly more of the siRNA-carrying nanoparticles accumulated around damaged tissues than the healthy brain tissues, and released large quantities of siRNA once they got there.

Although it’s early days, the system shows great promise for genetic therapies using siRNA. By using siRNAs to silence the genes responsible for out-of-control replication of cells, it could one day be used in the prevention of cancer – and siRNAs targeted to viral proteins could even be used to successfully treat HIV.

Read the full article here:

Porous silicon–graphene oxide core–shell nanoparticles for targeted delivery of siRNA to the injured brain
Jinmyoung Joo, Ester J. Kwon, Jinyoung Kang, Matthew Skalak, Emily J. Anglin, Aman P. Mann, Erkki Ruoslahti, Sangeeta N. Bhatia and Michael J. Sailor
Nanoscale Horiz., 2016, Advance Article, DOI: 10.1039/C6NH00082G

Susannah May is a guest web writer for the RSC Journal blogs. She currently works in the Publishing Department of the Royal Society of Chemistry, and has a keen interest in biology and biomedicine, and the frontiers of their intersection with chemistry. She can be found on Twitter using @SusannahCIMay.