You’ll never ‘be-leaf’ what makes up this battery!

Scientists at the University of Maryland have a new recipe for batteries: Bake a leaf, and add sodium. They used a carbonized oak leaf, pumped full of sodium, as a demonstration battery’s negative terminal, or anode, according to a paper published yesterday in the journal ACS Applied Materials Interfaces.

“Leaves are so abundant. All we had to do was pick one up off the ground here on campus,” said Hongbian Li, a visiting professor at the University of Maryland’s department of materials science and engineering and one of the main authors of the paper. Li is a member of the faculty at the National Center for Nanoscience and Technology in Beijing, China.

Other studies have shown that melon skin, banana peels and peat moss can be used in this way, but a leaf needs less preparation.

The scientists are trying to make a battery using sodium where most rechargeable batteries sold today use lithium. Sodium would hold more charge, but can’t handle as many charge-and-discharge cycles as lithium can.

One of the roadblocks has been finding an anode material that is compatible with sodium, which is slightly larger than lithium. Some scientists have explored graphene, dotted with various materials to attract and retain the sodium, but these are time consuming and expensive to produce. In this case, they simply heated the leaf for an hour at 1,000 degrees C (don’t try this at home) to burn off all but the underlying carbon structure.

The lower side of the maple leaf is studded with pores for the leaf to absorb water. In this new design, the pores absorb the sodium electrolyte. At the top, the layers of carbon that made the leaf tough become sheets of nanostructured carbon to absorb the sodium that carries the charge.

“The natural shape of a leaf already matches a battery’s needs: a low surface area, which decreases defects; a lot of small structures packed closely together, which maximizes space; and internal structures of the right size and shape to be used with sodium electrolyte,” said Fei Shen, a visiting student in the department of materials science and engineering and the other main author of the paper.

“We have tried other natural materials, such as wood fiber, to make a battery,” said Liangbing Hu, an assistant professor of materials science and engineering. “A leaf is designed by nature to store energy for later use, and using leaves in this way could make large-scale storage environmentally friendly.”

The next step, Hu said, is “to investigate different types of leaves to find the best thickness, structure and flexibility” for electrical energy storage. The researchers have no plans to commercialize at this time.

MIT engineers develop protein system to detect cancer cells

MIT engineers have developed a modular system of proteins that can detect a particular DNA sequence in a cell and then trigger a desired response, including killing cancer cells or cells infected with a virus.

The technology is based on a type of DNA-binding proteins known as zinc fingers. These proteins can be designed to recognise any DNA sequence.

“The technologies are out there to engineer proteins to bind to virtually any DNA sequence that you want,” said Shimyn Slomovic, a postdoc at Massachusetts Institute of Technology’s Institute of Medical Engineering and Science (IMES) and the paper’s lead author.

“We felt that there was a lot of potential in harnessing this designable DNA-binding technology for detection,” Slomovic said.

To create their new system, the researchers needed to link zinc fingers’ DNA-binding capability with a consequence – either turning on a fluorescent protein to reveal that the target DNA is present or generating another type of action inside the cell.

The researchers achieved this by exploiting a type of protein known as an “intein” – a short protein that can be inserted into a larger protein, splitting it into two pieces.

The split protein pieces, known as “exteins,” only become functional once the intein removes itself while rejoining the two halves. The researchers decided to divide an intein in two and then attach each portion to a split extein half and a zinc finger protein.

The zinc finger proteins are engineered to recognise adjacent DNA sequences within the targeted gene, so if they both find their sequences, the inteins line up and are then cut out, allowing the extein halves to rejoin and form a functional protein.

The extein protein is a transcription factor designed to turn on any gene the researchers want.
In the study, researchers linked green fluorescent protein (GFP) production to the zinc fingers’ recognition of a DNA sequence from an adenovirus, so that any cell infected with this virus would glow green.

The researchers can programme the system to produce proteins that alert immune cells to fight the infection, instead of GFP.

“Since this is modular, you can potentially evoke any response that you want. You could programme the cell to kill itself, or to secrete proteins that would allow the immune system to identify it as an enemy cell so the immune system would take care of it,” Slomovic said.

The MIT researchers also deployed this system to kill cells by linking detection of the DNA target to production of an enzyme called NTR. This enzyme activates a harmless drug precursor called CB 1954, which the researchers added to the petri dish where the cells were growing. When activated by NTR, CB 1954 kills the cells.

Future versions of the system could be designed to bind to DNA sequences found in cancerous genes and then produce transcription factors that would activate the cells’ own programmed cell death pathways.

Scientists discover neutralising antibodies to combat HIV infection effectively!

Scientists have identified a novel antibody that could more effectively detect and neutralise HIV virus in an infected patient.

Proteins called broadly neutralising antibodies (bNAbs) are a promising key to the prevention of infection by HIV, the virus that causes AIDS.

The bNAbs have been found in blood samples from some HIV patients whose immune systems can naturally control the infection.

These antibodies may protect a patient’s healthy cells by recognising a protein called the envelope spike, present on the surface of all HIV strains and inhibiting, or neutralising, the effects of the virus.
Researchers at the California Institute of Technology have discovered that one particular bNAb may be able to recognise this signature protein, even as it takes on different conformations during infection – making it easier to detect and neutralise the viruses in an infected patient.

The process of HIV infection begins when the virus comes into contact with human immune cells called T cells that carry a particular protein, CD4, on their surface.

Three-part (or “trimer”) proteins called envelope spikes on the surface of the virus recognise and bind to the CD4 proteins.

The spikes can be in either a closed or an open conformation, going from closed to open when the spike binds to CD4.

Last year, Pamela Bjorkman, Centennial Professor of Biology and her collaborators at Rockefeller University reported initial characterisation of a potent bNAb called 8ANC195 in the blood of HIV patients whose immune systems could naturally control their infections.

They also discovered that this antibody could neutralise the HIV virus by targeting a different epitope than any other previously identified bNAb.

Researchers found that although most bNAbs recognise the envelope spike in its closed conformation, 8ANC195 could recognise the viral protein in both the closed conformation and a partially open conformation.

“We think it’s actually an advantage if the antibody can recognise these different forms,” said Louise Scharf, a postdoctoral scholar in Bjorkman’s laboratory.

A potential medical application of this antibody is in so-called combination therapies, in which a patient is given a cocktail of several antibodies that work in different ways to fight off the virus as it rapidly changes and evolves.

“So 8ANC195 is one more antibody that we can use therapeutically; it targets a different epitope than other potent antibodies, and it has the advantage of being able to recognise these multiple conformations,” said Scharf.

The idea of bNAb therapeutics might not be far from a clinical reality. Scharf said that the same collaborators at Rockefeller University are already testing bNAbs in a human treatment in a clinical trial.

Scientists discover a sixth flavour | The taste of ‘fat’

According to researchers, fat, which now joins sweet, sour, salty, bitter and umami, has a “unique and unpleasant taste”, which they have named oleogustus.

This finding could lead to new ways of fighting obesity and heart disease, and to the creation of improved fat replacements, researchers said.

“Our experiments provide a missing element in the evidence that fat has a taste sensation, and that it is different from other tastes,” Professor Richard Mattes, from the Purdue University in US, said.

Researchers investigated the taste sensation of non-esterified fatty acids (NEFA), or free fatty acids, which are fat’s basic building blocks.

Results showed that the men and women indentified fat as having a taste, different from all the other samples, UK’s “Independent” reported.

Identifying the taste of fat has a range of important health implications. At high concentrations, the signal it generates would dissuade the eating of rancid foods, researchers said.

At low levels, it may enhance the appeal of some foods by adding to the overall sensory profile, they said.