Science Stoned

Discovery

•  Using a novel chemical reaction, they have created self-assembling cell membranes, the structural envelopes that contain and support the reactions required for life.

Long Term Goal

• to try to make an artificial cell, a synthetic living unit from the bottom up — to make a living organism from non-living molecules that have never been through or touched a living organism

Why would this help us?

• Presumably this occurred at some point in the past. Otherwise life wouldn’t exist.
• By assembling an essential component of earthly life with no biological precursors, they hope to illuminate life’s origins.
• We don’t understand this really fundamental step in our existence, which is how non-living matter went to living matter. 
• So this is a really ripe area to try to understand what knowledge we lack about how that transition might have occurred. That could teach us a lot — even the basic chemical, biological principles that are necessary for life.

Molecules that make up cell membranes have heads that mix easily with water and tails that repel it.

In water, they form a double layer with heads out and tails in, a barrier that sequesters the contents of the cell.

How do they do it?

• Devaraj and Budin created similar molecules with a novel reaction that joins two chains of lipids.Nature uses complex enzymes that are themselves embedded in membranes to accomplish this, making it hard to understand how the very first membranes came to be.
• In our system, we use a sort of primitive catalyst, a very simple metal ion
• The reaction itself is completely artificial. There’s no biological equivalent of this chemical reaction. This is how you could have a de novo formation of membranes.
• They created the synthetic membranes from a watery emulsion of an oil and a detergent. Alone it’s stable. Add copper ions and sturdy vesicles and tubules begin to bud off the oil droplets. After 24 hours, the oil droplets are gone, “consumed” by the self-assembling membranes.

Fully artificial life will require the union of both an information-carrying genome and a three-dimensional structure to house it.

The real value of this discovery might reside in its simplicity. From commercially available precursors, the scientists needed just one preparatory step to create each starting lipid chain.

“It’s trivial and can be done in a day,” Devaraj said. “New people who join the lab can make membranes from day one.”

The National Institute of Biomedical Imaging and Bioengineering supported this work. UC San Diego has filed a patent application on this discovery.

(Source: sciencedaily.com)

Discovery

• Wonder material graphene has revealed another of its extraordinary properties — University of Manchester researchers have found that it is superpermeable with respect to water.

Graphene’s Properties

•  It is the thinnest known material in the universe and the strongest ever measured.
• It conducts electricity and heat better than any other material.
• It is the stiffest one too and, at the same time, it is the most ductile. 

Graphene Oxide ( The Discovery)

• Graphene oxide is the same graphene sheet but it is randomly covered with other molecules such as hydroxyl groups OH-.
• Graphene oxide sheets stack on top of each other and form a laminate.
• The researchers prepared such laminates that were hundreds times thinner than a human hair but remained strong, flexible and were easy to handle.

Graphene Oxide’s Amazing Properties

• When a metal container was sealed with such a film(of graphene oxide), even the most sensitive equipment was unable to detect air or any other gas, including helium, to leak through.
• It came as a complete surprise that, when the researchers tried the same with ordinary water, they found that it evaporates without noticing the graphene seal.
• Water molecules diffused through the graphene-oxide membranes with such a great speed that the evaporation rate was the same independently whether the container was sealed or completely open.

Dr Rahul Nair, who was leading the experimental work, offers the following explanation

• Graphene oxide sheets arrange in such a way that between them there is room for exactly one layer of water molecules.
• They arrange themselves in one molecule thick sheets of ice which slide along the graphene surface with practically no friction.
• If another atom or molecule tries the same trick, it finds that graphene capillaries either shrink in low humidity or get clogged with water molecules.

Uses (Obvious)

• This unique property can be used in situations where one needs to remove water from a mixture or a container, while keeping in all the other ingredients
• Just for a laugh, we sealed a bottle of vodka with our membranes and found that the distilled solution became stronger and stronger with time.

BUT…..

The Manchester researchers report this experiment in their Science paper, too, but they say they do not envisage use of graphene in distilleries, nor offer any immediate ideas for applications.

(Source: sciencedaily.com)