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12

Lab Times

5-2016

News

Robo Power

Israeli scientists construct nanorobots, made from DNA origami, that expose but don’t release their cargo.

O

riginally used as an eye-pleasing way to wrap sake bottles at

wedding ceremonies in 17

th

century Japan, the art of paper

folding, or origami, has become very popular all over the

planet. The technique is so fascinating that it even inspired life sci-

entists: DNA origami, the folding of DNA strands, was born in 2006.

The implications and applications that unfold with this technique

seem sheer endless. In a recent article in

PLoS ONE

, scientists at

Bar-Ilan University, Israel, set their imagination free and came up

with a preliminary prototype of a thought-controlled nanorobot for

drug delivery (

PLoS ONE

, 11(8): e0161227).

What makes this nanobot so special is not that it is thought-

controlled - this has been done before. The truly exciting achieve-

ment here is that the drug cargo, the bot carries, is not simply

released into the bloodstream, it is reversibly exposed to and con-

cealed from its place of action, providing “explicit temporal control

of a drug, e.g. generating a sequence of alternating activation/in-

activation of the drug for arbitrary periods of time”. This clever tech-

nique should come in especially handy for the treatment

of psychological disorders, such as depression,

schizophrenia or attention deficit.

How did Ido Bachelet and colleagues

pull off this trick? First, they designed

a special version of their DNA origami

nanorobots, with metal (iron oxide) na-

noparticles attached to the robotic gates,

made of complementary DNA strands.

When placed in an electromagnetic field,

these nanoparticles heat, allowing the ro-

bots to be remote-controlled. What’s

more, the gates can be reversibly

closed or opened by controlling gate strand hybridisation through,

for instance, strand displacement or aptamer binding. “When the

(solid DNA) shell is closed, it sequesters molecular or nanoparticu-

late payloads of various types up to a size of 25 nm, such that they

are concealed from the environment. Opening of the shell exposes

these payloads, which remain stably tethered to the shell and are

not released,” the authors write.

To see whether their mind-controlled “nano drug dealers” work,

the Israeli team tested their setup, which also included a headset

for collecting EEG data from a human subject, on a living being, a

cockroach (

Blaberus discoidalis

). Bachelet

et al

. injected their na-

nobots (this time carrying fluorescent antibodies instead of drugs)

into adult cockroaches and placed them in an electromagnetic field.

Meanwhile, the human partner of this experiment, watched screens

“showing either nothing or a list of arithmetic problems” – the latter

generating brain wave patterns typical of cognitive load, the mental

stimulus in this setup. Eventually, the scientists checked the insects’

hemocytes for signs of fluorescence with flow cytometry and got

confirmation their proof-of-concept study was a big success.

There’s one minor disadvantage, though. The robots can-

not enter cells and thus can only engage cell surface targets.

“This seems like an inherent drawback of the system,” the

scientists admit, “However, it should be noted that any

therapeutic outcome could arguably be achieved from out-

side the cell, since almost all endogenous signals operate

through cell surface receptors (with exceptions such as steroid

hormones and nitric oxide).”

-KG-

(More research results from European labs on pp. 30-35)

Data sharing at QMUL

Not Tired

Spring tiredness, overfatigue after a long

day in the lab – that’s pretty normal. But

some people are chronically tired and no-

body knows why. Chronic fatigue syn-

drome, the Mayo Clinic defines, “is a com-

plicated disorder characterised by extreme

fatigue, which may worsen with physical or

mental activity, but doesn’t improve with

rest”. Studies, trying to find the cause of

the disorder (under discussion are viral in-

fections or psychological stress) and ways

to alleviate the syndrome’s symptoms are

abound.

One study, reporting that exercise

and behavioural therapy might work (the

PACE trial), appeared in the

Lancet

in 2011

(377(9768:823-36). Soon after its publi-

cation, though, a closer look at the study’s

data revealed several major flaws. In a blog

entry, David Tuller from the University of

California, Berkeley, for instance, wrote,

“The study included a bizarre paradox: par-

ticipants’ baseline scores for the two pri-

mary outcomes of physical function and fa-

tigue could qualify them simultaneously as

disabled enough to get into the trial but al-

ready ‘recovered’ on those indicators – even

before any treatment. In fact, 13 percent of

the study sample was already ‘recovered’ on

one of these two measures at the start of the

study.” And Bruce Levin, Columbia Univer-

sity, commented, “To let participants know

that interventions have been selected by a

government committee ‘based on the best

available evidence’ strikes me as the height

of clinical trial amateurism.”

With that much criticism on the table,

it’s only logical, colleagues would ask par-

ticipating universities – one of them is the

Queen Mary University of London, QMUL

– to share the study’s raw data. But, QMUL

refused. Even a petition, signed by 12,000

people, and an appeal to the UK Informa-

tion Commissioner, by health activist and

chronic fatigues sufferer, Alem Matthees,

couldn’t convince them otherwise. QMUL

uses the patients as an excuse: “QMUL has

no permission from participants to pub-

lish data, and to require disclosure would

damage trust and jeopardise future stud-

ies,” they said.

In mid-August, the UK’s First-Tier tribu-

nal confirmed, once more, the Information

Commissioner’s decision, dismissing an ap-

peal by QMUL to reverse the previous data

release order. QMUL’s reaction: “In comply-

ing with the Tribunal’s decision, we remain

mindful of the interests of trial participants

and acknowledge the assurance given by

the Tribunal that participants will be ade-

quately protected from personal identifica-

tion by the disclosure of this information.

[...] We will continue to engage with other

universities and bodies to debate the broad-

er implications of the decision for clinical

research.”

-KG-

Photo:

www.publicdomainpictures.net

/Olivia Jester