Is nanomedicine the next big thing? A growing number of top drug companies seem to think so.
The ability to encapsulate potent drugs in tiny particles measuring billionths of a meter in diameter is opening up new options for super-accurate drug delivery, increasing precision hits at the site of disease with, hopefully, fewer side effects.
Three deals struck this year by privately held Bind Therapeutics, together worth nearly $1 billion if experiments are successful, highlight a new interest in using such tiny carriers to deliver drug payloads to specific locations in the body.
U.S.-based Bind is one of several biotechnology firms that are luring large pharmaceutical makers with a range of smart drug nanotechnologies, notably against cancer.
And nanomedicine is also being put to work in diagnosis, with tiny particles used to improve imaging in scanners, as well as rapidly detecting some serious infections.
In future, researchers hope to combine both treatment and diagnostics in a new approach dubbed "theranostics" that would allow doctors to monitor patients via their medicines.
After much hype but limited clinical success, scientists in the nanotechnology field finally see a turning point.
"We have been hearing about the promise of nanomedicine for a long time, but it is now really starting to move," said Dan Peer, who runs a nanomedicine laboratory at Tel Aviv University.
"There is a new level of confidence in this approach among the big pharmaceutical companies ... We will see more and more products in clinical testing over the next few years and I think that is very exciting."
Nanoparticles made of polymers, gold and even graphene - a newly-discovered form of carbon - are now in various stages of development. In cancer alone, 117 drugs are being assessed using nanoparticle formulations, though most have yet to be tried on patients, according to Thomson Reuters Pharma data.
Other potential applications include treatments for inflammatory disorders, heart and brain diseases, and pain.
Companies are increasingly focused on better drug targeting to increase efficacy and lessen the collateral damage caused by medicinal "carpet bombing" - a particular problem in cancer, where toxic compounds are needed to kill tumors.
The work on drug-carrying nanoparticles parallels advances in using so-called "armed antibodies" to deliver drugs direct to cancer cells - an approach championed by Roche.
The Swiss group won U.S. approval in February for Kadcyla, its first such antibody-drug conjugate, which treats breast cancer with fewer side effects like hair loss.
"All these developments have prompted companies to look at new avenues because the older ways of using drugs haven't worked so well," said Robert Langer, a pioneer of nanomedicine who runs the world's largest biomedical engineering laboratory at the Massachusetts Institute of Technology.
Having worked on drug delivery since the 1970s, Langer has seen plenty of ups and downs.
The world's first nanomedicine was actually approved back in 1995 when U.S. regulators gave a green light to Doxil for treating Kaposi's sarcoma, a cancer often associated with AIDS.
Doxil - a hollow fatty ball known as a liposome with a cancer-killing drug inside it - was a breakthrough. Yet few other nanomedicines have followed.
Recent scientific advances have changed the game, however. Bind's nanoparticles, for example, are programmed to reach the right spot using targeting molecules that recognize specific proteins linked to disease on the surface of cells.
They also have a stealth covering that shields them from the immune system, in order to minimize adverse reactions.
Since January, Amgen, Pfizer and AstraZeneca have all signed up to use Bind's technology, which comes from work originally carried out in Langer's lab.
And Bind is not the only game in town. Another approach, using tiny particles of gold as drug carriers, is being explored in a deal that AstraZeneca signed in December with CytImmune.
"Anything you can do to improve targeting of tumors rather than normal tissue - whether that is through an armed antibody or nanoparticle approach - increases the chance of success," said Susan Galbraith, who leads AstraZeneca's oncology research.
The work remains early stage and Peer of Tel Aviv University says all the novel carriers will have to be studied closely for potential toxicity. However, experience with liposomes is good and versions of gold nanoparticles have also been used safely for many years to treat rheumatoid arthritis.
Injecting patients with gold may sound like a pricey option but with thousands of nanoparticles fitting into the width of a human hair, the amount of metal used is tiny. Gold, unlike some other metals, is not toxic and has been used in various medical treatments for many years without harmful effects.
Bind CEO Scott Minick also thinks his polymer technology will have cost advantages over expensive antibody drugs.
Further out, Kostas Kostarelos, professor of nanomedicine at University College London, has high hopes for graphene - a one-atom-thick form of carbon. His team is currently working with graphene nanomaterials in pre-clinical experiments.
"We will see parallel development of different materials, each offering something different therapeutically," he said.
Other venture-backed nanomedicine firms include Cerulean Pharma, whose technology has made a highly potent cancer drug tolerable but which recently had disappointing results in a clinical study, and two companies looking at new vaccines.
Selecta Biosciences has a deal on food allergy vaccines with Sanofi, while Liquidia Technologies is allied with GlaxoSmithKline on vaccines and inhaled products.
MIT's Langer is convinced more Big Pharma companies will think small in future.
"You can be sure others will jump on the bandwagon sooner or later. That doesn't mean they might not jump off for a little bit too - but they will jump back on. These technologies are here to stay," he said.