The fictional wizardry of J.K. Rowling's Harry Potter books is the inspiration for a life-saving medical technology designed for remote regions where climate and lack of trained medical personnel restrict one of the most fundamental clinical procedures – blood typing.

Giving someone the wrong blood in a transfusion causes the body to go into anaphylactic shock as the immune system is effectively forced to attack itself. Determining a patient’s blood type traditionally requires complex and expensive laboratory equipment, careful refrigeration of antibody reagents and a university degree in pathology. It is a test that must be 100 per cent accurate: a mistake can be fatal.

But inspired by the magical Harry Potter diary that absorbs ink and prints its own letters, Monash University researchers Professor Wei Shen and Professor Gil Garnier have invented a paper-based test that spells out the correct blood type … in blood.

Their innovation, which could be a significant boost to medical care in poorer and more remote regions of the world, uses a piece of bioactive paper. The paper can be stored in a variety of conditions, maintains its efficacy for months, can be manufactured easily and cheaply, and can be used by almost anyone.

The test works by having text and symbols to represent A, B and O blood types as well as Rhesus factor printed on the paper using special inks laden with the relevant antibodies for each blood type. A drop of blood is placed on each symbol, and the paper is washed with a saline solution. If the blood type is A, for example, it will interact with the antibody printed in that letter, causing it to coagulate and give an unambiguous report of the blood type.

“If this blood is specific to that antibody then the drop stays where it is and if it’s not specific, it will wash away,” says Professor Garnier, a chemical engineer at Monash and director of the Australian Pulp and Paper Institute.

The result can then be easily interpreted according to which letter or letters remain highlighted in red. This seemingly magical technology comes down to relatively simple science that uses the porous structure of the paper, says Professor Shen, also a chemical engineer at Monash.

“When blood cells coagulate, their size increases and they get locked into the fibre structure, whereas in a negative test the cells can be flushed away by a saline solution,” Professor Shen explains.

Paper test

As well as making life considerably easier for pathologists, the test has enormous potential for developing countries because it is easy and cheap to produce, does not require a refrigerated supply chain, and can be interpreted by an unskilled person.

Most countries have a printing and paper industry with the capacity to produce large quantities of paper. “And then instead of printing with conventional inks, we can print in inks containing antibodies,” Professor Shen says.

The key to this development being put into practice is the need for it to be as accurate as current blood-typing methods. So far, in more than 1000 comparisons between the paper-based and conventional assays, there has not been a single disagreement.

“We have to provide the same safety and that’s what the invention has done; we have the same efficacy as modern technology,” Professor Garnier says.

Professor Robert Pelton, a chemical engineer at McMaster University in Canada and leading expert on bioactive paper technology, says the test has the added advantage of easy disposal. “Dealing with matter such as blood, it’s great to be able to incinerate cleanly and not build up a hospital waste problem,” Professor Pelton says.

Professor Shen and Professor Garnier say the greatest appeal for them of the paper-based test is its simplicity and accessibility. “What Wei and I have tried so hard to do is to engineer something that any user without any education, without even being able to read, can use,” Professor Garnier says. “We want something that doesn’t rely on electronics and is robust, and this empowers the users.”

Blood types

Blood types are classified on the basis of molecules inherited from both parents that appear on the surface of red blood cells. These are capable of triggering adverse immune reactions when transfused into people with different combinations of these “antigenic” molecules. The most important for transfusions are the ABO and RhD molecules.

BLOOD GROUP AB

People that express both A and B antigens can receive red blood cells from any ABO group and are called “universal recipients”. They can only donate to AB people.

BLOOD GROUP O

Express neither A nor B antigens, making their blood acceptable to any ABO blood group and are called “universal donors”. They can only receive group O blood.

BLOOD GROUP A

Express the A molecule and react adversely to B-bearing red blood cells. They can receive only A or O group blood and donate to type A or AB.

BLOOD GROUP B

Express the B molecule and react adversely to A-bearing red blood cells. They can receive only B or O group blood and donate to type B or AB.

RHESUS TYPE

Blood also needs to be compatible for the presence (+) or absence (-) of Rhesus factor D (RhD) molecules. This is what gives a reading, such as A positive or A negative.

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