Biosensors Benefiting from Newly Created Protein Polymer Films

The biosensor market is seeing tremendous growth, partly due to the aging population and the increasing number of people with diabetes and other chronic diseases that require constant monitoring.  The market was valued at $15.6 billion in 2016 and is set to grow at a compound annual growth rate of 7.9 percent through 2020. Recent numbers put the market at $26 billion by 2022. The rising need for miniature diagnostic and monitoring devices is driving the need for advancements in materials. One of these advancements was recently created by Michigan State University Researchers (MSU). Their teams created multilayer protein polymer films by mixing dendrimers (tree-like polymers) and proteins to spontaneously produce multilayer films. How will this material be used to build more effective biosensors?

What are Biosensors?

Biosensors are medical devices that transmit data using two main parts: a biological component that acts as the sensor and an electrical component that detects and transmits the signal. The biological component can be nucleic acids, proteins such as enzymes or antibodies, plant proteins or lectins, or complex materials such as microorganisms and organelles. The biological component interacts with a chemical or substance being tested, creating a biological response that is converted into an electrical signal.

Applications are far-reaching from glucose monitoring for people with diabetes to biosensors that can directly test the malignant power of a tumor. Research just this year has explored diagnosing gastrointestinal diseases with a digestible biosensor. Scientists are even working on designing a biosensor for cancer detection that is assembled on a photovoltaic cell, which means data may be transmitted without needing an electrical power source.

The MSU team found numerous advantages to the multilayer films they created. Here's why they think these materials will improve biosensor production.

Advantages of Protein Polymer Films

As the name implies, biosensors require a biological component. However, there are some drawbacks to using biological components. They are often unstable, have complex production approaches, are costly, and some components are simply unavailable. On the other hand, synthetic materials are stable, can withstand harsh environments and are inexpensive to produce. The challenge is producing a synthetic material that behaves like a biological component. MSU researchers did just that. By mixing dendrimers, researchers produced multilayer films that retained the activity and function of protein enzymes, a critical biological component.

In the MSU experiment, the simplicity of their created polymer films is one of the main advantages of these enzymes. They create themselves. Here's how it happens.

As dendrimers multiply, they become more dense and spherical. The first-generation has one branching point; the second has two, and so on. The dendrimers form surface cavities that can hold molecules. When proteins mix with fourth-generation dendrimers, multilayer nanofilms measuring about 200 to 700 nm thick form spontaneously. 

Researchers found that the composition of the nanofilms was able to preserve the activity of the proteins for about two weeks. Their conclusion was based on other research where scientists incorporated enzymes, such as lysozyme which breaks down proteins, into the nanofilms. The proteins proved durable and resistant to cleaning agents and changes in medium acidity. They were also stable during storage.  

Additional Ways Polymers are Used to Create Biological-Like Material

Other researchers are experimenting with creating polymers that mimic biological behavior. Plastic antibodies are one example of a biomimetic material being used for this purpose. During this process, polymeric structures are produced in the presence of a molecule. The molecule is removed later, generating vacant spots to which it may rebind. Electropolymerization uses electrical stimuli to assemble a polymeric network. 

Conclusion

The potential for biosensors is exciting, and the use of synthetic polymers is the next step in making them even more effective.