Titanium dioxide -- It slices, it dices ...

March 30, 2007
Titanium dioxide -- It slices, it dices ...
Illustration of the cleavage of proteins near a titanium dioxide surface: when illuminated with ultraviolet light, hydroxyl radicals are formed in water near the semiconductor's surface and cut proteins at the location of the amino acid proline. Credit: NIST

Chemists from the National Institute of Standards and Technology and Arizona State University have proposed an elegantly simple technique for cleaving proteins into convenient pieces for analysis. The prototype sample preparation method, detailed recently in Analytical Chemistry, uses ultraviolet light and titanium dioxide and could be ideal for new microfluidic “lab-on-a-chip” devices designed to rapidly analyze minute amount of biological samples.

Because most proteins are very large, complex molecules made up of hundreds or thousands of amino acids, they usually must be cut up into more manageable pieces for analysis. Today, this most commonly is done by using special enzymes called “proteases” that sever the chains at well-known locations. The protease trypsin, for example, cuts proteins at the locations of the amino acids lysine and arginine.

Analyzing the residual fragments can identify the original protein. But enzymes are notoriously fussy, demanding fairly tight control of temperature and acidity, and the enzymatic cutting process can be time-consuming, from a matter of hours to days.

For a “radically” different approach, the NIST group turned to a semiconductor material, titanium dioxide. Titanium dioxide is a photocatalyst—when exposed to ultraviolet light its surface becomes highly oxidizing, converting nearby water molecules into hydroxyl radicals, a short-lived, highly reactive chemical species. In the NIST experiments, titanium dioxide coatings were applied to a variety of typical microanalysis devices, including microfluidic channels and silica beads in a microflow reactor. Shining a strong UV light on the area, in the presence of a protein solution, creates a small “cleavage zone” of hydroxyl radicals that rapidly cut nearby proteins at the locations of the amino acid proline.

Although development work remains to be done, according to the researchers, the NIST photocatalysis technique offers several advantages over conventional enzyme cleavage of proteins. It’s not particularly sensitive to temperature or acidity, and needs no additional reagents other than dissolved oxygen in the solution. It’s a simple arrangement, easy to incorporate into a wide range of instruments and devices, and titanium dioxide, an inorganic material, will last virtually forever in a broad range of conditions—enzymes have to be treated carefully and stored in temperature-controlled environments. The target amino acid, proline, is relatively sparse in most proteins, but it’s found at key locations, such as sharp turns in the molecule, that aid analysis. And it’s fast—in trials with the protein angiotensin I, the team obtained detectable cleavage patterns in as little as 10 seconds.

Citation: B.J. Jones, M.J. Vergne, D.M. Bunk, L.E. Locascio and M.A. Hayes. Cleavage of peptides and proteins using light-generated radicals from titanium dioxide. Anal. Chem. 2007, 79, 1327-1332.

Source: National Institute of Standards and Technology

Explore further: Researchers use nanotubes to better understand diseases

Related Stories

Researchers use nanotubes to better understand diseases

June 11, 2015

Researchers in UC's Department of Cancer Biology are collaborating with material scientists from the University of Houston to create and use nanotubes to capture and understand the regulation of proteins involved in a variety ...

Synthetic cells used to bioengineer new forms of silica

June 8, 2012

(Phys.org) -- Scientists do not fully understand how nature uses proteins to develop new materials and minerals, but learning more about the natural processes could lead to bioengineering methods such as the biological synthesis ...

Innovative light therapy reaches deep tumors

March 9, 2015

Light long has been used to treat cancer. But phototherapy is only effective where light easily can reach, limiting its use to cancers of the skin and in areas accessible with an endoscope, such as the gastrointestinal tract.

Entering the Nano Era

November 5, 2014

Modern hard drives only require an area of a few square nanometers for each bit of information. To protect ourselves from sunburn we use sunscreens that contain nanoparticles of titanium dioxide or zinc oxide. Is this the ...

A nanosized hydrogen generator

September 20, 2014

(Phys.org) —Researchers at the US Department of Energy's (DOE) Argonne National Laboratory have created a small scale "hydrogen generator" that uses light and a two-dimensional graphene platform to boost production of the ...

Recommended for you

Just how good (or bad) is the fossil record of dinosaurs?

August 28, 2015

Everyone is excited by discoveries of new dinosaurs – or indeed any new fossil species. But a key question for palaeontologists is 'just how good is the fossil record?' Do we know fifty per cent of the species of dinosaurs ...

Fractals patterns in a drummer's music

August 28, 2015

Fractal patterns are profoundly human – at least in music. This is one of the findings of a team headed by researchers from the Max Planck Institute for Dynamics and Self-Organization in Göttingen and Harvard University ...

Smart home heating and cooling

August 28, 2015

Smart temperature-control devices—such as thermostats that learn and adjust to pre-programmed temperatures—are poised to increase comfort and save energy in homes.

Smallest 3-D camera offers brain surgery innovation

August 28, 2015

To operate on the brain, doctors need to see fine details on a small scale. A tiny camera that could produce 3-D images from inside the brain would help surgeons see more intricacies of the tissue they are handling and lead ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.