In recent years, nanotechnology has attracted enormous interest from researchers and the public eye alike. Two-dimensional nanostructures are ultra-light, all while durable and possess an array of unique electronic, mechanical and optical properties. Graphene, the world’s first 2-D material, is ultra-light and so thin it’s essentially transparent. At the same time, it’s 200 times stronger than steel but also incredibly flexible. The unique properties 2D nanomaterials possess witness to their great potential in a variety of fields but as most things, 2D nanostructures don’t come without their limitations.
Because of that, researchers are constantly on the lookout to discover novel and more versatile 2D nanomaterials. A new potential candidate emerged in 2014 when several research groups managed to isolate a single-layer of phosphorus – a 2-D nanomaterial known as phospherene. Like graphene, phosphorene is durable but also extremely light. Viewed under a microscope, its structure looks a lot like a puckered honeycomb.
What’s even more exciting, however, is the wealth of benefits and opportunities 2D nanostructures like phospherene offer to researchers. Just this year, a team of researchers led by Dr. Suresh Neethirajan managed to create a single layer of phospherene – a “nanosheet” – and used it as a biomarker in detecting haptoglobin. Haptoglobin is a protein typically produced by the liver, which binds with hemoglobin (another protein which gives the red blood cells their characteristic colour); when red cells are destroyed, they release hemoglobin which binds to the haptoglobin. Typically, the body maintains a fine balance between the production and removal of the hemoglobin-haptoglobin complex but some conditions, like anemia for instance, can disrupt this balance.
Recently, haptoglobin has been identified as serving a key role in the initial body response to infection in bovines, and heightened levels might be indicative of a range of conditions. Heightened levels of haptoglobin primarily serve to prevent further tissue damage and promote repair, so the protein’s amount in the blood is proportional to the severity of the challenge. Bovine Respiratory Disease (BRD) is the primary cause of morbidity and mortality in livestock in the US, resulting from a combination of stress, underlying viral infection and a new bacterial infection. It can have a tremendous financial impact, resulting in significant losses of performance, carcass quality and health, and incurring additional labour and treatment costs. Additionally, haptoglobin has been linked to calving difficulties which incur thousands of dollars of costs every year. Mastitis, an inflammation of the mammary gland in dairy cows, has been shown to cost farmers the staggering $350 per cow per year. Treatment costs are only as little as 15% of the general cost of mastitis, with most of the other losses having to do with the reduction in milk yield because of udder damage – an effect which is most often long-lasting. The amount of haptoglobin in the milk and serum increases in mastitis, and heightened levels in the blood might be indicative of RBD and other bovine health conditions, which is why early detection of the protein is crucial to ensure the health and wellbeing of livestock, improve carcass quality and increase profits, whilst minimizing the treatment- and diagnosis-associated costs.
So far, to detect haptoglobin levels in cows, researchers have relied on methods such as spectroscopy and radioimmunoassay which though effective, don’t come without their limitations. Most of the currently used methods are expensive and require multiple steps, tend to have long examination times and require a team of specialist technicians which can infer additional costs. In short, to detect inflammation in cows as indicated by a higher level of the haptoglobin protein, one must have access to a testing facility and enough financial resources which might not always be a viable option.
Dr. Suresh Neethirajan’s team made a breakthrough in the detection of haptoglobin in a bovine sample by isolating a single layer of phosphorene through a process known as ‘liquid exfoliation’. This method was first developed by Brent and colleagues in 2014 and later modified; the bulk black phosphorus is ground in a mortar and pestle, then undergoes several additional steps to filter out the unexfoliated molecules. The end result is a two-dimensional layer of nanoparticles – a “nanosheet”. Following additional testing, the research team managed to demonstrate the efficiency of the phosphorene nanosheet in detecting the levels of haptoglobin in a sample.
The expensive and time-consuming methods for the detection of haptoglobin in bovines called for an easier-to-use, sensitive and selective alternative that would allow farmers to detect BRD in cows on-farm. The nanosheet developed by Dr. Suresh Neethirajan facilitates quicker decision making by providing them with a simple, quick and effective method to detect the levels of haptoglobin in both humans and bovines. The phosphorene sheet successfully labelled samples with an increased level of the haptoglobin protein in less than 60 seconds which makes the technique extremely useful for on-farm livestock diagnosis and montiroing of diseases like BRD and mastitis.
Up until now, there has been no single device or prototype method available for haptoglobin detection that offers the same accuracy, efficiency and speed of detection as the phosphorene-based method proposed by Dr. Suresh Neethirajan’s team. In addition to developing an effective handheld device for detection of disease and infection monitoring in bovines, the researchers also managed to demonstrate proof of concept that two-dimensional nanomaterials can be combined with biomolecules such as proteins and antibodies to create more sensitive and selective detection methods. The phospherene haptoglobin detection method produces rapid results – detection occurs within less than 60 seconds – which in turn can help farmers make faster decisions regarding the health and well-being of their livestock and lays the foundations for more enhanced detection methods and regular monitoring in both bovines and humans.
With the costs incurred by bovine diseases like BRD and mastitis, early detection of haptoglobin is of the essence as it may help farmers make faster decisions when it comes to their livestock’s health. The prototype put forward by Dr. Suresh Neethirajan’s is not only the first platform of its kind but produces accurate and rapid results in less than a minute. With this breakthrough, researchers have begun to uncover the myriad of benefits two-dimensional structures like phosphorene and graphene have to offer, and farmers can now quantify the levels of haptoglobin in both standard blood and serum samples directly on-farm. The phospherene nanosheet is user-friendly, and a cheaper, more reliable and simpler to use alternative to traditional methods for detection of haptoglobin, and is also in excellent agreement with the existing complex and traditional techniques (ELISA). This makes it a versatile and attractive choice for on-farm diagnostic applications and also demonstrates the myriad of benefits nanotechnologies and nanostructures have to offer to a range of different fields.
