As discussed in the previous blog, “Electrochemical Biosensors for the Diagnostics of Infectious Diseases”, the global demand for effective electrochemical biosensors has risen. Specifically, the demand is for point of care test (POCT) devices due to their ability to produce rapid results with better sensitivity at low costs and their availability in resource-scarce settings, where many of the outbreaks occur.
Now more than ever, the attention of the world is grasped by infectious diseases. Currently, the focus is centralised around a certain viral disease, however infectious diseases are caused by a variety of organisms, whether that is a virus, bacterium, fungi, or parasite. The diseases caused by such organisms can spread throughout a population either via human-to-human contact or via means of another host animal or insect (1).
Continuous glucose monitoring (CGM) devices are small implants worn under the skin, with the primary focus of allowing patients to check glucose levels in real time. To allow such, sensors measure glucose levels 24/7 which enables the individual to check trends and be alerted to periods of highs and lows. The information is sent digitally to a display device, such as a smart phone, and can be shared with a healthcare team; so they can review, and make adjustments for the appropriate treatment plan (1). The CGM however, does not measure the blood glucose directly, instead it measures the glucose present in the interstitial fluid that surrounds the body’s cells. As a result, there is a small time delay compared to a blood measurement, especially after eating or exercise. A finger-prick test is necessary if an individual is contemplating changing their treatment, for example to treat a hypoglycaemia, to ensure an informed decision is made with the most accurate result.
Periods of ‘severe bleeding’ after trauma or during surgery require real-time management of hemostasis to preserve life. Due to their ability to produce rapid results and a multitude of other characteristics, POCT is becoming the gold standard in hemostatic management. In recent years there has been an increasing demand for POC hemostatic tests and as a result of such, along with advancements in technology, there has been a significant increase in both the spectrum of tests available and the number of tests performed (1). Following is a review of the main groups of clinically available POC hemostasis tests.
The Rising Requirement for Developing POC Tests for Hemostasis
Several decades ago, the world of clinical diagnostics was revolutionised with the centralisation of diagnostics laboratories. This was spurred by developments in automation, the installation of sample transport systems and the introduction of communication between hospital and laboratory IT systems (1). However, today with new advancements in technology such as novel sensors and miniaturisation, a decentralised trend can be observed in the form of point of care testing (POCT). However, the need for POCT appears to have missed the mark. A recent international survey found that the most commonly used POCT were urine pregnancy tests and blood glucose monitors, when in fact clinicians desired greater use of POCT to diagnose acute cardiac disease, including hemostatic monitoring (2).
When comparing various biological assays or even assessing the performance of a single one, there are various factors we can look at. These include the likes of the limit of detection (LoD), dynamic range, specificity and selectivity. However, another important factor that we can consider is the sensitivity of a bioassay. Sensitivity can be defined as the ability of an assay to accurately distinguish between varying levels of a disease. A bioassay that is regarded as sensitive has the ability to discriminate between small changes in the target analyte concentration. Thus, it would be able to give a range of assay results, whereas a less sensitive test is unable to distinguish between small changes and therefore may present results as solely positive or negative (1).
Hemostasis is a tightly regulated natural process which leads to cessation of bleeding after damage to a blood vessel has occurred. It is regarded as the initial step of wound healing and can be broken down into three main steps. Vasoconstriction is the initial stage which restricts blood flow to the damaged area. Platelet plug formation is the second stage and is regarded as primary hemostasis. The final stage is coagulation and is regarded as secondary hemostasis.
The development of new and improvement of existing biosensors has been at the forefront of biochemistry for the last decade. With the idealistic biosensor being one that is highly accurate, simple and inexpensive. The cost and ease of use are often determinable by the design and inclusion of components of the biosensor. Therefore, when evaluating biosensors, their effectiveness is a key area to focus on. Two of the most prominent aspects of effectiveness used to compare biosensors are the limit of detection (LoD) and the dynamic range (1).
Diabetes mellitus, in all forms, continues to be a global burden with the prevalence ever-growing. In the last three decades, there has been over a 400% increase in the number of individuals diagnosed with the disease (1). Diabetes is clinically classified into two main categories based on the certain pathology of the disease, although there are other less common subtypes. Type 1 diabetes mellitus (T1DM) is described as an autoimmune disease (2), whilst type 2 diabetes is a developmental disease that is associated with obesity (3).