A recent study has started to lay the foundation for more accurate healthcare sensors by utilizing nanomaterials. Researchers have developed sensors using single-wall carbon nanotubes, which could significantly enhance continuous health monitoring and the detection of minute biological fluctuations, such as female hormone levels.
Carbon nanotubes in solution. Carbon nanotubes with different chirality, or“twist”, have different optical properties: one type of nanotube is yellow, and the other is violet. Image Credit: Mikael Nyberg
Scientists at the University of Turku, Finland, have successfully produced these sensors from single-wall carbon nanotubes—a nanomaterial consisting of a single atomic layer of graphene. However, a long-standing challenge in nanotube development lies in the manufacturing process, which produces a mix of conductive and semi-conductive nanotubes with varying chiralities—the way the graphene sheet is rolled into a cylindrical structure.
Since a nanotube’s electrical and chemical properties are largely dependent on its chirality, distinguishing between them is crucial.
Han Li, a Collegium Researcher in materials engineering at the University of Turku, has developed methods to separate nanotubes based on their chirality. In this study, researchers successfully differentiated between two carbon nanotubes with nearly identical chirality and identified their distinct electrochemical properties.
Although the difference in the chirality of the nanotubes is very slight, their properties are very different.
Ju-Yeon Seo, Doctoral Researcher, University of Turku
Accuracy and Sensitivity for Sensors
By purifying and isolating the nanotubes, researchers could analyze their differences as sensor materials. While nanotubes are often used in hybrid sensors alongside other surfactants, this study focused on sensors made entirely from nanotubes. The team also achieved precise control over nanotube concentration, allowing for direct comparison of different chiralities.
Notably, the study found that one type of nanotube (6.5) was more effective than another (6.6) in adsorbing dopamine—a process in which a material binds atoms or molecules to its surface. This property is particularly important for detecting substances present in extremely low concentrations.
Seo added, “The result is significant because by being able to precisely control the properties of carbon nanotubes we can fine-tune the ability of the sensor material to detect changes in specific substances.”
Currently, sensors enable monitoring of blood glucose levels, but researchers at the University of Turku aim to develop materials that can detect significantly lower concentrations of other biological markers.
The molecules that we are interested in, such as female hormones, are present in the body in concentrations that are millions of times lower than glucose. To study hormone fluctuations, the accuracy of biosensors needs to be improved significantly.
Emilia Peltola, Associate Professor, Materials Engineering, University of Turku
This study is the first to demonstrate that a sensor’s electrochemical response is influenced by nanotube chirality. Future research may use computational models to identify the optimal chirality for detecting specific molecules.
The Materials in Health Technology group at the University of Turku focuses on understanding how different material surfaces interact in biomedical applications. One of its key objectives is to develop next-generation sensor technologies that are not only more sensitive and accurate but also maintain their functionality in biological environments.
Journal Reference:
Seo, J.-Y., et al. (2025) Single-chirality single-wall carbon nanotubes for electrochemical biosensing. Physical Chemistry Chemical Physics. doi.org/10.1039/d4cp04206a.