Scientists develop a sensor for the simultaneous analysis of dopamine and paracetamol
Chemists from St. Petersburg State University, as part of a research team, have developed a novel type of electrode capable of quickly and efficiently determining the concentrations of dopamine and paracetamol in the human body. The detection of these substances is crucial for the therapy and diagnosis of a number of diseases, such as Parkinson's disease.
Simultaneous real-time monitoring of multiple biomolecules is a key challenge in modern bioanalytics. Dopamine (DA) is a crucial neurotransmitter; irregularities in its concentration can cause Parkinson's disease, schizophrenia, and other neurological disorders. Paracetamol (PA, acetaminophen) is a widely used analgesic and antipyretic, taken on its own and as a component of many medications. An overdose can lead to dysfunction of internal organs, particularly the liver.
These substances are often present in the body simultaneously, for instance, during drug therapy. For accurate diagnosis, these two elements need to be studied separately. Traditional methods for their separate detection are expensive, require bulky equipment that can only be operated by qualified personnel, making these methods poorly suited for rapid analysis. Current methods for creating electrodes modified with metal nanoparticles to improve sensitivity typically involve multiple stages.
Insert: Nanoparticles are particles of a substance ranging in size from 1 to 100 nanometers in all three dimensions, possessing unique physical and chemical properties that distinguish them from their larger counterparts. A nanomole (nmol) is a unit of measurement for an amount of a substance, equal to one billionth of a mole (10⁻⁹ mol), i.e., a very, very small part of a mole.
This approach involves the use of chemical reducing agents, binding agents, or complex laboratory equipment. Consequently, the separation process itself becomes more complex and expensive; moreover, the electrical contact within the composite material often deteriorates.
Scientists from St. Petersburg State University, St. Petersburg State Chemical-Pharmaceutical University, Far Eastern Federal University, and the Institute of Automation and Control Processes, FEB RAS, have proposed a fundamentally new method for manufacturing such electrodes. The new development makes it possible to create flexible electrodes suitable for high-precision analysis quickly, in a single step.
"We used a single, rapid process to create the electrode. It works as follows: a flexible polymer film (polyimide) is immersed in a gold salt solution, and then a beam of a blue laser is directed onto it. In the exposure zone, the heat simultaneously triggers two reactions: it converts the surface layer of the polymer into a porous graphene 'sponge' and reduces the gold ions, depositing the resulting nanoparticles directly onto the forming matrix," explained Professor Alina Manshina from the Department of Laser Chemistry and Laser Materials Science at St. Petersburg State University.
This method guarantees a uniform distribution of gold across the entire film surface and creates direct electrical contact between the metal and the graphene, eliminating the need for binding additives that impair conductivity. Studies have confirmed the formation of a unique material: gold particles sized 5–30 nanometers evenly coat the surface, and it is this specific technique that underpins the development's success. The graphene base provides high conductivity and surface area, while the gold components act as active catalytic centers, selectively accelerating the electrochemical oxidation of dopamine and paracetamol.
"Thanks to this architecture, the flexible electrode was able to detect both substances simultaneously but independently. The researchers achieved high sensitivity: the detector registers target molecules at ultra-low concentrations on the order of nanomoles per liter (nM). The developed sensor also demonstrated high efficiency when testing real biological samples – human saliva and urine containing trace amounts of dopamine and paracetamol," noted Alexander Vavilov, a postgraduate student at the Department of Laser Chemistry and Laser Materials Science at St. Petersburg State University.
More information:
doi.org/10.1016/j.diamond.2026.113358
Provided by St. Petersburg State University
