Nicotine capture polymers

A new synthetic polymer, with a pincer-like precise molecular structure, effectively captures nicotine molecules and its derivatives. It will be possible to use this polymer in the production of selective and sensitive chemical sensors to determine the concentration of nicotine in solutions, and in the near future even in gases. Moreover, the polymer is also suitable for a controlled and slow release of nicotine, that is, it could also be used for medical purposes.

The collaboration between the Institute of Physical Chemistry of the Polish Academy of Sciences and the Department of Chemistry at the University of Wichita (Kansas, USA) led to the creation of a polymer trap for nicotine. The polymer, which consists of a pincer-like molecular structure (tongs), effectively captures nicotine molecules and its chemical derivatives and is also able to release them in a controlled manner. The polymer could be used in reusable chemical sensors to detect nicotine in the fields of industry and biomedicine, as well as in nicotine-impregnated bandages for smokers trying to quit smoking.

            "The first nicotine trap was synthesized by our American partner, Professor Francis D'Souza, several years ago. It was a kind of molecular pliers that move freely in the solution and form conjugates (complexes) with nicotine molecules found in it. Recently, the US-Poland international research team was able to determine the placement within a polymer. The resulting material is solid, and therefore it can be used to build chemical sensors," says one of the Polish researchers involved in the project.

            The core of the polymer nicotine trap, for which a patent application was recently submitted, is a metalloporphyrin derivative, a molecule found, for example, in blood. The molecule includes a chemical ring containing a zinc atom in the center, and amide clamps associated with this ring. Nicotine binds to this polymer via its two nitrogen atoms: one of them binds to the zinc atom, while the other atom binds to the pins. "Due to the precise link at two points, we are sure that the molecule that was captured is nicotine," explains one of the researchers.

            Besides nicotine, the polymer also captures the alkaloid cotinine (cotinine) formed in the breakdown of nicotine and other alkaloids that often accompany nicotine found in tobacco leaves, for example, myosmine. The binding of the polymer to nicotine is stable, and still reversible. This characteristic is responsible for new chemical sensors for detecting nicotine and its derivatives being able to operate repeatedly.

            Nicotine is detected by means of a piezoelectric resonator coated through electro-polymerization with a thin polymer layer of submicron size. The entrapped nicotine increases the mass of the layer and subsequently reduces the resonant frequency of the resonator, a change that is simply measured. "It can be said that we weigh a layer of our polymer during the entire experiment. Since we know what the initial mass of the polymer is, and also that the polymer selectively captures nicotine and its derivatives, an increased mass of the layer means that these compounds are present in the solution," explains the researcher.

            Quartz resonators with a volumetric acoustic wave, used in experiments with the new polymer, enable the detection of nicotine in solutions. The researchers plan to collaborate with manufacturers of surface acoustic wave resonators. These resonators oscillate at much higher frequencies, which allows them to be more sensitive and after being coated with the polymer layer that captures nicotine, they will be able to detect nicotine in gases as well.

            In the method presented here, the detection and determination of nicotine is not limited to weighing. Since nicotine is electronically active, the researchers intend to measure the oxidation potential of the nicotine trapped in the polymer at the same time as measurements at resonant frequencies. Combined measurement of these two separate methods will increase the reliability of the detection.

            The new polymer could be used, among other fields, for the development of chemical sensors to detect the nicotine content in tobacco leaves and in biomedical studies where it is necessary to locate and quantify the breakdown products of nicotine in the patient's body fluids. Another possible application would be in nicotine-soaked bandages that aid in smoking cessation - the new polymer could be used for a prolonged and precise release of nicotine into the body through the skin.

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