MIPT: A method for selecting molecules suitable for targeted drug delivery

Main article: Targeted delivery of drugs in the body

2024: Presentation of the method for determining the size and shape of polymer molecules in solutions

Scientists from MIPT together with colleagues from the Kurchatov Institute and the Russian Academy of Sciences have developed a method for determining the size and shape of polymer molecules in solutions based on nuclear magnetic resonance data. The method will be used for targeted therapy of diseases. MIPT announced this on October 15, 2024.

Nuclear magnetic resonance (NMR) is a phenomenon caused by the interaction of the magnetic field of a nucleus of an atom with an external magnetic field. At the same time, not every nucleus is capable of contact - to establish a "bond," it is necessary that the number of protons and neutrons is not even. For example, on the NMR spectra, a peak is recorded in hydrogen, but not in deuterium.

To work out the procedure for selecting molecules, scientists from MIPT studied a two-component system in which deuterochloroform CDCl3 is the solvent, and polyethylene glycol HO- (CH2-CH2-O) 10-H is the dissolved substance.

The choice of just such a solvent, and not the traditionally used chloroform CHCl₃, is dictated by the fact that in the method we have developed, the signal is picked up precisely from the protons that are part of the dissolved polymer molecules, - explained Alexander Maksimychev, professor of the Department of General Physics at MIPT.

According to the researchers, the use of polyethylene glycol, whose molecules consist of 10 units, is due to the fact that a molecule with a small number of units is usually linear, and with a large one - spherical.

To measure the diffusion coefficient of polyethylene glycol molecules in deuterochloroform, a special technique was used in which, depending on the time, a decline in the intensity of spin echo signals was measured, "said Valery Ivanov, junior researcher at the Laboratory of Photonics of Quantum-Dimensional Structures at MIPT.

Fluid Dynamics

Spin echo is the spontaneous occurrence of a NMR signal and electron paramagnetic resonance after a sequence of radio-frequency field pulses is applied to the sample. The diffusion coefficient is a quantitative characteristic of the rate of spontaneous movement of particles of a substance, during which the concentration over the entire occupied volume is equalized.

In the course of research, scientists have found that the fading signal of a spin echo from dissolved spherical macromolecules is described by one term, exponentially decreasing over time. If the molecule has the shape of a rod, then the damped spin echo signal already contains two exponential terms corresponding to two diffusion coefficients, which differ by about two times.

The work was carried out with the partial support of the grant program of the Russian Scientific Foundation No. 23-19-00451.