Published on: 2026-06-29
Source: Peter the Great St. Petersburg Polytechnic University –
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Scientists at Peter the Great St. Petersburg Polytechnic University have patented a technology that allows “packaging” anti-tumor molecules into silicon dioxide nanoparticles and delivering them directly to a cancer tumor. The surface of the nanoparticles is modified with polyethyleneimine, which enables the carrier to hold several times more of the active substance and release it slowly and controllably. The method allows for a 30% reduction in the toxic load on the patient’s body, the scientists note.
Modern cancer therapy increasingly involves targeted delivery of antitumor agents directly into malignant formations. At the same time, many promising antitumor compounds, so-called small molecules, may degrade en route to the tumor or distribute non-selectively, which increases the toxic burden on healthy tissues. The problem is solved by “packaging” the active substance into a nanoscale carrier that protects the molecule, delivers it to the desired area, and releases it gradually. One of the most convenient materials for such a carrier is considered to be silicon dioxide (SiO2): it is biocompatible, chemically stable, and has a well-developed porous structure. Currently existing methods for encapsulating small molecules in SiO2 require precise selection of pH, temperature, and concentrations, often result in low loading or uncontrolled release, and are poorly scalable to industrial volumes.
A method that bypasses these limitations was developed at the Laboratory of Nano- and Microencapsulation of Biologically Active Substances at the Institute of Biomedical Systems and Technologies of SPbPU. The key idea of the scientists was to pre-coat SiO2 nanoparticles with polyethyleneimine (PEI). This polymer creates numerous amino groups with a high density of positive charge on the surface of the particles. Due to electrostatic attraction, hydrogen bonds, and donor-acceptor interactions, the active substance is held firmly and stably. The active substance used was a small molecule based on 2-aminothiophene with antitumor activity.
We essentially created a universal platform — a way to securely fix the active substance and then gradually release it precisely where it is needed. The main breakthrough here is the modification of the surface of nanoparticles with polyethyleneimine. It significantly increases the amount of substance that the carrier retains, and it retains it firmly: over 90 percent remains in the nanoparticles for 18 days. Moreover, the entire technology operates under mild conditions and without complex chemistry, making it easy to reproduce and scale. For the patient, this means less frequent dosing and reduced toxic exposure, and for the pharmaceutical industry — a real opportunity to bring the development to production,” noted Alexander Timin, head of the Laboratory of Nano- and Microencapsulation of Biologically Active Substances at SPbPU.
The entire synthesis consists of five stages and occurs at room temperature and neutral pH without aggressive reagents and complex technological features. According to the researchers, the carrier binds more than 70% of the introduced substance, and under physiological conditions retains over 90% for 18 days. The release is controlled and depends on the environment: in an acidic medium with a pH below 5.5, characteristic of tumor tissue, it accelerates. The particle size is 100–200 nanometers, and the free amino groups on the surface allow, if necessary, to ‘attach’ additional agents, such as fluorescent dyes or diagnostic radionuclides, turning the carrier into a theranostic one—that is suitable simultaneously for treatment and diagnosis.
The closest analogue to this development is an American patented technology where molecules are held by polyamines or carboxyl groups. However, such weak ionic functionalization results in a low charge density: the carrier accommodates little substance and requires precise tuning of synthesis conditions. By relying on PEI, the scientists from the Polytechnic succeeded in significantly increasing capacity, especially for hydrophobic, poorly soluble compounds, making the process reproducible and eliminating the risk of a sudden, uncontrolled release of the active substance.
Similar systems based on silicon dioxide are being developed worldwide, but we moved away from the usual weak ionic groups and focused specifically on polyethyleneimine. This resulted in a high charge density and, along with it, significantly greater capacity, especially for difficult, poorly soluble molecules. Equally important is that we managed to avoid the risk of a sudden, avalanche-like release: the substance is released gradually and accelerates only in the acidic environment characteristic of tumors. Currently, the main task is to move from test tubes to living systems: to assess safety and pharmacokinetics, to test the platform on other classes of drugs, and to adapt the methodology for semi-industrial volumes,” explained Senior Researcher of the Laboratory of Nano- and Microencapsulation of Biologically Active Substances at SPbPU Timofey Karpov.
Among the most obvious applications, the authors mention ovarian cancer, hepatocellular carcinoma, and breast cancer. These are solid tumors where both a high local concentration of the drug and reduced systemic toxicity are especially important. According to the researchers’ estimates, the technology is capable of reducing the frequency of drug administration several times and decreasing the toxic load on the body by at least 30%, while the yield of the target product during scaling remains at 95% or higher. The team’s future plans include conducting preclinical trials on living systems, expanding the list of loaded molecules, and bringing the laboratory protocol to semi-industrial volumes, paving the way for transferring the technology to the real sector.
The patent was obtained within the framework of project FSEG-2025-0007 “Development of approaches to creating targeted radiopharmaceuticals based on nanocontainers for combined therapy of malignant tumors” (Additional agreement No. 075-03-2025-256/1 dated 25.03.2025).
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