In a new study by the University of Newcastle, scientists have discovered a new feature of dendrimers that will make them as beneficial to the body as possible.

Dendrimers are particles composed of treelike branches extending in the form of a sphere from the central core. Scientists have experimented with them for decades to see if they can tolerate drugs and kill bacteria.

Dendrimers belong to the class of polymeric compounds, the molecules of which have a large number of branches. When they are obtained, with each elementary act of molecular growth, the number of branches increases. As a result, with an increase in the molecular weight of such compounds, the shape and rigidity of the molecules change, which, as a rule, is accompanied by a change in the physicochemical properties of dendrimers, such as intrinsic viscosity, solubility, density, etc.

The synthesis of dendrimers is carried out in such a way that during the growth of the polymer molecule there is no joining of the growing branches or the combination of molecules with each other. Likewise, the branches of one tree or the crowns of adjacent trees do not grow together. The “construction” of such molecules is carried out according to a predetermined plan, for example, using reacting groups of three types (A, B, and C), which must satisfy the requirements of a certain logical scheme: each group cannot react with its own kind (A does not interact with A and etc.), groups A and B can react with each other, but each of them cannot react with C, group C must be able to transform at a certain moment into group A.

The more the dendrimer grows, the more tentacles it grows and the less space remains between them. It turned out that at some point this makes them invisible to the immune system.

Sensors called complement pattern recognition (CPR) molecules help immune cells recognize foreign pathogens such as bacteria and viruses through unique patterns on their surfaces. These CPR molecules can respond to patterns that repeat in the range of 2 to 15 nanometers. When scientists created dendrimers with tentacles less than 1 nm apart, it turned out that the CPR molecules could not detect them.

The study authors explain that, for example, such very tiny dendrimers can be used as carriers to deliver drugs to the body without triggering the immune system. For example, these tiny particles can protect implants from immune rejection. The fact is that the activation of the complement system as the defense mechanisms of our immune system sometimes leads to inflammation and also induces anaphylactic reactions.

The research is published in the journal Nature Communications.