Scientists 3D print structures inside living human cells with precision

Researchers in Slovenia have developed a novel technique to 3D print precise polymer microstructures directly inside living human cells, overcoming significant challenges posed by the cell’s tiny, crowded interior. Using two-photon polymerization, a laser-based method, the team injected a biocompatible photoresist material (IP-S) into HeLa cells via ultra-fine glass needles. The laser then selectively polymerized the material at its focal point, enabling the creation of intricate 3D shapes—such as miniature elephants and lattice structures—within the cytoplasm without damaging the surrounding cellular environment. The study demonstrated that cells can accommodate these printed structures, with nuclei deforming to make space and cells maintaining normal behavior, including division and passing the structures to daughter cells. However, about 55% of cells with printed objects died within 24 hours, a mortality rate comparable to other invasive methods, and larger structures (over 5 micrometers) caused delays in cell division. While currently limited to small-scale