Scientists 3D-print micrometer-scale structures inside living cells with two-photon polymerization

Researchers have demonstrated a way to fabricate micrometer-scale three-dimensional structures directly inside living cells by combining a biocompatible photoresist with two-photon polymerization. Using a light-sensitive formulation introduced into cells and a tightly focused ultrafast laser beam, the team built submicron-resolution shapes - among them tiny geometric forms, barcode patterns, and a roughly 10 μm elephant - embedded within the cytoplasm.

The core advance is adapting multiphoton microfabrication, a mainstay of high-resolution 3D printing, to the crowded, dynamic environment of a living cell. Two-photon polymerization confines polymerization to a tiny focal volume, so structures are written voxel by voxel inside the cell without polymerizing the surrounding medium. That gives lithographic control at scales hobby and bench-top microfabricators will recognize, but applied on an intracellular scale.

Crucially, some cells survived the fabrication process and subsequently divided, and in at least one case the polymerized structure was passed to a daughter cell. That survival and inheritance point to immediate experimental possibilities: intracellular mechanical probes that report forces from inside the cell, miniature devices that perturb local mechanics, and new ways to study how cells sense and respond to rigid inclusions. For labs working on bio-MEMS, mechanobiology, and tissue engineering, printing inside cells could become a tool for placing probes or scaffolds with unprecedented positional precision.

The work is preliminary and deliberately cautious. Researchers note that viability, long-term effects, and functional consequences must be studied carefully before the technique is applied widely. Questions remain about how polymerized inclusions affect organelle traffic, gene expression, immune signaling, and long-term cell health. The formation process relies on an ultrafast laser and a photoactive resin that is described as biocompatible, but full toxicology, metabolic impact, and degradation behavior are not yet established.

For the 3D printing community this is a striking example of how additive manufacturing methods are migrating into biology. It highlights cross-disciplinary skills - optics, photochemistry, cell handling, and high-resolution motion control - and suggests new collaborations between desktop fabricators and wet labs. It also underscores limits: this is not a home experiment or a plug-in for consumer printers. Ultrafast lasers and cell culture conditions demand proper facilities and safety oversight.

What comes next is careful characterization and cautious expansion of applications. Expect follow-on studies on cell types, resin chemistry, laser parameters, and functional readouts. For those tracking the bleeding edge of microfabrication, the story is a reminder that the next frontier of printing may not be bigger or faster, but smaller and closer to the machinery of life itself.