The study develops poly(2-oxazoline) resins that are printed by two-photon polymerization into hydrogel grids and then covalently functionalized with RGD peptides. Measured microscopy observations show that ethyl-sidechain grids repel L929 fibroblasts, amine-bearing grids promote attachment, and RGD-functionalized grids accelerate early spreading. The 25 µm openings allow entry into cavities, whereas 10 µm openings restrict these cells to exterior surfaces. The demonstrated cell responses concern L929 fibroblasts; Figure 6 quantification comes from one experiment.

Small / 2026 / Interactive paper

A microscopic scaffold is more than a shape. Its surface can turn a passing cell into a resident.

Hoffmann and colleagues print tiny hydrogel grids with a laser, then change their chemistry. The result: three surfaces, three very different encounters with cells.

Build the architecture. Change the invitation.

The idea

A precise shape. A chemical invitation.

The extracellular matrix gives cells both a structure and signals. These synthetic grids let researchers tune those two ingredients separately.

Write with light

Two-photon absorption confines polymerization to a tiny laser focus in the water-based poly(2-oxazoline) resin. Moving the focus writes a three-dimensional grid; washing removes uncured resin.

Give the surface a signal

Amine side chains offer attachment sites for further chemistry. After printing, a peptide containing RGD — a short cell-adhesive motif — is covalently coupled to these groups.

Watch cells respond

L929 fibroblasts barely engage with the ethyl surface. Amine groups promote attachment; adding RGD accelerates their initial spreading.

Your virtual experiment

What makes a cell stay?

Change the surface. Open up the grid. See how the cells respond over time.

The encounter

Ethyl grids show little apparent interaction. Cells remain rounded rather than spreading on the scaffold.

25 µm openings offer space for these fibroblasts to enter the grid’s cavities.

Find a surface that encourages early spreading, with room for cells to enter.

The changing cell shapes and positions are a qualitative teaching model, based on the paper’s microscopy of L929 fibroblasts. The animation does not calculate adhesion rates, forces, cell numbers, or probabilities. Architecture and cell shapes are simplified, and displayed mesh sizes refer to the two designs studied. The two-level scene evokes the grids used for electron microscopy; the fluorescence time-lapse comparison used a one-layer grid.

RGD is an established cell-adhesive motif; the authors discuss integrin-mediated interaction as an explanation for the response. The interactive model separates surface chemistry from geometry to make the observed differences easier to explore.

What the experiments reveal

The first hours make the difference.

RGD gives an early advantage

The functionalized grids show the fastest, most pronounced initial spreading. At 3 h 20 min, no round cells remained in the observed RGD experiment.

Amine catches up

By 24 hours, cells spread extensively on both amine and RGD surfaces. After 72 hours, both grids were covered with spread cells; the ethyl surface remained sparsely occupied.

Geometry decides where

10 µm openings keep these cells on exterior surfaces. With 25 µm openings, cells can enter cavities and engage the scaffold in three dimensions.

Look at the evidence

The cells tell the story.

Original microscopy, preserved with labels and scale bars. Select a view, then open it to look closer.

Same materials. Two mesh sizes.

Scanning electron microscopy after 2 hours of cell culture. The ethyl grids remain clearly exposed. Amine and RGD grids support attached cells, with the larger openings allowing cells to reach into the structure.

Rows compare ethyl, amine, and amine + RGD. The left pair shows 10 µm openings; the right pair shows 25 µm. Each scale bar is 20 µm.

Why it matters

Design the setting. Then study the response.

A cell-culture scaffold can be designed at two levels: its architecture, and the signals on its surface.

The paper combines precision printing with post-printing chemistry, offering defined microenvironments for studying cell–material interactions. Selectively combining cell-adhesive and cell-repellent regions is a proposed next direction.

Beyond the still images

The supporting material

The paper’s supporting information adds characterization, cell time-lapses, and a view through the grid.

Surface‐Functionalized Poly(2‐Oxazoline)‐Based Grids Produced by Two‐Photon Polymerization as 3D‐Structured Hydrogels Promoting Cell Adhesion

Tim Hoffmann, David Pretzel, Steffi Stumpf, Lena-Marie Kaspar, Florian Behrendt, Christiane Höppener, Aaron Reupert, Volker Deckert, Lothar Wondraczek, Michael Gottschaldt, Klaus Liefeith, and Ulrich S. Schubert. Small (2026), e75866. DOI: 10.1002/smll.75866.

The article is open access under Creative Commons Attribution 4.0. Figures 4, 5, and 7 are cropped from the published pages, with their scientific content unchanged. The graphical abstract is an AI-generated conceptual illustration based on the paper. The interactive scene is a qualitative visualization of the reported cell observations.

Based on Hoffmann et al. · Small · 2026 10.1002/smll.75866 ↗

Swipe across the image to inspect the panels.

Hoffmann et al., Small (2026) · CC BY 4.0 · Cropped from the published page; scientific content unchanged.