A new cell-selective three-dimensional microincubator based on silicon photonic crystals

Area of Science:

• Biotechnology
• Materials Science
• Cell Biology

Background:

• Photonic crystals (PhCs) offer unique structural properties for microscale applications.
• Developing advanced microenvironments for selective cell culture is crucial for biological research and diagnostics.

Purpose of the Study:

• To investigate the potential of vertical, high aspect-ratio (HAR) photonic crystals (PhCs) as three-dimensional (3D) microincubators.
• To determine the selective cell culture capabilities of HAR PhCs for different human cell lines.
• To explore the application of these microstructures in label-free optical detection systems.

Main Methods:

• Fabrication of HAR PhCs using electrochemical micromachining, creating periodic arrays of gaps and silicon walls.
• Culturing of eight human cell lines (epithelial and mesenchymal) on silicon micromachined dice with flat and PhC surfaces.
• Analysis of cell proliferation, morphology, adhesion, and penetration into PhC gaps using fluorescence microscopy.

Main Results:

• HAR PhCs were successfully fabricated with dimensions suitable for microincubation (5 µm gaps, 50 µm depth, 3 µm walls).
• Only cell lines exhibiting a mesenchymal phenotype were able to penetrate the PhC gaps and adhere to the vertical silicon surfaces.
• Cell sedimentation was verified as a contributing factor to gap colonization.

Conclusions:

• Vertical HAR PhCs act as selective 3D microincubators, differentiating cell lines based on their phenotype.
• Mesenchymal cells can be cultured within HAR PhCs, demonstrating their potential for 3D cell-based assays.
• HAR PhCs combined with optical transducers offer a promising platform for label-free detection of cellular activities in a 3D microenvironment.