UV- and Visible-Light Photopatterning of Molecular Gradients Using the Thiol-yne Click Reaction

White light-assisted projection printing of submicron plasmonic nanostructures for advanced nanofabrication

Plasmonic nanoparticle printing from colloidal solutions is a vital facet of nanofabrication, offering unique advantages such as direct writing, a bottom-up approach, and on-demand printing for sensing, electronic devices, and healthcare applications. Despite its potential, plasmonic nanoprinting faces significant challenges in becoming practicable due to the limitations of the current techniques, such as complex setup, high cost, tedious process, and the usage of time-consuming spot scan techniques using lasers for pattern generation. Herein, for the first time, a novel white light-assisted projection printing technique (PPT) is demonstrated for fabricating plasmonic nanostructures. This notably simple approach can easily print arbitrary plasmonic patterns in just a few seconds. Additionally, submicron patterning capability is demonstrated with an impressive line width of ∼400 nm. More importantly, conductive patterns are achieved without additional post-treatments, such as annealing. Optothermal parallel trapping of biological cells and grayscale patterning for surface-enhanced Raman spectroscopy is demonstrated, showcasing the potential applications of the printing technique for advanced nanofabrication. The superior performance of this technique surpasses that of the existing optical printing technique, paving the way toward advanced nanofabrication for emerging applications.

Ligand-Nondestructive Direct Photolithography Assisted by Semiconductor Polymer Cross-Linking for High-Resolution Quantum Dot Light-Emitting Diodes

The photolithographic patterning of fine quantum dot (QD) films is of great significance for the construction of QD optoelectronic device arrays. However, the photolithography methods reported so far either introduce insulating photoresist or manipulate the surface ligands of QDs, each of which has negative effects on device performance. Here, we report a direct photolithography strategy without photoresist and without engineering the QD surface ligands. Through cross-linking of the surrounding semiconductor polymer, QDs are spatially confined to the network frame of the polymer to form high-quality patterns. More importantly, the wrapped polymer incidentally regulates the energy levels of the emitting layer, which is conducive to improving the hole injection capacity while weakening the electron injection level, to achieve balanced injection of carriers. The patterned QD light-emitting diodes (with a pixel size of 1.5 μm) achieve a high external quantum efficiency of 16.25% and a brightness of >1.4 × 105 cd/m2. This work paves the way for efficient high-resolution QD light-emitting devices.

Spatially-Encoding Hydrogels With DNA to Control Cell Signaling

Patterning biomolecules in synthetic hydrogels offers routes to visualize and learn how spatially-encoded cues modulate cell behavior (e.g., proliferation, differentiation, migration, and apoptosis). However, investigating the role of multiple, spatially defined biochemical cues within a single hydrogel matrix remains challenging because of the limited number of orthogonal bioconjugation reactions available for patterning. Herein, a method to pattern multiple oligonucleotide sequences in hydrogels using thiol-yne photochemistry is introduced. Rapid hydrogel photopatterning of hydrogels with micron resolution DNA features (≈1.5 µm) and control over DNA density are achieved over centimeter-scale areas using mask-free digital photolithography. Sequence-specific DNA interactions are then used to reversibly tether biomolecules to patterned regions, demonstrating chemical control over individual patterned domains. Last, localized cell signaling is shown using patterned protein-DNA conjugates to selectively activate cells on patterned areas. Overall, this work introduces a synthetic method to achieve multiplexed micron resolution patterns of biomolecules onto hydrogel scaffolds, providing a platform to study complex spatially-encoded cellular signaling environments.