No abstract

Surface-mediated transfection has drawn tremendous interest for gene therapy due to its localized gene delivery characteristic and promising perspective for combination devices in clinical applications. However, a method for the controllable load of genetic agents and tunable transfection efficiency to primary cells remains unsatisfactory. Herein, we present a polymeric spongy film with modification of polydopamine (PDA) for controlling load of plasmid DNAs and improving transfection to primary endothelial cells. We demonstrate that, via wicking action, the loading of DNA into the film is simple, rapid, and highly controllable while easily reaching ∼95 μg/cm2 by only a one-shot loading process. Meanwhile, PDA endows the spongy films with a very good photothermal conversion capability. Consequently, we obtain an enhanced transfection up to ∼85% to hard-to-transfect primary endothelial cells upon NIR irradiation. Furthermore, we realize a spatial cell transfection through NIR irradiation in the defined area, suggesting a high potential for precise gene therapy. This photothermal spongy film could serve as a robust platform for surface-mediated gene therapy, and extend the paradigm of a light enhanced delivery system.

Periodic porous structures have been introduced into functional films to meet the requirements of various applications. Though many approaches have been developed to generate desired structures in polymeric films, few of them can effectively and dynamically achieve periodic porous structures. Here, a facile way is proposed to introduce periodic stratified porous structures into polyelectrolyte films. A photo‐crosslinkable polyelectrolyte film of poly(ethylenimine) (PEI) and photoreactive poly(acrylic acid) derivative (PAA‐N3) is prepared by layer‐by‐layer (LbL) self‐assembly. Stratified crosslinking of the PEI/PAA‐N3 film is generated basing on standing‐wave optics. The periodic stratified porous structure is constructed by forming pores in noncrosslinked regions in the film. Thanks to the dynamic mobility of polyelectrolytes, this structural controlment can be repeated several times. The size of pores corresponding to the layer spacing of the film contributes to the structural colors. Furthermore, structural color patterns are fabricated in the film by selective photo‐crosslinking using photomasks. Although the large‐scale structural controlment in thick (micron‐scale and above) films needs to be explored further, this work highlights the periodic structural controlment in polymeric films and thus presents an approach for application potentials in sensor, detection, and ink‐free printing.

The increasing throughput of experiments in biomaterials research makes automatic techniques more and more necessary. Among all the characterization methods, microscopy makes fundamental contributions to biomaterials science where precisely focused images are the basis of related research. Although automatic focusing has been widely applied in all kinds of microscopes, defocused images can still be acquired now and then due to factors including background noises of materials and mechanical errors. Herein, we present a deep-learning-based method for the automatic sorting and reconstruction of defocused cell images. First, the defocusing problem is illustrated on a high-throughput cell microarray. Then, a comprehensive dataset of phase-contrast images captured from varied conditions containing multiple cell types, magnifications, and substrate materials is prepared to establish and test our method. We obtain high accuracy of over 0.993 on the dataset using a simple network architecture that requires less than half of the training time compared with the classical ResNetV2 architecture. Moreover, the subcellular-level reconstruction of heavily defocused cell images is achieved with another architecture. The applicability of the established workflow in practice is finally demonstrated on the high-throughput cell microarray. The intelligent workflow does not require a priori knowledge of focusing algorithms, possessing widespread application value in cell experiments concerning high-throughput or time-lapse imaging.

Inspired by nature, many functional surfaces have been developed with special structures in biology, chemistry, and materials. Many research studies have been focused on the preparation of surfaces with static structure. Achieving dynamical manipulation of surface structure is desired but still a great challenge. Herein, a polyelectrolyte film capable of regional and reversible changes in the microporous structure is presented. Our proposal is based on the combination of azobenzene (Azo) π−π stacking and electrostatic interaction, which could be affected respectively by ultraviolet (UV) irradiation and water plasticization, to tune the mobility of polyelectrolyte chains. The porous patterns can be obtained after regional ultraviolet irradiation and acid treatment. Owing to the reversibility of Azo π−π stacking and electrostatic interaction, the patterns can be repeatedly created and erased in the polyelectrolyte film made by layer-by-layer (LbL) self-assembly of poly(ethyleneimine)-azo and poly(acrylic acid). Furthermore, through two rounds of porous pattern formation and erasure, different functional species can be loaded separately and confined regionally within the film, showing potential applications in the functional surface. This work highlights the coordination of two noncovalent interactions in thin films for regional and reversible controlling its structure, opening a window for more in-depth development of functional surfaces.