Optically active, paper-based scaffolds for 3D cardiac tissue engineering

In this work, we report the design and fabrication of a light-addressable, paper-based, nanocomposite scaffold for optical modulation and read-out of in vitro grown cardiac tissue. The scaffold consists of paper cellulose microfibers functionalized with gold nanorods (GNRs) and semiconductor quantum dots (QDs), embedded into a cell-permissive collagen matrix. The GNRs enable cardiomyocyte activity modulation through local temperature gradients induced by near-infrared (NIR) laser illumination, with the local temperature changes reported by the temperature-dependent QD photoluminescence (PL). The micrometer size paper fibers promote the tubular organization of HL-1 cardiac muscle cells, while the NIR plasmonic stimulation modulates reversibly their activity. Given its high spatial resolution, NIR modulation offers an excellent alternative to electrode-based methods for cell activity modulation and is more compatible with 3D tissue constructs. As such, optical platforms based on nanocomposite scaffolds will have a significant impact on the progress of drug screening, toxicity studies, and heart disease modeling. ### Competing Interest Statement The authors have declared no competing interest.