3D Printing Silk-Based Bioresorbable Piezoelectric Self-Adhesive Holey Structures for In Vivo Monitoring on Soft Tissues

Abstract

Flexible and biocompatible adhesives with sensing capabilities can be integrated onto human body and organ surfaces, characterized by complex geometries, thus having the potential to sense their physiological stimuli offering monitoring and diagnosis of a wide spectrum of diseases. The challenges in this innovative field are the following: (i) the coupling method between the smart adhesive and the soft human substrates, (ii) the bioresorbable behavior of the material, and (iii) the electrical exchange with the substrate. Here, we introduce a multifunctional composite by mixing silk fibroin, featuring piezoelectric properties, with a soluble plant-derived polyphenol (i.e., chestnut tannin) modified with graphene nanoplatelets. This material behaves as a glue on different substrates and gives rise to high elongation at break, conformability, and adhesive performances to gastrointestinal tissues in a rat model and favors the printability via extrusion-based 3D printing. Exploiting these properties, we designed a bioresorbable 3D printed flexible and self-adhesive piezoelectric device that senses the motility once applied onto a phantom intestine and the hand gesture by signal translation. Experimental results also include the biocompatibility study using gastrointestinal cells. These findings could have applicability in animal model studies, and, thanks to the bioresorbable behavior of the materials, such an adhesive device could be used for monitoring the motility of the gastrointestinal tract and for the diagnosis of motility disorders.

Peptide-Functionalized Silk Fibers as a Platform to Stabilize Gelatin for Use in Ingestible Devices

“…As-prepared RS film showed a strong amide I absorption band between 1652 cm −1 and 1647 cm −1 (random coils) and an amide II absorption band at 1541 cm −1 [ 32 , 33 ]. These peaks indicate a higher reduction in the crystalline secondary structure due to CaCl 2 [ 34 ]. The new peaks at 2974 cm −1 and 2881 cm −1 in the spectrum of MO-07/RS ( Figure 2 b) belonged to the methylene C–H asymmetric/symmetric stretches of the MO-07 peptide.…”

“…Our previous study [ 34 ] reports a water-based method to produce RS composite gels. Briefly, the high content of Ca 2+ ions dispersed in RS film allows the re-dispersion in water to obtain a gel.…”

“…As-prepared RS film showed a strong a absorption band between 1652 cm −1 and 1647cm −1 (random coils) and an amide sorption band at 1541 cm −1 [32,33]. These peaks indicate a higher reduction in th talline secondary structure due to CaCl2 [34]. The new peaks at 2974 cm −1 and 2881 We proceeded with FTIR analysis to verify if the peptide was physisorbed or covalently linked to the silk fibres (Figure 2b).…”

“…This new arrangement facilitates the sliding of the molecules so that the strength reduces while the elongation increases. Our previous study [34] reports a water-based method to produce RS composite gels. Briefly, the high content of Ca 2+ ions dispersed in RS film allows the re-dispersion in water to obtain a gel.…”

“…These findings suggest gelatin's mechanical properties can be tuned by adding peptide-modified RS. Our previous study [34] reports a water-based method to produce RS composite gels. Briefly, the high content of Ca 2+ ions dispersed in RS film allows the re-dispersion in water to obtain a gel.…”