3D bioprinting of adhesive, anti-bacterial alginate/polyacrylamide-based customized boluses using digital light processing for radiotherapy applications

Boluses are a type of materials used to enhance skin dose during the treatment of superficial lesions. However, the current commercially available boluses cannot fully conform to irregular skin surfaces due to their uniform thickness, thereby compromising the efficacy of radiotherapy. Three-dimensional (3D) bioprinting boasts a huge potential in the creation of customized boluses, but the use of this technique is limited by shortcomings of the prevailing materials, such as their indirect printability and substance rigidity. As a potential substitute, hydrogels possessing a tensile modulus comparable to that of skin tissue are optimal candidates for customizing boluses. In this study, we developed a photocurable bioink for multifunctional boluses using digital light processing (DLP). Alginate, acrylamide, polyethylene glycol diacrylate, lithium phenyl-2,4,6-trimethylbenzoylphosphinate, and protocatechuic acid were synergistically combined to fabricate the bioink. The bolus printed using this bioink was endowed with enhanced toughness, superior adhesion, tissue equivalence, anti-dehydration and anti-bacterial properties, as well as excellent biocompatibility and radiation performance. In conclusion, the DLP-based 3D bioprinting of the proposed bioink can provide an avenue for obtaining personalized boluses in radiotherapy treatment of superficial tumors.