Development of a Novel Janus Biogel Bolus for Radiotherapy

Bolus is crucial for treating superficial lesions in radiotherapy. However, mechanical adhesion and biological mismatches of Bolus materials often impact the outcome of radiotherapy. This study introduces asymmetrical Janus biogel Bolus with one adhesive side and another with minimal adhesion. The biogel was fabricated employing a synergistic combination of distinct materials through physical and chemical interactions. The upper layer mainly comprises acrylamide and trehalose, abbreviated as PT, while the lower layer consists of acrylamide, trehalose, protocatechuic acid, nanoclay, and resveratrol, abbreviated as PTPNR. Mechanical, biological, and radiological tests were conducted to evaluate the Janus patch as a functional and biocompatible Bolus. The PTPNR layer demonstrated skin adhesion (repetitive adhesion force of 8 kPa), antibacterial (> 95%) and anti-inflammatory properties. The PT layer was a water retention and mechanical barrier (compression modulus ≈550 kPa). This Janus biogel design integrates principles from biomedical and engineering fields, making it suitable for use as a Bolus material in treating superficial tumors.