Breast cancer is the most frequent cancer among women. New therapeutic approaches need to be introduced to develop an effective cancer therapy, which could inhibit, or reverse cancer spread to distant locations. The most prevalent cancer treatment method is resection, during which the tumor with the adjacent tissue (margin) is removed. In such case, patient-tailored hydrogel matrices could be implanted into the resection area, preventing remaining cancer cells from spreading and increasing the tissue's regenerative potential. In this work, pectin from citrus peels, selectively reducing the proliferation of breast cancer cells  was introduced into the gelatin methacrylol (GelMA) network in order to obtain base matrix for breast soft tissue dressing.
GelMA hydrogels at concentrations of 5 and 10% (w/v), without or with the addition of 1 and 2% (w/v) pectin from citrus peel were used. For this purpose, GelMA was synthesized, solutions were prepared, and the crosslinking time of the samples was optimized (60 and 90s) using ultraviolet light and calcium ions (for specimens with pectin addition). The samples were subjected to stability testing in the cell culture medium for up to 21 days to determine which material, when used as a dressing/scaffold, would withstand the period of tissue replacement and regeneration. At the same time, DMA testing was performed to determine the mechanical properties of hydrogels and the effect of an additional polymer network- pectin on the material's stiffness. Then, the cross-sectional morphology of the samples with the highest stiffness and stability was analyzed using a scanning electron microscope. The hydrogel solutions were then examined for rheological properties to determine the viscosity of the materials at room temperature. Based on this, three materials crosslinked for the 90s were selected: 5% GelMA; 5% GelMA with 2% pectin; and 10% GelMA and were optimized for 3D printing purposes.
The specimens prepared from 5 and 10% GelMA and crosslinked for the 90s showed the highest stability. Additionally, it was noted that the longer crosslinking time of the samples allows for a more stable structure that can survive up to 21 days in the cell medium environment, exhibits greater stiffness after fabrication and 24h incubation in fluids. The scaffolds made of 5% GelMA with 2% Pectin and 10% GelMA were found to have the best printout quality with respect to the set parameters.
GelMA-pectin hydrogels were successfully developed in this work. The addition of 2% pectin from citrus peel into GelMA 5% led to stability improvement of the constructs. These materials can be successfully applied for soft tissue dressings, which can be implanted to the operated area after tumor resection.
Further studies on evaluation of the pectin cytotoxicity, and the influence of pectin presence on proliferation and expression of specific genes of cancer cells (studies using tumor cells in 3D cultures) are ongoing.
 – F. Salehi, H. Behboudi „Oxidative DNA damage induced by ROS-modulating agents with the ability to target DNA: A comparison of the biological characteristics of citrus pectin and apple pectin