Enhancing the stability of albumin foam-based support baths using pectin for embedded bioprinting

Abstract

Tissue engineering and regenerative medicine aim to restore or replace damaged tissues and organs and has key applications in developing advanced therapeutic solutions, physiologically relevant disease models, and engineered tissues that could one day help address the global organ shortage. Achieving these goals requires advanced biofabrication techniques capable of producing complex, cell-laden architectures with high precision and biological relevance—an area where embedded bioprinting has shown great promise. Embedded bioprinting enables the creation of complex, cell-laden structures by extruding bioinks into a support bath that physically supports the printed constructs. This strategy has expanded the range of printable bioinks and has allowed for the fabrication of intricate geometries; however, current support bath materials have several limitations including, insufficient oxygen and nutrient delivery and strenuous support bath removal steps. To combat such limitations, albumin-based foams have recently been proposed as a class of self-removable, oxygen- and nutrient-permeable support bath materials. The main drawback of using foams as a support is that their rapid degradation limits their use for longer, more complex prints. In this thesis, the stabilization of albumin foams through the incorporation of pectin, a biocompatible polysaccharide is reported. Three formulations—albumin-only (A8), albumin with 1% pectin (A8P1), and albumin with 2% pectin (A8P2)—were evaluated with respect to foam stability, bubble size and distribution, rheological properties, physicochemical properties, printability and biocompatibility. The addition of pectin significantly delayed liquid drainage and bubble coalescence while preserving key rheological characteristics such as shear-thinning and rapid recovery of properties after subjected to deformation. These enhancements supported the embedded printing of chitosan, a low-viscosity and slow-crosslinking hydrogel, into multilayered and freeform constructs with high fidelity. Cell viability assays further confirmed that pectin did not impair biocompatibility; notably, A8P1 provided the most favorable microenvironment and outperformed conventional gelatin-based FRESH baths during extended incubation, owing to enhanced oxygen diffusion and a more physiological pH. Collectively, these findings establish pectin-stabilized albumin foams as a simple, biocompatible, and self-removable support system that addresses key limitations of embedded bioprinting and broadens the range of printable bioinks. By enabling the reliable fabrication of complex, cell-laden constructs, this work contributes to the advancement of tissue engineering and regenerative medicine, supporting future applications in disease modeling, drug testing, and ultimately the development of engineered tissues and organs to combat the organ shortage crisis.

Date	2 Dec 2025
Original language	American English
Awarding Institution	École de technologie supérieure
Supervisor	Ali Ahmadi (Supervisor)