Recent advancements in 4D bioprinting have expanded opportunities in tissue engineering, allowing for the fabrication of dynamic scaffolds that adapt their shape in response to external stimuli. Among the various approaches, humidity-responsive hydrogels offer significant potential for creating complex adaptive structures by leveraging differential swelling upon immersion in culture medium. However, current strategies in the literature predominantly rely on initially planar constructs, generating unidirectional crosslinking gradients or 2D crosslinking patterns, while 3D printing is typically limited to producing simple starting geometries. This work aims to overcome these limitations by developing a fully 3D-bioprinted hydrogel with spatially controlled crosslinking patterns using vat photopolymerization. By tuning light exposure at different regions within the structure, more complex and programmable shape transformations can be achieved. A GelMA-based bioink with tartrazine photoabsorber, was optimized to precisely localize photopolymerization, minimizing unintended further crosslinking and preventing unwanted solidification. The mechanical and swelling properties of the printed hydrogels were systematically evaluated by varying exposure times, demonstrating how differential crosslinking can be exploited to program shape-morphing behavior. By selectively adjusting exposure conditions, well-defined zones with distinct swelling responses were created within the same structure, leading to controlled deformations. Furthermore, cytotoxicity tests confirmed the suitability of the developed hydrogels for biomedical applications. These findings contribute to advancing 4D bioprinting by providing a scalable and versatile strategy for generating biomimetic, shape-morphing scaffolds, paving the way for future applications in tissue engineering and regenerative medicine.
I recenti progressi nel 4D bioprinting hanno aperto nuove prospettive nell’ingegneria tissutale, consentendo la realizzazione di scaffold dinamici capaci di modificare la propria forma in risposta a stimoli esterni. Tra le diverse strategie esplorate, gli idrogel sensibili all’umidità offrono un elevato potenziale per la creazione di strutture complesse e adattive, sfruttando il rigonfiamento differenziale in mezzo di cultura. Tuttavia, gli approcci attuali si basano prevalentemente su geometrie planari iniziali, con gradienti di reticolazione unidirezionali o schemi bidimensionali, mentre la stampa 3D è generalmente limitata a forme di base semplici. Questo studio propone un approccio innovativo per superare tali limitazioni attraverso la stampa tridimensionale di idrogel con schemi di reticolazione spazialmente controllati, sfruttando tecnologie di fotopolimerizzazione LCD. Modulando l’esposizione alla luce in diverse regioni della struttura, è possibile ottenere trasformazioni morfologiche più complesse e programmabili. A tale scopo, è stato formulato un bioinchiostro a base di GelMA, ottimizzato con tartrazina come fotoassorbente, per controllare con precisione la fotopolimerizzazione ed evitare reticolazioni non controllate e solidificazioni indesiderate. Le proprietà meccaniche e di rigonfiamento degli idrogel stampati, analizzate variando i tempi di esposizione alla luce, dimostrano come la reticolazione differenziale possa programmare il comportamento morfogenetico del materiale. Regolando selettivamente le condizioni di esposizione, sono state ottenute zone con risposte di rigonfiamento distinte all'interno della stessa struttura, generando deformazioni controllate. Inoltre, i test di citotossicità hanno confermato l’idoneità per applicazioni biomediche. I risultati ottenuti contribuiscono all’avanzamento del 4D bioprinting, proponendo una strategia scalabile e versatile per la realizzazione di scaffold biomimetici a trasformazione morfologica, con applicazioni promettenti nell’ingegneria tissutale e nella medicina rigenerativa.
LCD-based 4D bioprinting of GelMA hydrogels: shape-morphing structures for tissue engineering
Ciotti, Elisa
2023/2024
Abstract
Recent advancements in 4D bioprinting have expanded opportunities in tissue engineering, allowing for the fabrication of dynamic scaffolds that adapt their shape in response to external stimuli. Among the various approaches, humidity-responsive hydrogels offer significant potential for creating complex adaptive structures by leveraging differential swelling upon immersion in culture medium. However, current strategies in the literature predominantly rely on initially planar constructs, generating unidirectional crosslinking gradients or 2D crosslinking patterns, while 3D printing is typically limited to producing simple starting geometries. This work aims to overcome these limitations by developing a fully 3D-bioprinted hydrogel with spatially controlled crosslinking patterns using vat photopolymerization. By tuning light exposure at different regions within the structure, more complex and programmable shape transformations can be achieved. A GelMA-based bioink with tartrazine photoabsorber, was optimized to precisely localize photopolymerization, minimizing unintended further crosslinking and preventing unwanted solidification. The mechanical and swelling properties of the printed hydrogels were systematically evaluated by varying exposure times, demonstrating how differential crosslinking can be exploited to program shape-morphing behavior. By selectively adjusting exposure conditions, well-defined zones with distinct swelling responses were created within the same structure, leading to controlled deformations. Furthermore, cytotoxicity tests confirmed the suitability of the developed hydrogels for biomedical applications. These findings contribute to advancing 4D bioprinting by providing a scalable and versatile strategy for generating biomimetic, shape-morphing scaffolds, paving the way for future applications in tissue engineering and regenerative medicine.File | Dimensione | Formato | |
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2025_04_Ciotti_Thesis_01.pdf
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2025_04_Ciotti_Executive Summary_02.pdf
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https://hdl.handle.net/10589/236398