Selective Laser Sintering (SLS) is a very promising technique for fabricating scaffolds for bone tissue engineering (BTE) applications. Compared to conventional manufacturing techniques, SLS allows the fabrication of porous interconnected scaffolds with complex geometrical features that can match the host tissue. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a biodegradable high molecular weight polymer suitable for bone regeneration and reconstruction. The investigation of the hydrolytic degradation of sintered PHBV sca olds is essential to understand the hydrolysis mechanism and the in vivo behavior for clinical applications. Sca olds were fabricated using three di erent laser energy densities (LEDs) and their e ect on the microstructure was studied. After 20 weeks of incubation in phosphate-bu ered saline (PBS) solution, the mechanical integrity of the sca olds was not a ected despite a reduction of elastic modulus and a signi cant decrease in molecular weight up to 54:1% that suggests a bulk erosion mechanism of degradation. Mass loss ranged from 2:54 to 4:17% after 20 weeks in PBS solution. The e ect of hydrolysis on the degree of crystallinity ( c) was also analyzed; a small increase in crystallinity showed that the amorphous phase was more subjected to the erosion mechanism. Surface degradation was taken into consideration by quantifying carboxyl (COOH) end group before and after incubation using X-ray photo-electron spectroscopy (XPS). Overall, the sca olds showed a great potential for medical applications as the mechanical properties remained satisfying after a long degradation time.
La tecnologia di Sinterizzazione Laser Selettiva (SLS) e una tecnica di fabbricazione di protesi ortopediche molto promettente. Rispetto alla tecniche tradizionali, la SLS permette di realizzare strutture porose e interconnesse con forme geometriche altamente complesse e che si possono adattare al sito di intervento. Il PHBV e un polimero biodegradabile ad alto peso molecolare adatto ad applicazioni ortopediche di ricostruzione ossea. Lo studio della degradazione idrolitica di queste strutture sinterizzate in PHBV e essenziale per comprendere il processo di idrolisi e prevedere il comportamento in vivo. Tre valori diversi di LED sono stati utilizzati per la produzione ed e stato analizzato il loro e etto sulla microstruttura nale. Dopo 20 settimane di incubazione in una soluzione di tampone fosfato salino (PBS) l'integrit a meccanica e strutturale dei campioni non e stata alterata, nonostante una riduzione del modulo elastico e una diminuzione del peso molecolare no al 54:1% che suggerisce che la degradazione comprenda l'intero volume. Nello stesso intervallo di tempo la riduzione di massa ha toccato valori dal 2:54 al 4:17%. L'e etto del processo di idrolisi sulla cristallinit a e stato a sua volta studiato; un incremento di cristallinit a lascia pensare che lo stato amorfo sia pi u vulnerabile all'idrolisi. L'erosione super - ciale e stata analizzata quanti cando la presenza di gruppi carbossilici (COOH) sulla super cie grazie alla spettroscopia fotoelettronica a raggi X. In conclusione i risultati ottenuti confermano il potenziale di queste protesi in ambito medico e chirurgico.
In vitro degradation of selective laser sintered PHBV scaffolds for bone tissue engineering applications
MONTICONE, DAVIDE
2018/2019
Abstract
Selective Laser Sintering (SLS) is a very promising technique for fabricating scaffolds for bone tissue engineering (BTE) applications. Compared to conventional manufacturing techniques, SLS allows the fabrication of porous interconnected scaffolds with complex geometrical features that can match the host tissue. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a biodegradable high molecular weight polymer suitable for bone regeneration and reconstruction. The investigation of the hydrolytic degradation of sintered PHBV sca olds is essential to understand the hydrolysis mechanism and the in vivo behavior for clinical applications. Sca olds were fabricated using three di erent laser energy densities (LEDs) and their e ect on the microstructure was studied. After 20 weeks of incubation in phosphate-bu ered saline (PBS) solution, the mechanical integrity of the sca olds was not a ected despite a reduction of elastic modulus and a signi cant decrease in molecular weight up to 54:1% that suggests a bulk erosion mechanism of degradation. Mass loss ranged from 2:54 to 4:17% after 20 weeks in PBS solution. The e ect of hydrolysis on the degree of crystallinity ( c) was also analyzed; a small increase in crystallinity showed that the amorphous phase was more subjected to the erosion mechanism. Surface degradation was taken into consideration by quantifying carboxyl (COOH) end group before and after incubation using X-ray photo-electron spectroscopy (XPS). Overall, the sca olds showed a great potential for medical applications as the mechanical properties remained satisfying after a long degradation time.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/149747