Glucose microenvironment sensitive degradation of arginine modified calcium sulfate reinforced poly(lactide-co-glycolide) composite scaffolds

Poly(lactide-co-glycolide) (PLGA) and calcium sulfate composites are promising biodegradable biomaterials but are still challenging to use in people with high levels of blood glucose or diabetes. To date, the influence of glucose on their degradation has not yet been elucidated and thus calls for more research attention. Herein, a novel calcium sulfate whisker with L-arginine was used to effectively tune its crystal morphology and was employed as a reinforced phase to construct the PLGA-based composite scaffolds (ArgCSH/PLGA) with a sleeve porous structure. ArgCSH/PLGA showed excellent elastic modulus and strength in the compression and bending models. Moreover, an in vitro immersion test showed that ArgCSH/PLGA possessed degradation and redeposition behaviors sensitive to glucose concentration, and the adsorbed Arg played a crucial role in the degradation process. The subsequent cell functional evaluation showed that ArgCSH could effectively protect cells from damage caused by AGEs and promote osteogenic differentiation. The corresponding degradation products of ArgCSH/PLGA displayed the ability to regulate osteoblast bone differentiation and accelerate matrix mineralization. These findings provide new insights into the interaction between biomaterials and the physiological environment, which may be useful in expanding the targeted choice of efficient bone graft biodegradable materials for diabetic osteoporosis.

Conductive Polyaniline Particles Regulating In Vitro Hydrolytic Degradation and Erosion of Hydroxyapatite/Poly(lactide-co-glycolide) Porous Scaffolds for Bone Tissue Engineering

In addition to biocompatibility and bioactivity, scaffolds with superior bone tissue regenerative capacity should possess excellent functionality (e.g., electroactivity and conductivity) and biodegradability matching with the rate of bone reconstruction. However, current conductive scaffolds display a reduced biodegradability rate and weakened biocompatibility. In this study, injectable conductive porous scaffolds were fabricated, incorporating camphor sulfonic acid-doped polyaniline (PANI) into hydroxyapatite/poly(lactide-co-glycolide) (HA/PLGA) scaffolds, using solvent-casting/particulate-leaching methodology. These scaffolds demonstrated excellent electroactivity, conductivity, hydrophilicity, thermodynamic properties, antibacterial properties, and biocompatibility. Their degradation behavior was explored by regulating the PANI content. The results demonstrated that adding an appropriate content of PANI would increase the pore size, porosity, and water absorption of the conductive scaffold and promote the formation of filamentous fiber byproducts with acidic hydrolysates, which accelerated the degradation rate of the scaffold. Owing to π-π stacking and hydrogen bonding, the conductive scaffold with 10 wt % PANI efficiently retarded the decrease in the thermal and mechanical properties of the scaffolds during a 16 week degradation. Thus, better regulation of degradation behavior and correlation would allow conductive porous scaffolds, such as bone implants, to achieve better bone ingrowth and restoration.

Balanced Mechanical and Biotribological Properties of Polymer Composites Reinforced by a 3D Interlocked Si3N4 Nanowire Membrane

Polymer composites have great potential applications in the hip joint replacement, where the combinations of high mechanical strength and excellent biotribological properties are required. In this work, a well-dispersed three-dimensional (3D) silicon nitride nanowire membrane (SNm) designed as a reinforcement and brushite (Bs) served as bioactive filler are constructed into the polymer matrix, forming SNm-reinforced Bs/polymer composites (SNm-Bs/Pm). Especially, SNm could form a 3D interlocked structure, where the ultralong silicon nitride nanowires are entangled with each other. SNm could effectively facilitate the penetration of the polymer matrix and improve the cohesion strength of the polymer, thereby promoting mechanical and biotribological properties for SNm-Bs/Pm. The performances for polymer composites are optimized by increasing the layer number of preform. By comparing SNm-Bs/Pm with one-layer preform, the tensile strength of SNm-Bs/Pm with six-layer preforms reaches 83.3 MPa with an increase of 767.7%. In addition, the friction coefficient and wear rate of SNm-Bs/Pm with six-layer preforms in fetal bovine serum medium achieve 0.06 and 0.21 × 10^-14 m³(N·m)^-1 and decrease by 82.4 and 72.4%, respectively. The present work provides a promising methodology of preparing interlocked SNm-reinforced polymer composites with enhanced mechanical and biotribological properties that are potential for hip joint replacement applications.