Evaluation of graphene-derived bone scaffold exposure to the calvarial bone_in-vitro and in-vivo studies

Graphene: A Multifaceted Carbon-Based Material for Bone Tissue Engineering Applications

Tissue engineering is an emerging technological field that aims to restore and replace human tissues. A significant number of individuals require bone replacement annually as a result of skeletal abnormalities or accidents. In recent decades, notable progress has been made in the field of biomedical research, specifically in the realm of sophisticated and biocompatible materials. The purpose of these biomaterials is to facilitate bone tissue regeneration. Carbon nanomaterial-based scaffolds are particularly notable due to their accessibility, mechanical durability, and biofunctionality. The scaffolds exhibit the capacity to enhance cellular proliferation, mitigate cell damage, induce bone tissue growth, and maintain biological compatibility. Therefore, they play a crucial role in the development of the bone matrix and the necessary cellular interactions required for bone tissue restoration. The attachment, growth, and specialization of osteogenic stem cells on biomaterial scaffolds play critical roles in bone tissue engineering. The optimal biomaterial should facilitate the development of bone tissue in a manner that closely resembles that of human bone. This comprehensive review encompasses the examination of graphene oxide (GO), carbon nanotubes (CNTs), fullerenes, carbon dots (CDs), nanodiamonds, and their respective derivatives. The biomaterial frameworks possess the ability to replicate the intricate characteristics of the bone microenvironment, thereby rendering them suitable for utilization in tissue engineering endeavors.

Biomechanical characteristics of self-expanding sinus stents during crimping and deployment_A comparison between different biomaterials

Self-expanding sinus stents are often used in functional endoscopic sinus surgery to treat inflamed sinuses. The PROPEL self-expanding sinus stent offers mechanical support to the sinus cavity to prevent restenosis. The stent is made of a bioabsorbable material (PLGA) that disappears after wound healing. However, complications such as foreign body sensation and severe stent migration/expulsion have been reported after implantation. Little is known about the contact characteristics of self-expanding sinus stents from when the stent is crimped into the insertion device through to deployment into the sinus cavity. This current study developed a test platform to analyze the biomechanical behavior of the stent during this process. Three common bioabsorbable materials, PLGA, PCL and Mg alloy, were evaluated to understand how the choice of material affects the biomechanical characteristics of self-expanding sinus stents. The results showed that the material can have a considerable influence on the contact characteristics during crimping and deployment. When crimped, the PLGA and Mg alloy stents showed much higher plastic strain and contact stress than the PCL stent. When deployed, the PCL stent had the largest contact area (4.3 mm²) and the lowest contact pressure (0.1 MPa) on the inner surface of the sinus canal. The results indicate that PCL could be a suitable choice for self-expanding sinus stents. This current study provides a method for observing the biomechanical characteristics of sinus stents during stent crimping and deployment.

Effect of nonaffine displacement on the mechanical performance of degraded PCL and its graphene composites: an atomistic investigation

Evaluating the mechanical properties of biodegradable implants can be challenging for in situ experiments and time-consuming for materials with a slow degradation rate, such as polycaprolactone (PCL). In this work, the effects of chain scission and water erosion on the mechanical properties of degraded PCL are investigated by molecular dynamics simulation. The decrease of the mechanical performance is correlated with the increase of the nonaffine displacement during the degradation. The nonaffine squared displacements (NSD) during the tensile deformation are calculated by subtracting the affine squared displacements from the mean squared displacements. After chain scission, short polymer chains increase the NSD of the system and weaken the modulus of the polymer matrix. The effect of the NSD is also observed in a water erosion model. When the bond break ratio is less than 5%, PCL still maintains a well-entangled network, which constrains the diffusion of the water molecules, resulting in a higher modulus of the erosion model than the chain scission model at a low degradation rate. The effect of NSD is also found in the PCL/graphene composites. For the degraded polymer chains, the diffusion of PCL is constrained by the graphene network, and such an effect increases during the degradation. As a result, the addition of graphene nanosheets slows down the decreasing trend of Young's modulus. Such findings can also explain the size effect of the graphene reinforcement on the mechanical properties of the polymer composites. This work provides atomistic insights into the mechanical property evolution during polymer degradation, revealing the possibility of tuning the mechanical performance by controlling the diffusion, which could be beneficial for the design and lifetime prediction of degradable implants.

Translating Material Science into Bone Regenerative Medicine Applications: State-of-The Art Methods and Protocols

In the last 20 years, bone regenerative research has experienced exponential growth thanks to the discovery of new nanomaterials and improved manufacturing technologies that have emerged in the biomedical field. This revolution demands standardization of methods employed for biomaterials characterization in order to achieve comparable, interoperable, and reproducible results. The exploited methods for characterization span from biophysics and biochemical techniques, including microscopy and spectroscopy, functional assays for biological properties, and molecular profiling. This review aims to provide scholars with a rapid handbook collecting multidisciplinary methods for bone substitute R&D and validation, getting sources from an up-to-date and comprehensive examination of the scientific landscape.