Multiwall Carbon Nanotube Composites as Artificial Joint Materials

Carbon materials and their metal composites for biomedical applications: A short review

Carbon materials and their hybrid metal composites have garnered significant attention in biomedical applications due to their exceptional biocompatibility. This biocompatibility arises from their inherent chemical stability and low toxicity within biological systems. This review offers a comprehensive overview of carbon nanomaterials and their metal composites, emphasizing their biocompatibility-focused applications, including drug delivery, bioimaging, biosensing, and tissue engineering. The paper outlines advancements in surface modifications, coatings, and functionalization techniques designed to enhance the biocompatibility of carbon materials, ensuring minimal adverse effects in biological systems. A comprehensive investigation into hybrid composites integrating carbon nanomaterials is conducted, categorizing them as fullerenes, carbon quantum dots, carbon nanotubes, carbon nanofibers, graphene, and diamond-like carbon. The concluding section addresses regulatory considerations and challenges associated with integrating carbon materials into medical devices. This review culminates by providing insights into current achievements, challenges, and future directions, underscoring the pivotal role of carbon nanomaterials and their metal composites in advancing biocompatible applications.

Osteogenesis, hemocompatibility, and foreign body response of polyvinylidene difluoride-based composite reinforced with carbonaceous filler and higher volume of piezoelectric ceramic phase

Hybrid polymer-ceramic composites have been widely investigated for bone tissue engineering applications. The incorporation of a large amount of inorganic phase, like barium titanate (BaTiO₃) with good dispersion, in a polymeric matrix using a conventional processing approach has always been challenging. Also, the comprehensive study encompassing the interactions of key components of living organisms (cell, blood, tissue) with such hybrid composites is not well explored in many published studies. Built on our earlier studies and recognizing the importance of poly(vinylidene fluoride) (PVDF) as a widely used polymer for a wide spectrum of biomedical applications, the present study reports the qualitative and quantitative analysis of the biocompatibility of PVDF composite (PVDF/30BT/3MWCNT) reinforced with large amounts of BaTiO₃ (30 wt %) and tailored addition of multiwalled carbon nanotubes (MWCNT; 3 wt %). The melt mixing-extrusion-compression moulding-based processing approach resulted in an enhancement of β-phase content, thermal stability, and wettability in the semi-crystalline PVDF composite. The enhanced hemocompatibility of PVDF/30BT/3MWCNT has been established conclusively by a series of in vitro blood-material interaction assays, including haemolysi, analysis of platelets attachment and activation, dynamic blood coagulation, and plasma recalcification time. The cytocompatibility study confirms an improved adhesion, proliferation, and migration of osteoprogenitor cells (preosteoblasts; MC3T3-E1) on PVDF/30BT/3MWCNT, in a manner better than neat PVDF, in vitro. When these cells were cultured in osteogenic differentiating media, the modulated osteogenesis, in terms of alkaline phosphatase activity, intracellular Ca²⁺ concentration, and calcium deposition on the PVDF/30BT/3MWCNT, was recorded. Following subcutaneous implantation of PVDF/30BT/3MWCNT in rat model, no apparent variation was recorded in the complete hemogram (blood hematology analysis) or serum biochemistry, post 30-, 60-, and 90-days surgery. Importantly, 90-days post-implantation, the fibrous capsule thickness was significantly reduced in the composites w.r.t PVDF alone, together with better blood vessel formation, indicating improved neovascularization around the composite. This study establishes the efficacy of inorganic fillers in enhancing the biocompatibility of PVDF, which could open up a wide range of biomedical applications.

Nanomaterials-Incorporated Chemically Modified Gelatin Methacryloyl-Based Biomedical Composites: A Novel Approach for Bone Tissue Engineering

Gelatin methacryloyl (GelMA)-based composites are evolving three-dimensional (3D) networking hydrophilic protein composite scaffolds with high water content. These protein composites have been devoted to biomedical applications due to their unique abilities, such as flexibility, soft structure, versatility, stimuli-responsiveness, biocompatibility, biodegradability, and others. They resemble the native extracellular matrix (ECM) thanks to their remarkable cell-adhesion and matrix-metalloproteinase (MMP)-responsive amino acid motifs. These favorable properties promote cells to proliferate and inflate within GelMA-protein scaffolds. The performance of GelMA composites has been enriched using cell-amenable components, including peptides and proteins with a high affinity to harmonize cellular activities and tissue morphologies. Due to their inimitable merits, GelMA systems have been used in various fields such as drug delivery, biosensor, the food industry, biomedical, and other health sectors. The current knowledge and the role of GelMA scaffolds in bone tissue engineering are limited. The rational design and development of novel nanomaterials-incorporated GelMA-based composites with unique physicochemical and biological advantages would be used to regulate cellular functionality and bone regeneration. Substantial challenges remain. This review focuses on recent progress in mitigating those disputes. The study opens with a brief introduction to bone tissue engineering and GelMA-based composites, followed by their potential applications in bone tissue engineering. The future perspectives and current challenges of GelMA composites are demonstrated. This review would guide the researchers to design and fabricate more efficient multifunctional GelMA-based composites with improved characteristics for their practical applications in bone tissue engineering and biomedical segments.

Future Prospects for Clinical Applications of Nanocarbons Focusing on Carbon Nanotubes

Over the past 15 years, numerous studies have been conducted on the use of nanocarbons as biomaterials towards such applications as drug delivery systems, cancer therapy, and regenerative medicine. However, the clinical use of nanocarbons remains elusive, primarily due to short- and long-term safety concerns. It is essential that the biosafety of each therapeutic modality be demonstrated in logical and well-conducted experiments. Accordingly, the fundamental techniques for assessing nanocarbon biomaterial safety have become more advanced. Optimal controls are being established, nanocarbon dispersal techniques are being refined, the array of biokinetic evaluation methods has increased, and carcinogenicity examinations under strict conditions have been developed. The medical implementation of nanocarbons as a biomaterial is in sight. With a particular focus on carbon nanotubes, these perspectives aim to summarize the contributions to date on nanocarbon applications and biosafety, introduce the recent achievements in evaluation techniques, and clarify the future prospects and systematic introduction of carbon nanomaterials for clinical use through practical yet sophisticated assessment methods.

Current Methods in the Study of Nanomaterials for Bone Regeneration

Nanomaterials show great promise as bone regeneration materials. They can be used as fillers to strengthen bone regeneration scaffolds, or employed in their natural form as carriers for drug delivery systems. A variety of experiments have been conducted to evaluate the osteogenic potential of bone regeneration materials. In vivo, such materials are commonly tested in animal bone defect models to assess their bone regeneration potential. From an ethical standpoint, however, animal experiments should be minimized. A standardized in vitro strategy for this purpose is desirable, but at present, the results of studies conducted under a wide variety of conditions have all been evaluated equally. This review will first briefly introduce several bone regeneration reports on nanomaterials and the nanosize-derived caveats of evaluations in such studies. Then, experimental techniques (in vivo and in vitro), types of cells, culture media, fetal bovine serum, and additives will be described, with specific examples of the risks of various culture conditions leading to erroneous conclusions in biomaterial analysis. We hope that this review will create a better understanding of the evaluation of biomaterials, including nanomaterials for bone regeneration, and lead to the development of versatile assessment methods that can be widely used in biomaterial development.

Applications of Carbon Nanotubes in the Internet of Things Era

The post-Moore's era has boosted the progress in carbon nanotube-based transistors. Indeed, the 5G communication and cloud computing stimulate the research in applications of carbon nanotubes in electronic devices. In this perspective, we deliver the readers with the latest trends in carbon nanotube research, including high-frequency transistors, biomedical sensors and actuators, brain-machine interfaces, and flexible logic devices and energy storages. Future opportunities are given for calling on scientists and engineers into the emerging topics.

Preparation, characterization, and feasibility study of Sr/Zn-doped CPP/GNS/UHMWPE composites as an artificial joint component with enhanced hardness, impact strength, tribological and biological performance

In order to solve the problem of aseptic loosening of artificial joints resulting from the wear particles of artificial joint components in total joint replacement (TJR), we synthesized a new kind of metalo-organic particle (Sr/Zn-doped CPP/GNS) using spark plasma sintering (SPS) as a filler to enhance the comprehensive performance of UHMWPE. Sr/Zn-doped CPP/GNS was interfused evenly with UHMWPE particles and cured in a hot press instrument to prepare Sr/Zn-doped CPP/GNS/UHMWPE composites. FTIR and SEM were carried out to characterize Sr/Zn-doped CPP/GNS particles. EDS was carried out to characterize Sr/Zn-doped CPP/GNS/UHMWPE. The micro-structure, hardness, impact strength, tribology and bio-activities of Sr/Zn-doped CPP/GNS/UHMWPE composite materials were also investigated. The results confirmed the effectiveness of this method. The hardness, impact strength, and tribology of the composites were enhanced by adding homodispersed Sr/Zn-doped CPP/GNS particles into UHMWPE. In the meantime, Sr/Zn-doped CPP/GNS/UHMWPE composites could significantly promote the growth of osteoblasts due to the bio-activity of Sr/Zn-doped CPP/GNS. Furthermore, the addition of Sr/Zn-doped CPP/GNS particle-fillers into UHMWPE could promote the secretion of OPG from osteoblasts and inhibit the secretion of RANKL from osteoblasts, and thus increase the OPG/RANKL ratio. All the results above showed that Sr/Zn-doped CPP/GNS/UHMWPE composites with appropriate Sr/Zn-doped CPP/GNS content possessed superior physicochemical performances and bio-properties, and could be considered as promising materials to treat aseptic loosening in total joint replacement.