In Vitro and in Vivo Studies of Novel Poly(d,l-lactic acid), Superhydrophilic Carbon Nanotubes, and Nanohydroxyapatite Scaffolds for Bone Regeneration

Abstract

Poly(D,L-lactide acid, PDLLA) has been researched for scaffolds in bone regeneration. However, its hydrophobocity and smooth surface impedes its interaction with biological fluid and cell adhesion. To alter the surface characteristics, different surface modification techniques have been developed to facilitate biological application. The present study compared two different routes to produce PDLLA/superhydrophilic vertically aligned carbon nanotubes:nanohydroxyapatite (PDLLA/VACNT-O:nHAp) scaffolds. For this, we used electrodeposition and immersion in simulated body fluid (SBF). Characterization by goniometry, scanning electron microscopy, X-ray diffraction, and infrared spectroscopy confirmed the polymer modifications, the in vitro bioactivity, and biomineralization. Differential scanning calorimetry and thermal gravimetric analyses showed that the inclusion of VACNT-O:nHA probably acts as a nucleating agent increasing the crystallization rate in the neat PDLLA without structural alteration. Our results showed the formation of a dense nHAp layer on all scaffolds after 14 days of immersion in SBF solution; the most intense carbonated nHAp peaks observed in the PDLLA/VACNT-O:nHAp samples suggest higher calcium precipitation compared to the PDLLA control. Both cell viability and alkaline phosphatase assays showed favorable results, because no cytotoxic effects were present and all produced scaffolds were able to induce detectable mineralization. Bone defects were used to evaluate the bone regeneration; the confocal Raman and histological results confirmed high potential for bone applications. In vivo study showed that the PDLLA/VACNT-O:nHAp scaffolds mimicked the immature bone and induced bone remodeling. These findings indicate surface improvement and the applicability of this new nanobiomaterial for bone regenerative medicine.

Innovative biodegradable poly(L-lactide)/collagen/<br />hydroxyapatite composite fibrous scaffolds promote osteoblastic proliferation and differentiation

“…Ceramics such as bioglass are used for bone regeneration due to their bioactivity and osteoconductive properties. 11,12 These materials are excellent as an implant to repair bone defect for their similar physical and chemical properties compared with bone mineral components, but they have some problems in terms of fracture and fragile. The polymer materials have good physical properties of toughness.…”

Nanoengineered implant as a new platform for regenerative nanomedicine using 3D well-organized human cell spheroids

“…Many groups develop 3D synthetic polymeric biocompatible and biodegradable materials allowing osteoinduction. [42][43][44] This 3D environment is favorable to proliferation, cell differentiation, and mineralization, when equipped with a large amount of single cells. The classical tissue-engineering strategy using single dispersed cells on a biocompatible biomaterial has been predominant over the last 20 years.…”

Graphene oxide/multi-walled carbon nanotubes as nanofeatured scaffolds for the assisted deposition of nanohydroxyapatite: characterization and biological evaluation

“…4 Due to its microstructure, biocompatibility, and osteoconductivity, nanosized HAp (nanohydroxyapatite, nHAp) has been widely investigated for applications in bone tissue regeneration. 4,[7][8][9] Nevertheless, the low tensile strength and fracture toughness of nHAp limit its application in large bone defects. In this context, the literature has introduced many different approaches to combine nHAp and different forms of carbon in order to enhance the mechanical properties of nHAp without impairing its bioactivity.…”

“…In this context, the literature has introduced many different approaches to combine nHAp and different forms of carbon in order to enhance the mechanical properties of nHAp without impairing its bioactivity. [9][10][11] Over the last few years, multi-walled carbon nanotubes (MWCNTs) and graphene oxide (GO) have attracted much attention due to their excellent mechanical and physicalchemical properties (low mass, high surface area, and high electrical and thermal conductivity). [12][13][14][15][16] Combining MWCNTs and GO with HAp in its many forms (such as nano) represents an alternative to improve the chemical, physical, and biological characteristics of polymeric nanocomposites, as well as to generate materials that can mimic bone tissues.…”

“…Although carbon nanotube (CNT) reinforcement in HAp matrices has been demonstrated, 20,22,23 as well as low cytotoxicity of these composites, 9,20 a full report on their physical-chemical properties, biological properties, and their dependence on the MWCNT-GO content is still missing. Recently, our group developed a novel routine to produce large-scale nHAp/MWCNT-GO nanocomposites using a wet-chemical method assisted by ultrasound irradiation.…”