Mesoporous Mn-doped hydroxyapatite nanorods obtained via pyridinium chloride enabled microwave-assisted synthesis by utilizing Donax variabilis seashells for implant applications.

Manganese-doped mesoporous hydroxyapatite (MnHAp) nanorods, a bio-apatite were synthesized via pyridinium chloride mediated microwave approach using bio-waste Donax variabilis seashells to treat orthopedic infections. This is the first report on using pyridinium chloride mediated mesoporous MnHAp nanorods synthesis. Pure and Mn doped HAp samples were examined using Raman spectroscopy, X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) studies to confirm the prepared HAp nanorods. Furthermore, the fabrication of manganese-doped HAp was successful with the formation of a hexagonal crystal lattice without disturbing the HAp phase. It is because, at the time of synthesis, PO43- ions form an electrostatic interaction with the Mn ions. Furthermore, Mn-doped HAp samples showed a reduction in their sizes of 15, 10-15, 5-10 nm width, and 80-100, 10-15, 20-30 nm length with varied pore diameters and surface area. The pure HAp, MnHAp-1, MnHAp-2, and MnHAp-3 nanorods disclose the surface area of 39.4, 18.0, 49.2, and 80.4 m2 g-1, with a pore volume of 0.0102, 0.0047, 0.0143, and 0.0447 cm3 g-1, the corresponding pore diameter was estimated to be 6, 7, 6, and 4 nm, respectively. Moreover, antibacterial activity reveals effective bactericidal action against infections causing pathogens whereas cytotoxicity examination (MTT assay), and zebrafish results reveal their non-toxic behavior. Therefore, it is evident from the study, that rapid fabrication of mesoporous and diverse structured MnHAp nanorods could be convenient with pyridinium chloride enabled microwave-assisted method as a bactericidal biomaterial for implant applications.

Nanocomposite-Coated Silk-Based Artificial Conduits: The Influence of Structures on Regeneration of the Peripheral Nerve.

In this study, silk filaments are coated with different concentrations (5, 7.5, and 10% w/w) of carbon nanofibers (CNFs) dispersed in poly-ε-caprolactone. The nanocomposite-coated silk filaments are subjected to knitting, braiding, and twisting. The tubular structures are covered with a silk fibroin/polyvinyl film for the nerve conduit application. Physical characterization of the developed nerve conduits demonstrates suitable mechanical properties comparable to native nerve tissue. Cell proliferation is confirmed through in vitro cell culture studies using Neuro 2a and rat primary cortical neural progenitor cells, which show that the proliferation happens along the interconnected macrochannels of the internal structure of the nerve conduit. The knitted structure presents better biological properties than the nerve conduits with other internal structures. The in vivo sciatic nerve implantation is performed in a rabbit model using the best conduit, i.e., 10% CNF-based nanocomposite-coated silk with a knitted inner structure without any biomolecules or tube filling gels. Regeneration of a 2 cm gap excised sciatic nerve is investigated by immunohistochemistry and histology of implanted nerve conduits removed after 30 days. Results suggest that the CNF-based conducting nanocomposite coating in this well-defined architecture of the conduit helps in signal transmission and neural growth during the regeneration of the transected nerve.

Ascorbic Acid-Assisted Microwave Synthesis of Mesoporous Ag-Doped Hydroxyapatite Nanorods from Biowaste Seashells for Implant Applications.

Post-surgery implant infection is one of the most challenging issues in orthopedics and it is mainly caused by infective micro-organisms. A potential approach to overcome this issue is developing biomaterials with efficient antibacterial activity. The main intention of this present research is devoted to ascorbic acid-assisted microwave synthesis of mesoporous (silver) Ag-doped hydroxyapatite (HAp) nanorods using biowaste seashells with antibacterial properties. XRD, FTIR, and Raman spectroscopy results revealed that the synthesized nanoparticles are hexagonal crystalline HAp. Further, the silver-doped HAp was also successfully produced without affecting the HAp crystalline phase by forming electrostatic interaction with PO43- ions during the synthesis. The morphological features confirm that the pure HAp is elongated mesoporous nanorods with 20 nm width and 300-500 nm length. However, silver doped HAp nanoparticles such as AgHA-1, AgHA-2, and AgHA-3 are found to be similar mesoporous rods but with different aspect ratios in sizes of 15, 10-15, and 5-10 nm width and 80-100, 10-15, and 20-30 nm length. The BET specific surface areas were obtained as 29 ± 3, 84 ± 2, 87 ± 2, and 128 ± 3 m2 g-1, and pore diameters were 4.68, 4.18, 9.30, and 3.77 nm, respectively, for pure HA, AgHA-1, AgHA-2, and AgHA-3. Therefore, HAp nanoparticles with different dimensions and mesoporous structures could be rapidly prepared using a microwave-assisted method and ascorbic acid as a supporting material. In addition, the synthesized HAp nanoparticles are analyzed for its antibacterial and cytotoxicity studies. The antibacterial and cytotoxicity study clearly reveals that the Ag-doped HAp nanorods are efficiently antibacterial and nontoxic in nature. Hence, it is clear that the ascorbic acid-enabled microwave-assisted method will be one of the best methods for the rapid production of HAp nanoparticles with different dimensions and mesoporous structures for its application as an implant material.

Carbon nanofiber amalgamated 3D poly-ε-caprolactone scaffold functionalized porous-nanoarchitectures for human meniscal tissue engineering: In vitro and in vivo biocompatibility studies.

We developed customizable biomolecule functionalized 3D poly-ε-caprolactone (PCL) scaffolds reinforced with carbon nanofibers (CNF) for human meniscal tissue engineering. 3D nanocomposite scaffolds exhibited commendable mechanical integrity and electrical properties with augmented cytocompatibility. Especially, the functionalized 3D (10wt% CNF) scaffolds showed ~363% increase in compressive moduli compared to the pristine PCL. In dynamic mechanical analysis, these scaffolds achieved highest value (~42 MPa at 10 Hz) among all tested scaffolds including pristine PCL and human menisci (33, 41, 56 years). In vitro results were well supported by the outcomes of cell proliferation analysis, microscopic images, Hoechst staining and extracellular-matrix estimation. Further, in vivo rabbit bio toxicity studies revealed scaffold's non-toxicity and its future potential as a meniscus scaffold. This study also indicates that the incorporation of CNF in polymer matrix may be optimized based on mechanical properties of patient meniscus and it may help in developing the customized patient specific 3D constructs with improved multifunctional properties.

Tissue engineering of human knee meniscus using functionalized and reinforced silk-polyvinyl alcohol composite three-dimensional scaffolds: Understanding the in vitro and in vivo behavior.

Tissue engineered constructs with rapid restoration of mechanical and biological properties remain a challenge, emphasizing the need to develop novel scaffolds. Here, we present a multicomponent composite three-dimensional scaffold structure with biomimetic reinforcement and biomolecule functionalization for meniscus tissue engineering. The scaffold structure was developed using 3:1 silk fibroin (SF) and polyvinyl alcohol (PVA). Autoclaved eggshell membrane (AESM) powder (1-3%w/v) was used as reinforcement to enhance biomechanical properties. Further to improve cell attachment and proliferation, these scaffolds were functionalized using an optimized unique combination of biomolecules. Comprehensive analysis of scaffolds was carried out on morphological, structural, mechanical and biological functionalities. Their mechanical properties were compared with different native human menisci. The results indicated that, functionalized SF-PVA with 3%AESM has shown similar order of magnitude of compressive and dynamic mechanical properties as in human meniscus. Moreover, 3% AESM based scaffolds were found to support better primary human meniscal cellular proliferation and extracellular matrix secretion. Immunohistochemical analysis revealed angiogenesis and biocompatibility with minimal inflammatory response for subcutaneously implanted scaffolds in New Zealand white rabbits. The developed reinforced and functionalized SF-PVA scaffolds can uniquely combine the potential for load-bearing properties with improved in vitro and in vivo support for meniscus tissue regeneration. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1722-1731, 2018.