Nanostructured zirconium titanate fibers prepared by particulate sol–gel and cellulose templating techniques

Polymeric scaffolds for dental pulp tissue engineering: A review

OBJECTIVES

The purpose of this review is to describe recent developments in pulp tissue engineering using scaffolds and/or stem cells. It is crucial to understand how this approach can revitalize damaged dentin-pulp tissue. Widespread scaffold materials, both natural and synthetic, and their fabrication methods, and stem-progenitor cells with the potential of pulp regeneration will be discussed.

DATA AND SOURCES

A review of literature was conducted through online databases, including MEDLINE by using the PubMed search engine, Scopus, and the Cochrane Library.

STUDY SELECTION

Studies were selected based on relevance, with a preference given to recent research, particularly from the past decade.

CONCLUSIONS

The use of biomaterial scaffolds and stem cells can be safe and potent for the regeneration of pulp tissue and re-establishment of tooth vitality. Natural and synthetic polymers have distinct advantages and limitations and in vitro and in vivo testing have produced positive results for cell attachment, proliferation, and angiogenesis. The type of biomaterial used for scaffold fabrication also facilitates stem cell differentiation into odontoblasts and the resulting biochemistry of tissue repair for each polymer and cell type was discussed. Multiple methods of scaffold design exist for pulp tissue engineering, which demonstrates the variability in tissue engineering applications in endodontics. This review explains the potential of evidence-based tissue engineering strategies and outcomes in pulp regeneration.

The Transformative and Versatile Role of Cellulose Nanomaterials in Templating and Shaping Multiscale Mesostructured Ceramics

The transformative and versatile role of cellulose nanomaterials (CNMs) as an enabling technology in the preparation of multiscale mesostructured ceramics, with pore sizes in the meso- (2-50 nm) and macroporosity (above 50 nm) range with controlled porous architecture across the structure is explored. CNMs have revolutionized functional advanced materials concepts and technology by using natural resources to derive superb properties. Its unique chemical and physical properties have inspired its exploitation as a reinforcement agent, stimuli responsive tool, and templating agent mostly for biologic and polymeric materials, as well as for metals and ceramics. CNMs can act as a sacrificial filler templating agent, a surface modifier agent, and as an aid for shaping macrostructures into bulk samples. A deep knowledge of the synergistic interaction mechanisms between CNMs and ceramic particles to assemble them in solution and into solid structures is key to advance this technology, and to develop a predictive understanding of synthesis and processing mechanisms that relates morphology evolution, processing, and final physical properties. The potential ease of processing and versatility of CNMs for functional ceramic technology, intimately linked to the CNMs' nature and properties, will make a significant impact with respect to the current state of the art.

Evaluation of the in vitro biodegradation and biological behavior of poly(lactic-co-glycolic acid)/nano-fluorhydroxyapatite composite microsphere-sintered scaffold for bone tissue engineering

The objective of this research was to study the degradation and biological characteristics of the three-dimensional porous composite scaffold made of poly(lactic- co-glycolic acid)/nano-fluorhydroxyapatite microsphere using sintering method for potential bone tissue engineering. Our previous experimental results demonstrated that poly(lactic- co-glycolic acid)/nano-fluorhydroxyapatite composite scaffold with a ratio of 4:1 sintered at 90ºC for 2 h has the greatest mechanical properties and a proper pore structure for bone repair applications. The weight loss percentage of both poly(lactic- co-glycolic acid)/nano-fluorhydroxyapatite and poly(lactic- co-glycolic acid) scaffolds demonstrated a monotonic trend with increasing degradation time, that is, the incorporation of nano-fluorhydroxyapatite into polymeric scaffold could lead to weight loss in comparison with that of pure poly(lactic- co-glycolic acid). The pH change for composite scaffolds showed that there was a slight decrease until 2 weeks after immersion in simulated body fluid, followed by a significant increase in the pH of simulated body fluid without a scaffold at the end of immersion time. The mechanical properties of composite scaffold were higher than that of poly(lactic- co-glycolic acid) scaffold at total time of incubation in simulated body fluid; however, it should be noted that the incorporation of nano-fluorhydroxyapatite into composite scaffold leads to decline in the relatively significant mechanical strength and modulus during hydrolytic degradation. In addition, MTT assay and alkaline phosphatase activity results defined that a general trend of increasing cell viability was seen for poly(lactic- co-glycolic acid)/nano-fluorhydroxyapatite scaffold sintered by time when compared to control group. Eventually, experimental results exhibited poly(lactic- co-glycolic acid)/nano-fluorhydroxyapatite microsphere-sintered scaffold is a promising scaffold for bone repair.

In vivo study of microarc oxidation coated biodegradable magnesium plate to heal bone fracture defect of 3mm width

Microarc oxidation (MAO) coated magnesium (Mg) with improved corrosion resistance appeal increasing interests as a revolutionary biodegradable metal for fractured bone fixing implants application. However, the in vivo corrosion degradation of the implants and bone healing response are not well understood, which is highly required in clinic. In the present work, 10μm and 20μm thick biocompatible MAO coatings mainly composed of MgO, Mg₂SiO₄, CaSiO₃ and Mg₃(PO₄)₂ phases were fabricated on AZ31 magnesium alloy. The electrochemical tests indicated an improved corrosion resistance of magnesium by the MAO coatings. The 10μm and 20μm coated and uncoated magnesium plates were separately implanted into the radius bone fracture site of adult New Zealand white rabbits using a 3mm width bone fracture defect model to investigate the magnesium implants degradation and uninhibited bone healing. Taking advantage of the good biocompatibility of the MAO coatings, no adverse effects were detected through the blood test and histological examination. The implantation groups of coated and uncoated magnesium plates were both observed the promoting effect of bone fracture healing compared with the simple fracture group without implant. The releasing Mg²⁺ by the degradation of implants into the fracture site improved the bone fracture healing, which is attributed to the magnesium promoting CGRP-mediated osteogenic differentiation. Mg degradation and bone fracture healing promoting must be tailored by microarc oxidation coating with different thickness for potential clinic application.

An overview on cellulose-based material in tailoring bio-hybrid nanostructured photocatalysts for water treatment and renewable energy applications

A combination between the nanostructured photocatalyst and cellulose-based materials promotes a new functionality of cellulose towards the development of new bio-hybrid materials for various applications especially in water treatment and renewable energy. The excellent compatibility and association between nanostructured photocatalyst and cellulose-based materials was induced by bio-combability and high hydrophilicity of the cellulose components. The electron rich hydroxyl group of celluloses helps to promote superior interaction with photocatalyst. The formation of bio-hybrid nanostructured are attaining huge interest nowadays due to the synergistic properties of individual cellulose-based material and photocatalyst nanoparticles. Therefore, in this review we introduce some cellulose-based material and discusses its compatibility with nanostructured photocatalyst in terms of physical and chemical properties. In addition, we gather information and evidence on the fabrication techniques of cellulose-based hybrid nanostructured photocatalyst and its recent application in the field of water treatment and renewable energy.

Recent advancements in regenerative dentistry: A review

Although human mouth benefits from remarkable mechanical properties, it is very susceptible to traumatic damages, exposure to microbial attacks, and congenital maladies. Since the human dentition plays a crucial role in mastication, phonation and esthetics, finding promising and more efficient strategies to reestablish its functionality in the event of disruption has been important. Dating back to antiquity, conventional dentistry has been offering evacuation, restoration, and replacement of the diseased dental tissue. However, due to the limited ability and short lifespan of traditional restorative solutions, scientists have taken advantage of current advancements in medicine to create better solutions for the oral health field and have coined it "regenerative dentistry." This new field takes advantage of the recent innovations in stem cell research, cellular and molecular biology, tissue engineering, and materials science etc. In this review, the recently known resources and approaches used for regeneration of dental and oral tissues were evaluated using the databases of Scopus and Web of Science. Scientists have used a wide range of biomaterials and scaffolds (artificial and natural), genes (with viral and non-viral vectors), stem cells (isolated from deciduous teeth, dental pulp, periodontal ligament, adipose tissue, salivary glands, and dental follicle) and growth factors (used for stimulating cell differentiation) in order to apply tissue engineering approaches to dentistry. Although they have been successful in preclinical and clinical partial regeneration of dental tissues, whole-tooth engineering still seems to be far-fetched, unless certain shortcomings are addressed.

Influence of the component interaction over Cu/ZrO2 catalysts induced with fractionated precipitation method on the catalytic performance for methanol steam reforming

A series of binary Cu/ZrO₂ catalysts by choosing different composition ratios and different precipitation sequences have been prepared for the production of hydrogen by steam reforming of methanol (SRM).

In vivo biocompatibility of Mg implants surface modified by nanostructured merwinite/PEO

Magnesium (Mg) alloys have been suggested as biodegradable bone implant materials due to their good intrinsic biocompatibility and great mechanical properties. Although magnesium has attractive properties as an orthopedic implant material, its quick degradation and low bioactivity may lead to the loss of mechanical integrity of the implant during the bone healing process. In this paper, we endeavor to surmount the abovementioned defects using the surface coating technique. We have recently coated AZ91 magnesium implants with merwinite (Ca3MgSi2O8) through the coupling of plasma electrolytic oxidation (PEO) and electrophoretic deposition method. In this work, we are specifically focused on the in vivo examinations of the coated implants in comparison with the uncoated one. For the in vivo experiment, the rod samples, including the uncoated and merwinite/PEO coated implants, were imbedded into the greater trochanter of rabbits. The results of the in vivo animal test indicated an improvement in biodegradability including slower implant weight loss, reduction in Mg ion released from the coated implants in the blood plasma, lesser release of hydrogen bubbles and an improvement in biocompatibility including an increase in the amount of bone formation and ultimately a mild bone inflammation after the surgery according to the histological images. In summary, proper surface treatment of magnesium implants such as silicate bioactive ceramics may improve their biocompatibility under physiological conditions to making them suitable and applicable for future clinical applications.

Hollow microtubes made of carbon, boron and gold: novel semiconducting nanocomposite material for applications in electrochemistry and temperature sensing

Novel semiconducting material is synthesized and applied for construction of NTC thermistor and functionalization of working electrodes. It has a form of carbon microtubes coated with a shell of inorganic nanocomposite.

In vivo study of nanostructured akermanite/PEO coating on biodegradable magnesium alloy for biomedical applications

The major issue for biodegradable magnesium alloys is the fast degradation and release of hydrogen gas. In this article, we aim to overcome these disadvantages by using a surface modified magnesium implant. We have recently coated AZ91 magnesium implants by akermanite (Ca2 MgSi2 O7 ) through the combined electrophoretic deposition (EPD) and plasma electrolytic oxidation (PEO) methods. In this work, we performed the in vitro and in vivo examinations of these coated implants using L-929 cell line and rabbit animal model. The in vitro study confirmed the higher cytocompatibility of the coated implants compare to the uncoated ones. For the in vivo experiment, the rod samples were implanted into the greater trochanter of rabbits and monitored for two months. The results indicated a noticeable biocompatibility improvement of the coated implants which includes slower implant weight loss, reduction in Mg ion released from the coated samples in the blood plasma, lower release of hydrogen bubbles, increase in the amount of bone formation and ultimately lower bone inflammation after the surgery according to the histological images. Our data exemplifies that the proper surface treatment of the magnesium implants can improve their biocompatibility under physiological conditions to make them applicable in clinical uses. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 1798-1808, 2015.

Surface microstructure and in vitro analysis of nanostructured akermanite (Ca2MgSi2O7) coating on biodegradable magnesium alloy for biomedical applications

Magnesium (Mg) alloys, owing to their biodegradability and good mechanical properties, have potential applications as biodegradable orthopedic implants. However, several poor properties including low corrosion resistance, mechanical stability and cytocompatibility have prevented their clinical application, as these properties may result in the sudden failure of the implants during the bone healing. In this research, nanostructured akermanite (Ca2MgSi2O7) powder was coated on the AZ91 Mg alloy through electrophoretic deposition (EPD) assisted micro arc oxidation (MAO) method to modify the properties of the alloy. The surface microstructure of coating, corrosion resistance, mechanical stability and cytocompatibility of the samples were characterized with different techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electrochemical corrosion test, immersion test, compression test and cell culture test. The results showed that the nanostructured akermanite coating can improve the corrosion resistance, mechanical stability and cytocompatibility of the biodegradable Mg alloy making it a promising material to be used as biodegradable bone implants for orthopedic applications.