Papers by Author: Norberto Roveri

Abstract: The study of nanocrystalline calcium phosphate physical-chemical characteristics and, thereafter, the possibility to imitate bone mineral for the development of new advanced biomaterials is constantly growing. The availability to use synthetic biomimetic hydroxylapatites (HA), since they are the most important inorganic constituents of hard tissues in vertebrates, represents a great turning point in bone tissue engineering because of their chemical similarity to the biological mineral component. The ability to control the architecture and strength of a bone tissue engineering scaffold is critical to achieve a harmony between the scaffold and the host tissue. The scaffold attempts to mimic the function of the natural extracellular matrix, providing a temporary template for the growth of target tissues. Scaffolds should have suitable architecture and strength to serve their intended function. Rapid prototyping (RP) technique is applied to tissue engineering to satisfy this need and to create a scaffold with fully interconnected pore structure directly from the scanned and digitized image of the defect site. In this study, we developed a biomimetic mineralized collagen/Polycaprolactone composite by self-assembling process of collagen fibers and nucleation of a nanostructured HA mimicking the natural bone. This new solution provides a hybrid material, based on natural components of bone (collagen and HA) and the support of the widely-tested PCL (polycaprolactone) giving the scaffolds ideal characteristics such as resorption, biocompatibility and 3-D printability. CAD design of the microstructure and bioprinting fulfills the need to finely control the scaffold’s shape to best fit the anatomical defect, the possibility of customization and the ability to perfectly control spatial distribution of pores and their morphology. The results allowed the conclusion that these scaffolds are biocompatible and allow the colonization and proliferation of MSC (mesenchymal stem cell). The in vivo results confirm the scaffold’s biocompatibility and its composition and structure create the basis for bone tissue regeneration.

Abstract: The ability to control the architecture and strength of a bone tissue engineering scaffold is critical to achieve a harmony between the scaffold and the host tissue. The scaffold attempts to mimic the function of the natural extracellular matrix, providing a temporary template for the growth of target tissues. The study of nanocrystalline calcium phosphate physical-chemical characteristics and, thereafter, the possibility to imitate bone mineral for the development of new advanced biomaterials is constantly growing. Scaffolds should have suitable architecture and strength to serve their intended function. Rapid prototyping (RP) technique is applied to tissue engineering to satisfy this need and to create a scaffold directly from the scanned and digitized image of the defect site. Design and construction of complex structures with different shapes and sizes, at micro and macro scale, with fully interconnected pore structure and appropriate mechanical properties are possible by using RP techniques. In this study we present a new biocompatible hybrid scaffold obtained through two different experimental methods and formed by synthetic biomimetic Hydroxyapatite (HA) nanocrystals with high surface reactivity which synergistically interacts with Poly(e-caprolactone) (PCL) and polylactic acid (PLLA). The aim of this pilot study is to test the adhesion and the proliferation of human mesenchymal stem cells (MSC) on both the scaffolds. MSC growth and distribution was evaluated 24 h and 7 days after in-vitro seeding. The results allowed the conclusion that these scaffolds are biocompatible and allow the colonization and proliferation of MSC, therefore, due to their mechanical properties, they are adequate for bone tissue engineering.

Abstract: Nature is full of many interesting things to work with, but many natural resources are also protected. In this view the recycling of aquaculture and fishery residues may lead to the manufacture of new devices and the isolation of new molecules with potential application in medicine. The aim of the present study was to explore the possibility to transform the cuttlefish bone into an hydroxyapatite scaffold suitable for bone tissue engineering application. The mixture of different lamellar porous structure of cuttlefish bone from the species Sepia Officinalis was selected and characterized, according to morphology (including porosity, surface development, surface characteristics) and mechanical properties. The material was transformed into suitable scaffold for bone tissue regeneration, trying to totally or partially convert calcium carbonate (aragonite) into calcium phosphate (hydroxyapatite HA) using hydrothermal transformation. The studies on cell attachment and proliferation (by MTT assay at different experimental times), cell morphology with Scanning Electron Microscopy (SEM), alkaline phosphatase (ALP) and osteocalcin (OC) activities and expressions by mouse osteoblast-like MC3T3-E1 cells on HA were investigated at different experimental times in cultures, in comparison with those observed on titanium specimens used as a control (ET and ST). Cell proliferation was less in HA transformed cuttlefish bone scaffolds than in ET and ST specimens. In contrast, good performance for osteoblasts differentiation was observed on HA transformed cuttlefish bone scaffolds, similar to those observed onto titanium scaffolds.

Abstract: New biomimetic carbonate-hydroxyapatite nanocrystals (CHA) have been designed and synthesized in order to obtain a remineralization of the altered enamel surfaces. Synthesized CHA mimic for composition, structure, nano dimension and morphology bone apatite crystals and their chemical-physical properties resemble closely those exhibited by enamel natural apatite. CHA can chemically bound themselves on the surface of natural enamel apatite thanks to their tailored biomimetic characteristics. The remineralization effect induced by CHA represents a real new deposition of carbonate-hydroxyapatite into the eroded enamel surface scratches forming a persistent biomimetic mineral coating, which covers and safeguards the enamel structure. The experimental results point out the possibility to use materials alternative to fluoride compounds which is commonly utilized to contrast the mechanical abrasions and acid attacks. The apatitic synthetic coating is less crystalline than enamel natural apatite, but consists of a new biomimetic apatitic mineral deposition which progressively fills the surface scratches. Therefore the application of biomimetic CHA may be considered an innovative approach to contrast the acid and bacteria attacks.

Abstract: The use of specific remineralizing agents in toothpastes may help to prevent caries and treat dentinal sensitivity. In this study, applied nanotechnologies were used to develop a filler for toothpastes with remineralizing properties. Carbonate hydroxyapatite nanocrystals, with size, morphology, chemical composition and crystallinity comparable with that of dentine, were synthesized in mild condition. The remineralizing effect was studied with a scanning electron microscopy putting materials onto the slices of dentine previously demineralized with ortophosphoric acid. The application of the materials showed the progressive closure of the tubular openings of the dentine with plugs within 10 minutes and a regeneration of a surface mineral layer within 6 hours. This rates of remineralization seems to be compatible with the development of toothpastes with remineralizing effect.