Chemistry, ultrastructure and porosity of monophasic and biphasic bone forming materials derived from marine algae

Abstract

The research on bioceramics during the last decades has proved that the bioactivity of inorganic bone grafts depends fundamentally on an optimal combination of chemistry and structural porosity. This study presents a comparison of a resorbable monophasic hydroxyapatite (HA) and several newly developed resorbable biphasic hydroxyapatite -ß-tricalcium phosphate (HA/TCP) composites both derived from naturally grown red marine algae with respect to the phase composition, microstructure and porosity. The highly porous three dimensional mineral scaffold of the native alga is maintained in the final products all investigated materials and possesses a pronounced interconnecting microporous structure. There are generally high values of specific porosity calculated for all tested materials: 1.07 cm 3 /g for pure phycogenic HA and between 0.65 cm 3 /g and 1.04 cm 3 /g for phycogenic biphasic HA/TCP composites with various HA/TCP ratios. The ultrastructure of the phycogenic HA/TCP composites changes significantly with the building and the increase of the ß-TCP phase due to the bigger polyedric ß-TCP crystals compared to the finer polycrystalline HA. Despite these structural changes the interconnected porous scaffold is kept throughout the production process. In all investigated materials the porosity is mainly based on pores with pore sizes between 1 and 10 lm in diameter, which is given by the structure of the natural alga. The specific chemistry combined with the structural porosity is decisive for the high in-vivo bioactivity of the studied materials.Keywords: bone forming material, calcium phosphates, porosity, microstructure, chemistry Die Forschung an biokeramischen Materialien während der letzten Jahrzehnte hat ergeben, dass die Bioaktivität anorganischer Knochenersatzmaterialien grundsätzlich auf einer optimalen Kombination chemischer Parameter und Porosität basiert. Die vorliegende Studie präsentiert einen Vergleich zwischen einem monophasischen resorbierbaren Hydroxylapatit (HA) und mehreren neu entwickelten resorbierbaren biphasischen Hydroxylapatit -ß-Trikalziumphosphat (HA/TCP) Materialien, die aus natürlich gewachsenen Rotalgen gewonnen wurden, bezüglich Phasenzusammensetzung, Mikrostruktur und Porosität. Das dreidimensionale mineralische Stützgewebe der natürlichen Alge besitzt eine ausgeprägt interkonnektierende Mikroporosität und wird bis zu den Endprodukten aller untersuchten Materialien beibehalten. Die durchgeführten Analysen zeigen generell hohe Werte im Hinblick auf die spezifische Porosität: reiner phykogener HA 1.07 cm 3 /g sowie die phycogenen biphasischen HA/TCP Materialien mit unterschiedlichen HA/ TCP Verhältnissen zwischen 0.65 cm 3 /g und 1.04 cm 3 /g. Die Ultrastruktur der phykogenen biphasischen HA/TCP Materialien ändert sich signifikant mit der Bildung und der Konzentrationssteigerung der ß-TCP Phase auf Grund der größeren polyedrischen ß-TCP Kristalle im Vergleich zu dem feinen polykristallinen HA. Trotz dieser strukturellen Ä nderungen bleibt die interkonnektierend poröse Stützstruktur währ...

Promoting catalysis and high-value product streams by in situ hydroxyapatite crystallization during hydrothermal liquefaction of microalgae cultivated with reclaimed nutrients

“…18,[21][22][23] Certain marine algae (Corallina officinalis and Amphiroa ephedrathe) have be used as a calcium source for HAp crystallization, but only after prior removal of organics and using an external phosphorus source. 24,25 We have used RN-algae to crystallize HAp in situ, and act as both the calcium and phosphorus source without pre-treatment.…”

Porous Biphasic Calcium Phosphate Scaffolds from Cuttlefish Bone

“…The synthesis of bone analogs, which are based on natural structures that can mimic natural bone, offers an exciting range of avenues 34 . There have been numerous reports on preparation of porous HA ceramics by using natural materials of biologic origin, e.g., HA derived from coral, 9,10 from bovin bone, 12 marine algae, 35 or mollusc shells 36,37 . In strong contrast, the synthesis of porous BCP ceramics from natural biological materials, which promise tailored bioresorption, has been relatively unexplored.…”

“…In strong contrast, the synthesis of porous BCP ceramics from natural biological materials, which promise tailored bioresorption, has been relatively unexplored. Spassova et al 35 used red marine algae to produce HA/β‐TCP composites of different HA/β‐TCP ratios by an adapted hydrothermal process. By varying the Mg addition and the parameters of the hydrothermal process, the concentration ratio of HA and β‐TCP was controlled to obtain biphasic composites with a β‐TCP content of up to 95 wt%.…”

A Novel Technique for Orthodontic Gap Closure with Access through the Maxillary Sinus

“…β-TCP, on the other hand, exhibits much greater biodegradability. To combine the positive aspects of the two calcium phosphates, biphasic materials with different ratios of HA and β-TCP have been developed [21][22][23].…”