Introduction
Despite great progress made in developing orthopedic implants, the development of titanium (Ti) implants with ideal early osseointegration remains a big challenge. Our pilot study has demonstrated that Si-TiO
2
nanotubes on the surface of Ti substrates could enhance their osteogenic activity. Hence, in this study, we aim to comprehensively evaluate the effects of silicon-doped titania (Si-TiO
2
) nanotubes on the osseointegration property of Ti implants.
Materials and Methods
The Ti implants were surface modified with Si-TiO
2
nanotubes through in situ anodization and Si plasma immersion ion implantation (PIII) method. Three groups were divided as Ti implants (Ti), Ti modified with TiO
2
nanotubes (TiO
2
-NTs) and Ti modified with Si-TiO
2
nanotubes (Si-TiO
2
-NTs). The morphology of Si-TiO
2
nanotubes was observed by scanning electron microscope. The growth and osteogenic differentiation of MC3T3-E1 cells on the Ti implants were evaluated. Further, the pull-out tests and in vivo osseointegration ability evaluation were performed after implanting the screws in the femur of Sprague Dawley rats.
Results
The Si-TiO
2
nanotubes could be seen on the surface of Ti implants. The MC3T3-E1 cells could grow on the surface of Ti, TiO
2
-NTs and Si-TiO
2
-NTs, and showed fast proliferation rate on the Si-TiO
2
-NTs. Moreover, the production of some osteogenesis-related proteins (ALP and Runx2) at one week and calcium deposition at four week was also enhanced in Si-TiO
2
-NTs rather than other groups. In vivo osseointegration results showed that Si-TiO
2
nanotube-modified Ti screws had higher pullout force at two and four weeks as well as enhanced new bone formation at six weeks compared to bare Ti screws and Ti screws modified with TiO
2
nanotubes alone.
Discussion
The modification of Si-TiO
2
-NTs on the Ti substrate could generate a nanostructured and hydrophilic surface, which can promote cell growth. Moreover, the existence of the TiO
2
nanotubes and Si element also can improve the in vitro osteogenic differentiation of MC3T3-E1 cells and early bone formation around the implanted screws. Together, findings from this study show that surface modification of Ti implants with Si-TiO
2
nanotubes could enhance early osseointegration and therefore has the potential for clinical applications.
Crude palm oil and crude palm olein were hydrolyzed with lipase from Candida rugosa to produce a free fatty acid (FFA) rich oil. The percentages of FFA produced and carotene degradation after the hydrolysis process were determined. The palm oil and hydrolyzed palm oil were subsequently subjected to column chromatography. Diaion HP‐20 adsorbent was used for reverse phase column chromatography at 50C. Isopropanol or ethanol, and n‐hexane were used as the first and second eluting solvents, respectively. The objective of hydrolyzing the palm oil was to produce more polar FFA‐rich oil in order to enhance the nonpolar carotene bind to the nonpolar HP‐20 adsorbent in the column chromatography process. Hydrolyzing palm oil with lipase from Candida rugosa gave 30‐ and 60‐fold, respectively, of FFA in the crude palm oil and crude palm olein in 24 h at 50C. Approximately, 15.56 and 17.48% of carotene degraded in crude palm oil and crude palm olein, respectively. For column chromatography, using isopropanol or ethanol as the first eluting solvent, unhydrolyzed oil and hydrolyzed oil showed the carotene recovery infraction two (carotene‐rich fraction) of about 36–37 and 90–96%, respectively. Over 90% of carotene recovery was obtained from
The effects of enzymatic hydrolysis on crude palm olein (CPOlein) by lipase from Candida rugosa were investigated. Reaction variables, namely water content, reaction temperature and enzyme concentration on hydrolysis of CPOlein were examined. Comparison was also made between CPOlein and hydrolyzed crude palm olein (HCPOlein) for melting point, percentage of free fatty acids (FFA) and viscosity. The optimum conditions for the production of hydrolyzed oil or FFA‐rich oil in enzymatic hydrolysis of CPOlein were reaction temperature of 50C, 1% (w/w) lipase from C. rugosa and 50% (w/w) water content. FFA in CPOlein increased to 97.9% after the hydrolysis process, which showed an increase of 61 folds. The differences in viscosity between the CPOlein and HCPOlein at different temperatures were statistically significant (P < 0.05). The slip melting point of CPOlein was 17C. After hydrolysis, the melting point for CPOlein increased by 160%, reaching 44.4C.
Carotene from crude palm oil (CPO) and degummed palm oil (DPO) was separated using synthetic polymer adsorption chromatography. Diaion HP‐20 adsorbent was used for reverse‐phase chromatography and column temperature was kept at 50C. Both 2‐propanol and n‐hexane were used as the first and the second eluting solvents, respectively. Phosphoric acid was used to remove the minor components in CPO in the degumming process. The turbidity of DPO was lower than that of CPO and the retention time in the column for DPO was shorter (21.3 min) compared to CPO (29 min) due to the removal of the minor components by phosphoric acid. Degumming process caused a reduction of 1.67 mg of total carotene content and 55.67 ppm of carotene concentration in CPO. This is probably due to the removal of carotenoids during the degumming process. After column chromatography, carotene recovery for CPO was 30.23% and 54.82% for the first and second fractions, respectively. On the other hand, carotene recovery for DPO was 33.91% for the first fraction and 46.25% for the second fraction. This indicated that the separation of carotene in CPO was more efficient than DPO in the column chromatography due to the longer retention time in the column.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.