Surface hydroxylation regulates cellular osteogeneses on TiO2 and Ta2O5 nanorod films.

Titanium and tantalum have been widely used for orthopedic and dental implant applications. However, how their inherent surface features regulate cellular osteogeneses still remains elusive. In this study, we engineered two distinct TiO2 and Ta2O5 nanorod films as the two model oxidized surfaces to investigate their intrinsic osteogenic behaviors. The results indicated that the distinctive gradient on zeta potential against pH, corresponding to the deprotonation rate, but not the hydroxyl amount or hydroxylation polarity played a critical role on the cellular osteogenic performance. TiO2 nanorod film with a higher deprotonation rate significantly upregulated the expression of osteogeneses-related gene and protein, comparing to that of Ta2O5 nanorod film. These results might be attributed to that surface with higher deprotonation rateprovided more Bronsted acid-base surface sites to react with protein residues, leading to a mild change in conformation of the absorbed proteins, and subsequently facilitating to trigger the integrin-focal adhesion cytoskeleton actin transduction pathway. This study, therefore, provides a new insight into the understanding the role of material surface hydroxylation on cellular osteogenic responses.

Effect of algae growth on aerobic granulation and nutrients removal from synthetic wastewater by using sequencing batch reactors.

The effect of algae growth on aerobic granulation and nutrients removal was studied in two identical sequencing batch reactors (SBRs). Sunlight exposure promoted the growth of algae in the SBR (Rs), forming an algal-bacterial symbiosis in aerobic granules. Compared to the control SBR (Rc), Rs had a slower granulation process with granules of loose structure and smaller particle size. Moreover, the specific oxygen uptake rate was significantly decreased for the granules from Rs with secretion of 25.7% and 22.5% less proteins and polysaccharides respectively in the extracellular polymeric substances. Although little impact was observed on chemical oxygen demand (COD) removal, algal-bacterial symbiosis deteriorated N and P removals, about 40.7-45.4% of total N and 44% of total P in Rs in contrast to 52.9-58.3% of TN and 90% of TP in Rc, respectively. In addition, the growth of algae altered the microbial community in Rs, especially unfavorable for Nitrospiraceae and Nitrosomonadaceae.