Effects of different sulfonation times and post-treatment methods on the characterization and cytocompatibility of sulfonated PEEK

Polyetheretherketone (PEEK) has been becoming a popular implant material in orthopaedic applications. The lack of bioactivity affects PEEK’s long-term lifetime, and appropriate surface modification is an effective way to enhance its bioactivity. Sulfonation of PEEK can endow PEEK with a 3 D porous network surface and improve its bioactivity. This study is aimed at exploring an optimal sulfonation time and a post-treatment method of PEEK sulfonation. PEEK was immersed into concentrated sulfuric acid for different sulfonation times and experienced different post-treatment methods to turn into sulfonated PEEK (SPEEK). The immersion times were 0.5 min (SPEEK0.5), 1 min (SPEEK1), 3 min (SPEEK3), 5 min (SPEEK5) and 7 min (SPEEK7), and the post-treatment methods were acetone rinsing (SPEEK-T1), hydrothermal treatment (SPEEK-T2) and NaOH immersion (SPEEK-T3). Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy, hydrophilic property, ion release and cell viability evaluations were performed to optimize the sulfonation time, and the SEM, EDS, ion release and cell viability were analysed to optimize the post-treatment method. The results showed a porous network structure was formed on all samples of SPEEK, and the porous structure became more obvious and the S concentration increased with increasing sulfonation time. However, too long of an immersion time (SPEEK7) tended to damage the superficial porous structure and left a higher content of sulfuric acid, which could inhibit the growth of MC3T3E1 cells on its surface. In addition, the surface morphology, residual sulfuric acid and cytocompatibility of SPEEK-T1, SPEEK-T2 and SPEEK-T3 were not distinctly different. In conclusion, a 5-min sulfonation time was considered to be the optimal selection, and acetone rinsing, hydrothermal treatment and NaOH immersion showed the same effect in removing the residual sulfuric acid. The understanding of optimal sulfonation time and post-treatment method can provide a theoretical basis in preparing SPEEK for orthopaedic applications.

Lichen secondary metabolites in Umbilicaria antarctica evaluated by acetone rinsing ( Short Communication )

Study of the extracts from an Antarctic lichen Umbilicaria antarctica was done using a spectrophotometric approach. Secondary compounds were extracted by acetone rinsing from dried thalli of U. antarctica. The extracts were dried out, and diluted in ethanol. Then, spectral absorbance of the extracts were measured within the wavelength of 190-700 nm. The spectra of the secondary compounds obtained by acetone rinsing (EAR – re-diluted (ethanol) extract gained during acetone rinsing) were compared with those from untreated thalli (control) and ethanol extract from the thalli of U. antarctica that passed acetone rinsing (ART). Spectral absorbance curves of the extracts gained by acetone rinsing were attributed to different prevailing secondary metabolites: usnic acid, lecanoric acid (U. antarctica). Spectral absorption curves of control thalli exbibited similar shape as ART spectral curves, however, the absorbance in the range of 230-310 nm reached higher values in control than in ART. Spectral absorbance curves from ART showed that a part of secondary metabolites still remained in the thalli. Photosynthetic pigments (carotenoids and chlorophylls) remained uneffected by acetone rinsing.

Recovery of bis(1-chloro-2-propyl) ether from aqueous solution onto activated carbon

Recovery of bis(1-chloro-2-propyl) ether from aqueous solution onto activated carbon The results of the studies of bis(1-chloro-2-propyl) ether adsorption from aqueous solution onto AG5 activated carbon were presented here. Dynamic adsorptivity, mass transfer zone and the velocity of the adsorption front of the 10cm adsorption bed depth for the velocity of flow 9 and 25 cm/min were determined. For the regeneration of the adsorption bed, acetone rinsing was used. Total washout of adsorbed bis(1-chloro-2-propyl) ether from the bed was obtained. After the regeneration the adsorbent has not shown deterioration of adsorption properties. To isolate bis(1-chloro-2-propyl) ether from acetone, distillation was used.

The gastropod Arion fuscus prefers cyanobacterial to green algal parts of the tripartite lichen Nephroma arcticum due to low chemical defence

Although the tripartite terricolous lichen Nephroma arcticum is easily accessible to lichen-feeding gastropods, grazing marks are mainly restricted to localized cephalodia with N-fixing Nostoc. We tested if this gastropod preference for cephalodia can be explained by differences in carbon based secondary compounds (CBSCs) in cyanobacterial versus green-algal tissues. CBSCs were non-destructively removed from air-dry thalli by 100% acetone. Compound deficient and control thallus parts were offered to the slug Arion fuscus and grazing preferences were quantified by area measurements in ArcGIS™. The concentrations of CBSCs (phenarctin, usnic acid, nephroarctin and methyl gyrophorate) in thallus parts with and without cephalodia were quantified with HPLC. Compared to purely green-algal parts, cephalodial parts with adjoining fungal tissues contained less defensive compounds, and were preferred by A. fuscus. The cephalodia themselves do not contain any CBSCs. After acetone rinsing, A. fuscus did not discriminate between green-algal and cyanobacterial parts. The results were consistent with the hypothesis that CBSCs in green-algal parts of N. arcticum play a herbivore-defensive role. It is further hypothesized that grazing of cephalodia may lead to N-starvation and reduced growth of N. arcticum thalli in southern portions of its range where lichenivorous gastropods are more abundant. This may play a role in shaping the southern distribution limit of this arctic-boreal lichen species.