15502-m-pleumeekers

Sample# Dilution Results (EU/ml) Spike recovery (%) Status Mean ± SD (EU/ml) 1 1/10 0.26 59 Valid 0.15 ± 0.09 2 1/10 0.10 90 Valid 3 1/10 0.10 55 Valid Table 2. Results from bacterial endotoxin testing. Assay sensitivity 0.005 Endotoxin Units per ml (EU/ml). Valid test parameter: each sample is tested with a positive product control (PPC) of 0.1 EU/ml. If the spike recovery is between 50 and 200 % of the PPC, the result is valid. According to the FDA, endotoxin levels in medical devices are not to exceed 0.5 EU/ml or 20 EU/device. [352] The removal of EMIMAc residues from the bilayer BNC scaffolds was analyzed with ATR-FTIR spectroscopy. The strong peak at wavenumber 1566 cm -1 , observed in the ATR spectrum of EMIMAc solution, was used to detect EMIMAc residues in the ATR spectra of bilayer BNC scaffolds. This peak is composed of two overlapped peaks that correspond to the carboxyl group of the acetate and an underlying ring mode of the cation, as shown by previous studies. [355, 356] A small peak at 1566 cm -1 was also found in the ATR spectra of bilayer BNC scaffolds after 1 and 7 days of purification. However, the absence of the peak at 1566 cm -1 in the ATR spectra of samples that were washed for 14 days confirmed the removal of EMIMAc residues from the bilayer BNC scaffolds. (Figure 3A) In-vitro cytotoxicity testing supported this observation. An one-way ANOVA was conducted to compare the effect of cytotoxic residues extracted from BNC bilayer scaffolds (i.e. at 7 and 14 days of purification) and control conditions on cell viability. There was a significant effect of extracted cytotoxic residues on levels of cell viability for the four conditions, F (3, 20) = 120.42, p <0.0001, ω = 0.97. Post hoc comparisons using the Tukey HSD test indicated that the mean cell viability for the 14-day condition (97.8 ± 4.7%) was significantly higher than the 7-day (18.4 ± 3.6%) and positive control conditions (25.6 ± 5.5%) at the p <0.05 level. Furthermore, there was no significant difference between the negative control and 14-day conditions. Thus, the cytotoxic potential of bilayer BNC scaffolds, after 14 days of washing with endotoxin-free water, was classified as non-cytotoxic (cell viability > 71%). (Figure 3B) 161 NOVEL BILAYER BNC: AN ECM-INSPIRED SCAFFOLD 8