Influence of the number of washings for embryos on non-invasive preimplantation chromosome screening results.

Objective: To explore the effect of varying numbers of embryo washings prior to blastocyst formation in non-invasive preimplantation chromosome screening (NICS) on the accuracy of NICS results. Methods: In this study, 68 blastocysts from preimplantation genetic testing (PGT)-assisted pregnancy were collected at our institution. On the fourth day of embryo culture, the embryos were transferred to a new medium for blastocyst culture and were washed either three times (NICS1 group) or ten times (NICS2 group). A trophectoderm (TE) biopsy was performed on the blastocysts, and the corresponding embryo culture media were collected for whole genome amplification (WGA) and high-throughput sequencing. Results: The success rate of WGA was 100% (TE biopsy), 76.7% (NICS1 group), and 89.5% (NICS2 group). The success rate of WGA in embryo medium on days 5 and 6 of culture was 75.0% (33/44) and 100% (24/24), respectively. Using TE as the gold standard, the karyotype concordance rate between the results of the NICS1 and NICS2 groups' embryo culture medium samples and TE results was 43.5% (10/23) and 73.5% (25/34), respectively. The sensitivity and specificity of detecting chromosomal abnormalities were higher in the NICS2 group than in the NICS1 group when TE was used (83.3% vs 60.0%; 62.5% vs 30.8%, respectively). The false-positive rate and false-negative rate (i.e., misdiagnosis rate and missed diagnosis rate, respectively) were lower in the NICS2 group than in the NICS1 group (37.5% vs 69.2%; 16.7% vs 40.0%, respectively). Conclusion: The NICS yielded favorable results after ten washings of the embryos. These findings provide a novel method for lowering the amount of cell-free DNA contamination from non-embryonic sources in the medium used for embryo development, optimizing the sampling procedure and improving the accuracy of the NICS test.

Designing SAPO-18 with energetically favorable tetrahedral Si ions for an MTO reaction.

The silicon site location in silicoaluminophosphate zeolites has significant influences on their acidic and catalytic properties. Herein, AEI analogue silicoaluminophosphates with controlled tetrahedral silicon centers (T sites) were synthesized using specially designed amines as expected organic structure-directing agents (OSDAs). DFT calculations show that the OSDAs with different electronegativity can direct Si atoms into the T sites with more favorable energy advantages. Their catalytic performances in a methanol-to-olefin (MTO) reaction also reflected that OSDAs controlled the Si location in the framework, and the T3 sites had better performance than T1 sites. This finding provides evidence that OSDAs are capable of guiding the Si ions into more favorable T sites, achieving desirable catalytic properties as solid acid catalysts.