Sorting spermatozoa by morphology using magnetophoresis

The chances of successful fertilisation, be it in natural pregnancy, or in vivo and in vitro assisted reproduction, are significantly dependent on the percentage of morphologically normal spermatozoa. Here, we propose sorting spermatozoa by magnetophoresis and shear flow to reduce the percentage of abnormal sperm cells for assisted reproduction. By applying resistive force theory, we develop a theoretical model to compute the swimming velocity as a function of the sperm physical parameters, as well as magnetic field properties. As spermatozoa parameters vary, we implement a statistical approach and run a Monte Carlo simulation to obtain the swimming velocity displayed in box-and-whisker plots. The difference between the velocity of conditionally satisfactory spermatozoa and morphologically abnormal spermatozoa can be enlarged through various combinations of magnetophoresis and shear flow. There exists a clear trend that by using a greater magnetic force or flow rate in the direction against the sperm heading, the percentage of conditionally satisfactory sperm obtainable can be increased, although at the expense of a lower yield. It has been demonstrated that spermatozoa subjected to magnetic fields exhibit uncompromised fertilisation capability. Therefore, sorting by magnetophoresis has the potential to increase the chances of conception in assisted reproduction technology.     

Suppression of Problematic Compound Oligomerization by Cosolubilization of Nondetergent Sulfobetaines

Numerous small organic compounds exist in equilibrium among monomers, soluble oligomers, and insoluble aggregates in aqueous solution. Compound aggregation is a major reason for false positives in drug screening, and even soluble oligomers can interfere with structural and biochemical analyses. However, an efficient way to manage the equilibrium of aggregation‐prone compounds, especially those involved with soluble oligomers, has not been established. In this study, solution NMR spectroscopy was used as a suitable technique to detect compound oligomers in equilibrium, and it was demonstrated that cosolubilization of nondetergent sulfobetaines (NDSBs) can largely suppress compound oligomerization and aggregation by shifting the equilibrium toward the monomers. The rotational correlation time was obtained from the ratio of the selective and nonselective longitudinal NMR relaxation times, which directly and quantitatively reflected the apparent sizes of the compounds in the equilibrium. The rotational correlation time of the aggregation‐prone compound SKF86002 (1 mM ) was substantially reduced from 0.31 to 0.23 ns by cosolubilization of 100 mM NDSB195. NDSB cosolubilization allowed us to perform successful structural and biochemical experiments with substantially fewer artifacts, which represents a strategy to directly resolve the problematic oligomerization and aggregation of compounds.