Comparison of the specificity and affinity of surface immobilised Affimer binders using the quartz crystal microbalance.

To enable multiplexed protein analysis through the use of microarrays, reliable molecules capable of specifically binding to a protein of interest with high affinity are required. Further, this specificity and affinity must be retained upon immobilization to the microarray surface. This study investigates the performance of surface bound Affimer proteins, comparing the affinity and specificity of different binders for closely related immunoglobulin molecules using the quartz crystal microbalance with dissipation monitoring (QCM-D). It is demonstrated that the surface bound Affimer proteins are highly specific, differentiating between their target IgG and other closely related IgG subclasses. The binding affinities of the protein aptamers for their target IgG molecules are determined to be in the nanomolar range, comparable to typical antibody-antigen binding affinities. While measurements herein are done using QCM-D, the high specificity and binding affinities of the surface bound Affimer proteins opens applications in a range of microarray biosensors.

Metabolic profiling of follicular fluid and plasma from natural cycle in vitro fertilization patients--a pilot study.

OBJECTIVE: To investigate changes in follicular fluid (FF) and plasma composition during the follicular and periovulatory phases of the menstrual cycle in patients undergoing assisted conception, using proton nuclear magnetic resonance ((1)H-NMR) spectroscopy-based metabolite profiling. DESIGN: A pilot prospective laboratory study. SETTING: Assisted conception clinic in a university hospital. PATIENT(S): Ten women undergoing natural-cycle (NC) in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) with either male factor subfertility or unexplained subfertility. INTERVENTION(S): FF and plasma were collected during the midfollicular phase or at the LH-surge and at the time of oocyte collection. MAIN OUTCOME MEASURE(S): (1)H-NMR spectroscopy was performed on the fluids and the metabolic profiles compared across the phases with the use of principal components analysis (PCA). RESULT(S): LH-surge FF resembled periovulatory FF more than midfollicular FF, with higher levels of lactate and pyruvate and lower glucose. Periovulatory plasma contained higher levels of glucose and acetate and lower glycoprotein, trimethylamine, and glycine compared with midfollicular and LH-surge plasma. CONCLUSION(S): NMR-based metabolite profiling of FF and plasma has potential for identifying changes across menstrual stages, studying the impact of exogenous hCG administration, and in the pursuit of biomarkers to predict fertility treatment outcome.