Early feasibility and usability study of a novel obstetric blood loss quantifying device.

OBJECTIVE: To study the accuracy and usability of a novel obstetric blood loss quantifying tool in clinical settings. METHODS: A mixed-methods study was conducted in an Irish tertiary maternity unit. The accuracy of measuring the blood content (hemoglobin concentration) of elective Caesarean section birth waste with a novel obstetric blood loss quantifying device was compared, using Bland-Altman and correlation analysis, with staff volumetry and a reference hemoglobinometer. Hospital staff (nurses, midwives and doctors) opinion of the usability of the device was studied by an anonymous questionnaire which generated a System Usability Scale (SUS) score. SUS scores range from 0 to 100 with higher scores reflecting greater usability. RESULTS: The device was used by 19 different hospital staff members (nine nurses, four midwives and six doctors) in 19 elective Caesarean deliveries that had varying levels of PPH risk. Bland-Altman analysis produced mean biases of -0.7 ± 1.5 g/dL and 0.2 ± 1.2 g/dL for the device and staff measurements respectively. The width of the limits of agreement was narrower for device measurements than for staff measurements (4.5 g/dL and 5.7 g/dL respectively). The device's measurements of hemoglobin content correlated more strongly with the hemoglobinometer rather than with hospital staff measurements (Spearman correlation coefficients of 0.9 and 0.6 respectively). This suggests that the device is more accurate in determining the blood content of the birth waste than hospital staff volumetric measurements. Hospital staff members assigned the device a mean SUS score of 82 which suggests that the device is highly usable. CONCLUSION: An early feasibility study in clinical settings suggests that a novel device for quantifying obstetric blood loss was more accurate than volumetry in measuring the hemoglobin content of birth waste. Health professionals also found the device highly usable. This data suggests that there is much potential in transitioning from a "human-made" to a "machine-made" assessment of blood loss. Future studies will entail additional testing of the device to assess its impact on the morbidities associated with postpartum hemorrhage.

Single-Cell Droplet Microfluidic Screening for Antibodies Specifically Binding to Target Cells.

Monoclonal antibodies are a main player in modern drug discovery. Many antibody screening formats exist, each with specific advantages and limitations. Nonetheless, it remains challenging to screen antibodies for the binding of cell-surface receptors (the most important class of all drug targets) or for the binding to target cells rather than purified proteins. Here, we present a high-throughput droplet microfluidics approach employing dual-color normalized fluorescence readout to detect antibody binding. This enables us to obtain quantitative data on target cell recognition, using as little as 33 fg of IgG per assay. Starting with an excess of hybridoma cells releasing unspecific antibodies, individual clones secreting specific binders (of target cells co-encapsulated into droplets) could be enriched 220-fold after sorting 80,000 clones in a single experiment. This opens the way for therapeutic antibody discovery, especially since the single-cell approach is in principle also applicable to primary human plasma cells.

Efficient cell pairing in droplets using dual-color sorting.

The use of microfluidic droplets has become a powerful tool for the screening and manipulation of cells. However, currently this is restricted to assays involving a single cell type. Studies on the interaction of different cells (e.g. in immunology) as well as the screening of antibody-secreting cells in assays requiring an additional reporter cell, have not yet been successfully demonstrated. Based on Poisson statistics, the probability for the generation of droplets hosting exactly one cell of two different types is just 13.5%. To overcome this limitation, we have developed an approach in which different cell types are stained with different fluorescent dyes. Subsequent to encapsulation into droplets, the resulting emulsion is injected into a very compact sorting device allowing for analysis at high magnification and fixation of the cells close to the focal plane. By applying dual-color sorting, this furthermore enables the specific collection and analysis of droplets with exactly two different cells. Our approach shows an efficiency of up to 86.7% (more than 97% when also considering droplets hosting one or more cells of each type), and, hence, should pave the way for a variety of cell-based assays in droplets.

Surface-enhanced Raman scattering (SERS) and surface-enhanced resonance Raman scattering (SERRS): a review of applications.

Surface-enhanced Raman scattering (SERS) and surface-enhanced resonance Raman scattering (SERRS) can provide positive identification of an analyte or an analyte mixture with high sensitivity and selectivity. Better understanding of the theory and advances in the understanding of the practice have led to the development of practical applications in which the unique advantages of SERS/SERRS have been used to provide effective solutions to difficult analytical problems. This review presents a basic theory and illustrates the way in which SERS/SERRS has been developed for practical use.

Short-wave infrared excited SERS.

Optimisation of colloidal properties allows Surface Enhanced Raman Scattering (SERS) to be recorded from a range of analytes at 1546 nm, demonstrating the potential of SERS for use in a wavelength region of particular value for applications such as homeland security.