view article

Figure 4
Acoustic transparency of hydrogels. Many hydrogels are acoustically transparent to the waveform and frequency used to transfer crystals (or other materials) onto X-ray data-collection micromeshes (11.5 MHz). The intensity of the reflected sound is shown for hydrogels of acrylamide (green), agarose (red) and gelatin (blue). In all hydrogel cases, a concave pedestal was deposited to a height of 4.4 mm in one well of a 384-well polypropylene plate. Water was then added to a height of 6.7 mm. Five acoustic pings were then transmitted through each well using the Echo 550 and the reflected intensities were recorded as a function of time. The five pulses were averaged for each substance and the averaged values were plotted on a single graph; the horizontal axis is the measured reflected intensity (arbitrary units) and the vertical axis is time. In our control (purple), a Thermanox cover slip was placed on an agarose support to show an example of a material that is acoustically semi-transparent (see Supplementary Fig. S1). Because the speed of sound in all of these substances is virtually identical to that in water, the vertical axis is displayed as a distance (in millimetres). The expected location of the interface between the hydrogel and the water is indicated. Acoustic transfer of crystals from a support matrix to micromeshes can only occur if the largest reflection is from the air–water interface. In the case of the three classes of hydrogels tested, the observed acoustic reflection from the gel–water interface was zero, indicating that all of these materials are possible candidates for positioning specimens at the acoustic focus point.

Journal logoBIOLOGICAL
ISSN: 1399-0047
Follow Acta Cryst. D
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds