Frequently Asked Questions
Rather than using physical wells, DropArray™ has a hydrophobic coating covering the entire area of a flat surface except for a series of hydrophillic spots. These spots form an array that conforms to the well layout of the ANSI/SBS 4-2004 standard. Using standard microplate pipetting devices, liquid dispensed on these spots form droplets that remain in a fixed position, even when the plate is shaken or inverted. Plastic walls surround the entire flat surface, which serves to contain washing buffers that are added in bulk to the plate. Unlike a standard microplate that requires dispensing and aspiration from each well, DropArray plates add or remove bulk liquids like washing buffers to the entire plate at once. This enables liquids to be added or removed at very low velocities compared to using a traditional pipette. By reducing turbulence in these wash steps, far fewer cells are lost from the assay droplets, even with suspension cells. Evaporation is controlled by using Curiox’ Liquid Lid sealing fluid. This special fluid, which is added and removed in the same manner as wash buffer, eliminates assay droplet evaporation yet ensures good gas exchange for multi-day assays.
DropArray enables convenient low volume cell-based assays in the range of 2 – 4 microliters (384 well format) or 8 – 12 microliters (96 well format). Alternative low volume plates require special washing systems, which still disrupt cells far more than the DropArray system due to the high velocity of liquid leaving or entering a pipette tip.
DropArray™ allows seamless use on any conventional dispenser, gripper, stacker, reader or imager.
The DropArray™ plate can perform with a low confluence of 80 cells per mm2 to a very high confluence of 630 cells per mm2. For first time users, we recommend 250 cells per mm2. The cell growth rate on DropArray™ plate is no different compared to a conventional microplate.
The Liquid Lid fluid is highly gas-permeable and allows gaseous exchange for optimal cell growth.
The Liquid Lid is a proprietary mixture of perfluorocarbon liquids with a viscosity similar to water. It is added slowly to the DropArray plate, which prevents assay droplets from being disturbed or dislodged. When the Liquid Lid is poured off the plate, any residual Liquid Lid evaporates.
Liquid Lid can be recycled by filtering with a 0.22 micron or a 0.45 micron pore size filter system, and/or optionally autoclaved with conventional laboratory glassware.
Depending on cell-line and assay requirements, cells can survive up to 2 weeks without media exchange. Media can be aspirated manually or washed off using DropArray™ HT/LT Washing Stations before applying fresh media.
DropArray™ plates are tissue culture compatible. DropArray plates can be easily coated with DNA, poly-lysine, Collagen, fibronectin, silane-compatible substrates, or any other cell culture coatings.
Typical use is 110 ml for a 1x washing step, ~ 2 minutes, and 330 ml for a 3x washing step, which takes a total of 5 minutes.
The introduction of bulk wash buffer over the flat DropArray™ slide discourages air bubbles to interfere with the washing of the reacting surfaces.
The use of the proprietary DropArray™ Liquid Lid removes any air bubbles present.
Yes, contact dispensing and non-contact dispensing from your dispenser can be achieved in the presence of an optimized volume of Liquid Lid.
DropArray plates have a pitch distance between each hydrophilic spot conforming to the SBS/ANSI standard, which is sufficient to prevent adjacent droplets from touching. DropArray™ Liquid Lid maintains the hydrophobic pattern between wells and prevents evaporation of the droplets. During the wash process, the HT/LT Washing Station first adds 80 ml of wash buffer and then gently rocks the plate, avoiding the turbulence and high velocity liquid exchange of traditional washers.
A 5-step cell-immunostaining assay with a short incubation typically takes 2.5 hours.
The DropArray™ HT Washing Station HT200 has a PC-HT200 RS232C port for communication with automation controllers.
Baud rate = 9600 and Data bits = 8.