Assay plate formats

HTS is usually carried out it multiwell plates and the industry has settled on certain standard formats. One key standard is that most screening assays are carried out in 96 (8 12) or 384 (16 24) well plates with a standard footprint. This standard is important because most automation is optimized for use with these plates and attendant assay volumes in the 100 pL range. Furthermore, source plates containing test compound are typically stored in a similar configuration, allowing for more efficient transfer of test compound from the source plate to the assay plate. Various types of plates are available to match different assay formats, including... 

Assay conditions as determined by ASSAY VALIDATION are performed in the chosen PLATE FORMAT with an acceptable signal to background ratio as described by the Z factor. 

We have developed chemiluminescent immunoenzymatic assays for (3-ago-nist drugs in the 96-well-microtiter-plate format. Such competitive assays have been used for determination of clenbuterol and of the overall content of p-agonist drugs in the sample. They matched the standard requirements of precision and accuracy, and were more sensitive compared to the conventional colorimetric methods. Moreover, CL detection was very rapid, making these assays suitable for screening analysis. 

A standard Lowry-based protein assay has been adjusted to the special conditions encountered with skin [126], Basically, proteins reduce an alkaline solution of Cu(II)-tartrate to Cu(I) in a concentration-dependent manner. Then, the formation of a blue complex between Folin-Ciocalteau reagent (a solution of complex polymeric ions formed from phosphomolybdic and phosphotungstic heteropoly acids) and Cu(I) can be measured spectrophotometrically at 750 nm. A calibration curve can be obtained by dissolving known amounts of stratum corneum in 1 M sodium hydroxide. A piece of tape that has not been in contact with skin is subjected to an identical procedure and serves as negative control. The method was recently adapted to a 96-well plate format, notably reducing analysis times [129],... 

For higher throughput applications, injection-molded plastic microtiter plates have served as the formats of choice for automated assay development. Thermoplastics such as polystyrene, polycarbonate, and polypropylene are used for a variety of purposes including storage and assay plates, lids, pipette tips, and Eppendorf PCR tubes. Polystyrene plates are used for cell culture and ELISAs. Polycarbonate reagent bottles are popular, while polypropylene storage plates and PCR tubes are standards. 

Fig. 2. Plate format for siRNA library screening. A 384-well daughter plate contains library siRNA as well as wells for positive and negative control siRNA and additional controls as needed for each specific assay. Reference wells are designafed.

Hartmann, T Schmitt, J., Rohring, C., Nimptsch, D Noller, J. and Mohr, C. (2006) ADME related profiling in 96 and 384 well plate format — a novel and robust HT-assay for the determination of lipophilicity and serum albumin binding. Current Drug Delivery, 3, 181-192. 

The modified Lowry assay can also be done in a 96-well microtiter plate format. The assay has a working range of 1 to 1500 pg/ml. 

Use of the BCA protein assay in a microtiler-plate format which utilizes a microwave oven as the heat source to shorten the color development time to 20 sec. 

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