HTS - Microplates 1. Material

Polypropylene (PP) and polystyrene (PS) are the standard materials used to manufacture the majority of microplates. Polystyrene is a highly clear polymer with excellent optical properties which makes it ideal for precise optical measurements. Polystyrene is also characterised by its ability to bind biomolecules, such as proteins, and it is therefore often used for manufacturing immunological products. Polystyrene is suitable for work with cell cultures.

Polypropylene is characterised by its excellent chemical and thermal stability. It is the ideal polymer for storage vessels or microplates. Polar molecules, such as proteins or DNA, are binding less to polypropylene than to polystyrene. In addition to polystyrene and polypropylene microplates, Greiner Bio- One manufactures microplates with special requirement profiles, such as the UV-Star® microplates made from different polyolefins.

These polyo lefins are characterised by their low level of autofluorescence (Fig.1), exceptionally high clarity, especially in the UV range (Fig.2), and greater chemical stability when compared with polystyrene.


Figure 1:
More than 100 x lower autofluoresence of the UV-Star polyolefin compared
with polystyrene


Figure 2:
Light transmission the UV range. Comparison of polystyrene/polyolefins
  2. µClear® and UVStar®

The move from isotopic to non-isotopic assays (fluorescence/ luminescence), and new applications in high-throughput and high-content screening increased the demand for clear bottom plates, microplates with pigmented walls and thin film bottoms.

Up to now, clear bottom microplates have mostly been manufactured using a two-component injection moulding procedure by sticking or welding the components together. The development of a completely new and patented processing technique has made it possible for us to produce microplates with ultra-thin films, without the use of adhesives or solvents – the µClear® and UV-Star® products. This special method eradicates the risk of leaking wells (Fig. 3).

a) b)
Figure 3:
Wells filled with methylene blue after threefold freezing and thawing:
a) single well of a Greiner Bio-One UVStar® microplate
b) single well of a 96 well UV-transparent microplate of a competitor

The choice of suitable films is the decisive factor, and this will influence the quality of a clear bottom microplate. Both for µClear® and UVStar® microplates, Greiner Bio- One uses bipolar stretched foils. Strict controls before and during production guarantee a constant quality. Polarised light is either not depolarised (UVStar®) or is only depolarised to a slight degree (µClear®) (Fig. 4) and the autofluorescence of the microplates is minimised (Fig. 4).


Figure 4:
Autofluorescence of different 384 well microplates at an excitation wavelength
of 485 nm.

The 96 well µClear® microplates and 384 well µClear® microplates have a film thickness of 190 µm +/- 20 µm. In the 1536 well microplates with a transparent bottom (µClear®) the film thickness is 75µm +/- 10 µm. UVStar® microplates generally have a film thickness of 135 µm +/- 10 µm.

3. Black or White ?

White microplates are usually used for luminescence measurements (E.g. Luciferase Reporter Assays) and black microplates for fluorescence measurements (e.g. Green Fluorescence Protein). The critical properties in these methods, such as background, autofluorescence or crosstalk are considerably improved by the use of black or white pigmented microplates. The optical and physical properties of the Greiner Bio-One microplates were

investigated in laboratory. Higher pigment concentrations produced a much lower autofluorescence of the microplates. At shorter wavelengths, this influence is more pronounced than at the normal fluorescein wavelength combination of 485 / 520 nm (Fig. 5 and 6.). When comparing different white fractions, the same results were obtained for phosphorescence.



4. MICROLON® , FLUOTRAC™, LUMITRAC™

MICROLON® , FLUOTRAC™ and LUMITRAC™ are standing for the quality of Greiner immunology products. MICROLON® are clear microplates for transmission measurements. FLUOTRAC™ are black microplates for fluorescence measurements. LUMITRAC™ are white microplates for luminescence measurements.

MICROLON® 600, FLUOTRAC™ 600 and LUMITRAC™ 600 are high binding polystyrene surfaces that have been specifically treated to provide an increased protein binding. MICROLON® 200, FLUOTRAC™ 200 and LUMITRAC™ 200 are medium binding polystyrene surfaces. The polystyrene surface of a medium binding microplate is more hydrophobic than the surface of a high binding microplate, and therefore tends to be more suitable for non polar proteins and peptides. The consistency and reproducibility of our immunology products is constantly evaluated using a competitive ELISA (Fig. 7).

 

In general, high binding microplates are recommended for ELISAs. The protein binding to the polystyrene surface can vary greatly and depends, among other things, on properties such as charge or size. When developing a new assay, it is therefore advisable to compare high binding and medium binding microplates in advance.

5. Cell Culture Products / CELLSTAR® / TC

The polystyrene surface of an untreated microplate is hydrophobic and does not offer adherent cell lines a surface conducive to growth. Cell culture microplates from the CELLSTAR® range are specifically treated. This treatment leads to polar groups, such as carboxy and hydroxy groups, being incorporated into the plastic surface, making it hydrophilic. This significantly improves the adhesion of cells and the binding of proteins to the plastic surface. CELLSTAR® products are consistently evaluated using different cell lines. Cell culture treated microplates

6. Lids for Microplates
Four different polystyrene lid designs are available:
High profile lids
High profile lids with condensation rings
Low profile lids
Ultra low profile lids

Lids are available in two options, sterile and non-sterile. If microplates are supplied with lids, as in the case of CELLSTAR® products, the 96 well microplates always include lids with a high profile (“lid, high profile”) and the 384 well microplates always include plate lids with a low profile (“lid, low profile”). In addition all products are also available without lids, which means that the type of lid can be selected as required.

Greiner Bio-One microplates :

Are manufactured under DIN ISO 9001 guidelines

Can be traced all the way back to production through a
defined LOT number system

Have uniform external dimensions and tolerances,
which are conform to the recommendations of the
Society for Biomolecular Screening (SBS)

Are non-pyrogenic (<0.06 EU/ml) and regularly tested
using a FDA-approved LAL - test(Limulus Amoebocyte
Assay)

Are tested by an independent laboratory in a
quantitative PCR and are free of:
- DNases, RNases
- human DNA
-RNA/DNA polymerase inhibitors

Available with barcode labels on request