N° 6

FORUM
TECHNICAL NOTES & APPLICATIONS FOR LABORATORY WORKCONTENT
1. Introduction
2. Sealers available fromGreiner Bio-One

SEALERS FOR MICROPLATESAND THEIR AREAS OF
APPLICATION IN MOLECULAR
BIOLOGY AND CELL CULTURE
1/ INTRODUCTION
Tightly sealed microplates are a basic prerequisite for their use in molecular biology, high-throughput screening, or cell culture. At present, three different sealing
methods are commonly used:
1. Heat sealing of microplates
2. Sealing of microplates with CapMats
3. Adhesive sealers for microplates

Heat sealing is the most widely used method, especially when sealing polypropylene storage plates for storing active substances in high-throughput screening.
Heat sealing has the disadvantage that the microplates are ultimately destroyedby the sealing process and the high temperatures may reach samples contained
within the wells, especially critical for temperature-sensitive samples or cells.
In addition, Heat sealing requires the acquisition of an appropriate device, which
may be comparatively expensive for small research groups.

3. Technical features andapplications
4. Appendix
5. Ordering informationFORUMN° 6CapMats are also very popular for sealing microplates,
especially in molecular biological applications such as
PCR. The reuse of CapMats is widespread, but entails therisk of cross-contamination from carry-over of sample
material. In order to avoid the disadvantages of heat sealing and CapMats, the use of adhesive sealers presents
an interesting alternative.

2/ SEALERS AVAILABLE FROM
GREINER BIO-ONE„CLASSICAL SEALERS”„ADVANCED SEALERS”/ SILVERseal
aluminium foil

/ VIEWseal
UV-transparent foil

AMPLIseal is a highly transparent sealer that demonstrates minimal autofluorescence, rendering it ideal for
real-time PCR. The strongly adhering acrylate adhesive
provides reliable sealing without interference with PCRor fluorescence measurements.
VIEWseal is a highly transparent sealer ideally suited for
precise optical measurements and protein crystallisation.
Characterised by an exceptionally high optical transparency even in the shorter wavelength range (<340 nm),
VIEWseal also displays minimal autofluorescence. The
silicone adhesive sticks only when pressure is applied to
the film surface. Thus VIEWseal is easy to work with, evenwhen wearing gloves (the sealer does not adhere to them).
Substances in powder form and biological model organisms like Drosophila melanogaster or Caenorhabditis
elegans also do not stick to vessels sealed with VIEWseal.

/ EASYseal
ELISA foil
/ BREATHseal
breathable foil
/ AMPLIseal
PCR foil

ACRYLATE ADHESIVESILICONE ADHESIVE

Figure 1: Classification of adhesive sealers

Greiner Bio-One supplies a full set of five different sealersthat can be divided into two different classes on the basisof the adhesive used (Fig. 1). “Classical Sealers” such as
SILVERseal, EASYseal, BREATHseal and AMPLIseal arecoated with an acrylate adhesive. The “Advanced Sealer”
VIEWseal is coated with a pressure-sensitive siliconeadhesive.
EASYseal is the adhesive sealer for everyday laboratory
coverage and protection requirements of microplates(e.g. in ELISA applications). Additionally, EASYseal issuitable for optical measurements in the visible wavelength range.
SILVERseal is a pierceable aluminium foil ideal for PCRapplications and for sample storage. Thermally resistantto both heat (+110 °C) and cold (-70 °C), SILVERseal sealers
remain flat when removed from their paper backing and arethus especially easily applied to all kinds of microplates.

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BREATHseal is a gas-permeable, pierceable foil ideal
for cultivating bacteria, yeast or cells in microplates.
BREATHseal consists of heat-sealed rayon fibres with apore size from 10 to 50 μm. The pores are layered in such away that the membrane acts as a filter, ensuring both reliable protection and optimal oxygen supply. All sealers arefree of DNase, RNase, human DNA and are non-pyrogenic.

3/ TECHNICAL FEATURES ANDAPPLICATIONSEVAPORATION RATES

Sealing properties are crucial for the usage of sealers
as vapour diffusion barrier. The evaporation rate of waterat 60 °C in polypropylene microplates covered with adhesive sealers is shown in Fig. 2. After 20 h incubation
at 60 °C the evaporation rate in microplates sealed withAMPLIseal and VIEWseal was less than 2 %, whereas
sealing with EASYseal and SILVERseal resulted in approximately 5.5 % and 7.5 % evaporation, respectively.
For long-term storage of volatile substances it should betaken into account that sealers cannot provide a 100 %vapour diffusion barrier. After storage of polypropylene
microplates filled with isopropanol over an eight weekFORUM8ODEvaporation [%]N° 672h64h52,01,8

VIEWseal

1,6EASYseal

1,420 hAMPLIseal

1 ,2
1 ,0

40,8

30,6

20,40,2

10,00
AMPLIseal

VIEWseal

EASYseal

230

SILVERseal

280

330

380

430

480

530

580

630
[nm]

Figure 2: Evaporation rate in 96 well polypropylene
microplates filled with water and incubated at 60 °C for 2 h, 4 h
and 20 h, respectively.

Evaporation [%]period at room temperature, the evaporation rate for microplates sealed with SILVERseal and VIEWseal was approximately 10 % (Fig. 3), and AMPLIseal approximately 30 %.

35

Figure 4: Light adsorption of VIEWseal, EASYseal
and AMPLIseal

The superior optical and sealing properties of VIEWseal
and AMPLIseal render them especially useful for protein
crystallisation applications as well. Because the sealers
are easily removed, crystals can be properly harvested
without disturbing contents within the microplate wells.
AMPLIseal is characterised by a very low polarisation oflight and therefore ideally suited for crystal detection
with polarised light (Fig. 6). However, AMPLIseal is notresistant to some substances used for crystallisation
screens, e.g. dioxane.

30
25
20
15
10
50
VIEWseal

EASYseal

AMPLIseal

Figure 3: Evaporation rate in 96 well polypropylene
microplates filled with isopropanol and stored for eight weeks
at room temperature.

Fluorescence [RFU]SILVERseal

1200
1000
800
600
400

OPTICAL PROPERTIES

VIEWseal and AMPLIseal feature a high optical transparency, even in the shorter wavelength range (Fig. 4), as
well as a low level of autofluorescence (Fig. 5). Therefore
both sealers are ideally qualified for applications withsensitive optical detection systems, such as real-time
PCR or fluorescence measurements in high-throughput
screening. With exceptionally low adsorption in the lower
UV, VIEWseal is the best selection for DNA or protein
measurements.

2000
VIEWseal

AMPLIseal

EASYseal

Competitor 1

Competitor 2

Figure 5: Autofluorescence of AMPLIseal
compared to VIEWseal and other sealing films.
The wavelength combination used (479 nm / 520 nm)
corresponds to the excitation and emission maximumof SybrGreen.

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Marker 2

VIEW

AMPLI

SILVER

Marker 10Strip Plates

N° 6Tubes

FORUM

Figure 7: Comparison of PCR products
from classical reaction vessels (tubes/strips) with PCR products
from 96 well polypropylene microplates sealed with sealers

CHEMICAL AND TEMPERATURE STABILITY

The chemical stability of sealers is a major quality criterion
for many areas of application. For testing the chemicalstability of the sealers, polypropylene microplates werefilled with twelve different solvents, properly sealed
and then turned upside-down. As a result the sealers
were in direct contact with the solvents. After one week,
the sealers were inspected visually (Appendix, Tab. 2).
VIEWseal and SILVERseal are clearly superior to AMPLIseal
and EASYseal with regard to chemical resistance. Due to its
porous nature, BREATHseal was not included in this test.
Temperature stability is especially important for PCR applications and storage at low temperatures. SILVERseal,
VIEWseal and AMPLIseal tolerate a wide temperature
range (-70 °C to 100 °C) and are therefore appropriate
for both PCR and sample storage at low temperatures(Appendix, Tab. 3). No significant differences were foundwith regard to yield and fragment sizes when sealed
polyproplylene microplates were compared to PCR products from classical thin wall vessels (Fig. 7).

CULTIVATION OF MICROOGANISMS IN MICROPLATESIn many research projects, bacteria, yeast or cells arecultivated in individual vessels such as test tubes,
Erlenmeyer flasks or 50 ml centrifuge tubes. With increasing automation and an increasing number of samples
to be processed, 96 well MASTERBLOCK® and even 384
well microplates came into focus. Essential for optimal
growth, oxygen supply is limited in microplates closedwith standard sealers or lids. As a gas-permeable sealer,
BREATHseal ensures optimal oxygen supply to significantly improve cell growth (Fig. 8) and, at the sametime, provide reliable protection against contamination.
BREATHseal is additionally well-suited for the use ofmicroplate shakers.

OD

Figure 6: Microscopic detection of protein crystals
with polarised light through AMPLIseal

1,0EASYsealBREATHseal

0,8Lid0,60,40,20,0

For EASYseal -40 °C to 120 °C is the recommended temperature range. BREATHseal can be used from -80 °C to60 °C; however, due to its porous structure increased
evaporation must be taken into account, especially athigher temperatures.

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02468101214
Hours [h]Figure 8: Growth of Escherichia coli at 37 °C
in MASTERBLOCK® sealed with BREATHseal, EASYseal and lids

FORUM

N° 64/ APPENDIX

Application

PCR

SILVERseal

EASYseal

AMPLIseal

VIEWsealyes

yes

yes

yes

-40 °C to +100 °C-70 °C to 100 °C-80 °C to +60 °C

yesyes2)yes

Real-time PCR
Storage-70 °C to 100 °C-40 °C to + 120 °C

Cultivation

BREATHseal

1)

Optical measurements

yes 3)

yes 4)

yes5)

Protein crystallisation

yes7

Table 1: Applications1 ) Non-sticky2) Gas-permeable3) Standard optical measurements in the visible wavelength range
4) Highly transparent, for precise optical measurements, fluorescence measurements
5) Highly transparent, for precise optical measurements, fluorescence measurements, measurements in the lower UV6) Not resistant to some substances used for crystallisation screens, e.g. dioxane7) Slightly birefringent
This table can only be used as an orientation aid, since the behaviour of the product depends on the respective application.
Tests under practical conditions are absolutely essential in many cases.

Chemicals

EASYseal(Item No. 676001)

VIEWseal(Item No. 676070)

AMPLIseal(Item No. 676040)

SILVERseal(Item No. 676090)

Acetone1443

Acetonitrile

1341

Acetic acid 1 %1143

Glacial acetic acid

3343Chloroform

3444DMSO

1331Ethanol

3111H2SO4 0.5 M

1111

HCI 32 %3134Isopropanol

1111Methanol

3141Phenol

434

3Table 2: Chemical stability of the sealers
1 = Stable= no visible change in the sealer after one week’s incubation.
3 = Moderately stable = after one week, optical and physical changes in the sealer (clouding tears on removal).
4 = Unstable= adhesive and foil are dissolved, wells not leak-tightThis table can only be used as an orientation aid for the suitabiliy of the respective sealers, since their behaviour against chemicals
depends on the respective application. Tests under practical conditions are absolutely essential in many cases.

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FORUMN° 6ProductTemperature stability

EASYseal-40 °C to + 120 °C

VIEWseal-70 °C to + 100 °C

AMPLIseal-80 °C to + 110 °C

SILVERseal-70 °C to + 100 °C

BREATHseal

n.a. / Evaporation rate 4200 g H2O/m² in 24 h

Table 3: Temperature stability
This table can basically be used as an orientation aid for the temperature suitability of the respective sealers, since the behaviour ofthe product depends on the respective application. Tests under practical conditions are absolutely essential in many cases.

5/ ORDERING INFORMATION
Sealers
Item no.

Description

FeaturePierceable

SterileQty. inner / outer

676001EASYsealclear

676090SILVERseal

aluminium foil

676070VIEWsealclear

100 / 1,200

100 / 2,000
yes

100 / 1,200

676040AMPLIsealclear

100 / 2,000

676050BREATHseal

gas permeable

50 / 2,500

676051

BREATHseal

gas permeable

50 / 500

F073 013 [rev. 07.2022]+Devices of Greiner Bio-One are to be used by properly qualified persons only in accordance with the relevant Instructions for Use (IFU), whereapplicable. For more information contact your local Greiner Bio-One sales representative or visit our website (www.gbo.com).
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Bio-One GmbH is expressly prohibited. Media owner: Greiner Bio-One GmbH / Represented by Managing Directors Jakob Breuer and Heinz Schmid.
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