Technical

Because of the critical nature of the Life Sciences sector in both human and financial terms, iST Scientific LLP. is committed to ensuring that our products are specified and used correctly. Our team of industry experts will be very happy to advise you on the most appropriate products for your application. We also consider it our duty to provide you with all of the information you need on Micro Plates and the rest of our range so that you can make the correct informed choices.

For further technical help and support regarding our products and services please get in touch with us.

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Given recent developments in the Life Sciences Industry involving a greater requirement for sterilisation, you can rest assured that we can deliver sterilised versions of many of our MicroPlate Seals in line with your own stringent requirements … supported by our renowned capabilities in technical excellence, access to state-of-the-art R&D laboratories and accreditation to ISO 13485.

Because you need to know the bio burden levels of incoming materials in order to determine the required sterilising dose – and the effect on packaging integrity and regular monitoring of any changes to these criteria – our products are sterilised in accordance with ISO1137-2-2006, the Standard that defines two methods of verifying a given SAL for irradiated products.

Although ‘sterile’ is an absolute term, the assurance that an item is sterile is a probability function. The Sterility Assurance Level (SAL) of a product is defined as the probability of that item being non-sterile after exposure to a validated sterilising process. Some materials are resistant to sterilisation, so we conduct tests and validation to ensure that the effects of sterilisation on some polymers and packaging materials are not detrimental to performance and shelf life.

A Microtitre plate or MicroPlate (sometimes referred to as a MicroWell plate) is a flat plate with multiple wells used as small test tubes. MicroPlates have become a standard tool in analytical research and clinical diagnostic testing laboratories, which comply with standards established by the Society of Biomolecular Sciences (SBS). They are used in virtually every Life Sciences application involving filtration, separation, optical detection, storage, reaction, mixing, incubation or cell culture, as they simplify the handling of large numbers of samples and enable automation.

A MicroPlate typically has 6, 24, 96, 384 or even 1536 sample wells arranged in a 2:3 rectangular matrix. Depending on the application, different types of plates are available which differ in volume, base shape and material. Typically, each well holds between tens of nanolitres to several millilitres of liquid.

Since practically every experiment includes incubation and/or necessitates sample storage, it is essential that plates can be securely sealed in order to avoid contamination and evaporation. Several types of sealing systems are available and different techniques used including heat sealing, adhesive closure, sealing mats and lids.

Compatibility between MicroPlate and sealing process and materials is paramount, therefore the appropriate parameters must be understood and the limitations of both sealing options and the plates themselves appreciated.

IST Scientific LLP provides expert advice in effectively helping you choose the right seal for the right plate in the right application, in the most cost effective way.

MicroPlate Materials

The material from which MicroPlates are made differs according to their application.

Polypropylene is favoured for incubation and sample storage because of its high resilience to chemicals and temperature, particularly thermo cycling. Different sealing options can also be used with polypropylene – especially heat sealing.

Polystyrene is used for most optical detection MicroPlates. Polycarbonate is inexpensive, generally used for disposable MicroPlates for PCR (polymerase chain reaction) – a method of DNA amplification. Cyclo-olefin copolymers are now being used to transmit UV light.

Different sizes and types of plate bases, coupled with the correct selection of purity of plastic grades, including ‘low binding’ variants, influence the type of application and ultimately, the seal that will be achieved.

Useful Tips:

Only MicroPlates that comply with standards established by the Society of Biomolecular Sciences (SBS) should be used.
Raised chimneys around each well produce the best results.
MicroPlates that have a raised rim close to the perimeter of the wells should be avoided. This can prevent uniform contact between the hot plate and the wells.
For flexible MicroPlates which could bend and move during the sealing process, adapter trays to stabilise the MicroPlate position on the plate stage should be used. For example, a flexible 96-well polypropylene MicroPlate can be placed on top of a 96-well polystyrene MicroPlate to provide positional support.

PCR Adapter Plate

Because of the rigorous nature of the PCR process, we offer an adapter tray for PCR MicroPlate support. This ensures integrity and supports optimum results during denaturation, annealing and extension, which are carried out 20-35 times in a thermal cycler to produce replicates of the DNA template.

Heat sealing has become the preferred method of sealing MicroPlates. It creates an airtight and chemically-resistant seal without the complications of using adhesives for the application. Sealing the wells protects the contents from evaporation, condensation, oxidation and cross-contamination during transport or storage.

IST Scientific LLP has a comprehensive range of high performance heat sealing MicroPlate films and foils to meet the needs of the life science laboratory. These are available in individual sheets (LabSheet™) or rolls (LabRoll™) for low, medium and high throughput applications.

Heat Seals

Films or foils are welded to the MicroPlates using heat-sealing devices to produce a secure and effective seal, normally to raised rims around the individual wells of the MicroPlate.

Heat seals are available in a range of materials suitable for peeling, piercing, storage, transport and temporary or long-term sealing. Seals that can withstand sub-zero or high temperatures are also available.

Specifying MicroPlates

Firstly, it is crucial to specify thermal seal-friendly MicroPlates. Seal quality depends on many factors including MicroPlate design, material, batch-to-batch consistency and various other physical features.

Only MicroPlates compliant with standards established by the Society of Bimolecular Sciences (SBS), should be used. SBS plates are STD 96, 384 and 1536 well formats, including deep well and PCR MicroPlates. Skirtless and half-skirt PCR plates require plate supports. Raised rims around each well produce the best results.

MicroPlates produced from polypropylene offer the most effective and reliable heat seal. Other heat seals, however, are designed to be compatible with other specific polymer (MicroPlate) substrates such as polystyrene and COC. Avoid acrylic MicroPlates because they are not compatible with thermal MicroPlate sealing.

The Heat Sealing Process

Specifying the correct heat and dwell time ratios are critical to a good seal in order to ensure secure incubation and storage as well as easy subsequent removal (pierceable seals could have a tendency to adhere permanently to the MicroPlate). Even and complete sealing rims are a hallmark of closure integrity.

To optimise the process, start by carefully peeling off the seal material by lifting one of the corners. Inspect the underside of the removed material. If there are unbroken impressions of each well, the MicroPlate was properly sealed.

The well impression should match the thickness of the chimney wall.

If the well impressions on the seal are significantly thicker than the chimney wall, decrease the sealing temperature or the dwell time.

Thick impressions may indicate excessive melting of the seal, resulting in difficult removal and reduced resealing capacity.

Heat Sealing Devices

IST Scientific LLP’s LabCub HeatSealer is a small footprint, semi-automatic table top model designed to handle SBS format MicroPlates.

Devices for heat sealing MicroPlates are available from a number of different manufacturers. They differ from device to device: some take individual sheets whilst others use rolls; some are designed for only certain manufacturer’s plates – with inserts, support frames or adapter plates required for other plates. Manual and automatic types are also available.