Filtertips are generally accepted as the solution in the prevention of cross-contamination in PCR reactions. A main source of this contamination is the formation of aerosols in the shaft of the pipette used during the PCR liquid handling. Carry-over of previously pipetted DNA, RNA and proteins can cause false positive signals.
The use of a filter in a filter tip eliminates the formation of aerosols in the shaft of the pipette, because it blocks the air-to-liquid interface between the sample and the shaft. This simple idea has evolved in numerous types and brands of filtertips and filter materials.Most filters are made of inert 3-dimensional cross-linked PE (Polyethylene)
The most important parameter for a filter tip is the pore size and the ratio of filter length and pore size of the applied filter material. The pore size must be smaller than 25 µm to protect against aerosols at all. If the pore size is between 20 and 25 µm, a filter will give reasonable protection, however liquid will pass when overloaded. Below 20 µm, a filter will give superior protection. When pore sizes get below 14 µm, it becomes too difficult to pipet liquids in a reproducible manner, because of the airflow barrier. Therefore, it makes no sense to use filters with this small pore size.The costs and investments to manufacture a filter material with an average pore size of 18 µm are high. BIOplastics’ Self Sealing Non Collapsing (SSNC) filter tip meets this 18 µm pore size specification and is build up with a density gradient from top to bottom. It is the perfect balance between superior protection and accurate pipetting.
The filtering capacity of a certain filter is defined as the ratio of filter length and pore size.
The longer a filter is, the better it filters. This relation is almost linear. BIOplastics filters have
the longest length available in the market when compared to other brands. By applying a gradient within the filter (see picture 3-dimensional GRADIENT filter) the aerosols air flow length is even extended and aerosol particles are additionally forced to a non linear track. When these three factors are combined, the result is a superior filter tip.
BIOplastics BV has designed multi purpose racks in which tips are packed. Tips are made of medical grade extreme clear and soft PP with no molecule binding properties. The soft tips ensure superior pipetting, easy pipette seating and releasing, thus preventing RSI. Each rack consists of a colored bottom part, a transparent hinged lid and a multi-purpose interchangeable tip insert. The empty box can be used for storage. The multi-purpose interchangeable tip insert can hold PCR plates and strips. Additional tube grids are available which enable you to make your own 0.5 ml / 1.5 ml microcentrifuge tube storage / freezer rack. Whenever you buy racked tips you end up with not only an excellent tip, but also a good start for an even more organized lab!