The most important aspect in the successful use of pin tools is to start with clean pins.  We strongly recommend that you use our specially developed pin cleaning  solution VP 110 at the beginning and end of each day to keep the pins clean.  It only takes a few seconds treatment in the VP 110 solution to remove built up compounds, proteins and finger oil.  Just dip in the diluted VP 110 solution for 10 to 30 seconds followed by blotting and triple dipping* in a distilled water bath and an alcohol (isopropanol,  ethanol or methanol) bath to clean a pin tool.  Simple as that to keep your pin tool delivering consistent volumes every time.  Complete detailed washing instructions can be found in Technical Note 40.

Our most common Technical Service question involves poor precision or accuracy and in virtually every case the problem goes away when the customer uses our VP 110 Pin Cleaning Solution and proper pin cleaning technique.  It is a simple and inexpensive way to consistent results.

Click here for a list of published articles that cite using the products on this page.

One of the problems that has arisen in spotting DNA onto membranes or glass slides has been that the spotting solutions often have high surface tension which results in variable volume hanging drops and therefore, variable spot diameters.  We had first noticed that distilled water has a very high surface tension and when just used with dye (food coloring) to make practice arrays this mixture produced very irregular spot sizes.  We also found that the irregular spot size can be eliminated by adding a detergent such as Tween 20, Sarkosyl, or proteins, carbohydrates or carrier DNA to the solution.  However there are many protocols where it is not possible to add these surface tension lowering compounds to the solution.

Another way to address the problem of  high surface tension liquids is to clean the pins with our VP 110 solution (diluted before use) which cleans the pin of proteins and other residues and changes the surface tension of the pin thus compensating for the high surface tension of the liquid.   Just dipping the pins into this solution briefly cleans the pins and changes the surface tension of the pin.  The pins are washed in water and ethanol to remove any residual solution and used right away.  This pin cleaning treatment results in very uniform dispense volumes.

Another problem encountered with pin tools is that if they are not cleaned after use or if they are contaminated by finger oil they will not deliver a consistent volume.  One 10 second treatment with the V&P Pin Cleaning Solution removes built up protein and oils and dramatically improves delivery consistency.

Another similar problem with high surface tension buffer solutions is that they do not wick and fill slot pins uniformly.  This also results in variable spot sizes.  This phenomenon can also be over come by cleaning the slot pins with the V&P Pin Cleaning Solution as above.  The ability to have slots fill by capillary action is very desirable when working with small volumes of DNA or PCR reaction products.  This wicking ability allows you to recover even the "dregs" at the bottom of a PCR well.

The 2 ul slot blots to the right were made with a VP 408S2 Slot Pin Replicator using just distilled water and 5% red food coloring on Hybond-N Nylon membrane (Amersham Pharmacia, P/N RPN 1510 N) illustrates the problem.

Once the V&P Pin Cleaning Solution has cleaned the slots and modified the surface tension of the pin, the modified surface tension remains even after 15 rinses in 100% ETOH or distilled water.  It even remains on the pins after treatment with 5% bleach.  Thus the replicator pins can be used for many blots or transfers without re-treatment.   We recommend that the V&P Pin Cleaning Solution be diluted 1 to 5 and used at the beginning of each spotting session.  After dilution and use, the V&P Pin Cleaning Solution can be stored and used again and again.  

V&P Pin Cleaning Solution, concentrated solution, 30 ml/bottle.....VP 110.

When it comes to keeping pins clean the type of blotting paper used is also very important.  Cheap blotting paper contains lint which can stick to the pin tips and interfere with pickup of liquid on the pins.  We strongly recommend using a lint free blotting paper.   We also have a super absorbent polypropylene pad in a tray covered by lint free paper (VP 540DB)  that will hold up to 27 ml of liquid.  This means you can make 100-10,000 blots with out changing the blotting paper.

FLAME TREATMENT

We have also found you can significantly lower the surface tension on the pin by flaming** from ETOH or isopropanol.  This also results in very uniform drop size and slot filling.  This is convenient if you can accommodate  flaming in your replicating or spotting procedure. 

* Triple dipping entails removing the pins from the bath and immediately dipping back in 3 times.  This gives a thorough washing of the pins.

** Flaming just entails igniting the alcohol on the pin and NOT heating the pins directly in a Bunsen burner which can damage the corrosion resistant properties of the stainless steel pins.
 

Before V&P
Pin Cleaning Solution Treatment


After V&P
Pin Cleaning Solution Treatment