PolyVivo AK12 In-Vivo Surgical Usage

The note below is from an answer to a question from a customer who was planning to use AK12 for in-vivo animal work. The customer's identity and any proprietary details regarding their work have been removed. Generally this is the same advice that would be given for in-vivo usage with this polymer as a thermogel.:

Dear (Customer),

Thanks for asking about this. For creating a good thermosensitive gel using AK12 the best method is to dissolve as a solution between 10-30% (w/v) in water or saline and then add your [...omitted...] to the solution (testing at Akina has shown that it doesn't really matter too much what else is in the aqueos solution, checkout: http://www.akinainc.com/pdf/AK12%20Viscosity%20and%20Thermal%20properties.pdf). Most of our work has focused around 20% w/v and this is known to solidify nicely but still be easily dissolved at cold temperatures so this would be a suggested concentration to work with. So a couple of important notes:

1. AK12 due to being a short polymer is extremely sticky and viscous in its dry and natural state. I can't really change that fact (even though I wish I could), that's simply the physical form that polymers of this type/size take. If you want to subdivide/move to a new container I would suggest avoiding using a spatula as it will stick strongly to anything it touches. A better idea is to make up the aqueos solution in the bottle the AK12 came in (e.g. adding 5ml of saline to ~1g AK12 would yield a 20% soln) and then transfer/subdivide the solution of known concentration.

2. AK12 only dissolves cold. This is somewhat similar to pluronic in that (counter-intuitively) the best way to dissolve AK12 is to put it in a refrigerator (whatever you do, do not heat to dissolve! This will only damage the polymer and make it dissolve even slower). The dissolution also takes some time (at the very least overnight) so best to let it dissolve overnight or even better a few days and then use it. Keep this in mind when planning timing for your animal surgeries, you will need to dissolve the AK12 well in advance of your surgery date. At 4C the AK12 solution is stable for about 2-3 weeks. After a month or so in aqueous solution in the fridge it will gelate due to degradation and not work as a cold-water soluble material so if you find some "left-overs" much later on chances are they may not be good.

3. Make sure to keep the AK12 solution cold right up to the time of surgery. May even be worth your while to take a small styrofoam box in with you to surgery with the AK12 solution in it and a small ice-pack. AK12 is a little "trigger-happy" when it comes to gelling and will start to solidify up even if you are working in a warm room (27-30C) so for injection/insertion purpose keeping it cold is optimal.

Hope this helps and good luck,

John Garner Manager Akina, Inc. 1291 Cumberland Avenue West Lafayette, IN 47906 Phone: 765-464-0501 ext6# Fax: 765-464-0820 jg@akinainc.com jgakinainc@gmail.com http://www.akinainc.com/