I want to combine a polymer solution (polymer+distilled water) with hydroxyapatite crystals as my scaffold fabrication technique consists of a freezing step, I use 5 ml syringes as mold and put them into a cryostat. Even I completely mix the polymer solution with HA particles, after the reaction time is completed I see that all the HA crystals accumulate in the dip point of the syringe. Therefore, the bottom side of the biomaterial contains all the amount of HA, however, the upper side of it does no contain any HA particles. I want to spread HA crystals homogeneously into my polymer network. Is anyone know how to solve this problem? Thanks in advance.
P.S: I thought to put them into liquid nitrogen first and then into the cryostat. But I do not want to change the experiment procedures at the first stage.
unfortunately that will not be possible so long as the solution is completely liquid when you add that HAP particles into them. The particles are heavy and will always sink to the bottom. Can you wait till your solution begins to polymerize and then add the particles so they can stay suspended? Or can you make the particles in a suspension so that they will be too disperse to settle? You can try to make the particles very fine and then sonicate the particles to create a suspension and then add to the solution and see if it says dispersed.
You can produce your scaffold wıth freeze dryıng then cover your scaffold wıth SBF
http://www.ncbi.nlm.nih.gov/pubmed/25687000
I agree with Victoria. As one more option, you can try to perform polymerization or freezing under continuous agitation or vibration (e.g., using an ultrasonic system); however, this could be difficult to realize in practice. Furthermore, searching in literature using the proper keywords such as “how to homogeneously distribute ceramic particles inside a polymeric matrix” could result in additional approaches.
Dear Professor Victoria Wu thank you for your answer. Unfortunately, I have to put them into cryostat immediately. Because the polymerization process should be carried on in freezing conditions as I use ice crystals as porogen I will use nano-hydroxyapatite crystals at this time. Do you think they also need an additional process to make the particles finer? I will keep your advice. Thank you so much again for your cooperation.
Dear Professor Junjun Tan thank yo so much for your cooperation. I will look deeply into your literature.
Dear Professor Farzin Asghari Sana thank yo so much for your cooperation.
Dear Professor Sergey V.Dorozhkin thank yo so much for your cooperation.
Hi Kubra,
Which type of HAP particles are you using? Nano or micro particles? If you have a system where you can use aqueous products, you might want to consider nanoXIM HAp nanoparticles water-based pastes from FLUIDINOVA. Have a look here: http://www.fluidinova.com/nano-hydroxyapatite-pastes-for-injectable-bone-substitute-biomaterial
http://www.fluidinova.com/nano-hydroxyapatite-pastes-for-injectable-bone-substitute-biomaterial
Dear Paulo Quadros thank you for your advice. I am using this product:
http://www.sigmaaldrich.com/catalog/product/aldrich/289396?lang=en®ion=TR
Dear colleague, you must use a dispersant like PEG
you can read the paragraph :2.2 Synthesis of thin film; CA/HAp/PEG1000
in accompagning Article: Synthesis and characterization of composite based on celluloseacetate and hydroxyapatite application to the absorption of harmfulsubstancesKhalil Azzaoui,∗, Abdelatif Lamhamdi, El Miloud Mejdoubi
Try to use nano-hydroxyapatite particles for your composite and increase the freezing speed by using a -80 freezer or liquid nitrogen and try to flip up and down the syringe.
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