our research relating to produce ha/peta-tcp from calicium phosphate phases for bone tissue by solid state what is the effect of particle size on bioactivity?
This would depend on the application and method of fabrication. So is the produced HA/B-TCP material intended for depositions onto subsequent material surfaces, for use as insert/soft screw, for scaffolding purposes or simply as a spacer/cement? Basically is it for use in bulk, coating or other applications? The more detail you give to your specific application and process, the easier it is for bio-material specialists to determine if they have relevant information, which is better than giving some very general and pointless information.
Well depends from Micro to nano scale , for tissue engineering and regenerative medicine, Nano Ha has shown to be more osteogenic as it has higer surface area, and higher bioactivity, it effects the dissolution process.
Check out a review by Julian jones, called from Hench to Hybrids, published in Acta Bio. gives you more detialed information.
Agree with Saadi. Nanosize has larger surface area for osteoblast cell's attachment. However, be careful with nanosize because there are peak threshold. Less than certain nano value will not enhance osteogenic properties as cells can't grip on the surface
The particle size of the biomaterial has significant effect on the bioactivity as well as the biocompatibility of the materials. This is a complex problem with multi-factorial effects and need to be addressed on a case to case basis. You may look at any of the basic text books on bioceramics / biocompatibility. The following references could also be helpful
doi.10.1016/j.msec.2011.06.013
doi.10.1002/jbm.820290105
doi.10.1016/j.msec.2011.06.013
Calcium and phosphates are used by cells. When a compound, say HA is completely densified by long sintering it becomes almost inert. Almost all life processes proceed in solution. Solid extremely insoluble HA is almost like nothing. That has been overcome by the mixture of beta TCP with HA. Check the solubities for HA and TCP.
As long as other variables are constant, i.e. pH for example. The smaller the size the larger the biocompatibility because solubility increases (Kelvin´s Law) so a nano HA is better than a micro HA. I should say, what increases is the kinetics not the biocompatibility. You can have the best of both, mix some HA for cell support (low solubility , you do not want the ground under your feet to dissolve) with some high solubility HA (nano or poorly sintered).
Solubility increase has a limit, remember that osmotic pressure goes with concentration. Too much can negatively affect cells.
Instead of sintered nano HA (how to keep nano particles without flocculating?) you can have good solubility by using non fired but very well homogenized HA (preceramic HA or again barely fired HA).
High solubility phosphates (MCPM, DCPD) unfortunately are very acidic.
A last say, particle shape also matters, avoid sharp edge particles.
I agree with all previous comments. You need to think of all 3 characteristics of your particles, not just particle size. Material properties, shape and particle size all affect response synergisticly and when you mix particles with different material properties (e.g. HA and TCP) the ratio of particle types also affects the answer to your question. You may need to run some preliminary experiments varying only one characteristic at a time to get the answer.
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