This is with reference to the development of a local drug delivery system for bone infections, using a ceramic/polymer composite material. I want to know if there are better methods to determine exactly where the drug is dispersed inside the material, if at all.
Hi, SEM will be useful only if the surface of the material is porous in nature. BET of the material before and after drug loading may aid you to determine drug in matrix. If this doesn t work, AFM, Atomic force microscopy can surely aid to determine drug determination at within matrix as it scans at the atomic level of the materia. Pls find the ref
Alright Harita, thankyou so much. I find your idea of using BET to determine drug inside the matrix particularly interesting. The material is porous, so I should expect that the pore volume of my material should differ, before and after drug loading. Thanks for the AFM manual as well.
Thankyou so much for your answer Fatima, I think you are saying that TGA can help by telling us the amount of loaded drug through percentage weight loss. However what I really want to know is the site of drug adsorption or drug attachment (even if it is just by some physical bonding) with the biomaterial. This will have implications on the pharmacokinetic profile of the drug.
Whats your preparation protocol. r u mixing the drug before the preparation or after preparing the matrix, ......if you are loading the drug before preparation, you can estimate the surface adsorbed one by choosing the solvent which will solubilise only the drug not the matrix.
With respect ur adsorption analysis, Its depend upon the form of drug...if its in crystal form, crystals can be clearly seen in SEM or if its thickness of deposition is more......you can view that using SEM itself. else you can analyse through the XPS analysis. whats the property of drug, water soluble?
Thankyou Venkatachalam Natarjan. The drug is added during the preparation of the matrix, so I expect that it should be present on the inner pores as well, and not just on the surface. The experiments include more than one drug, two are water soluble, and the third one is hydrophobic. All three are amorphous in nature. All three are organic compounds.
Pertaining to my original question, do you mean that we can fracture the surface of the material and then estimate if the drug is present on the inner pores (through SEM)? How valid would that characterization be? And do you think we would need further validation for this through some other technique (FTIR/Elemental Analysis)?
Most of the drug will be inside the matrix(i.e with ceramic and polymers) if you would have included the drugs in your polymer and ceramic mixture just before casting into matrix.
So whatever in the surface can be proved by ATR-FTIR/XPS. Moreover you can conclude by hypothesis that, whatever the results you are getting(from ATR-FTIR/ XPS) in your surface of your sample will be the result of surface of inside matrix too (its depend upon your process of preparation of your matrix).
If you want to prove the concept further - you can confirm by slicing your matrix in different depths and analyse the presence of drug in the surface of that each samples by ATR-FTIR( i feel ATR-FTIR analysis and estimation of drug by simple wash of every slicing is enough to prove that the drug is also dispersed in surface. (SEM will not workout in your case).
Right. I agree with you on slicing the material and testing the presence of drug inside the matrix by FTIR, I think it would be a viable option. That is why I had my doubts about SEM in this case, because I believe we cannot prove much about the chemical composition of the visible moieties through SEM. Thankyou so much for the answer.
Dear Mariam,
If the chemical composition of the drug you are using is very different from the ceramic/polymer chemistry, for example it contain specific elements that are different from the composite, then you may still want to consider using SEM with EDXA (elemental microanalysis). You can analyse several cross sections of the sample.
I have added the foll9owing just to give you an idea: http://www.glafo.se/pdf/2006/sem_edx_analyses.pdf
Good luck
Basil
Raman microspectroscopy might also be an option. It has the advantage of high spatial resolution hyperspectral imaging, is not hindered by water (as oposed to FTIR). Hybriscan Technology offers a Raman microscope integrated with a SEM so you can measure your Raman, SEM and EDX images in one session.
If you can make a cross section of your matrix is should give you the distribution of your drug in your matrix I suppose.
Dear Basil Annaz and Rolf Wolthuis, thankyou so much for the suggestions. I might have to resort to using different equipments and doing these characterizations separately, but I will look into both options. Thanks again.
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