I am working on mesoporous silica nanoparticles. One can find the loading and entrapment efficiency using UV method. For example, I did the TGA for mesoporous silica from 30-900 degree celsius and also did TGA for Mesoporous silica with drug. The weight loss percentage of mesoporous silica is 8 % and mesoporous silica with drug is 37%. so drug loading percentage in nanoparticles = 37 - 8 = 29 %. This is correct or wrong?
Hello dear, It is possible since the silica is inorganic material and its thermal stability is highest regard to drugs. Best regrads
Hello Prabhuraj RS, this topic has been discussed previously on RG. You can find interesting answers there:
https://www.researchgate.net/post/How_we_can_calculate_drug_loading_on_NPs_through_Thermogravimetric_analysis_TGA/1
I already checked that link. I also rise a question there also. Thanks.
Dear Prabhuraj,
I have the impression your subtractive scheme might work. As stated by Yi Bao, at first one needs to analyze the whole TGA mass loss profile as function of the temperature program. Are the loaded vs not loaded samples TGA profiles similar? Is the additional mass loss for the loaded sample overlaps the not loaded? In case not, the steps are resolved, and you probably can infer directly the amount of drug sample by this step.
I would recommend to focus on the TGA curve evolution as function of temperature. In your question it seems to me you are reporting the total mass loss occurring in the range 30 - 900 degC which I guess is anyway a too broad temperature range to investigate.
Let's extend this reasoning with a conjecture: if your not loaded sample gives a mass loss of 8%, and your loaded sample of 37%, it might also be possible that some of the adsorption sites in the mesoporous silica are replaced by the drug. This means that the 37 - 8 = 29% is a lower bound of the present drug percentage.
Without you sharing the TGA curves (and heating rate used) is somewhat difficult to say more.
Dear Samuele Giani,
I did TGA for nanoparticle and nanoparticle with drug. Temperature range : 25 - 900 degree celsius. I found a paper recently online. I calculate drug loading with the help of that paper. I attach the image (drug loading %) and paper for your reference. Drug loading % calculated by UV method is 10.7%.Drug loading by TGA is 9.58%. one or two drug loading % by uv can be varied. Its not a big problem. I consider only 101-600 degree celsius. I am not consider from 25-100 degree because there will be presence of water molecules in that range. Give your suggestions. sorry for late reply.
very interesting paper
1) in the paper you cite the authors calculate the drug load as nanoparticle - nanoparticle with drug % based on the mass loss in the range 100-600 °C. For example S1/S2: 11.76-9.08=2.68%
2) in the paper the S4 result is a typo: the correct value should be 5.88%
3) so according to this scheme your drug load is 12.531-2.947=9.584%
for a refined calculation you could eventually better estimate the temperature interval of the second mass loss by plotting the DTG (first derivative of the TGA curve). In this way you can set the evaluation left limit corresponding to the inflection point in the TGA curve. The choice of 100 °C sounds a good theoretical value estimate (boiling point of water) but in the TGA experiment water desorption temperature can be shifted in temperature.
4) in the paper the mass loss steps are overlapping. Unfortunately there is no indication of the heating rate used. By slowing down the heating rate one can hope to have a better resolved (i.e. separated) transitions.
5) it bugs me a bit that the first step starts so abruptly and the TGA profile at high temperatures indicate that the mass loss continues: i hope they performed a proper blank subtraction. Have you also properly done this? This could have an impact on the results.
PS: the TGA image attachment went missing. only paper attached
I attached TGA Curve and drug loading calculation image for your reference.
it would be nice to have just NP and loaded NP profiles. Which heating rate did you use? Can you also perform a lower heating rate?
Heating rate : 10 degree celsius/min. Analysis was done in the following way
1) only nanoparticles
2) nanoparticles with drug
3) drug
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