Hello everybody!
I fabricated a nanoparticle composite and after a certain amount of drug, the loading capacity decreased. for example, the loading capacity increased until 40 mg and after it in 50mg of the drug, the loading capacity was decreased.
One of the reason is the saturation of the drug solution causing aggregation
Did you add the drug in increase volume?
Increasing additives (in this case drug) after a certain limit can cause disruption of physical bonds present among polymer chains. That is why we optimize the concentration of additives. In your case, 40mg is optimized concentration of that drug. Increasing or decreasing it can cause unfavorable results.
Most complex nanopreparations are a combination of a carrier and an active substance (load). The carrier is a composition that can form nanoparticles of the desired size. The active substance usually cannot do so, so it is added to the carrier. Different carriers produce particles of different sizes and with different properties (pH-dependence, etc.) The mechanisms of incorporation of the substance can be very different. The general rule of thumb is that there is a limit to carrier saturation, when the excess active substance can no longer be incorporated into the carrier. This is exactly what you are observing. This limit can be determined experimentally. In general, the maximum particle load depends on the nature of the carrier, the active substance, and the technology for producing the particles. In case of long-term storage the particles may lose part of the active substance due to possible changes in the structure of the particles during storage. Even if it is a lyophilizate stored in the freezer.
Henry Kolge Hello Henry
Thank you for your answer and help. No, I add the drug in a constant volume.