Hi all,
I cannot resuspend nanoparticles (ZIF-8, UiO-66 and UiO-66 Peg) in water without them immediately forming a pellet and sinking. I tried pipetting up and down and vortexing for a few minutes, bit nothing helped. They did not deliver mRNA to cells either. Any suggestions?
Thanks,
Maria
Maria Victorova , some options if you haven't tried them yet:
1. reduce the amount of NP powder you are trying to resuspend in water (Milli-Q?);
2. ultrasonicate the suspension for 10-30 min or longer;
3. change the solvent, for example, saline solution, instead of water, but you will need to check the stability of NPs.
As for drug (target molecule) delivery issues:
1. mRNA is very susceptible. If your nanocarrier system is not properly protecting mRNA, it can undergo enzymatic degradation in the cell culture medium.
2. Nanocarriers can degrade/aggregate or undergo modification in cell culture media, thus failing in function or reducing drug delivery efficiency.
Try to check the stability of your NP samples with and without the loaded drug/molecule in a solvent (water/buffer) and cell culture media.
A few publications that could be useful:
Article Synthesis and modification of ZIF-8 and its application in d...
Article Synthesis of the Metal-Organic Framework UiO-66 in the Form ...
Article Stability of ZIF-8 in water under ambient conditions
Article ZIF-8 Degrades in Cell Media, Serum, and Some-But Not All-Co...
Article Transcellular Delivery of Messenger RNA Payloads by Cationic...
Hi, Susanna Gevorgyan is right. Generally speaking, nanoparticles aggregate together in a dry state. Resuspending them requires breaking them apart - that's what ultrasonication is for. You need a high-intensity US tip which can cause cavitation. Cavitation generates a strong local shear field separating the particles. Low-power US bath is usually insufficient. However, it is equally as important to stabilize the dispersed nanoparticles and prevent re-agglomeration. You can either use a charge-repulsion which is controlled by the solvation of the particle surface with solvent molecules, i.e., by choice of solvent. The zeta potential should be at least 10 mV, positive or negative, but ideally more than 20. Another possibility is interaction with a polymer (RNA in your case) that can adsorb on the particle surface and provide sterical stability. The condition is that the polymer is adsorbed in brush-like conformation, repelling the brushes adsorbed on other particles. To make that, the polymer has to have the right affinity to the particle surface (not too weak, not too strong). That also partially depends on the type of solvent due to the competing-interaction mechanism in solutions. The polymer cannot break the aggregates though, so it is ideally introduced to dispersed particles or present during the ultrasonication. Otherwise, it will adsorb on the aggregated particles. If you are interested, I provide a link to our studies on this topic:
Article Phase diagram of bare particles in polymer nanocomposites: U...
Article Thermodynamic Parameters Controlling Nanoparticle Spatial Pa...
Article Bulk Polymer Nanocomposites with Preparation Protocol Govern...
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