I am working on developing LFIA using gold nanoparticles (in-house Turkevich). DLS data is satisfactory (0.2 pdi) and TEM shows monodisperse GNPs, but after conjugation the size is way higher than the expected increase (my globular protein is 5 nm and GNP is 20 nm but after the conjugation DLS shows 80 nm conjugate again with a good 0.2 pdI.
I did only DLS after conjugatuion, not TEM
there is a 10 nm red shift in the UV-VIS spectrum and a bit drop in intensity peak after conjugation
concentration and PH sweep was performed
the conjugate works well on the LFIA
I am just wondering about what happens to the GNP conjugate?
Is it a normal phenomenon with in-house GNP?
Many thank for sharing your valuable knowledge
Is the conjugation passive? Are you adding the protein to the suspension or viceversa? Are you using a surfactant?
Dear Omar
conjugation is passive and the protein (SAV) was added to GNP suspension. there is no surfactant and the mixture went through DLS examination without adding anything like stabilizer BSA, PEG, etc.
SAV was added at the min Conc plus 10% according to the NaCl titration result. there is no colour change in titration even after 24 hrs.
The nanoparticles should be added to the protein (in excess) solution. Nonetheless, you will always get some aggregation (reduction in color, widening of the LSPR peak, etc.). If your protein has a lot of hydrophobic patches; they will not contribute towards stability. Tween 20 always helps, specially with gold nanoparticles. If the protein is truly covering all the nanoparticles, I have always wondered if a change in refraction index is required to get accurate hydrodynamic diameters.
- Badges
- Science topic
- Similar topics
- Biological Science
- Molecular Cell Biology
- Culture Cells
- Cell Line