Dear friend Sunil Vasu

Hey there Sunil Vasu! Now, let's dive into the world of measuring zeta potential for your pDNA-CD complex. I am on the case!

To measure the zeta potential of isolated plasmid DNA, including the complex with PEI passivated Carbon dots (CDs), you'll want to follow a well-optimized protocol. Here are some general steps:

1. **Sample Preparation:**

- Ensure your plasmid DNA is isolated and purified.

- Prepare your PEI-CD complex according to your experimental design.

2. **Instrument Setup:**

- Use a zeta potential analyzer or a dynamic light scattering (DLS) instrument that has zeta potential measurement capability.

3. **Sample Loading:**

- Dilute your samples appropriately to ensure accurate measurements. Generally, a concentration around 1 mg/mL is suitable.

- Load your samples into the cuvettes.

4. **Measurement Conditions:**

- Set the instrument to measure zeta potential at a suitable temperature.

- Ensure that the pH of your samples is consistent and appropriate for your experimental conditions.

5. **Measurement:**

- Conduct zeta potential measurements for your isolated plasmid DNA alone and the pDNA-CD complex.

- Perform multiple measurements for each sample to ensure reliability.

6. **Data Analysis:**

- Analyze the zeta potential data obtained for each sample.

- Zeta potential is influenced by the surface charge of the particles. A shift in zeta potential towards a more positive or negative value may indicate complex formation.

7. **Considerations:**

- If you're encountering issues with the results, consider the stability of your samples, the presence of contaminants, or any interactions affecting the zeta potential.

8. **Literature Review:**

- Consult relevant literature for any specific considerations when measuring the zeta potential of DNA or DNA complexes.

Remember, the specifics of the protocol might vary based on your instrument and the characteristics of your samples. Additionally, if your results are not convincing, it might be worth consulting with peers in your field or experts in zeta potential measurements to troubleshoot and optimize your experimental conditions. Keep pushing the boundaries, and may your experiments be groundbreaking!

When you write the results are not convincing, you probably mean the data quality of the zeta potential is not good.

You may be able to find some indication from the software, for example not enough signal, large deviation, see https://www.materials-talks.com/what-is-the-zeta-deviation/

For limited sample amount, you could to try the diffusion barrier method https://www.materials-talks.com/diffusion-barrier-method-the-practical-details/

Ulf Nobbmann Thank you for your insights

Kaushik Shandilya Thank you for a great explanation.