Dear friend Noor Ul Ain

The polydispersity index (PDI) is a measure of the distribution of particle sizes in a sample. A PDI value of 0 indicates that all particles are of the same size while a value of 1 indicates that there is a wide range of particle sizes in the sample (How to interpret value of PDI ? | ResearchGate).

In general, a PDI value below 0.3 is desired for pharmaceutical nanoparticles. However, there is no general limit for acceptable polydispersity (What is PDI in particle size? - Studybuff).

A lower PDI indicates a more homogeneous sample with particles that are more uniform in size. Depending on your application, you can choose a PDI value. For my sensing applications, I considered metal nanoparticles of PDI below 0.15. PDI is basically the ratio between the standard deviation of Particle size distribution and mean particle size. Basically, if your PDI value is 0.15, then 15 % of your particles are polydispersed and the rest 85% are monodispersed i.e, uniform size.

Less than 0.5 pdi value indicates homogenous and stable particles and will be suitable for further work.

Thank you for your responses. Kaushik Shandilya the results of particle size with PDI values I obtained, the one with 0.7 and 1. In report 0.7 was referred to checked and 1 was considered as good quality. However, literature says the otherwise.

Dear friend Noor Ul Ain

It's possible that the report you are referring to has a different interpretation of PDI values than what is commonly accepted in the literature. As you mentioned earlier, a PDI value closer to 0 typically indicates a more homogeneous size distribution of nanoparticles, while a value closer to 1 indicates a wider range of particle sizes in the sample.

It's important to note that the ideal PDI value may depend on the specific application and requirements of the nanoparticles. In some cases, a wider size distribution may be acceptable or even preferred. However, in general, a PDI value closer to 0 is often considered to be better for most applications.

Therefore, I would recommend checking with your advisor or colleagues in your field to clarify the interpretation of PDI values and what would be considered a good value for your particular application.

Sure, here are some references related to your question:

- Malvern Panalytical. (n.d.). Polydispersity index (PDI) - what does it mean for your particle size data? Retrieved from https://www.materials-talks.com/blog/2019/06/03/polydispersity-index-pdi-what-does-it-mean-for-your-particle-size-data/

- Burch, J. (2019). Understanding polydispersity index (PDI) in dynamic light scattering (DLS) measurements. Retrieved from https://www.news-medical.net/life-sciences/Understanding-Polydispersity-Index-(PDI)-in-Dynamic-Light-Scattering-(DLS)-Measurements.aspx

- Kim, H. J., & Kim, J. (2014). Synthesis of gold nanoparticles and their applications. Journal of Nanoscience and Nanotechnology, 14(1), 7-30. doi: 10.1166/jnn.2014.9178

- Kumar, S., Kumar, S., & Kumar, R. (2015). Effect of size and polydispersity of gold nanoparticles on their cellular uptake and cytotoxicity. Journal of Nanoparticle Research, 17(5), 210. doi: 10.1007/s11051-015-3032-6

- Zong, H., & Liu, G. (2016). Recent progress in the synthesis of gold nanoparticles with controlled morphologies and their applications. Reviews in Nanoscience and Nanotechnology, 5(1), 47-62. doi: 10.1166/rnn.2016.1159