Weeks 6 and 7: Initial Observations Continued

Hi everyone and welcome to weeks 6 and 7 of my blog! In these last weeks, I was trained on how to carry out dynamic light scattering (DLS) and light microscopy (LM) to help me characterize my microspheres. Based on what I see from these tests, I will make some edits to my protocol to improve and optimize it.

To do light microscopy on the sample, I placed 20 μl of the silk sphere suspension under an inverted light microscope and then I used the installed software to visualize the details of microspheres at a x40 magnification. From the images, I was able to see the general spread of the microspheres throughout the solution. As indicated by the SEM images I took from the prior week, the LM images showed that the microspheres were not evenly distributed throughout the supernatant and sometimes agglomerated. Agglomeration occurs when smaller microspheres are associated into a cluster composed of two or more particles. Agglomerates decrease the number of microparticles at a constant filler concentration. Therefore, the clustering of particles should be avoided as much as possible which helps to ensure a more even release of CUROSURF surfactant drug in the lungs of infants with NRDS.

The DLS characterizations helped to describe the size distribution profiles of the microspheres. This was done through a value called the polydispersity index. The polydispersity index (PDI) describes the width or spread of the particle size distribution; a PDI closer to zero means a more homogeneous sample of microspheres size, while a higher PDI (closer to one) indicates a more polydisperse or aggregate sample. In beginning trials, the DLS data showed that the initial microspheres samples had a PDI of 0.98.

Now that I have data and observations from this first initial trial of microspheres, I will make adjustments in the methodology to account for the changes that need to be made. Specifically I will focus on how I can improve the sizing and spread of the microspheres.

See you next week!