How do I make DLS measurements with DMSO in my solvent? - WKB319064
ENVIRONMENT
- DynaPro® Plate Reader III
- NanoStar®
- DYNAMICS software
- Aurora® Microplates’ cycloolefin plates
- Whatman™ polypropylene-based Anotop™ filters
- Quartz cuvettes
ANSWER
To perform DLS measurements with DMSO, use fresh, filtered solvents and ensure compatibility with your instrument and accessories. The DynaPro Plate Reader III and NanoStar are both suitable, with NanoStar preferred for volatile organics. Adjust solvent and sample parameters in DYNAMICS, including refractive index and viscosity. Always include a DMSO-based negative control to ensure data integrity. Use appropriate microwell plates and filters to avoid contamination and maintain measurement quality.
ADDITIONAL INFORMATION
How do I make DLS measurements with DMSO in my solvent?
Dimethyl sulfoxide (DMSO) is commonly used to study small-molecule drug compounds and can be used in DynaPro® Plate Reader or NanoStar®. Key considerations include cleanliness, compatibility, and proper parameter settings in DYNAMICS software.
Challenges working with DMSO
DMSO is hygroscopic and can easily absorb contaminants. Use filtered DMSO and clean glassware to avoid unwanted particles. The document shows a comparison of filtered vs. unfiltered DMSO using autocorrelation function (ACF) data.
Recommendations for DMSO
- Use fresh, filtered solvents and clean glassware.
- Ensure chemical compatibility with DMSO.
- Use Whatman™ Anotop™ filters for filtration.
- Use Aurora® cycloolefin plates for Plate Reader experiments.
- Exercise caution with high DMSO concentrations and elevated temperatures.
- Remove uncovered well plates after experiments to prevent evaporation damage.
Experiment parameter considerations for high-quality DLS data
Define an appropriate custom Solvent:
Set correct refractive index and viscosity values in DYNAMICS. For pure DMSO at 589 nm and 20°C, use aRI = 1.47 and viscosity = 2.24 cP.
Sample dn/dc (for Mw-S measurements):
Adjust dn/dc values in DYNAMICS based on the solvent. DMSO lowers the sample's dn/dc compared to water.
Assigning parameters
OPTION 1: Plate Templates (Plate Reader)
Assign parameters using Plate Templates before or after data collection. Excel can be used for bulk parameter assignment.
OPTION 2: Event Schedule (NanoStar, Mobius)
Use Set Sample Name command to assign parameters before data collection.
OPTION 3: Sample node (All DynaPro instruments)
Assign parameters post data collection using the Sample node.
Running experiments in DMSO
Optimizing the solvent offset/baseline scattering intensity:
Ensure sample intensity is 2–3x that of pure DMSO to maintain signal-to-baseline ratio.
Always include a negative-control for your solvent:
Prepare a DMSO-negative control with the same concentration and buffer as your samples to ensure consistency and troubleshoot contamination.