1. Results Problem Drug discovery involves a titration process in which the effects of different concentrations of potential drug compounds are analyzed. Current methods of analysis involve steps which are labor intensive, error prone and, more importantly time consuming. Traditional Method Thermal Inkjet and Titration Tool A B Solution Thermal Inkjet Technology Hewlett Packard Titration Tool and Print Head • Two jittering methods were tested for mixing results: Jitter- while- dispense (JWD) and Jitter- post- dispense (JPD). • JPD has been determined to be the optimal mixing method for both large and small dispense volumes, based on the slopes in the data plotted above. • Plot A displays results for 50 nL dispense volume, and plot B displays results for 200 nL dispense volumes. Thermal Inkjet Dispense for Pharmaceutical ResearchLindsey Rucker, Hugh Hobbs, AhsonSaeedSchool of Chemical, Biological, and Environmental Engineering HP applies their thermal inkjet printing technology to simplify the drug titration method. One HP consumable print head is loaded, which is capable of dispensing over a range of 15 pL to 1 µL. This leads to reduced labor costs and time requirements, and increased precision. In essence thermal inkjet technology consists of a resister and a fluid reservoir. The resister is positioned directly under (above) the filling reservoir. The resistor rapidly heats the fluid forming a bubble which pushes a drop of ink out of the nozzle. 16 of the nozzles depicted at the left are present on the printer heat used in the instrument. HP Direct Titration Method • Simplifies drug titration method • Leads to reduced labor costs • Reduction in time Improvements Over the Old Method Proposal Traditional Method HP Method Is Mixing Achievable? Qualitative Method Bond Number: A ratio of the body forces to the surface tension forces. A bond number less than 1 indicates that the surface tension forces are dominating the body forces. Jittering Method “Jittering”: oscillation of the well plate using the stage to induce shear between the deposited fluid, and fluid already in well. The stage can oscillate in the front to back direction (FB) or dual axis (FBLR). Challenge: Why Mixing Is Necessary • The team recommends to use JPD in the FBLR direction for larger dispense volumes. JPD is also the optimal mixing method for small volumes, however, stage direction requires further testing. • It is recommended to further investigate the jitter time and amplitude for both large and small dispense volumes. r=fluid density α = acceleration due to gravity L = radius of capillary tube g= surface tension of the interface • DMSO penetrating in single point • Cell death caused by high concentration at points of penetration. Cell death Quantitative Method A significant change in counts is caused by the solution not being fully mixed. Once the fluorescence signal, or counts, reaches a steady level, the conclusion can be made that mixing has occurred. This has been determined to be the best method to quantify mixing using kinetic data. No Jitter Acknowledgements Immediately after dispense 5 seconds after dispense 1 minute after dispense • The Engineering Team would like to thank: • Hewlett Packard • Kenneth Ward • Heather Paris • Ken Duda • Michael J Day • Philip H Harding No Cell Death Jitter Immediately after dispense