By: Chandra Varney and Sophia Cai Mentor: Tanja Homrichhausen CURING CANCER Delivery of Hydrophobic Drugs By: Chandra Varney and Sophia Cai Mentor: Tanja Homrichhausen Dr. Michelle Bothwell

INTRODUCTION Scientists searching for a cure for cancer must create drugs that can pass clinical trials. One obstacle is that the majority of cancer-fighting drugs are hydrophobic, while bloodstreams are hydrophilic. In order to effectively mix the drug in your blood, emulsifiers must be used to prevent the drug from grouping together. Even if an emulsifier works well, sometimes only a small amount of the drug can be released into the bloodstream. An effective cure has a balance between how well its emulsifier works and how much of the actual drug is released.

Background: Emulsifiers Hydrophilic Head Hydrophobic Tail Surfactant Surfactants within a hydrophobic drug (heads are in the hydrophilic bloodstream).

Experiment 1: Emulsifier Effectiveness In the experiment, we tested different emulsifiers (Tween 80 and Lysozyme) to compare their effectiveness. We mixed an emulsifier with a hydrophobic drug and tested both the emulsifying activity and emulsion stability. Make buffer (fake blood) with a pH of 7.4. Homogenize buffer, drug (edible oil), and an emulsifier. Dilute mixture and test absorption level with a Spectrophotometer after 1, 2, 3, 4, 5, and 10 minutes.

Experiment 2: Drug Release Rate Ideally, the vast majority of the drug will be released into the bloodstream. The speed of delivery can be chosen, depending on the drug’s cause. Mixed hydrophobic drug with emulsifier (Tween 80) and dilute with buffer. Put samples into Centrifuge to separate the released drug from the oil (unused drug). Dilute with buffer and test absorption level. Compare results with a standard curve to see how much of the drug was actually released.

Definitions Emulsifier – substance that mixes a drug in the bloodstream (includes surfactants and proteins) Surfactants – emulsifier that has a hydrophilic head and a hydrophobic tail; mixes drug quickly for a short amount of time (ex: Tween 80) Protein – bulky emulsifier; mixes drug slowly, stabilizes quickly (ex: Lysozyme) Hydrophobic – “water hating,” attracts to other hydrophobic substances (non-polar substance) Hydrophilic – “water loving,” attracts to other hydrophilic substances (polar substance)

Homogenizer – a tool that blends substances together Spectrophotometer – tool that measures a liquid’s light absorption Centrifuge - tool that separates molecules of different densities by spinning quickly Emulsifying Activity - the mixed state just after mixing the drug and blood Emulsion Stability – a measure of how stable an emulsifier works by seeing how long it takes to reach emulsifier’s half life

Our Emulsifier Combined Tween 80 and Lysozyme to create our own emulsifier. Why? Tween 80 mixes the drug and blood almost instantly, but slows down in a couple minutes. Lysozyme mixes the drug at a slow rate, but stabilizes soon, instead of dropping its mixing rate. We created our own emulsifier with 75% Tween 80 and 25% Lysozyme. We hoped to create a drug that immediately mixes the drug and stabilizes before dropping in speed.

Conclusion By completing the two experiments on Tween 80 and Lysozyme, we learned: Tween 80 (a surfactant) immediately mixes the drug and the blood, but slows down its mixing rate exponentially. Lysozyme (a protein) doesn’t mix the blood and drug quite as instantly, but it does keep a consistent rate Our emulsifier successfully met our intentions. It did start higher than Lysozyme alone and stabilized at a higher rate than Tween 80.