Release Studies

Hi everyone,

This week, I set up and ran a drug release study. The goal of a drug release study is to measure the amount of drug released from a gel after a particular duration of time.

To set up the release study, I first mix the gels with a drug solution as described in last week’s blog post. After the gels are mixed, I squeezed approximately 200 milligrams from the syringe into a labeled vial. For each acid/salt used (sodium chloride, sodium sulfate, hydrochloric acid, sulfuric acid) and for each concentration of acid/salt used (0, .2 millimol, .35 millimol), I created three gels. In total, I had twenty-seven vials. After the gels are placed into the vials, they are covered by a solvent and set in a warm room, or a room that is kept around 37C.

Once the study is set up, the next crucial component is taking time points. In this lab, time points are times when some solvent is taken from each vial and placed into a tube that is labeled for the time and for the vial whose content it contains. The rest of the solvent from the vial is thrown out, and then new solvent is added to the vial. This week, I took time points at one hour (after set up), three hours, twenty-four hours, forty-eight hours, and ninety-six hours.

After the time points are taken, a test to determine how much drug was released at each time point can be performed. This is done by taking a small amount of each solvent from the tubes and placing it into an ultraviolet transparent plate (see first picture below). Then the plate is placed into a spectrometer (see second picture below) that sends a particular light through each well and records the absorbance. In addition to placing the solvent/drug solutions onto the plate, a group of standards is created and placed onto the plate. Standards are solutions in which the concentration of drug is known. This is important for calculating the amount of drug because it is from the standard solutions that a linear relationship can be made between the absorbance and the concentration of drug.

Over the past week, I performed all three of those steps. Now, I have to process the data from the spectrometer and examine how the drug was released. Hopefully, I can get this done soon and present it in this blog.

Russell Llave

http://www.isogen-lifescience.com/spectrostar-omega

http://www.usascientific.com/96-well-half-area-uvstar.aspx

Massing and Mixing

Hi everyone,

Over the past week, I have come up with my research plan (listed below) and have begun my project.

I will examine the effects of different acids and salts on the release of vancomycin. The salts I will be using are sulfate (SO4 -2) and chloride (Cl-), while the acids I will be using are H2SO4 and HCl. I will also hopefully use thiocyanate (SCN-) (a salt), which the lab just ordered. The reasoning behind the selection of these salts is the Hofmeister series, which, according to Wikipedia, is “a classification of ions in order of their ability to salt out or salt in proteins”. Although the gels are not proteins, the salt out and salt in principles are still applicable. Simply, salting in causes an increase in solubility, while the opposite is true for salting out.

After gels are created and mixed with the vancomycin and a specific salt or acid, the release of vancomycin will be recorded at multiple time points and hopefully, this analysis will result in a specific trend that states that a particular salt or acid alone can affect drug release a certain way.

With that in mind, this week, I created a polymer solution that contained the gel in a solvent and a drug solution that contained vancomycin and a salt or acid. This was accomplished Monday and Wednesday. On Friday, I mixed the solutions together by placing each solution in a syringe and linking the two syringes with a coupler (something that links two syringes). However, when I did this, I realized that I was left with a very small amount of gel. This is probably because when drawing up the solutions into a syringe, I have to use a specific tip. Some of the solution was left in the tip, which I threw away, causing a deficit in the amount of gel I needed. Because I did not have enough polymer or gel solution to add sufficient mass to the syringes, I had to make even more solutions. This I accomplished after realizing my mistake, and I hope to finish mixing the gels on Monday.

This is my first week where I really performed lab work (last week was mostly planning). Having not been in lab for so long, I was clumsy, lost, and confused often. I did not know where to find certain materials. It took me a very long time to perform simple tasks such as getting a certain mass of a material. Furthermore, I made a mistake that requires me to redo hours of my work. Nevertheless, the more time I have been in lab, the more I’ve comfortable I become, and hopefully, I will make less mistakes in the future.

Russell

First Day

Hi everyone!

Yesterday I spent my first day at Arizona State University.

On Tuesday, my sister, an Arizona State junior majoring in biomedical engineering (my intended major), invited me to shadow her throughout the day when I was not in lab. At 8 a.m., I attended her Biomaterials class with her where I learned about the degradation of three different materials: metals, ceramics, and polymers. Fortunately, the part of the lecture about the degradation of of polymers related to the research done at Dr. Vernon's Biomaterials lab, the lab where I am performing my senior research project. In addition, after I finished my time in lab, I visited my sister's Micro-computing class and learned more about circuits.

After her first class, I went to lab and talked to my mentor, Dr. Overstreet. He first updated me on the research that has gone on in the lab ever since I left over the summer. Afterwards, he gave me more information and specificity about my project.

I will be studying the effects of different acids and salts on the hydrogels created in the lab. Over the next week, I will be creating a research plan deciding which salts to use and calculating the quantities of all the materials. Hopefully, next week, I will be able to really begin my project.

And here are the pictures of the inside and outside of the building where my lab is, ISTB1.




Russell Llave

Picture 1: http://www.kpff.com/portfolio/project/arizona-state-university-istb-1
picture 2: https://cfo.asu.edu/fdm-leed-istb1