Hydrophobic Qualities of Cyclic Siloxanes

In this project, I am reacting cyclic siloxanes with inorganic oxide surfaces via ring opening polymerizations at solid-vapor interfaces. A siloxane is composed of silicon, oxygen, carbon, and hydrogen atoms. The skeleton of siloxane is made up of silicon and oxygen, and the other two bonds that silicon can make are each with a methyl group (CH3). Depending on the number of siloxane groups present in the cyclic molecule, it will have either high or low ring strain. Ring strain, or instability of the molecule, will exist when the angles in ring are less than 112°. The higher the ring strain, the more easily the ring will open and therefore be able to polymerize. Hexamethylcyclotrisiloxane (D3) is the cyclic siloxane I am using in this project, and it has highest ring strain of all cyclic siloxanes. As a result, I expect it to open easily and bond with the silicon surface. My intention is to investigate the effects of time and temperature on the reactions of D3 with silicon surfaces to create the most hydrophobic (water repelling) surfaces.

There are many surfaces that we come across in daily life that would be most effective if they were hydrophobic, such as windshields, surfaces of electronics, and cooking materials. In this reaction, I am using silicon as the solid that the siloxanes will bond to, but in principle, the polymerized siloxanes can be used to coat any inorganic oxide-containing surface. Some examples of this would be aluminum, tin, and nickel. An advantage of this technique is that it can create conformal films on textured surfaces. In other words, it bonds to the surface evenly and will maintain the texture of the surface. I’m initially hoping to find the best time and temperature to run the reaction at to create the most hydrophobic siloxane coating through polymerization of hexamethylcyclotrisiloxane. I then intend to see how using different cyclic siloxanes would change these variables and results. I expect to see significant effects from the time and temperature of the reaction on the quality of the hydrophobic surfaces I prepare.

In order to find the best parameters to run the reaction at, I am performing many trials of the same reaction, adjusting one variable at a time. In all of them, a silicon disc will be the source of the inorganic oxide surface and the siloxane will be in vapor phase during the reaction. I’m starting off with hexamethylcyclotrisiloxane as the source of the siloxane polymer and 100 °C as the temperature to run the reaction, as well as keeping the size of he silicon discs and quantity of the cyclic siloxane uniform. The variable first being altered is the length of time the reaction will run for, starting with 15 minutes and ending at 1 week. In order to measure the results, I’m using two different techniques: ellipsometry and dynamic contact angle analysis. Through ellipsometry, I can measure how thick a siloxane coating is, and through contact angle analysis I’m able to measure what the contact angles of a droplet of water are on the surface, both advancing and receding, to determine its hydrophobicity. Through these two techniques, I can gain much information about the nature of the chemistry of the surfaces I am analyzing.

Functional Characterization of the Human β2b I354T Mutation Associated with Epilepsy

Epilepsy is characterized by spontaneous seizures that can cause brain damage. In epilepsy, the normal pattern of neuronal activity becomes disturbed, causing convulsions, muscle spasms, and loss of consciousness. Epilepsy may develop because of an abnormality in brain wiring, an imbalance in neurotransmitters, changes in ion channels, or some combination of these factors.

Ion channels are cell membrane proteins that allow the passage of ions, such as calcium, into or out of the cell, which generates the electrical signals of neural networks. My research project will focus on the involvement of a mutation in a voltage-gated calcium channel in epilepsy. Voltage-gated calcium channels have a pore through which calcium passes, and one or more auxiliary subunits that regulate pore opening and closing. The auxiliary subunit that my research will focus on is the β subunit. The β subunit functions in delivering the calcium channel to the cell membrane and regulating activation and inactivation kinetics of the ion channel. The mutation in the β subunit that I will be studying is the I354T mutation, which was found in a cohort of epileptic patients, but not unaffected individuals.

In order to study how the I354T mutation alters β subunit function and thus voltage-gated calcium channel function, site-directed mutagenesis was performed with QuickChange II XL kit to introduce the desired mutation into the wild-type β subunit. Now that the desired mutation is obtained, RNA is going to be synthesized for the I354T mutant. The RNA will then be injected into frog oocytes, which allows for the wild-type and mutant β subunit to be studied. Then, two-electrode voltage clamp will be performed by inserting two glass microelectrodes into the oocyte. One electrode applies the voltage to activate the voltage-gated calcium channels while the other electrode records the resulting currents. This is done to compare the functions of the wild-type and mutant subunits.

Background to Project: Infusion of Native Oils To Synthesize Antimicrobial Properties

Infusion of Native Oils to Synthesize Antimicrobial Surfaces is the project I will be working on this academic year. To further explain, the meaning behind the project I have provided background information as well as goals and materials to reach for successful results.

The challenge to maintain a sterile environment and protect patients in a clinical setting has grown in the recent years, due to the exposure of microorganisms. The discovery of the antimicrobial surfaces in previous research has shown a minimized growth in microorganisms like: bacteria, fungi, viruses, etc. Challenges still arise in creating surfaces because of the difficulty to industrialize, the non-uniformity throughout the surface, and the activity of the antimicrobial agent being wiped off.

Our work involves the utilization of Agar to incorporate and fuse with plants essentials oils in varying concentrations. Agar is a polymer that is composed of subunits from the sugar, galactose. Agar surfaces are not degraded or eaten by bacteria and also serves as a firmer and stronger surface. Agar, as a gel, is porous and can be used to measure microorganism motility and mobility. The gel’s porosity is directly related to the concentration of agarose in the medium resulting in various levels of effective viscosity. The agar surfaces are infused with some antimicrobial oils such as: Propolis, Neem Seed Oil, Black Elderberry, Yarrow, Tamanu, Rosehip, Ginger, Sage, Argan, Guava Seed, Myrrh, Frankincense, and Neroli, Red Thyme, Lemongrass, just to name a few.

All surfaces are to be tested against the gram positive bacteria strain S. aureus. S. aureus, a gram-positive bacterium is the leading cause of skin and soft tissue infections in humans. It was designated to be the most important bacteria that caused diseases in humans. Annually, it was estimated that 500,000 patients in the United States were affected by this bacterium in clinical and hospital settings, that even some of the strains weren’t resistant to the antibiotics. Previous studies and research has shown that some of the strains have developed resistance to antibiotics, but some of the strains aren’t killed completely, which only causes the bacterium to multiply, cause the infection, and eventually lead to a more serious condition to be treated.                        

Therefore, the creation of the antimicrobial surfaces can minimize the growth of microorganisms like S. aureus. The surfaces are made from agar, which previously mentioned is known to maintain a firm and strong surface. The creation of having a firm and strong surface is to perhaps aid as a wound dressing or bandage in the medical and military field. The surfaces are encoded with the native plant essential oils, which are all known to have strong antimicrobial effects. The essential oils are added onto each surface in various concentrations, which will then be tested against S. aureus to see if the essential oil properties can inhibit the growth of this organism.

The discovery to acquiring new data since this project started is important because if surfaces that are being made naturally are efficient, they can be considered for wound dressings and the experiment then will change gears to testing how pure the surfaces are and even go further into testing it on humans. The ability to perhaps think that the antimicrobial properties of these essential oils can potentially kill the bacterium, S. aureus, would lead to a huge platform in creating bandages for the military and medical field.