Aris Zhu

Aris Zhu, Hamilton High School, Chandler, Arizona

CASA: A Novel Intracanal Medicament for Endodontic Infections

Currently, calcium hydroxide (CaOH) is used as an intracanal medicament to treat root canal infections. However, CaOH paste is ineffective against persistent bacteria Enterococcus faecalis and fungus Candida albicans, which may give rise to health conditions including heart valve infection or periodontitis, respectively. Furthermore, the high pH of CaOH causes dental pulp necrosis, which delays tissue healing. To improve antimicrobial properties and limit cytotoxicity, salicylic acid was added in a 3.7:1 mass ratio to create a neutral paste to disinfect the canal. Using a modified disk diffusion antibiotic sensitivity test, CASA was plated with common endodontic microbes in a root canal infection to determine its antimicrobial activity. CASA produced larger zones of inhibition than CaOH for all species tested, indicating that CASA is the more efficacious antimicrobial agent. Notably, CASA yielded an inhibition zone 2.76 times that of CaOH in the presence of E. faecalis. Cytotoxicity studies and observation of dental pulp stem cells (DPSCs) under fluorescence microscopy indicated a high tolerance for DPSCs for CASA with a measured IC50 of 0.25 mg/ml, a far higher dose than tissue would be exposed to during standard treatment. Viability staining with E. faecalis and C. albicans confirmed the antimicrobial properties of CASA precipitate. CASA was found to be dosage dependent with increasing concentration resulting in greater bacterial lethality against S. aureus and E. coli. Because CASA was found to have greater antimicrobial effect and biocompatibility to dental pulp, CASA has the potential to replace CaOH in treatment for recurrent root canal infections.

Nikita Kumari

Nikita Kumari, Arizona State University (Graduate Student)

Diving Deep into the Red: Novel Cyanine Dyes for Super-Resolution Imaging

Fluorescent probes help biologists illuminate the inner workings of cancer cells. In this work, we study the photophysical properties of a novel class of far-red fluorescent probes that could allow live tissue to be imaged in greater depth and detail than is possible with current techniques. One of the limitations for super-resolution fluorescence microscopy techniques is the low brightness of the fluorophore which dictates signal-to-noise ratio for the fluorescence detection. The low brightness of the fluorophore could be because of various non-radiative decay pathways from the excited state to the ground state of the molecule which competes with the radiative pathway, decreasing the fluorescence quantum yield. The most prominent non-radiative pathway for cyanine fluorophores is the ability of an excited-state electron to go from trans (fluorescent form) to cis (non-fluorescent) state which is known as photoisomerization. We attempt to eliminate this trans-cis photoisomerization to happen by rigidifying the backbone of the cyanine. We applied this strategy on pentamethine cyanine dye which is a far-red cyanine fluorophore. The photophysical characterization of the newly synthesized restricted dye in comparison to traditional pentacyanine showed that the installation of the ring system restricts the photoisomerization, showed by temperature-independent emission, and solvent viscosity independent properties. The resulting molecule exhibit the characteristic features of conformational restraint, including improved fluorescence quantum yield and extended lifetime. The new rigidified molecule was found to have desired photophysical properties and improved the quality of super-resolution image obtained.

Elizabeth Fear

Elizabeth Fear, Horizon Honors High School (research conducted at the University of Arizona)

Effect of Hydration on Rhodopsin Activation

Rhodopsin, responsible for vision under dim light, is a prominent member of the G-Protein Coupled Receptor (GPCR) protein class which is targeted by a third of all pharmaceuticals. Two states of rhodopsin exist in physiological equilibrium: active and inactive. We hypothesized that hydration plays a crucial role in the shift to the active conformation. The fraction of active rhodopsin is quantified via UV-visible absorbance spectroscopy upon light exposure in the presence of various dehydrating osmolytes that generate osmotic pressure. We found that water does play an influential role in rhodopsin activation and that dehydration with osmotic stress favors the inactive state. As countless physiological processes involve GPCRs, greater insight into the relationship between water and rhodopsin activation can enable treatments of GPCR dysfunction across human anatomy.

Swapnika Raola

Swapnika Raola, University of Southern California (Undergraduate Student)

End-point PCR Analysis Using Capillary Flow as an Alternative to Gel Electrophoresis

We are finding a faster alternative to gel electrophoresis for template DNA identification. Using the same primer, bacteria strains Escherichia coli K-12 and O157:H7 form different amplicon lengths. We believe that amplicon length can affect capillary flow through interfacial tension.

Thus, we ask, “Does differing amplicon length and interfacial tension affect the capillary flow of  escherichia coli K-12 and Escherichia coli O157:H7 DNA solution?” If so, bacteria can now be identified through analysis of capillary flow, a process that takes two minutes rather than gel electrophoresis’s two hours. We found there are significant differences in capillary flow between the two strains and found that interfacial tension is probably the mechanism. Therefore, researchers can use our capillary flow model as a faster alternative to gel electrophoresis.

Hersh Nanda

Hersh Nanda, BASIS Chandler/ASU Science Program (High School Student)

An innovative polydimethylsiloxane microfluidic biosensing platform for rapid detection of viruses

The objective of this research project was to develop an innovative procedure for the fabrication of a versatile PDMS (polydimethylsiloxane) microfluidic device that is capable of detecting viruses and small molecules. The detection of these analytes is accomplished by integrating a gold biosensor with the PDMS microfluidic device and using a process called surface detection – a process wherein the gold biosensor allows glycoproteins (secreted by viruses) and small molecules to bond to it. The detection of the small molecules is directly observable while the detection of a virus is by inference by examining the glycoprotein(s) that are associated with the virus. This device falls in the category of lab-on-a-chip (LOC) devices that integrate one or several laboratory functions on a single highly miniaturized device.

The three main steps in the design procedure were: fabrication of gold biosensor, development of PDMS mold (or, PDMS mold making), and device validation (through a process called sensing).

After the device was produced, tests were run using LabSpec software to validate the biosensor capability and sensitivity in detecting viruses such as Ebola virus (through prior empirical data) and small molecules such as cannabidiol (CBD). This device, by virtue of its design, is capable of detecting any virus as long as the virus secretes a glycoprotein, and there is a molecule that is able to bond that glycoprotein to the biosensor. Therefore, this device is potentially capable of detecting influenza virus, SARS-CoV, hepatitis C virus, and even the novel COVID-19.

This device has broad application in biomedicine and offers a several benefits which include but are not limited to versatility in detection of diverse analytes (including new viruses), ability to detect analytes with small sample size, increased efficiency (less time to fabricate the device and quickly scale production to large volumes), lower production cost, device portability in the field, and ease of use for healthcare professionals.

The conclusions from this project are also applicable to the current COVID-19 pandemic, in which countries are dealing with shortages in testing kits for diagnosis. This project demonstrates that there is a less expensive and more efficient method for rapidly diagnosing infectious diseases, which can significantly enhance the ability of countries to rapidly detect and isolate infected people during pandemics and save human lives.

Note: This project was conducted through the ASU-SCENE program under the supervision and guidance of Assistant Professor Dr. Chao Wang, and a PhD student, MD Ashif Ikbal at the Nanoscience and Biotechnology labs at Arizona State University.