Bulletin of the American Physical Society
84th Annual Meeting of the APS Southeastern Section
Volume 62, Number 13
Thursday–Saturday, November 16–18, 2017; Milledgeville, Georgia
Session B2: Biophysics and Medical Physics |
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Chair: Sharon Careccia, Georgia College Room: MSU Building University Banquet Room B |
Thursday, November 16, 2017 11:00AM - 11:12AM |
B2.00001: Novel exchange-coupled core/shell nanoparticles for advanced magnetic hyperthermia Caroline Collins, Joshua Robles-Garcia, Raja Das, Manh H. Phan, Harry Srikanth Of any disease, probably the most well-known is cancer, and while there are treatments available, a new form of treatment is needed that is safer for the patient. Studies on magnetic nanoparticles (MNPs) have shown their promise in biomedical applications, such as magnetic hyperthermia, which employs MNPs for localized destructive heating of cancer cells. It has been found that as the size of the MNP decreases, the heating efficiency drastically decreases. Recently, however, a large improvement in heating efficiency has been reported in exchange-coupling of MNPs between a soft and a hard magnetic material. In this study, we optimized the heating efficiency of exchange-coupled MNPs composed of a soft magnetic core (Fe$_{\mathrm{3}}$O$_{\mathrm{4}})$ and a hard magnetic shell (CoFe$_{\mathrm{2}}$O$_{\mathrm{4}})$ by tuning both the shape of the nanoparticles and their concentration in solution. The MNPs show high magnetization (\textasciitilde 80 emu/g) and superparamagnetic-like behavior at room temperature. We compare the specific absorption rate (SAR) for each set of MNPs and correlate the results to shape distribution and concentration in solution. This study shows that exchange-coupled MNPs for magnetic hyperthermia are promising as route for non-harmful cancer treatment. A new approach for controlling the inductive heat for cancer treatment using a mixture of spheres and cubes is proposed. [Preview Abstract] |
Thursday, November 16, 2017 11:12AM - 11:24AM |
B2.00002: Simulating nanoscale particle suspensions using a coupled lattice-Boltzmann and Langevin-dynamics method: application to particle transport in cellular blood flow. Zixiang Liu, Yuanzheng Zhu, Rekha Rao, Jonathan Clausen, Cyrus Aidun A novel computational approach coupling the lattice-Boltzmann (LB) method and a Langevin-dynamics (LD) approach has been developed to simulate nanoscale particle (NP) suspensions in the presence of both thermal fluctuation and many-body hydrodynamic interactions (HI). The Brownian motion of NPs is explicitly driven by the stochastic force term in the LD. The LB method is coupled with the LD in a two-way fashion through a discrete forcing source distribution term in the LB method. The validity and accuracy of this LB-LD approach is demonstrated through several verification problems, including velocity relaxation of an isolated particle, self-diffusion of a Brownian particle, and relaxation of a polymer chain. Good agreement between simulation and theory is observed. The verified algorithm is applied to study the migration of NPs in cellular blood flow within microvasculature. For NPs of diameter 1\textasciitilde 100 nm, Brownian diffusion, compared to the red blood cell (RBC)-enhanced diffusion, is shown to be the predominant driver for the NP radial diffusion process. For larger NPs of diameter \textasciitilde 500 nm, Brownian diffusion and RBC-enhanced diffusion are shown to be comparably significant. [Preview Abstract] |
Thursday, November 16, 2017 11:24AM - 11:36AM |
B2.00003: Nanofibrous gelatin structures: Effect of high-yield electrospinning on the fiber formation and stability Amanda Kennell, Anna Krum, Andrei Stanishevsky PhD Nanofibrous biopolymer materials represent an attractive platform for many biomedical applications. Such materials are frequently made by the electrospinning process, which is based on complex electrohydrodynamic phenomena leading to the formation of solid nanofibers from electrified polymer solutions. Textural properties and composition of nanofibers and fibrous assemblies play a big role in the physiological performance of electrospun biopolymer structures. In this study, gelatin nanofibers were produced at a rate of up to 20 g/h by using a recently developed high-yield free-surface electrospinning process. The dense nanofibrous flow in this process moves at 0.2–0.7 m/s speed due to the effect of ionic wind, which allowed easy assemblage of the resulting nanofibers. Depending on the type of gelatin and process parameters, the fiber diameter varied from 100 nm to 2000 nm. Nanofibrous gelatin mats with up to 3 mm thickness were physically and chemically crosslinked to increase the material stability in simulated body fluids (SBFs). The effect of process conditions on the changes in the fiber morphology and textural properties of as-prepared, crosslinked, and SBF-exposed nanofibrous mats was explored. Initial results on the tensile properties of gelatin nanofibers are discussed. [Preview Abstract] |
Thursday, November 16, 2017 11:36AM - 11:48AM |
B2.00004: Imaging and Treatment Isocenter Coincidence for a Linear Accelerator Using Oblique Projection Imaging Jake Downey, Marian Axente, Chenguang Liu Modern radiotherapy treatments involve advanced patient imaging systems to allow for more accurate and reproducible patient positioning. This is known as image guided radiotherapy (IGRT). To conduct IGRT, the user needs to validate that the coincidence of the imaging system and the treatment beams' center is within acceptable tolerances (\textless 2mm). The equipment under investigation was a double oblique kV projection imaging system and a C-arm gantry mounted medical linear accelerator (linac). Using radiochromic film, the coincidence of the linac mechanical center, and radiation beam center was found to be 0.91mm. The imaging system center was calibrated to be \textless 1mm from linac mechanical center. Using IGRT, a hidden spherical target phantom was aligned. Marked radiochromic films were also inserted in the phantom to capture the target shadow made by the treatment beam. The test indicated an alignment error of 1.3\textpm 0.27mm between the imaging and treatment center, which was within stated tolerance. These experiments provide a conclusive and deconvoluted map of uncertainties using IGRT as well as understanding of quality assurance methods used by a medical physicist in a clinical setting. [Preview Abstract] |
Thursday, November 16, 2017 11:48AM - 12:00PM |
B2.00005: Photodeactivation of pathogenic bacteria using methylene blue and graphene quantum dot Zachary Thomas, Khomidkhodzha Kholikov, Saidjafarzoda Ilhom, Skyler Smith, William Craddock, Ali Er A biocompatible photodynamic therapy agent that generates a high amount of~singlet oxygen with high water dispersibility and excellent photostability~is desirable. In this work, a graphene-based biomaterial which is a~promising alternative to a standard photosensitizers was produced and its efficiency compared to a standard photosensitizer, methylene blue. Graphene quantum dots (GQDs) were synthesized by irradiating benzene~and nickel oxide mixture using nanosecond laser pulses. High-resolution~transmission electron microscopy (HR-TEM) results show GQDs whose~size less than 5 nm with very good water dispersibility were successfully obtained. UV-Vis spectra and photoluminescence spectra shows~that GQDs have an absorption peak around 270 nm and maximum emission at 430 nm with the excitation wavelength of 310 nm. Deactivation of Escherichia coli (E. coli) a gram-negative bacterium with methylene blue and carbon nanoparticles was studied by irradiating with different wavelengths. The results show a significant decrease in the number of colony forming units of E. coli. Our results show that GQDs can potentially~be used to develop therapies for the eradication of pathogens in open~wounds, burns, or skin cancers. [Preview Abstract] |
Thursday, November 16, 2017 12:00PM - 12:12PM |
B2.00006: Sorption of Potential Toxicants by PDMS in Microfluidic Devices Alexander Auner, Kazi Tasneem, Lisa McCawley, Dmitry Markov, Shane Hutson The need for deeper understanding of how organoids can interact in toxicant assessment applications has advanced the design of interconnected polydimethylsiloxane (PDMS) organ-on-chip devices. Microfluidic devices adsorb chemicals through exposed PDMS surfaces creating problematic changes in dose response curves and timing of delivery. Recent efforts have attempted to quantify what molecular agents used in microfluidic devices will be adsorbed by PDMS. Of sixteen potentially toxic chemicals used in our applications, we identified five which adsorbed to PDMS using both visible light and infrared absorption spectroscopy. Spectrometer peak calibration from our chemicals allowed us to establish quantitative relationships for chemical absorption and extract time dependent adsorption coefficients, saturation amount and forward and reverse rate constants. The relationship between adsorption and select molecular properties was investigated, and we have shown the octanol-water partition coefficient (Log P) to be a decent predictor of absorption for chemicals with Log P \textgreater 2.7. Experimental rate constants were used to model adsorption due to continuous and bolus exposure of several toxicants in a device. From this analysis, we determined that timing is critical for delivery of chemicals that reversibly bind to PDMS in order for cells to not be over- or under-dosed by a few orders of magnitude. [Preview Abstract] |
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