Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session E33: Devices for Biological Applications and Biological Materials |
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Sponsoring Units: FIAP Chair: Alan Johnson, Univ of Pennsylvania Room: BCEC 204B |
Tuesday, March 5, 2019 8:00AM - 8:12AM |
E33.00001: Laser-activated Polymer Devices for Intracellular Delivery Weilu Shen, Eric Mazur, Stefan Kalies, Marinna Madrid, Alexander Heisterkamp A challenge in the biomedical field to advancing fundamental studies of biologically interesting molecules for clinical use is the direct delivery into the cytoplasm in an efficient way. Established methods such as electroporation and viral transduction each come with respective strengths and weaknesses that fit different application needs. We present a delivery method that combines 11-ns laser pulses of 1064 nm wavelength and polymer substrates to create transient pores in cells. These polymer devices are are low-cost, biocompatible, and have simple fabrication techniques. Adherent cells are grown on the substrates, and pores only form on the cells in localized regions excited with the laser pulses, allowing spatial selectivity. The medium surrounding the cell contain the cargos, and they diffuse into the cell before the transient pores self-seal. We are able to deliver membrane-impermeable cargos of sizes up to 40 kDa. We obtained efficiencies of up to 40% with viabilities of 60% for calcein green in HeLa and Panc-1 cells. Scanning electron microscopy and optical profilometry are used to study the substrate surface morphology. This laser-activated polymer device can deliver important material directly into cells, furthering the field of nanomedicine in a cost-effective manner. |
Tuesday, March 5, 2019 8:12AM - 8:24AM |
E33.00002: Controlling the Association of Metallic Nanoparticles with Polysaccharides for Use in Biomedical Theranostics Josh Sampson, Arandi Bezerra, John Dutcher Metallic nanoparticles (NPs) exhibit a localized surface plasmon resonance (LSPR) that make them suitable for a variety of important applications, including their use as theranostic probes in biomedicine, and for dramatic signal enhancements in Raman and infrared spectroscopy. Improvements in the stability of NPs can be achieved through association with polysaccharides [1]. We have generated “bare” gold NPs using a two-step laser ablation process in Milli-Q water using a green pulsed laser, resulting in monodisperse NPs that are between 5 and 10 nm in diameter. We have chemically modified the NPs to strongly associate with the abundance of hydroxyl groups present on polysaccharides. For dispersions containing modified NPs and polysaccharides, we compared the NP LSPR measured using UV-Vis spectroscopy and the stability of the dispersions to that for dispersions containing bare NPs and the same polysaccharides. By controlling the association of NPs with polysaccharides to achieve improved dispersion stability, a key impediment to their use in biomedical theranostics can be removed. |
Tuesday, March 5, 2019 8:24AM - 8:36AM |
E33.00003: A high-sensitivity 16-channel magnetic sensor for magnetocardiographic experiments Young Jin Kim, Igor M Savukov Multichannel parallel magnetic measurements are required for various applications in many fields such as neuroscience and biomedical research. We recently constructed a portable, low-cost, high-sensitivity 16-channel magnetic sensor for magnetocardiography (MCG) applications. The sensor is based on a high-sensitivity atomic magnetometer (AM) with a novel configuration of nearly parallel pump and probe laser beams. The AM-based 16-channel magnetic sensing is realized in a single module by using a single large rubidium vapor cell, two broad laser beams, and a 16-channel photodiode matrix, leading projected 10-fold reduction of the cost of sensors. For MCG experiments with the sensor, its main components except lasers are located inside a magnetically shielded room. We describe the basic principle and the design of the 16-channel magnetic sensor. We also present human heart signals directly recorded by the sensor. |
Tuesday, March 5, 2019 8:36AM - 8:48AM |
E33.00004: Detection of Biofilm Infections in Human Fluid Samples using DNA-Functionalized Carbon Nanotube Vapor Sensors Emilie Benson, Christopher Kehayias, Alan T Johnson Human fluid samples collected from individuals suffering from various biofilm-related infections were analyzed using single-stranded DNA-functionalized carbon nanotube (ssDNA-CNT) vapor sensors. Fluids from infected individuals were collected and categorized by infection type: staph infections and non-staph infections. The samples were placed in individual flasks that were heated in a water bath, and a vapor handling system was used to sequentially deliver the headspace of the samples to an array of CNT devices configured as an “electronic nose”. Each array comprised up to 100 sensors, with each sensor functionalized with one of ten unique sequences of ssDNA, thereby yielding a ten-dimensional output response characteristic of the volatile odor signature of the samples. The resulting data space was dimensionally reduced using linear discriminant analysis (LDA), resulting in a differentiation of staph versus non-staph data clusters. |
Tuesday, March 5, 2019 8:48AM - 9:00AM |
E33.00005: Triggered gelation of microfluidic polymer droplets to identify and isolate viable antigen-speific immune cells Brendan Deveney, Julie Brouchon, John Heyman, Yuan Yuan, David A Weitz The isolation of antigen-specific immune cells is fundamental to the study of autoimmune diseases and to the development of effective immunotherapies, yet practical technologies for doing so are lacking. We present here a new method for the triggered gelation of polymeric microfluidic assay droplets that enables the isolation of viable antigen-specific T-cells in microfluidic devices. Specifically, T-cell/target cell pairs are coencapsulated in liquid droplets prior to droplet conversion into gel microspheres compatible with fluorescence activated cell sorting. We aim to use this platform to perform high-throughput cell-cell interaction assays and isolate individual immune effector cells together with their cognate target cells for future immontherapy development. |
Tuesday, March 5, 2019 9:00AM - 9:12AM |
E33.00006: Emergence of quantized vortices in microfluidic devices Jeremias Gonzalez, Bin Liu Structured vortices in microfluidic flows are often associated with suspensions of active matter that move in a collective fashion. For instance, vortical flows at microscales have been observed in bacterial swarms, with their forming mechanisms attributed to the self-propulsion of individuals and the cell-cell interactions. Here, we demonstrate that an array of microscale vortices can emerge purely due to the geometry and dimensionality in a steady flow. Specifically, we show that a chain of vortices can be induced in a rectangular cavity that is sheared under a steady flow. Interestingly, these vortices have an intrinsic aspect ratio, with their numbers quantized by the length of the cavity. We also elucidate that such intrinsic flow structures can be generalized to a wide class of confining geometries, indicating a fundamental mechanism of vortex formation in microscale flows. |
Tuesday, March 5, 2019 9:12AM - 9:24AM |
E33.00007: Graphene Probes for Detecting Electrical Activity of Individual Synapses Yuchen Zhang, Rui Wang, Mingjian Shi, Bryson Brewer, Lijie Yang, Donna Webb, Deyu Li, Yaqiong Xu Complex neural circuits connected by billions of neurons with trillions of synapses require techniques that map the electrical activity of neural networks with extraordinary temporal and spatial resolution to decipher the underlying mechanisms for multiple aspects of neuroscience. By combining graphene transistors with scanning photocurrent microscopy, we can detect the local electrochemical environment changes induced by electrical activity of individual synapses of primitive hippocampal neurons, enabling us to estimate extracellular potential variations of individual synapses during depolarization. The ultrafast nature of graphene photocurrent response allows decoding of the activity patterns of individual synapses with sub-millisecond temporal resolution. As such, our new neurotechnology will offer promising potential for recording the electrical signals of a large population of synapses in neural networks. |
Tuesday, March 5, 2019 9:24AM - 9:36AM |
E33.00008: Development of a Mass Spectrometer for Sequencing Single Protein Molecules Benjamin Wiener, Nicholas Drachman, Mathilde LePoitevin, William Maulbetsch, Oliver G Isik, Derek Stein I will describe a new nanopore-based mass spectrometer designed to sequence proteins. The instrument will combine a nanopore ion source capable of extracting ionized aimio acids directly from solution into a vacuum chamber using electric fields[1] with a magnetic sector for separation by charge-to-mass ratio. The mass-separated ions will travel into an array of channeltron-style detectors capable of continuously monitoring the full mass range of interest and tagging each detected ion with its precise arrival time. In addition, our design features tunable hardware which will allow us to precisely align and adjust the position of our ion source to achieve the detection efficiency necessary for sequencing. |
Tuesday, March 5, 2019 9:36AM - 9:48AM |
E33.00009: Microfluidic calorimetric immunosensor: experimental results and COMSOL simulations of heat transfer in microchannel Saif Mohamad Ishraq Bari, Louis Reis, Gergana Nestrova Recent years have witnessed significant progress in the development of detection technologies for lab-on-a-chip immunoassays that provide increased sensitivity and specificity. The calorimetric technique allows the detection of reactions that are not compatible with other methods. Optimization of thermal transport through the microchannel relates to increasing sensitivity and high-throughput of sample analysis. This study presents the design and fabrication of calorimetric immunosensor for quantification of TNF-α. The impact of channel height (100μm, 500μm, 1000μm), lower channel wall thickness (170μm, 500μm, 1000μm), and MEMS materials (PDMS, glass) were simulated using COMSOL Multiphysics® to investigate the effect of these parameters on the heat transfer within the microchannel. Computational analysis indicates that reducing the channel height and the thickness of the lower channel wall results in an increased temperature difference. The simulations results were validated experimentally in a microfluidic immunosensor with an integrated antimony/ bismuth thermopile for quantification of TNF-α. The accuracy of the developed technology was validated using conventional ELISA. |
Tuesday, March 5, 2019 9:48AM - 10:00AM |
E33.00010: Detection of Early-Stage Ovarian Cancer using DNA-Decorated Carbon Nanotube Vapor Sensors Christopher Kehayias, Emilie Benson, Ali Ghorashi, William Watkins, Alan T Johnson We propose an “electronic nose” technology based on arrays of carbon nanotube field-effect transistors (CNT-FETs) as a minimally invasive diagnostic for ovarian cancer. We measured the real-time electrical response of the sensor arrays to volatile organic compounds (VOCs) in the headspace of blood plasma samples collected from 21 patients with malignant ovarian cancer (six of whom had early-stage cancer), 16 patients with benign ovarian lesions, and 21 age-matched healthy subjects. Sensor arrays comprised 100 CNT-FETs, where each device was functionalized with one of ten different sequences of single-stranded DNA, providing a ten-dimensional output for each sample tested. A linear discriminant analysis tool was used to dimensionally reduce the ten-dimensional data space. A machine-learning package was then used to classify samples as malignant, benign, or healthy based on a training subset of the data, leading to correct classification of 88% of the samples in the test set. Moreover, all early-stage samples were correctly classified as malignant. This signifies a promising step towards a reliable diagnostic for ovarian cancer in the early stage, when standard therapeutic procedures are highly effective. |
Tuesday, March 5, 2019 10:00AM - 10:12AM |
E33.00011: Prediction of crystal structure and study of transport and optoelectronic properties of NH2 substituted trans-stilbene derivative: A new promising ambipolar organic semiconductor Dwaipayan Chakraborty, Priya Johari Organic Semiconductor (OS) is an emerging class of energy materials, for its several advantages over its inorganic counterpart, such as large area, flexibility, low cost and most importantly their environment friendly manufacturing process. This class of materials can start a new electronic era, if their charge transport properties can be improved.Computational designing and study of new semiconducting organic molecules has come up as a great support in this regard. In this effort, we therefore rationally designed a promising Donor(D)-π-Acceptor(A) type molecule NNDM-NH2, a trans-stilbene derivative. We first calculated the molecular properties of this newly designed molecule and found important characteristics of molecule to exhibit high charge carrier mobility in solid. Further, on predicting its crystal structure and calculating the corresponding properties, we found that this new organic semiconductor owns a high charge carrier mobility of ~ 2.11 cm2/Vs for hole and 0.64 cm2/Vs for electron, together with desirable electronic and optical properties. Thus, revealing NNDM-NH2 as a potential candidate for the application in opto-electronic devices. In addition, it has found to have remarkable non linear optical (NLO) properties. |
Tuesday, March 5, 2019 10:12AM - 10:24AM |
E33.00012: XAS signature of ferroelectricity in Croconic Acid Fujie Tang, Pratikkumar H Dhuvad, Xuanyuan Jiang, Mehmet Topsakal, Deyu Lu, Xiaoshan Xu, Xifan Wu Molecular ferroelectrics (FE) based on ordering hydrogen bonds have potentially high electric polarization and ordering temperature compared with the conventional oxide FE materials. In particular, croconic acid (C5O5H2) has a FE polarization of 26 μC/cm2, in which the polar mode is strongly coupled to the intermolecular proton transfer. We applied X-ray absorption spectroscopy (XAS), a characterization technique that is sensitive to local structural and chemical properties, to probe the hydrogen bond structures of the croconic acid. First-principles simulations were used to interpret oxygen K-edge XAS features of croconic acid. The calculated XAS spectra semi-quantitatively agree with the three main experimental features at ~531.2 eV, 533.6 eV and 541.1 eV, respectively. The electron excitations in the two low-energy spectral features are found to be closely associated with the proton transfer, which gives rise to the FE polarization and can be recognized as a spectral signature of the FE in the croconic acid. |
Tuesday, March 5, 2019 10:24AM - 10:36AM |
E33.00013: Conformation of DNA in periodic temperature gradient created by plasmonic heating Ryoko Shimada, Hitomi Sakai Different molecules in mixed solutions can be separated from each other along a temperature gradient. This phenomenon, so-called Soret effect, is quite important for molecular manipulation in various research fields. Among various techniques, plasmonic heating from periodic metal domains is one of the effective ways to create a periodic temperature gradient for observation of the Soret effect. In this work, we utilized the plasmonic heating from periodic silver (Ag) domains under emission of blue light (400 – 440 nm) to create the periodic temperature gradient (with a large amplitude of ~ 0.5 K/mm), thereby attempting to observe the Soret effect of DNA mixed in polyethylene glycol (PEG) solutions. The DNA molecules, labeled with fluorescent dyes, were concentrated in high temperature zones, confirming the positive Soret effect. In addition, for large DNA molecules (~ 166 Kbp), the conformation appeared to be distorted possibly because of the microscopic Soret effect within the molecule. Details of this observation will be discussed on site. |
Tuesday, March 5, 2019 10:36AM - 10:48AM |
E33.00014: Excess heat capacity measurement of nano/bio-materials by photo-thermal conversion calorimetry Xing Li, Chia-Ching Chang, Dar-Bin Shieh, Cheng-Yang Tsai Photothermal therapy in medical care including cancer is gradually being valued. We modified Thermal activity monitor to measure the heat generated by the photothermal reaction of nanoparticles. The thermal Activity Monitor is a freestanding multichannel microcalorimeter. We use this system to measure the photothermal reaction excess heat and calculate the specific heat of the photothermal nanoparticles. Furthermore, We can calculate the elevated net temperature. In addition, this method can also measure the excess heat generated by various nanoparticles and proteins excited by laser at a specific wavelength. According to this result, we can accurately know the thermal reaction effect of the nanoparticles to achieve better treatment. |
Tuesday, March 5, 2019 10:48AM - 11:00AM |
E33.00015: Para-phenylenediamine crosslinked alginate gels and their mechanical properties Rosa Maria Badani Prado, Rangana Wijayapala, Santanu Kundu Alginate hydrogels are widely applicable in bioengineering and pharmaceutical applications due to their biocompatibility. Conventionally, calcium ions are used to crosslink alginate chains. However, gel modulus decreases in physiological solutions due to ion exchange with the medium, leading to a deterioration of their microstructure. This can be overcome by replacing the crosslinking calcium ions with covalent bonds. Here, we investigate chemically crosslinked alginate hydrogels using para-phenylenediamine (PPD) as a crosslinker. PPD binds the carboxylic groups present in β-D-mannuronic acid and α-L-guluronic acid residues of alginate chains. The gel modulus is tuned by changing polymer and crosslinker concentrations. These gels show higher moduli and are more brittle as compared to ionic alginate gels for the same crosslinker concentration. A comparison of mechanical properties with respect to the ionic alginate gels will be presented. |
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