Cyclodextrin- grafted electrospun cellulose acetate nanofibers via "Click" reaction for removal of phenanthrene

Cataloged from PDF version of article.Beta-cyclodextrin (p-CD) functionalized cellulose acetate (CA) nanofibers have been successfully prepared by combining electrospinning and "click" reaction. Initially, p-CD and electrospun CA nanofibers were modified so as to be azide-p-CD and propargyl-terminated CA nanofibers, respectively. Then, "click" reaction was performed between modified CD molecules and CA nanofibers to obtain permanent grafting of CDs onto nanofibers surface. It was observed from the SEM image that, while CA nanofibers have smooth surface, there were some irregularities and roughness at nanofibers morphology after the modification. Yet, the fibrous structure was still protected. ATR-FTIR and XPS revealed that, CD molecules were successfully grafted onto surface of CA nanofibers. The adsorption capacity of p-CD-functionalized CA (CA-CD) nanofibers was also determined by removing phenanthrene (polycyclic aromatic hydrocarbons, PAH) from its aqueous solution. Our results indicate that CA-CD nanofibers have potential to be used as molecular filters for the purpose of water purification and waste water treatment by integrating the high surface area of nanofibers with inclusion complexation property of CD molecules. (C) 2014 Elsevier B.V. A

pH-responsive nanofibers with controlled drug release properties

Cataloged from PDF version of article.Smart polymers and nanofibers are potentially intriguing materials for controlled release of bioactive agents. This work describes a new class of pH responsive nanofibers for drug delivery systems with controlled release properties. Initially, poly(4-vinylbenzoic acid-co-(ar-vinylbenzyl) trimethylammonium chloride) [poly(VBA-co-VBTAC)] was synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. Then, ciprofloxacin was chosen as the model drug for the release study and encapsulated into pH-responsive polymeric carriers of poly(VBA-co-VBTAC) nanofibers via electrospinning. The morphology of the electrospun nanofibers was examined by scanning electron microscopy (SEM). The structural characteristics of the pH responsive nanofibers were investigated by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The release measurements of ciprofloxacin from pH responsive nanofibers were also performed by high-performance liquid chromatography (HPLC) analysis. To show the pH sensitivity of these nanofibers, the release profile of ciprofloxacin was examined under acidic, neutral and basic conditions. The results indicate that pH responsive nanofibers can serve as effective drug carriers since the release of ciprofloxacin could be controlled by changing the pH of the environment, and therefore these drug loaded pH-responsive nanofibers might have potential applications in the biomedical field. This journal is © The Royal Society of Chemistry

Guided and magnetic self-assembly of tunable magnetoceptive gels

Self-assembly of components into complex functional patterns at microscale is common in nature, and used increasingly in numerous disciplines such as optoelectronics, microfabrication, sensors, tissue engineering and computation. Here, we describe the use of stable radicals to guide the self-assembly of magnetically tunable gels, which we call ‘magnetoceptive’ materials at the scale of hundreds of microns to a millimeter, each can be programmed by shape and composition, into heterogeneous complex structures. Using paramagnetism of free radicals as a driving mechanism, complex heterogeneous structures are built in the magnetic field generated by permanent magnets. The overall magnetic signature of final structure is erased via an antioxidant vitamin E, subsequent to guided self-assembly. We demonstrate unique capabilities of radicals and antioxidants in fabrication of soft systems with heterogeneity in material properties, such as porosity, elastic modulus and mass density; then in bottom-up tissue engineering and finally, levitational and selective assembly of microcomponents

Bioactive surface design based on functional composite electrospun nanofibers for biomolecule immobilization and biosensor applications

Cataloged from PDF version of article.The combination of nanomaterials and conducting polymers attracted remarkable attention for development of new immobilization matrices for enzymes. Hereby, an efficient surface design was investigated by modifying the graphite rod electrode surfaces with one-step electrospun nylon 6,6 nanofibers or 4% (w/w) multiwalled carbon nanotubes (MWCNTs) incorporating nylon 6,6 nanofibers (nylon 6,6/4MWCNT). High-resolution transmission electron microscopy study confirmed the successful incorporation of the MWCNTs into the nanofiber matrix for nylon 6,6/4MWCNT sample. Then, these nanofibrous surfaces were coated with a conducting polymer, (poly-4-(4,7-di(thiophen-2-yl)-1H-benzo[d]imidazol-2-yl) benzaldehyde) (PBIBA) to obtain a high electroactive surface area as new functional immobilization matrices. Due to the free aldehyde groups of the polymeric structures, a model enzyme, glucose oxidase was efficiently immobilized to the modified surfaces via covalent binding. Scanning electron microscope images confirmed that the nanofibrous structures were protected after the electrodeposition step of PBIBA and a high amount of protein attachment was successfully achieved by the help of high surface to volume ratio of electroactive nanofiber matrices. The biosensors were characterized in terms of their operational and storage stabilities and kinetic parameters (K mapp and Imax). The resulting novel glucose biosensors revealed good stability and promising Imax values (10.03 and 16.67 μA for nylon 6,6/PBIBA and nylon 6,6/4MWCNT/PBIBA modified biosensors, respectively) and long shelf life (32 and 44 days for nylon 6,6/PBIBA and nylon 6,6/4MWCNT/PBIBA modified biosensors, respectively). Finally, the biosensor was tested on beverages for glucose detection. © 2014 American Chemical Society

Use of commercial off-the-shelf digital cameras for scientific data acquisition and scene-specific color calibration

Author Posting. © Optical Society of America, 2014. This article is posted here by permission of Optical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Optical Society of America A: Optics, Image Science, and Vision 31 (2014): 312-321, doi:10.1364/JOSAA.31.000312.Commercial off-the-shelf digital cameras are inexpensive and easy-to-use instruments that can be used for quantitative scientific data acquisition if images are captured in raw format and processed so that they maintain a linear relationship with scene radiance. Here we describe the image-processing steps required for consistent data acquisition with color cameras. In addition, we present a method for scene-specific color calibration that increases the accuracy of color capture when a scene contains colors that are not well represented in the gamut of a standard color-calibration target. We demonstrate applications of the proposed methodology in the fields of biomedical engineering, artwork photography, perception science, marine biology, and underwater imaging.T. Treibitz is an Awardee of the Weizmann Institute of Science—National Postdoctoral Award Program for Advancing Women in Science and was supported by NSF grant ATM-0941760. D. Akkaynak, J. Allen, and R. Hanlon were supported by NSF grant 1129897 and ONR grants N0001406-1-0202 and N00014-10-1-0989 and U. Demirci by grants R01AI093282, R01AI081534, and NIH U54EB15408. J. Allen is grateful for support from a National Defense Science and Engineering Graduate Fellowship

Nanostructured Optical Photonic Crystal Biosensor for HIV Viral Load Measurement

Detecting and quantifying biomarkers and viruses in biological samples have broad applications in early disease diagnosis and treatment monitoring. We have demonstrated a label-free optical sensing mechanism using nanostructured photonic crystals (PC) to capture and quantify intact viruses (HIV-1) from biologically relevant samples. The nanostructured surface of the PC biosensor resonantly reflects a narrow wavelength band during illumination with a broadband light source. Surface-adsorbed biotarget induces a shift in the resonant Peak Wavelength Value (PWV) that is detectable with <10 pm wavelength resolution, enabling detection of both biomolecular layers and small number of viruses that sparsely populate the transducer surface. We have successfully captured and detected HIV-1 in serum and phosphate buffered saline (PBS) samples with viral loads ranging from 104 to 108 copies/mL. The surface density of immobilized biomolecular layers used in the sensor functionalization process, including 3-mercaptopropyltrimethoxysilane (3-MPS), N-gamma-Maleimidobutyryl-oxysuccinimide ester (GMBS), NeutrAvidin, anti-gp120, and bovine serum albumin (BSA) were also quantified by the PC biosensor

Statistical Modeling of Single Target Cell Encapsulation

High throughput drop-on-demand systems for separation and encapsulation of individual target cells from heterogeneous mixtures of multiple cell types is an emerging method in biotechnology that has broad applications in tissue engineering and regenerative medicine, genomics, and cryobiology. However, cell encapsulation in droplets is a random process that is hard to control. Statistical models can provide an understanding of the underlying processes and estimation of the relevant parameters, and enable reliable and repeatable control over the encapsulation of cells in droplets during the isolation process with high confidence level. We have modeled and experimentally verified a microdroplet-based cell encapsulation process for various combinations of cell loading and target cell concentrations. Here, we explain theoretically and validate experimentally a model to isolate and pattern single target cells from heterogeneous mixtures without using complex peripheral systems.Wallace H. Coulter Foundation (Young Investigator in Bioengineering Award)National Institutes of Health (U.S.) (Grant R01AI081534)National Institutes of Health (U.S.) (Grant R21AI087107

Nisin Production by Immobilized Microbial Cell Culture during Batch and Fed-Batch Fermentations with Various pH Profiles

In this study, nisin production has been enhanced by using batch and fed-batch fermentation with calcium-alginate immobilized cell culture. Due to the inhibitory effects of original phosphate rich growth medium on the immobilizing beads, an altered complex growth medium for nisin production was used. Various pH profiles were evaluated for both batch and fed-batch fermentations. For batch fermentations, a 2.1 fold higher nisin activity was obtained by allowing the pH to drop freely after 4 hrs of fermentation at constant pH. A periodic pH profile exhibited a detrimental effect on nisin production during batch fermentations. For fed-batch fermentations, a 2.9 fold higher nisin activity was obtained by allowing the pH to remain at pH of 6.8. Approximately the same maximum concentration, 3300 IU/ml, of nisin was observed when the best pH profile for batch and fed batch experiments were compared. The results also showed that immobilized cell culture can be used in order to improve nisin fermentation for both batch and fed-batch fermentation

Proton hot spots and exclusive vector meson production

We explore consequences of the existence of gluonic hot spots inside the proton for coherent and incoherent exclusive vector meson production cross sections in deep inelastic scattering. By working in the dilute limit of the Color Glass Condensate framework to compute the cross sections for Gaussian hot spots of fluctuating color charges and employing a nonrelativistic vector meson wave function, we are able to perform large parts of the calculation analytically. We find that the coherent cross section is sensitive to both the size of the target and the structure of the probe. The incoherent cross section is dominated by color fluctuations at small transverse momentum transfer (t), by proton and hot spot sizes as well as the structure of the probe at medium t and again by color fluctuations at large t. While the t-dependence of the cross section is well reproduced in our model, the relative normalization between the coherent and the incoherent cross sections points to the need for additional fluctuations in the proton.Peer reviewe