@article{snyder_davis_berg_pearce_romanyuk_jiricek_paskova_ivanisevic_2019, title={Passivation of semipolar (10-1-1) GaN with different organic adsorbates}, volume={236}, ISSN={["1873-4979"]}, DOI={10.1016/j.matlet.2018.10.109}, abstractNote={Expanding the functionality of electronic materials is often reliant on the attachment of organic molecules to the surface. In this study, several methods for passivating the surface of semipolar (10-1-1) GaN with different chemistries were examined; this included simple physisorption, in-situ functionalization using phosphonic acids, and a two-step carboxylic acid attachment with a peroxide pretreatment. The binding of a variety of different organic adsorbates on semipolar substrates was quantified using X-ray photoelectron spectroscopy (XPS). Our results confirm binding at the organic-inorganic interface through the presence of amine/amide species on the surface. The wide variety of organic molecules, and their binding to inorganic electronic materials, can be exploited to impart specific functionalities in technologies spanning fields of energy, biomedical science, and chemical sensing.}, journal={MATERIALS LETTERS}, author={Snyder, Patrick J. and Davis, Hailey and Berg, Nora G. and Pearce, Brady and Romanyuk, Oleksandr and Jiricek, Petr and Paskova, Tania and Ivanisevic, Albena}, year={2019}, month={Feb}, pages={201–204} }
 @article{berg_pearce_rohrbaugh_jiang_nolan_ivanisevic_2017, title={Gallium containing composites as a tunable material to understand neuronal behavior under variable stiffness and radiation conditions}, volume={71}, ISSN={["1873-0191"]}, DOI={10.1016/j.msec.2016.10.022}, abstractNote={We report a composite biomaterial containing nanostructured GaOOH and Matrigel™ that can be modulated with respect to its stiffness and radiosensitization properties. A variety of concentrations of GaOOH were added to the composite to alter the mechanical properties of the material as well as to tune the radiosensitizing properties to the composite. PC-12 cells were used to study the combined effects of different stimuli on cell behavior. NGF was given to the cells to record their morphology as well as viability. An increase in the substrate stiffness caused an increase in neurite outgrowth but a decrease in cell viability. In addition, increasing the radiation dose decreased neurite outgrowth but increased cell viability when radiosensitizing particles were present. A subtractive effect between radiosensitizing and mechanical stimuli was observed when PC-12 cells were grown on the GaOOH containing composite.}, journal={MATERIALS SCIENCE & ENGINEERING C-MATERIALS FOR BIOLOGICAL APPLICATIONS}, author={Berg, Nora G. and Pearce, Brady L. and Rohrbaugh, Nathaniel and Jiang, Lin and Nolan, Michael W. and Ivanisevic, Albena}, year={2017}, month={Feb}, pages={317–321} }
 @article{pearce_berg_ivanisevic_2017, title={Synthesis and optical characterization of mixed nanostructured aluminum-gallium oxy-hydroxide}, volume={5}, ISSN={["2166-3831"]}, DOI={10.1080/21663831.2016.1232317}, abstractNote={ABSTRACT Nanostructured oxy-hydroxide materials with varied compositions of aluminum and gallium were synthesized in an environmentally friendly way with water as the only solvent. The tunability of optical properties of these materials through concentration ranges is particularly of interest for organic/inorganic hybrid materials in optoelectronic devices. Size comparisons of the materials were performed using dynamic light scattering measurements. The measured size of the particles decreased with increasing Al. This supports the blue shift seen from the GaOOH emission wavelength to the Al0.5Ga0.5OOH emission wavelength in the photoluminescence spectra. The X-ray diffraction showed the formation of a possible amorphous layer in Al0.5Ga0.5OOH and Al0.2Ga0.8OOH. GRAPHICAL ABSTRACT IMPACT STATEMENT A water-based synthesis for mixed aluminum–gallium nanostructured oxides is presented with size comparisons and optical characteristics demonstrating emission wavelength tunability.}, number={2}, journal={MATERIALS RESEARCH LETTERS}, author={Pearce, Brady L. and Berg, Nora G. and Ivanisevic, Albena}, year={2017}, pages={124–127} }
 @article{berg_paskova_ivanisevic_2017, title={Tuning the biocompatibility of aluminum nitride}, volume={189}, ISSN={["1873-4979"]}, DOI={10.1016/j.matlet.2016.11.041}, abstractNote={High-quality, electronic-grade, aluminum nitride thin films grown by reactive sputtering were studied in vitro. The semiconductor material showed high degree of stability in cell culture with very little Al leaching over time. Unlike other III-nitride materials, clean AlN does not promote the adhesion of cells to its surface. The work demonstrates that functionalization with peptides can be used to reverse this behavior. The presence of AlN in cell culture does not have any adverse effects on neurotypic cell behavior as confirmed by cell viability and reactive oxygen species assays.}, journal={MATERIALS LETTERS}, author={Berg, Nora G. and Paskova, Tania and Ivanisevic, Albena}, year={2017}, month={Feb}, pages={1–4} }
 @article{pearce_berg_jiang_ivanisevic_2016, title={Aqueous stability of nanostructured aluminum and gallium oxyhydroxide before and after functionalization with lysine}, volume={184}, ISSN={["1873-4979"]}, DOI={10.1016/j.matlet.2016.08.071}, abstractNote={Composites of nanostructured aluminum and gallium oxyhydroxide (AlOOH and GaOOH) and l-lysine were synthesized using an environmentally friendly approach. These composites were investigated to determine the effects of the functionalization on the aqueous stability and leaching of aluminum and gallium. The organic and inorganic components present in the samples were assessed with X-Ray photoelectron spectroscopy (XPS) and Fourier transformed-infrared spectroscopy (FT-IR). In the GaOOH-lysine composite, XPS provided evidence of both the presence of gallium and lysine. Crystallographic information was gathered using X-Ray diffraction (XRD). The FT-IR and XRD spectra of the composite materials were dominated by peaks related to lysine, due to the nature of these samples. Inductively coupled plasma-mass spectrometry (ICP-MS) data were collected of the functionalized and non-functionalized samples left in solution for periods of 1 days, 5 days and 7 days. This provided evidence of improved aqueous stability of the AlOOH-lysine composite with no effect seen in the GaOOH-lysine composite. The findings of this study will be used in determining the importance of lysine functionalization for future biomolecule-nanomaterial composites.}, journal={MATERIALS LETTERS}, author={Pearce, Brady L. and Berg, Nora G. and Jiang, Lin and Ivanisevic, Albena}, year={2016}, month={Dec}, pages={278–281} }
 @article{pearce_berg_rahn_ivanisevic_2016, title={In situ and ex situ functionalization of nanostructured gallium oxy-hydroxide with a porphyrin dye}, volume={38}, ISSN={["1932-8745"]}, DOI={10.1002/sca.21315}, abstractNote={Summary}, number={6}, journal={SCANNING}, author={Pearce, Brady L. and Berg, Nora G. and Rahn, Matthew S. and Ivanisevic, Albena}, year={2016}, month={Dec}, pages={671–683} }
 @article{berg_pearce_snyder_rohrbaugh_nolan_adhikari_khan_ivanisevic_2016, title={Interfaces with Tunable Mechanical and Radiosensitizing Properties}, volume={8}, ISSN={["1944-8252"]}, DOI={10.1021/acsami.5b11639}, abstractNote={We report the fabrication of a composite containing nanostructured GaOOH and Matrigel with tunable radiosensitizing and stiffness properties. Composite characterization was done with microscopy and rheology. The utility of the interface was tested in vitro using fibroblasts. Cell viability and reactive oxygen species assays quantified the effects of radiation dosages and GaOOH concentrations. Fibroblasts' viability decreased with increasing concentration of GaOOH and composite stiffness. During ionizing radiation experiments the presence of the scintillating GaOOH triggered a different cellular response. Reactive oxygen species data demonstrated that one can reduce the amount of radiation needed to modulate the behavior of cells on interfaces with different stiffness containing a radiosensitizing material.}, number={34}, journal={ACS APPLIED MATERIALS & INTERFACES}, author={Berg, Nora G. and Pearce, Brady L. and Snyder, Patrick J. and Rohrbaugh, Nathaniel and Nolan, Michael W. and Adhikari, Prajesh and Khan, Saad A. and Ivanisevic, Albena}, year={2016}, month={Aug}, pages={21956–21961} }
 @article{berg_franke_kirste_collazo_ivanisevic_2016, title={Photoluminescence changes of III-Nitride lateral polarity structures after chemical functionalization}, volume={3}, ISSN={["2053-1591"]}, DOI={10.1088/2053-1591/3/12/125906}, abstractNote={The photoluminescence changes of a III-Nitride semiconductor with various surface topographies were studied after chemical functionalization. AlxGa1−xN with a composition of 70% aluminum was used and the surfaces were functionalized with a fluorophore dye-terminated peptide using a linker molecule. The stability of the wafers in water was studied using inductively coupled plasma mass spectrometry prior to modifying the material. The leaching data demonstrated that the AlGaN material in highly stable in biological conditions over 7 d. The attachment of the dye to the wafer was investigated using x-ray photoelectron spectroscopy and photoluminescence spectroscopy (PL). The PL spectrum showed a clear signature of the dye with a pronounced emission peak at approximately 260 nm, indicating a successful attachment to the surface.}, number={12}, journal={MATERIALS RESEARCH EXPRESS}, author={Berg, Nora G. and Franke, Alexander and Kirste, Ronny and Collazo, Ramon and Ivanisevic, Albena}, year={2016}, month={Dec} }
 @article{berg_ivanisevic_2015, title={Nanostructured gallium nitride powder functionalized with a fluorophore terminated peptide}, volume={2}, ISSN={["2053-1591"]}, DOI={10.1088/2053-1591/2/9/095018}, abstractNote={Nanostructured gallium nitride (GaN) powder was functionalized with a biomolecule terminated with a fluorophore. The fluorophore was used to enhance and modulate the luminescent properties of the semiconductor powder. A simple two-step wet-chemistry in situ modification approach resulted in covalent attachment of the peptide to the powder. X-ray photoelectron spectroscopy survey data confirmed qualitatively that the peptide molecules were successfully attached to the surface of the powder with the presence of a phosphorus peak as well as an increase in nitrogen atomic percentage on the surface of the material. The bonding and stability of the modification to the nanostructured surface was assessed by quantitatively analyzing high-resolution regional scans. Photoluminescence Spectroscopy mapped changes to the optical properties of the powder upon dye terminated peptide attachment. A clear shift in the luminescence peak was recorded after the powder was functionalized. The results demonstrate a straight-forward way to alter the emission characteristics of a nanostructured semiconductor material. The role of material defects on the powder surface is used to explain the initial and altered luminescence properties.}, number={9}, journal={MATERIALS RESEARCH EXPRESS}, author={Berg, Nora and Ivanisevic, Albena}, year={2015}, month={Sep} }
 @article{berg_nolan_paskova_ivanisevic_2014, title={Surface Characterization of Gallium Nitride Modified with Peptides before and after Exposure to Ionizing Radiation in Solution}, volume={30}, ISSN={0743-7463 1520-5827}, url={http://dx.doi.org/10.1021/la5040245}, DOI={10.1021/la5040245}, abstractNote={An aqueous surface modification of gallium nitride was employed to attach biomolecules to the surface. The modification was a simple two-step process using a single linker molecule and mild temperatures. The presence of the peptide on the surface was confirmed with X-ray photoelectron spectroscopy. Subsequently, the samples were placed in water baths and exposed to ionizing radiation to examine the effects of the radiation on the material in an environment similar to the body. Surface analysis confirmed degradation of the surface of GaN after radiation exposure in water; however, the peptide molecules successfully remained on the surface following exposure to ionizing radiation. We hypothesize that during radiation exposure of the samples, the radiolysis of water produces peroxide and other reactive species on the sample surface. Peroxide exposure promotes the formation of a more stable layer of gallium oxyhydroxide which passivates the surface better than other oxide species.}, number={51}, journal={Langmuir}, publisher={American Chemical Society (ACS)}, author={Berg, Nora G. and Nolan, Michael W. and Paskova, Tania and Ivanisevic, Albena}, year={2014}, month={Dec}, pages={15477–15485} }