This PDF file contains the front matter associated with SPIE Proceedings Volume 9171, including the Title Page, Copyright information, Table of Contents, Invited Panel Discussion, and Conference Committee listing.

The impedance and electrical conductivity behavior of gellan gum hydrogels containing the conducting fillers poly(3,4- ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) and vapour grown carbon nanofibers (VGCNF) is presented. Impedance analysis showed that an equivalent circuit consisting of a Warburg element in series with a resistor could be used to model the gels’ behavior. It is demonstrated that the addition of the conducting fillers PEDOT:PSS and VGCNFs can result in a measurable improvement in the conductivity of hydrogels with high water content and swelling ratios. Incorporation of combinations of these conducting fillers resulted in an improvement of the conductivity of gellan gum-containing hydrogels with water content (swelling ratio) of at least 97.5% (40) from 1.2 ± 0.1 mS/cm to 4 ± 0.6 mS/cm.

This study focuses on the use of silver based nanoparticle as fillers in DNA host materials to form nancomposites for applications in Electro-Magnetic Interferences (EMI) shielding. For relatively low-conductivity EMI shielding nanocomposites, silver-oxide coated cenospheres are investigated as fillers. The filler loadings are varied to determine a percolation threshold for the desired low conductivity and shielding effectiveness. Microwave absorption as well as DC surface resistivity measurements are undertaken to characterize the obtained films.

In this study, we investigated the effect of substrates on the electrical properties of transferred graphene. A wide range of substrates such as silicon carbide (SiC), glass, kapton, photo-print paper, polydimethylsiloxane (PDMS) and Willow glass were selected based on their surface properties, flexibility and lattice match. Four monolayers of graphene were transferred onto each of these substrates. A comparative study of the electrical characteristics of the transferred graphene film only and graphene/guanine film on the different substrates was undertaken.

Hyper Rayleigh Scattering (HRS) is an optical process routinely used to measure the first hyperpolarizability of molecular compounds. In order to investigate the build-up of the first hyperpolarizability of DNA, we report the investigation of the first hyperpolarizability of two of its constituents, namely the bases Thymine and Adenine at the fundamental wavelength of 800 nm. In the both cases, the weakness of the HRS signal intensities recorded requires long acquisition times and statistical analysis of the data to ensure that the sensitivity is reached. For Thymine, the absence of fluorescence is verified with the recording of the HRS line spectrum. Then, Thymine first hyperpolarizability is measured and found to be β_T = 2.9 x 10^-30 esu using a 10 mM concentration aqueous solution. For Adenine, the problem is complicated by the presence of fluorescence. Hence, we can only determine an upper limit for the first hyperpolarizability which is set as β_A < 4.2 x 10^-30 esu.

Many papers have been published on the properties of deoxyribonucleic acid (DNA) and DNAhexadecyltrimethylammonium chloride (CTMA) and their applications in electronics and photonics. This paper is a review of some of the properties and their related applications for other types of naturally occurring materials, nucleic acid bases or nucleobases which make up the DNA molecules. Nucleobases under investigation included guanine, cytosine, adenine and thymine. Potential applications include electron blocking layers for organic light emitting diodes, gate dielectrics for organic thin film transistors and protective layers for polymer-based capacitors.

An alternative fabrication method for dye-doped DNA-surfactant complex films was developed and amplified spontaneous emission (ASE) and lasing under low energy optical pumping were demonstrated. In this new preparation technique, thin DNA-cethyltrimethylammonium (CTMA) complex films made by a spin coating method were stained with a hemicyanine dye by soaking them in acetone solution of the dye for one day. Molar ratio of the dye to DNA base pair for the final products was estimated to be 0.2, the value was much higher than those achieved via usual mixing method. ASE threshold value under pumping of a pulsed frequency-doubled YAG laser was about 0.3 mJ/cm². Laser emission was also attained under the excitation with two interfering beams forming a dynamic grating of gain coefficient. Durability test indicated that 70% of their initial performance was maintained after 1 hour of continuous pumping. The technique was applied to water soluble dyes because the DNA complex was insoluble to water as well as acetone. We employed anionic Eosin Y dye, succeeding in sample formation and ASE emission. Different types of surfactants were also complexed with DNA, showing variation of emission peak wavelength. These results give a clue about the structure of the complex or interaction modes between DNA and surfactants, strongly suggesting that dye molecules are not intercalated into nor bound to DNA double strand directly, but are incorporated in the complex system via ion-exchange process or aggregating with cationic surfactants.

We review the results of recent experimental studies on random lasing phenomenon in biopolymeric matrices: DNA-CTMA and starch, loaded with different luminescent dyes (DCNP and Rh6G). New experimental results for DNA-CTMA:DCNP system are presented. The random lasing originates due to the light scattering induced by formation of microcrystals or clusters in the bulk of biosystem. We propose a simple model for light transport in the scattering medium accounting for the inhomogeneities in polymer matrices simulated using Monte Carlo method and present some preliminary results related to ray scattering.

The Materials and Manufacturing Directorate of the Air Force Research Laboratory (AFRL) began studies of deoxyribonuclaic acid (DNA) as a polymer material in 2001 due to the availability of multi-gram quantities of 98% pure DNA extracted from Japanese salmon waste products. The research studies that followed explored the electrical, optical and electrooptical characteristics of thin films of DNA combined with the surfactant hexacytltrimethylammonium chloride making the resulting DNA-CTMA complex soluble in most polar solvents and insoluble in water. The films were produced mainly by spin coating although other techniques were also used. The focus was to measure the fundamental properties, such as volume electrical resistivity, dielectric constant, refractive index and thermal conductivity, and to explore various applications using test device configurations such as an optical modulator, OFET, OLED and energy storage capacitor fabricated using DNA-CTMA. The initial high molecular weight of 2,000 to >8,000 kDa was reduced by high power ultrasonic treatment, which provided molecular weight materials from 1,000 down to ~200 kDa. These lower molecular weight materials revealed changes in some properties of the DNA-CTMA material. This paper brings together the results of these studies to show the potential of DNA as a polymer material.

Photo-Seebeck effect of conjugated polymers (CPs) from thiophenes and selenophenes were explored for a flexible energy conversion device. CP films were obtained by oxidative polymerizations, which grow conductive channels as polymerization proceeds. Through an optimized polymerization condition, highly conductive CP films were obtained with lower oxidation level. Taking advantage of their high electrical conductivity, the CP films were further explored as a transparent photo-thermo-electric film, because their absorption energy is easily controlled by the degree of oxidation or doping. Upon exposure to a near IR source, the CP films got heated, to result in temperature rise on a substrate. The generated heat was effectively converted into electricity to confirm a photo-Seebeck effect from the CP film under a light exposure. Efficient near-IR photothermal effect and heat to electric conversion have been realized in CP films that could benefit in exploiting multifunctional film displays, invisible NIR sensors, and hybrid energy harvesters.

Polymer materials offer unique opportunities in nanophotonics and nanobiosystems since both top-down and bottom-up strategies can be pursued and combined towards the nanoscale. Besides, polymer materials can be, with simple methods, functionalized with nonlinear optical or fluorescent materials (organic, inorganic, or metal). The ensemble can be optically structured in a flexible way to obtain a polymer-based photonic nanostructure (host) containing active materials (guest), which may provide an enhancement of the guest optical response, leading to attractive applications. We have developed two important fabrication techniques, namely interference and one-photon absorption direct laser writing, which present different advantages and allow both to obtain desired micro and nanometric 2D and 3D structures. These polymer-based structures are promising for many potential applications, for example, laser, nonlinear optics, and plasmonics.

Diatom algae are single-celled, photosynthetic organisms with a cell wall called a frustule—a periodically patterned nano-structure made of silica. Throughout the last decade, diatom frustules have been studied for their potential uses as photonic crystals and biomimetic templates for artificially developed metamaterials. A MATLAB program characterizing their pore structure as a function of angle was developed, potentially giving insight into how their geometric characteristics determine their optical properties.

The development of new pH-sensitive fluorescent probes based on a push-pull architecture is presented with a 2- dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofurane as strong electron acceptor group. With a small structural change, it is possible to obtain a large range of phenolic pKa from 4.8 to 8.6 with some close to neutrality, underlining the role of the electron density modulation on the acidic properties. Remarkable changes in the optical properties (both absorption and fluorescence) were observed as a function of the pH. Ratiometric imaging of intracellular pH was carried out with the most promising probes and highlighted the possibility to distinguish near-neutral minor pH fluctuations in cells.

Hyper Rayleigh and Hyper Raman spectra of neat water have been recorded in two different geometrical configurations where the incident fundamental beam is impinging on the cell at right angle from the collection direction and in retroreflection. A polarization analysis is also performed for the hyper Rayleigh experiment to underlines the differences in measuring some elements of the first hyperpolarizability tensor of the molecules present in the liquid solution under study. These data, beyond the comparison of the cross sections for the different bands observed, allows for a better insight into the quadratic nonlinear optical response from neat water.

A palladium (Pd) nanowire-based hydrogen (H₂) sensor has been fabricated with a novel viral-templated assembly route. A filamentous M13 bacteriophage was used as the viral-template for assembly of Pd nanowires at ambient conditions. Scanning electron microscopy determined Pd nanowire distribution and morphology with the devices. The phage template concentration controlled the number of physical and electrical nanowire connections across the device. A greater phage concentration resulted in a higher connection density and thicker Pd deposition. A lower phage concentration generated devices which formed chain-like nanowires of Pd nanocrystals, whereas a higher phage concentration formed devices with a continuous mesh-like structure. The lower concentration devices showed 51-78% instantaneous response to 2000 ppm H₂ and response time less than 30 s.

Production of silver nanoparticles (AgNPs) using different biological methods is gaining recognition due to their multiple applications. Although, several physical and chemical methods have been used for the synthesis and stabilizing of AgNPs, yet, a green chemistry method is preferable because it is cost effective and environmentally friendly. The synthesis was done using Aloe Vera (AV) extract because it has chemical compounds such as “Antrokinon” that are known for its antibacterial, antivirus and anticancer properties. We hypothesize that AV extract can produce a stable nanoparticles within the 100 nm range and be biologically active. The biological compounds were extracted from AV skin with water and ethanol which was used as the reduction agent for the synthesis of nanoparticles. The biological extract and AgNO3 were blended and heated to synthesize AgNPs. The reaction process was monitored using UV-Visible spectroscopy. Fourier Transfer Infrared spectroscopy (FTIR) was used for the characterization of biological compounds and their substituent groups before and after the reaction process. Dynamic Light scattering (DLS) method was used to characterize particle size of AgNPs and their biomolecular stability. Results showed that biological compounds such as aliphatic amines, alkenes (=C-H), alkanes (C-H), alcohol (O-H) and unsaturated esters(C-O), which has an average particle size of 109 and 215.8 nm and polydispersity index of 0.451 and 0.375 for ethanol and water extract, respectively. According to TEM measurements the size of AgNPs are in the range 5-20 nm The results suggested that ethanol derived AgNPs contained higher yield of organic compounds, thus has better solubility power than water. Ag NPs can be used to control salmonella in poultry industry.

Preliminary studies toward the assembly of a gold-polypyrrole (PPy) peapod-like chemiresistive ammonia (NH3) gas sensors are presented. The proposed synthesis process will use electropolymerization to embed gold nanoparticles in polypyrrole nanowires. Viral-templating of gold nanoparticles and PPy electrodeposition via cyclic voltammetry are the focus of this investigation. A gold-binding M13 bacteriophage was used as a bio-template to assemble continuous chains of gold nanoparticles on interdigitated Pt working electrodes. The dimensions of the resulting nanowire-like structures were examined and the electrical resistance measured. PPy films were electropolymerized using an interdigitated planar, Pt electrode integrated counter and reference electrode. Morphological characterization of the polymer films was completed.

A gold-binding M13 bacteriophage was used as a model system to explore templating of inorganic material on geometrically transformed viruses . Gold-binding filamentous phage were converted to spheroid form with a short chloroform treatment, and the resulting morphology was investigated with electron microscopy. Binding studies revealed that spheroid-shaped gold-binding phage preserved its affinity for gold. Spheroids adhered to a planar substrate assembled clusters or rings of gold nanoparticles. This gold-binding phage served as a demonstration of a highly shape-modifiable viral-template for inorganic materials.

Nanometer-sized metallic colloidal particles with plasmonic resonances in the visible range are widely investigated for their attractive optical properties as sensors, for imaging and cancer treatment. Their second-order nonlinear optical properties are remarkably high. In this work, silver colloidal solutions have been synthesized by a simple and quick method in aqueous solutions with different protective agents (PVA, PVP). The first hyperpolarizability β values of Ag per atom and per particle for nanospheres at 1064 nm have been measured. Silver nanoparticles, which possess intense visible region surface plasmon absorption bands, prove to be excellent nonlinear scatterers.

In this paper, a detailed optical characterization of a series of 4-nitro/cyan, 2-nitro/cyan and 2,4-nitro/cyan substituted azobenzenes is carried out. The first-order hyperpolarizabilities of organic chromophores were determined by solvatochromic method. Different nonlinear optical behaviour is evidenced when the ortho position of an azo molecule is occupied by acceptor and donor substituents. An increase of first-order hyperpolarizability was noticed in the case of 2,4-disubstituted azobenzenes as compared to the monosubstituted ones. Solvent effect on the UV-Vis absorption spectra of azo-polymers was investigated using Kamlet-Taft multiparameter equation. Kamlet-Taft equation revealed that hydrogen bond acceptor properties and dipolarity/polarizability of the solvent have a significant contribution upon the solvatochromic behavior of azo-derivatives.