Organosilica Imprints for Preserving and Enhancing Biocatalytic Activity of Immobilized Enzyme

Enzymes are naturally occuring sustainable catalysts that offer competitive catalysis to synthetic routes. There exist growing demands for environmentally-friendly and sustainable catalysis, which have led to a surge of research in biocatalysis. 1-3 However, the major bottleneck for the industrial applications of enzymes is the long term operational stability and difficultly in recovery and reusability of enzymes. 4-6 The goal of this study was to develop biocatalytic surface with organo-silica enzyme imprints that can recover, stabilize and reuse enzymes. The complete encapsulation was expected to enhance thermal and chemical stability, and the plasmonic nanostructures were expected to provide the ability to enhance the biocatalytic activity when light was used as an external trigger. The target enzyme was horseradish peroxidase (HRP)

Graphene Oxide - Gold Nanostar based sensor for chemiresistor and SERS sensing

As part of a bigger project of building a multimodal electronic nose for 2,4 di-nitro toluene and 2,4,6 trinitrotoluene, the objective of this study was to develop a novel type of sensor to detect specific analytes and their concentrations. A chemiresistor based system involving gold and graphene nanostructures is proposed so that it has both chemiresistive and SERS sensing capabilities (fig. 1). It was expected that if succeeded, the sensor would show clearly the orthogonality between the optical SERS reading and the chemiresistive reading in terms of sensing analytes. This study hopes to eventually integrate chemiresistor sensing and SERS sensing for selective, qualitative and quantitative sensing of volatile organic compounds, especially explosives, but it is applicable to a wide range of sensing

Flexible Plasmonic Sensing Substrates and their application in Explosive Sensing

With an increasing use of improvised explosive devices in combat and terrorism, there is an urgent need for novel methods of trace explosive detection that can provide an inexpensive and effective solution. This study focuses on the development of such platform using flexible surface enhanced Raman scattering (SERS) substrates. Gold nanorods(AuNR) functionalized with peptides selective to explosive molecules, trinitrotoluene(TNT) and dinitrotoluene (DNT) were immobilized on various substrates to fabricate a flexible SERS substrate. The peptide conjugated AuNRs can detect TNT and DNT vapors, and the cysteamine conjugated nanorods could detect TNT in aqueous solution down to 100 nM. Additionally, we also proposed the design of a 3D structures to improve the sensitivity of SERS detection. The synthesis of 3D nanostructures involves the growth of zinc oxide nanowires on paper substrates, followed by the adsorption of gold nanorods on the ZnO nanowires. The resulting structure had a higher surface area and higher number of AuNRs within the laser footprint compared to paper adsorbed with AuNRs enabling and are expected to exhibit higher SERS enhancement. The ZnO-AuNR paper substrate showed higher SERS sensitivity than planar silicon and plasmonic paper surfaces. The unique design of zinc oxide – paper hybrid substrate improved the sensitivity of SERS based detection. The advances in the development of unique SERS substrates and the design of the recognition elements for explosive detection is a critical step towards to the design of SERS based chemical sensors

Using BNC as Bioplasmonic Sensors

This study aimed to find a technique for using BNC (bacterial nanocellulose) as a plasmonic biosensor with a hot spot localized surface. A template protein (Hb) was imprinted on Au nanorods and was followed with the polymerization of APTMS and TMPS. The protein was then removed to leave an artificial receptor, which enabled protein rebinding. We were successful in developing a procedure for this study, and in the future we will be developing a technique that will allow multiple detection of proteins

Study On Relation Between Gold Nanorattle Core Diameter and Sensitivity to Target Proteins in Solution

Using two methods of determining the sensitivity of gold nanorattles (AuNRTs) bound to glass substrates, the relation between the diameter of the cores of the AuNRTs and their quantified sensitivity was explored. Both methods indicated an increase in sensitivity with an increase in core diameter

Nanoantenna-Microcavity Hybrids with Highly Cooperative Plasmonic-Photonic Coupling

Nanoantennas offer the ultimate spatial control over light by concentrating optical energy well below the diffraction limit, whereas their quality factor (Q) is constrained by large radiative and dissipative losses. Dielectric microcavities, on the other hand, are capable of generating a high Q-factor through an extended photon storage time but have a diffraction-limited optical mode volume. Here we bridge the two worlds, by studying an exemplary hybrid system integrating plasmonic gold nanorods acting as nanoantennas with an on-resonance dielectric photonic crystal (PC) slab acting as a low-loss microcavity and, more importantly, by synergistically combining their advantages to produce a much stronger local field enhancement than that of the separate entities. To achieve this synergy between the two polar opposite types of nanophotonic resonant elements, we show that it is crucial to coordinate both the dissipative loss of the nanoantenna and the Q-factor of the low-loss cavity. In comparison to the antenna-cavity coupling approach using a Fabry-Perot resonator, which has proved successful for resonant amplification of the antenna's local field intensity, we theoretically and experimentally show that coupling to a modest-Q PC guided resonance can produce a greater amplification by at least an order of magnitude. The synergistic nanoantenna-microcavity hybrid strategy opens new opportunities for further enhancing nanoscale light-matter interactions to benefit numerous areas such as nonlinear optics, nanolasers, plasmonic hot carrier technology, and surface-enhanced Raman and infrared absorption spectroscopies.Comment: Revised version after acceptanc

Single cell preparations of Mycobacterium tuberculosis damage the mycobacterial envelope and disrupt macrophage interactions

For decades, investigators have studied the interaction o

Distance-dependent plasmon-enhanced fluorescence of upconversion nanoparticles using polyelectrolyte multilayers as tunable spacers

Lanthanide-doped upconversion nanoparticles (UCNPs) have attracted widespread interests in bioapplications due to their unique optical properties by converting near infrared excitation to visible emission. However, relatively low quantum yield prompts a need for developing methods for fluorescence enhancement. Plasmon nanostructures are known to efficiently enhance fluorescence of the surrounding fluorophores by acting as nanoantennae to focus electric field into nano-volume. Here, we reported a novel plasmon-enhanced fluorescence system in which the distance between UCNPs and nanoantennae (gold nanorods, AuNRs) was precisely tuned by using layer-by-layer assembled polyelectrolyte multilayers as spacers. By modulating the aspect ratio of AuNRs, localized surface plasmon resonance (LSPR) wavelength at 980 nm was obtained, matching the native excitation of UCNPs resulting in maximum enhancement of 22.6-fold with 8 nm spacer thickness. These findings provide a unique platform for exploring hybrid nanostructures composed of UCNPs and plasmonic nanostructures in bioimaging applications