Confinement-Induced Enhancement of Antigen-Antibody Interactions within Binary Nanopatterns to Achieve Higher Efficiency of On-Chip Immunosensors

Highly sensitive and reproducible CNTs@Ag modified Flower-Like silver nanoparticles for SERS situ detection of transformer Oil-dissolved furfural

Accurately evaluating the aging state of oil paper insulation in electrical equipment is a key to ensure the safe operation of the power transformer. For achieving highly sensitive in-situ detection of dissolved furfural in transformer oil with good reproducibility, flower-like silver nanoparticles modified with carbon nanotubes (CNTs@Ag-F-AgNPs) was synthesized by a combination of electroless silver plating and redox method. The large specific surface area and strong adsorption capacity of CNTs@Ag promoted the formation of more "hot spots". CNTs@Ag-F-AgNPs were adsorbed on Si-Au substrate via mercapto groups on the coupling agent 1'4 phenyldimercaptan molecule (BDT). Using rhodamine 6G (R6G) as probe molecule, the enhanced factor reached 6.96 × 10⁹. Then, the substrate was used for in-situ SERS detection of transformer oil-dissolved furfural at different concentrations and the detection limit was 2.25 mg/L at 1703 cm^-1 (Stretching vibration of C = O in furfural molecule), fulfilling requirements of furfural content detection after severe aging of transformer (4 mg/L). Besides, the relative standard deviation (RSD) of characteristic peak intensity at ten different positions was only 1.74%. These results exhibite that three-dimensional nanostructure with high sensitivity and good reproducibility exhibited a wide application range for in situ detection of dissolved trace furfural in transformer oil.

Efficient Light-Harvesting Systems with Tunable Emission through Controlled Precipitation in Confined Nanospace

Light harvesting is a key step in photosynthesis but creation of synthetic light-harvesting systems (LHSs) with high efficiencies has been challenging. When donor and acceptor dyes with aggregation-induced emission were trapped within the interior of cross-linked reverse vesicles, LHSs were obtained readily through spontaneous hydrophobically driven aggregation of the dyes in water. Aggregation in the confined nanospace was critical to the energy transfer and the light-harvesting efficiency. The efficiency of the excitation energy transfer (EET) reached 95 % at a donor/acceptor ratio of 100:1 and the energy transfer was clearly visible even at a donor/acceptor ratio of 10 000:1. Multicolor emission was achieved simply by tuning the donor/acceptor feed ratio in the preparation and the quantum yield of white light emission from the system was 0.38, the highest reported for organic materials in water to date.

Multiplex surface plasmon resonance biosensing and its transferability towards imaging nanoplasmonics for detection of mycotoxins in barley

A 6-plex mycotoxin assay was developed on a portable nanostructured iSPR and compared with a benchmark double 3-plex SPR assay.

Insights into the effect of nanoconfinement on molecular interactions

Being confined within nanoscale space, substances may exhibit unique physicochemical properties. The effect of nanoconfinement on molecular interactions is of significance, but a sound understanding has not been established yet. Here we present a quantitative study on boronate affinity (covalent) and electrostatic (non-covalent) interactions confined within mesoporous silica. We show that both interactions were enhanced by the confinement and that the enhancement depended on the closeness of the interacting location, as well as on the difference between the pore size and the molecular size. The overall enhancement could reach 3 orders of magnitude.

Nanoparticle cluster arrays for high-performance SERS through directed self-assembly on flat substrates and on optical fibers

We demonstrate template-guided self-assembly of gold nanoparticles into ordered arrays of uniform clusters suitable for high-performance SERS on both flat (silicon or glass) chips and an optical fiber faucet. Cluster formation is driven by electrostatic self-assembly of anionic citrate-stabilized gold nanoparticles (~11.6 nm diameter) onto two-dimensionally ordered polyelectrolyte templates realized by self-assembly of polystyrene-block-poly(2-vinylpyridine). A systematic variation is demonstrated for the number of particles (N ≈ 5, 8, 13, or 18) per cluster as well as intercluster separations (S(c) ≈ 37-10 nm). Minimum interparticle separations of <5 nm, intercluster separations of ~10 nm, and nanoparticle densities on surfaces as high as ~7 × 10(11)/in.(2) are demonstrated. Geometric modeling is used to support experimental data toward estimation of interparticle and intercluster separations in cluster arrays. Optical modeling and simulations using the finite difference time domain method are used to establish the influence of cluster size, shape, and intercluster separations on the optical properties of the cluster arrays in relation to their SERS performance. Excellent SERS performance, as evidenced by a high enhancement factor, >10(8) on flat chips and >10(7) for remote sensing, using SERS-enabled optical fibers is demonstrated. The best performing cluster arrays in both cases are achievable without the use of any expensive equipment or clean room processing. The demonstrated approach paves the way to significantly low-cost and high-throughput production of sensor chips or 3D-configured surfaces for remote sensing applications.

Prospects of nanotechnology in clinical immunodiagnostics

Nanostructured materials are promising compounds that offer new opportunities as sensing platforms for the detection of biomolecules. Having micrometer-scale length and nanometer-scale diameters, nanomaterials can be manipulated with current nanofabrication methods, as well as self-assembly techniques, to fabricate nanoscale bio-sensing devices. Nanostructured materials possess extraordinary physical, mechanical, electrical, thermal and multifunctional properties. Such unique properties advocate their use as biomimetic membranes to immobilize and modify biomolecules on the surface of nanoparticles. Alignment, uniform dispersion, selective growth and diameter control are general parameters which play critical roles in the successful integration of nanostructures for the fabrication of bioelectronic sensing devices. In this review, we focus on different types and aspects of nanomaterials, including their synthesis, properties, conjugation with biomolecules and their application in the construction of immunosensing devices. Some key results from each cited article are summarized by relating the concept and mechanism behind each sensor, experimental conditions and the behavior of the sensor under different conditions, etc. The variety of nanomaterial-based bioelectronic devices exhibiting novel functions proves the unique properties of nanomaterials in such sensing devices, which will surely continue to expand in the future. Such nanomaterial based devices are expected to have a major impact in clinical immunodiagnostics, environmental monitoring, security surveillance and for ensuring food safety.

Rapid and sensitive biomolecular screening with encoded macroporous hydrogel photonic beads

We present a new method to prepare inverse opaline photonic beads with good spherical shape and superior optical performance by simply introducing an interfacial tension system into a template replication method. When the scaffolds of these beads were composed of poly(ethylene glycol) diacrylate hydrogel, they could provide a homogeneous water surrounding, which remedied many shortcomings of biomolecular microcarriers introduced by the presence of the solid surface of them. The suspension array, which used these macroporous hydrogel photonic beads as coding elements, showed obvious advantages in multiplexed capability, rapid biomolecular screening (within 12 min), and highly sensitive detection (with limit of detection of approximately 10(-12) M).

Biogenic nanoporous silica-based sensor for enhanced electrochemical detection of cardiovascular biomarkers proteins

The goal of our research is to demonstrate the feasibility of employing biogenic nanoporous silica as a key component in developing a biosensor platform for rapid label-free electrochemical detection of cardiovascular biomarkers from pure and commercial human serum samples with high sensitivity and selectivity. The biosensor platform consists of a silicon chip with an array of gold electrodes forming multiple sensor sites and works on the principle of electrochemical impedance spectroscopy. Each sensor site is overlaid with a biogenic nanoporous silica membrane that forms a high density of nanowells on top of each electrode. When specific protein biomarkers: C-reactive protein (CRP) and myeloperoxidase (MPO) from a test sample bind to antibodies conjugated to the surface of the gold surface at the base of each nanowell, a perturbation of electrical double layer occurs resulting in a change in the impedance. The performance of the biogenic silica membrane biosensor was tested in comparison with nanoporous alumina membrane-based biosensor and plain metallic thin film biosensor. Significant enhancement in the sensitivity and selectivity was achieved with the biogenic silica biosensor, in comparison to the other two, for detecting the two protein biomarkers from both pure and commercial human serum samples. The sensitivity of the biogenic silica biosensor is approximately 1 pg/ml and the linear dose response is observed over a large dynamic range from 1 pg/ml to 1 microg/ml. Based on its performance metrics, the biogenic silica biosensor has excellent potential for development as a point of care handheld electronic biosensor device for detection of protein biomarkers from clinical samples.

Grading the commercial optical biosensor literature-Class of 2008: 'The Mighty Binders'

Optical biosensor technology continues to be the method of choice for label-free, real-time interaction analysis. But when it comes to improving the quality of the biosensor literature, education should be fundamental. Of the 1413 articles published in 2008, less than 30% would pass the requirements for high-school chemistry. To teach by example, we spotlight 10 papers that illustrate how to implement the technology properly. Then we grade every paper published in 2008 on a scale from A to F and outline what features make a biosensor article fabulous, middling or abysmal. To help improve the quality of published data, we focus on a few experimental, analysis and presentation mistakes that are alarmingly common. With the literature as a guide, we want to ensure that no user is left behind.