SPR

The purpose of this review was to evaluate the hazard Index and Incremental life cancer risks associated with heavy metal contaminations of the soil for residents in the country. Many scientific articles have been accessible online in the Nigeria were evaluated for the estimation of [Hazard Index and Incremental Life Cancer Risk] for individual heavy metals. The heavy metals considered in this work are; [Lead (Pb), Copper (Cu), Iron (Fe), Manganese (Mn), Zinc (Zn), Chromium (Cr), and Cadmium (Cd)] The concentrations of these metals were obtained from the literature and modeled for, hazard index (HI), and carcinogenic risk (ILCR) via ingestion, inhalation, and dermal pathways for adults following the United State Environmental Protection Agency [USEPA] method. The hazard index for all the exposure pathways (ingestion, inhalation, and dermal contact) was found to be 21914, 1020.7, 580.8, 2.641, 0.272, 0.05165, 0.021, and 0.011[mg/kg/day], for Fe, Mn, Cr, Pb, Cu, Zn, Ni, and Cd respect...

Polymer hydrogels have been widely explored as therapeutic delivery matrices because of their ability to present sustained, localized and controlled release of bioactive factors. Bioactive factor delivery from injectable biopolymer hydrogels provides a versatile approach to treat a wide variety of diseases, to direct cell function and to enhance tissue regeneration. The innovative development and modification of both natural-(e.g., alginate (ALG), chitosan, hyaluronic acid (HA), gelatin, heparin (HEP), etc.) and synthetic-(e.g., polyesters, polyethyleneimine (PEI), etc.) based polymers has resulted in a variety of approaches to design drug delivery hydrogel systems from which loaded therapeutics are released. This review presents the state-of-the-art in a wide range of hydrogels that are formed though self-assembly of polymers and peptides, chemical crosslinking, ionic crosslinking and biomolecule recognition. Hydrogel design for bioactive factor delivery is the focus of the first s...

A  graphene  coated  high  sensitive  surface  plasmon  resonance  (SPR)  biosensor  is
presented  for biomedical applications specialy  the detection of DNA Hybridization. The
detection technique is attenuated total reflection (ATR) method, which is  worked on  the
adsorption  of  biomolecules  and  refractive  index  change  near  the  sensor  surface.  This
proposed sensor is sensed nucleotides bonding happened between double-stranded (dsDNA)
helix structure, based on the change of surface plasmon resonance (SPR) angle-the change
of  minimum  reflectance  (Rmin)  attributor  and  the  resonance  frequency  characteristics
(RFC)-maximum  transmittance  (Tmax)  attributor.  Numerical  analysis  shows  that  the
variation of RFC and SPR angle for mismatched DNA strands is quiet negligible whereas
that for complementary  DNA strands is considerably countable. Here, sensor is designed
based on graphene material as biomolecular recognition elements (BRE) and the sharp SPR
curve of gold (Au). Graphene is used to perform faster immobilization between target DNA
and probe DNA.This sensor can successfully detect the hybridization of target DNAs to the
probe  DNAs  pre-immobilized  on  graphene  with  capability  to  distinguish  single-base
mismatch. In additionally the methodology of this study is presented for diagnosis of the
single-nucleotide polymorphisms (SNP) which uses a graphene coated DNA sensor.
Numerical calculations show that the proposed graphene coated on gold SPR biosensor
has 1 + 0.4 L; (where L is the number of graphene sub-layers) times more sensitivity than
the  conventional  SPR  biosensor  when  SPR  angle-Rmin  attributor  is  used  as  detecting
parameters. The enhanced sensitivity is due to increased SPR angle change about 40L% by
adding graphene layer and using the optical property of graphene. On the other hand, use of
RFC-Tmax  attributor enhances 1+.95 L sensitivity comparing with conventional SPR sensor.
The  proposed  frequency-angle  readout  based  SPR  sensor  could  potentially  open  a  new
window of detection for biomolecular interactions. We also highlight the advantage of using
graphene sublayer by performing the sensitivity analysis.

The way in which organisms detect specific volatile compounds within their environment, and the associated neural processing which produces perception and subsequent behavioural responses, have been of interest to scientists for decades. Initially, most olfaction research was conducted using electrophysiological techniques on whole animals. However, the discovery of genes encoding the family of human olfactory receptors (ORs) paved the way for the development of a range of cellular assays, primarily used to deorphan ORs from mammals and insects. These assays have greatly advanced our knowledge of the molecular basis of olfaction, however, while there is currently good agreement on vertebrate and nematode olfactory signalling cascades, debate still surrounds the signalling mechanisms in insects. The inherent specificity and sensitivity of ORs makes them prime candidates as biological detectors of volatile ligands within biosensor devices, which have many potential applications. In the previous decade, researchers have investigated various technologies for transducing OR:ligand interactions into a readable format and thereby produce an olfactory biosensor (or bioelectronic nose) that maintains the discriminating power of the ORs in vivo. Here we review and compare the molecular mechanisms of olfaction in vertebrates and invertebrates, and also summarise the assay technologies utilising sub-tissue level sensing elements (cells and cell extracts), which have been applied to OR deorphanisation and biosensor research. Although there are currently no commercial, “field-ready” olfactory biosensors of the kind discussed here, there have been several technological proof-of-concept studies suggesting that we will see their emergence within the next decade.▶ Discovery of olfactory receptor (OR) genes facilitated novel cellular assays used to deorphan ORs. ▶ There is agreement on vertebrate olfactory signalling but debate surrounds signalling in insects. ▶ Here we review and compare the molecular mechanisms of olfaction in vertebrates and invertebrates. ▶ We also summarise assay technologies applied to OR deorphanisation and biosensor research. ▶ Proof-of-concept studies suggest that commercial olfactory biosensors will soon appear.

In this article, numerically a surface plasmon resonance (SPR) biosensor is developed based on Graphene-MOS2-Au-TiO2-SiO2 hybrid structure for formalin detection. This developed sensor sensed the presence of formalin by applying attenuated total reflection (ATR). In ATR method, we developed and observed two characteristics curve, one is "SPR angle versus minimum reflectance (Rmin)" and another is "SPR frequency (SPRF) versus maximum transmittance (Tmax). In the proposed sensor, Chitosan is used as probe legend to perform specific reaction with the formalin (40% formaldehyde) as target legend. Here, graphene and MoS2 both are used as biomolecular acknowledgment element (BAE). And TiO2 as well as SiO2 bilayers are used to improve sensor sensitivity and Gold (Au) is to sharp SPR curve. In numerical results, the variation of SPRF and SPR angle for inappropriate sensing of formalin is quiet insignificant which confirms the absence of formalin. On the other hand, these variations for appropriate sensing is considerably significant that confirms the presence of formalin. At the end of this article, a study of variation of sensitivity of the proposed biosensor in corresponding to the increment of refractive index with a refractive index step 0.01 RIU is measured. In inclusion of TiO2-SiO2 bilayers with Graphene-MOS2, maximum sensitivity of 85.375% more is numerically reported.

Carbohydrate binding proteins, such as lectins, are crucial in numerous biological recognition processes. While binding may be mediated by a single monosaccharide, several lectins have shown exquisite epimer and linkage recognition indicating that a larger structure is essential for optimal interaction. Several approaches have been described for their detailed study, including lectinosorbent assays, microarrays and surface plasmon resonance (SPR). Most of these approaches ignore that the aglycon-bound monosaccharide is often in a non-natural conformation that affects the occurring binding event. In this paper we demonstrate that oxime-bound glycans, employed in such approaches, occur predominantly in the open form (~70%). Through the use of a secondary amine, the aglycon-bound monosaccharide in the resulting neo-glycopeptide probe is forced into the ring-form. Resulting structures were analyzed by means of nuclear magnetic resonance and differential derivatization experiments. The impact of ring closure was further demonstrated through interaction studies using SPR and various lectins with distinct binding specificities.

Secreted Frizzled-related proteins (sFRPs) are modulators of the Wnt signaling pathway that plays important roles in both embryogenesis and oncogenesis. sFRPs have been proposed to antagonize Wnt activity by binding to Wnts. However, the affinity of this binding is unknown. Here we show, using surface plasmon resonance and purified proteins, that sFRP1, sFRP2, sFRP4, and Frzb bind directly to Wnt3a with affinities in the nanomolar range. However, only sFRP1 and sFRP2 antagonize Wnt3a activity by blocking Wnt3a induced β-catenin accumulation in L cells. Furthermore, sFRP2, but not Frzb, antagonizes Wnt3a signaling in an ES cell model of mesoderm differentiation. These results provide the first measurement of binding affinity of sFRPs for a Wnt, which together with the measurement of antagonistic activity of sFRPs could help understand how sFRPs regulate Wnt signaling.

Protein microarrays, on which thousands of discrete proteins are printed, provide a valuable platform for functional analysis of the proteome. They have been widely used for biomarker discovery and to study protein–protein interactions. The accomplishments of DNA microarray technology, which had enabled massive parallel studies of gene expression, sparked great interest for the development of protein microarrays to achieve similar success at the protein level. Protein microarray detection techniques are often classified as being label-based and label-free. Most of the microarray applications have employed labelled detection such as fluorescent, chemiluminescent and radioactive labelling. These labelling strategies have synthetic challenges, multiple label issues and may exhibit interference with the binding site. Therefore, development of sensitive, reliable, high-throughput, label-free detection techniques are now attracting significant attention. Label-free detection techniques monitor biomolecular interactions and simplify the bioassays by eliminating the need for secondary reactants. Moreover, they provide quantitative information for the binding kinetics. In this article, we will review several label-free techniques, which offer promising applications for the protein microarrays, and discuss their prospects, merits and challenges.

Brooks, E. N., Powers, J. E., and Cortés, E. 2010. Analytical reference points for age-structured models: application to data-poor fisheries. – ICES Journal of Marine Science, 67: 165–175. Analytical solutions for biological reference points are derived in terms of maximum lifetime reproductive rate. This rate can be calculated directly from biological parameters of maturity, fecundity, and natural mortality or a distribution for this rate can be derived from appropriate metadata. Minimal data needs and assumptions for determining stock status are discussed. The derivations lead to a re-parameterization of the common stock–recruit relationships, Beverton–Holt and Ricker, in terms of spawning potential ratio. Often, parameters in stock–recruit relationships are restricted by tight prior distributions or are fixed based on a hypothesized level of stock resilience. Fixing those parameters is equivalent to specifying the biological reference points. An ability to directly calculate refe...

In this paper, a high sensitive photonic crystal fiber (PCF) based surface plasmon resonance (SPR) biosensor is numerically studied. In this structure, as a plasmonic material, gold (Au) is used because of its chemical activeness. And a layer of sensing medium is used outside of the fiber to make the structure effective. Any unknown biomolecular analyte can be detected by placing or flowing it on the metal surface. Guiding properties and results are investigated using Finite element method (FEM). Results show that maximum sensitivity is 4000 nm/RIU, as well as resolution, is 2.5 × 10 −5 RIU of the proposed sensor.