A novel electroconductive interface based on Fe3O4 magnetic nanoparticle and cysteamine functionalized AuNPs: Preparation and application as signal amplification element to minoring of antigen‐antibody immunocomplex and biosensing of prostate cancer

In this study, a novel electroconductive interface was prepared based on Fe₃O₄ magnetic nanoparticle and cysteamine functionalized gold nanoparticle. The engineered interface was used as signal amplification substrate in the electrochemical analysis of antibody‐antigen binding. For this purpose, biotinilated‐anti‐prostate‐specific antigen (PSA) antibody was bioconjugated with iron oxide magnetic nanoparticles (Fe₃O₄) and drop‐casted on the surface of glassy carbon electrode (GCE). Also, secondary antibody (HRP‐Ab2) encapsulated on gold nanoparticles caped by cysteamine was immobilized on the surface of GCE modified electrode. A transmission electron microscopy images shows that a sandwich immunoreaction was done and binding of Ab1 and Ab2 performed successfully. Various parameters of immunoassay, including the loading of magnetic nanoparticles, the amount of gold nanoparticle conjugate, and the immunoreaction time, were optimized. The detection limit of 0.001 μg. L^?1 of PSA was obtained under optimum experimental conditions. It is found that such magneto‐bioassay could be readily used for simultaneous parallel detection of multiple proteins by using multiple inorganic metal nanoparticle tracers and are expected to open new opportunities for early stage diagnosis of cancer in near future.     

Direct Nanoscale Characterization of Deep Levels in AgCuInGaSe2 Using Electron Energy‐Loss Spectroscopy in the Scanning Transmission Electron Microscope

A new experimental framework for the characterization of defects in semiconductors is demonstrated. Through the direct, energy‐resolved correlation of three analytical techniques spanning six orders of magnitude in spatial resolution, a critical mid‐bandgap electronic trap level (E_V + 0.56 eV) within Ag_0.2Cu_0.8In_1?xGa_xSe₂ is traced to its nanoscale physical location and chemical source. This is achieved through a stepwise, site‐specific correlated characterization workflow consisting of device‐scale (≈1 mm²) deep level transient spectroscopy (DLTS) to survey the traps present, scanning probe–based DLTS (scanning‐DLTS) for mesoscale‐resolved (hundreds of nanometers) mapping of the target trap state's spatial distribution, and scanning transmission electron microscope based electron energy‐loss spectroscopy (STEM‐EELS) and X‐ray energy‐dispersive spectroscopy for nanoscale energy‐, structure, and chemical‐resolved investigation of the defect source. This first demonstration of the direct observation of sub‐bandgap defect levels via STEM‐EELS, combined with the DLTS methods, provides strong evidence that the long‐suspected Cu_In/Ga substitutional defects are indeed the most likely source of the E_V + 0.56 eV trap state and serves as a key example of this approach for the fundamental identification of defects within semiconductors, in general.     

Bioavailability and Concentration of Heavy Metals in the Sediments and Leaves of Grey Mangrove, <Emphasis Type="BoldItalic">Avicennia marina</Emphasis> (Forsk.) Vierh,in Sirik Azini Creek,Iran

The concentration and bioavailability of Ni, Cu, Cd, Zn, and Pb in the sediments and leaves of grey mangrove, Avicennia marina, were studied throughout Sirik Azini creek (Iran) with a view to determine heavy metals bioavailability, and two methods were used. Results show that Zn and Ni had the highest concentrations in the sediments, while Cd and Cu were found to have the lowest concentrations in the sediments. Compared to the mean concentrations of heavy metals in sedimentary rock (shales), Zn and Cu showed lower concentration, possibly indicating that the origin of these heavy metals is natural. A geo-accumulation index (I _geo) was used to determine the degree of contamination in the sediments. I _geo values for Zn, Cu, Pb, and Ni showed that there is no pollution from these metals in the study area. As heavy metal concentrations in leaves were higher than the bioavailable fraction of metals in sediments, it follows that bioconcentration factors (leaf/bioavailable sediment) for some metals were higher than 1.     

Development of a New Pollution Index for Heavy Metals in Sediments

This study aims to investigate the pollution rate of heavy metals on the western seaboard of Bandarabbas in southeast Iran using a new pollution index. The bulk of the analysis was conducted on sediments, followed by selection of a few samples to perform experiments on chemical partitioning studies as well as biological accessibility. On this basis, the proportions of natural and anthropogenic elements were calculated. Finally, with regard to chemical separation results, the pollution rate was calculated based on Muller's geo-chemical index, enrichment factor, pollution index, and a new "Risk" index. Chemical separation showed the anthropogenic origin of elements are as follows: Ni(27.5%) > Zn(6.5%) > Pb(2%) > Al (0.2%). The newly developed pollution index is indicative of "low environmental pollution "for Ni.     

A novel bioassay for the monitoring of carcinoembryonic antigen in human biofluid using polymeric interface and immunosensing method

Carcinoembryonic antigen (CEA) is a member of a family of cell surface glycoproteins. Recognition of CEA is needed to monitor the physiological status of the patient for treatment and also it is important to assess the severity of the disease. In this work, we reported a novel sandwich‐type electrochemical immunosensor based on gold nanoparticles functionalized cysteamine‐glutaraldehyde (AuNPs‐CysA‐GA) and it successfully designed to detection of the CEA biomarker in a human plasma sample. The AuNPs‐CysA‐GA provides a large surface area for the effective immobilization of CEA antibody, as well as it ascertains the bioactivity and stability of immobilized CEA antigens. Biotinylated‐anti‐CEA antibody (Ab1) was immobilized on the surface of glassy carbon electrode (GCE) modified AuNPs‐CysA‐GA. Also, secondary antibody (HRP‐Ab2) was costed immobilized to complete the sandwich part of immunosensor. Field emission scanning electron microscope (FE‐SEM and EDS), was employed to monitor the sensor fabrication procedure. The immunosensor was used for the detection of CEA using differential pulse voltammetry (DPVs) technique. The proposed interface led to enhancement of accessible surface area for immobilizing high amount of anti‐CEA antibody, increasing electrical conductivity, boosting stability, and biocompatibility. Finally, the low limit of quantitation (LLOQ) of the proposed immunosensor was obtained as 7 ng/mL with the linear range of 0.001‐5 μg/L. The proposed immunoassay was successfully applied for the monitoring of the CEA in unprocessed human plasma samples. Obtained results paved that the proposed bioassay can be used as a novel bioassay for the clinical diagnosis of cancer based on CEA monitoring.     

How Transmembrane Inner Ear (TMIE) plays role in the auditory system: A mystery to us

Different cellular mechanisms contribute to the hearing sense, so it is obvious that any disruption in such processes leads to hearing impairment that greatly influences the global economy and quality of life of the patients and their relatives. In the past two decades, transmembrane inner ear (TMIE) protein has received a great deal of research interest because its impairments cause hereditary deafness in humans. This evolutionarily conserved membrane protein contributes to a fundamental complex that plays role in the maintenance and function of the sensory hair cells. Although the critical roles of the TMIE in mechanoelectrical transduction or hearing procedures have been discussed, there are little to no review papers summarizing the roles of the TMIE in the auditory system. In order to fill this gap, herein, we discuss the important roles of this protein in the auditory system including its role in mechanotransduction, olivocochlear synapse, morphology and different signalling pathways; we also review the genotype-phenotype correlation that can per se show the possible roles of this protein in the auditory system.