An electro-active system of immuno-assay (EASI assay) utilising self assembled monolayer modified electrodes

Electrochemical biosensors for monitoring of selected pregnancy hormones during the first trimester: A systematic review

The hormones human chorionic gonadotropin, progesterone, estrogen and four of its metabolites (estradiol, estrone, estriol, estetrol), as well as relaxin play an essential role in the development of the fetus during the first trimester. Imbalances in these hormones during the first trimester have been directly linked to miscarriages. However, frequent monitoring of the hormones is limited by the current conventional centralized analytical tools that do not allow a rapid response time. Electrochemical sensing is considered an ideal tool to detect hormones owing to its advantages such as quick response, user-friendliness, low economic costs, and possibility of use in point-of-care settings. Electrochemical detection of pregnancy hormones is an emerging field that has been demonstrated primarily at research level. Thus, it is timely with a comprehensive overview of the characteristics of the reported detection techniques. This is the first extensive review focusing on the advances related to electrochemical detection of hormones linked to the first trimester of pregnancy. Additionally, this review offers insights into the main challenges that must be addressed imminently to ensure progress from research to clinical applications.

Biomolecules Detection Using a Silver-Enhanced Gold Nanoparticle-Based Biochip

Silver-enhanced labeling method has been employed in immunochromatographic assays for improving the sensitivity of detecting pathogens. In this paper, we apply the silver enhancement technique for biomolecular signal amplification in a gold nanoparticle-based conductimetric biochip. We show that the response of the silver-enhanced biochip comprises two distinct regions namely: (a) a sub-threshold region where conduction occurs due to electron hopping between silver islands and the electrolyte and (b) an above-threshold region where the conduction is due to a direct flow of electrons. These two regions are characterized by different conduction slopes, and we show that combining the information from both these regions can improve the sensitivity of the biochip. Results from fabricated prototypes show a dynamic range of more than 40 dB and with a detection limit less than 240 pg/mL. The fabrication of the biochip is compatible with standard complementary metal-oxide-semiconductor (CMOS) processes making it ideal for integration in next-generation CMOS biosensors.

Analytical methods for determination of mycotoxins: a review

Mycotoxins are small (MW approximately 700), toxic chemical products formed as secondary metabolites by a few fungal species that readily colonise crops and contaminate them with toxins in the field or after harvest. Ochratoxins and Aflatoxins are mycotoxins of major significance and hence there has been significant research on broad range of analytical and detection techniques that could be useful and practical. Due to the variety of structures of these toxins, it is impossible to use one standard technique for analysis and/or detection. Practical requirements for high-sensitivity analysis and the need for a specialist laboratory setting create challenges for routine analysis. Several existing analytical techniques, which offer flexible and broad-based methods of analysis and in some cases detection, have been discussed in this manuscript. There are a number of methods used, of which many are lab-based, but to our knowledge there seems to be no single technique that stands out above the rest, although analytical liquid chromatography, commonly linked with mass spectroscopy is likely to be popular. This review manuscript discusses (a) sample pre-treatment methods such as liquid-liquid extraction (LLE), supercritical fluid extraction (SFE), solid phase extraction (SPE), (b) separation methods such as (TLC), high performance liquid chromatography (HPLC), gas chromatography (GC), and capillary electrophoresis (CE) and (c) others such as ELISA. Further currents trends, advantages and disadvantages and future prospects of these methods have been discussed.

MCM-41 mesoporous material modified carbon paste electrode for the determination of cardiac troponin I by anodic stripping voltammetry

An anodic stripping voltammetric method for the determination of cardiac troponin I (cTnI) at a MCM-41 mesoporous material modified carbon paste electrode (MCM-MCPE) was investigated. The test was based on the dual monoclonal antibody "sandwich" principle using colloidal gold as a labeled substrate. Four main steps were carried out to obtain the analytical signal, i.e. electrode preparation, immunoreaction, silver enhancement, and anodic stripping voltammetric detection. The anodic stripping peak current increased linearly with the concentration of cTnI over the range of 0.8-5.0ng/ml. A detection limit of 0.5ng/ml was obtained. The established method was applied to detect cTnI in acute myocardial infarction (AMI) samples using routine enzyme-linked immunoadsorbent assay (ELISA) for comparison analysis, and good results were obtained.