A Simple, Efficient and Ultrasensitive Gold Nanourchin Based Electrochemical Sensor for the Determination of an Antimalarial Drug: Mefloquine

Gold-Nanohybrid Biosensors for Analyzing Blood Circulating Clinical Biomacromolecules: Current Trend toward Future Remote Digital Monitoring

Mortality level is worsening the situation worldwide thru blood diseases and greatly jeopardizes the human health with poor diagnostics. Due to the lack of successful generation of early diagnosis, the survival rate is currently lower. To overcome the present hurdle, new diagnostic methods have been choreographed for blood disease biomarkers analyses with the conjunction of ultra-small ideal gold nanohybrids. Gold-hybrids hold varieties of unique features, such as high biocompatibility, increased surface-to-volume ratio, less-toxicity, ease in electron transfer and have a greater localized surface plasmon resonance. Gold-nanocomposites can be physically hybrid on the sensor surface and functionalize with the biomolecules using appropriate chemical conjugations. Revolutionizing biosensor platform can be prominently linked for the nanocomposite applications in the current research on medical diagnosis. This review encloses the new developments in diagnosing blood biomarkers by utilizing the gold-nanohybrids. Further, the current state-of-the-art and the future envision with digital monitoring for facile telediagnosis were narrated.

Gold nano-urchin integrated label-free amperometric aptasensing human blood clotting factor IX: A prognosticative approach for "Royal disease"

This article is clearly presenting the development of a biosensor for human factor IX (FIX) to diagnose the blood clotting deficiency, a so-called 'Royal disease' using an interdigitated electrode (IDE) with the zinc oxide surface modification. Gold nano-urchins (GNUs) with 60 nm in diameter was integrated into a streptavidin-biotinylated aptamer strategy to enhance the active surface area. Two different comparative studies have been done to validate the system to be practiced in the current work holds with a higher capability for the high-performance sense. Whereby, the presence and absence of GNUs in the aptasensing system for FIX interaction were investigated using the amperometric measurement, using a linear sweep voltage of 0-2 V at 0.01 V step voltage. The detection limit was 6 pM based on 3σ calculation when GNUs integrated aptamer assay was utilized for FIX detection, which shows 8 folds sensitivity enhancement comparing the condition in the absence of GNU and 50 folds higher than sensitive radio-isotope and surface plasmon resonance assays. Albeit, the surface and molecular characterizations were well demonstrated by scanning electron microscopy, atomic force microscopy, 3D nano-profilometry and further supports were rendered by UV-Vis spectroscopy and Enzyme-linked apta-sorbent assay (ELASA). Furthermore, the spiking experiment was done by FIX-spikes in human blood serum in order to demonstrate the stability with a higher non-fouling.

An electrochemical aptasensor for staphylococcal enterotoxin B detection based on reduced graphene oxide and gold nano-urchins

Detection of staphylococcal enterotoxin B (SEB) as a bacterial toxin causing severe food poisoning is of great importance. Herein, we developed an electrochemical aptasensor for SEB detection using a screen printed electrode modified with reduced graphene oxide (rGO) and gold nano-urchins (AuNUs). Afterward, the single-stranded DNA probe was attached to the surface of AuNUs on the modified electrode and then the specific aptamer was attached to the probe. In the presence of SEB molecules, the aptamer detached from the electrode surface and after applying the electrochemical signal generator, hematoxylin and the peak current of differential pulse voltammetry (DPV) were recorded. Due to the intercalation mechanism of hematoxylin-DNA interaction, the detachment of aptamer from electrode surface decreased the DPV peak current and the calibration graph (peak current vs SEB concentration) can be used for quantification of SEB. The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) and also field emission scanning electron microscope imaging were used for electrode characterization. Selectivity experiments of the developed aptasensor showed a very distinct difference between SEB and other nonspecific molecules. A wide linear range from 5.0 to 500.0 fM was achieved and the detection limit was calculated as 0.21 fM. The performance of the aptasensor was checked in spiked food samples as simulated real samples and the results showed no significant difference compared to the synthetic samples. Results of selectivity and repeatability of the aptasensor were satisfactory. In addition, better recovery percentages and also lower standard deviation of aptasensor compared to a commercial ELISA kit of SEB detection proved the superior performance of the proposed aptasensor.