Fabrication of highly sensitive gold nanourchins based electrochemical sensor for nanomolar determination of primaquine

Formulation and clinical advancement of nanourchins: a novel multibranched nanoparticulate drug-delivery system

Nanourchins are multibranched nanoparticles with unique optical properties and surface spikes. Because of their unique properties, gold nanourchins have advantages over gold nanoparticles. The most used nanourchins are gold, tungsten, carbon, vanadium and sea urchins. The synthesis of various nanourchins and their clinical advancement are discussed in this review. ZFNs, TALENs and CRISPR/Cas9 are discussed to facilitate understanding of advancements in nanourchins. Nanourchins have been studied for Parkinson's disease, Alzheimer's disease and bioimaging. The synthesis of molybdenum diselenide nanourchins and their bioconjugations are also discussed. Nanourchins can be further explored to improve drug targeting and delivery. Researchers from several fields may contribute to the study of nanourchins as prospective nanocarriers with target specificity.

Carbon Nanomaterial-Based Drug Sensing Platforms Using State-of-the- Art Electroanalytical Techniques

Background:

Currently, nanotechnology and nanomaterials are considered as the most popular and outstanding research subjects in scientific fields ranging from environmental studies to drug analysis. Carbon nanomaterials such as carbon nanotubes, graphene, carbon nanofibers etc. and non-carbon nanomaterials such as quantum dots, metal nanoparticles, nanorods etc. are widely used in electrochemical drug analysis for sensor development. Main aim of drug analysis with sensors is developing fast, easy to use and sensitive methods. Electroanalytical techniques such as voltammetry, potentiometry, amperometry etc. which measure electrical parameters such as current or potential in an electrochemical cell are considered economical, highly sensitive and versatile techniques.

Methods:

Most recent researches and studies about electrochemical analysis of drugs with carbon-based nanomaterials were analyzed. Books and review articles about this topic were reviewed.

Results:

The most significant carbon-based nanomaterials and electroanalytical techniques were explained in detail. In addition to this; recent applications of electrochemical techniques with carbon nanomaterials in drug analysis was expressed comprehensively. Recent researches about electrochemical applications of carbon-based nanomaterials in drug sensing were given in a table.

Conclusion:

Nanotechnology provides opportunities to create functional materials, devices and systems using nanomaterials with advantageous features such as high surface area, improved electrode kinetics and higher catalytic activity. Electrochemistry is widely used in drug analysis for pharmaceutical and medical purposes. Carbon nanomaterials based electrochemical sensors are one of the most preferred methods for drug analysis with high sensitivity, low cost and rapid detection.

Influence of oxygen plasma treatment on structural and spectral changes in silica-coated gold nanorods studied using total internal reflection microscopy and spectroscopy

This paper shows how oxygen plasma treatment affects the structural, localized surface plasmon resonance (LSPR) spectral, and spatial orientation changes in single gold nanorods coated with a mesoporous silica shell (AuNRs@SiO2) in comparison with bare AuNRs with the same aspect ratio (AR). Single AuNRs@SiO2 subjected to different plasma treatment times were characterized using scanning electron microscopy and total internal reflection scattering (TIRS) microscopy and spectroscopy. The AR of the single AuNRs without a silica shell was decreased by structural deformation, while their LSPR linewidth was increased with increasing plasma treatment time. In contrast, single AuNRs@SiO2 showed much higher structural and spectral stability due to the silica shell under the energetic plasma treatment. Furthermore, there was no noticeable variation in the three-dimensional (3D) orientations of single AuNR cores in the silica shell before and after the plasma treatment. The results support that no significant structural and spectral changes occur in single AuNRs@SiO2 and that the silica coating enhances the stability of AuNR cores against oxygen plasma treatment. Therefore, fundamental information on the relationship among plasma treatment time, structural change, LSPR damping, and defocused orientation patterns is provided at the single-particle level.

Single-particle study: effects of oxygen plasma treatment on structural and spectral changes of anisotropic gold nanorods

Oxygen plasma treatment is a common method for removing the surfactant capping material from gold nanoparticles, improving their functionalization and lowering their cytotoxicity for biological studies. This single-particle study investigates the effects of oxygen plasma treatment on the structural and localized surface plasmon resonance (LSPR) spectral variations of anisotropic gold nanorods (AuNRs). Single AuNRs subjected to different plasma treatment times were characterized by scanning electron microscopy and dark-field microscopy. The AuNR length was a gradually decreasing function of plasma treatment time. After 120 s of plasma treatment, the aspect ratio of the AuNRs was reduced by a major structural deformation. Furthermore, increasing the plasma treatment time gradually broadened the LSPR linewidth of the single AuNRs. This trend was attributed to the decreased aspect ratio and the increased plasmon damping. These results provide vital and fundamental information on the relationship among plasma treatment time, structural change, and LSPR damping at the single-particle level.

Polarization- and wavelength-dependent defocused scattering imaging of single gold nanostars with multiple long branches

We demonstrate the polarization- and wavelength-dependent defocused scattering properties at the localized surface plasmon resonance (LSPR) wavelengths of singe AuNSs having multiple long branches protruding from their surfaces.

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.

Direct Visualization of Wavelength-Dependent Single Dipoles Generated on Single Gold Nanourchins with Sharp Branches

We present the optical properties of singe gold nanourchins (AuNUs) with sharp branches on their surfaces under dark-field (DF) microscopy and spectroscopy. The DF intensities of the single AuNUs were changed periodically as a function of the rotation angle at three localized surface plasmon resonance (LSPR) wavelengths. Furthermore, we demonstrate the generation of single dipoles with different LSPR wavelengths in multiple directions on the same AuNU surface. The multiple LSPR dipoles generated on the AuNU surface were further visualized under defocused DF microscopy and verified by characteristic doughnut-shaped defocused scattering field distributions. ᅟ.

Gemini surfactant with pyrrolidinium head groups and a hydroxyl-substituted spacer: surface properties and assisted one-pot synthesis of dendritic Au nanocrystals

Dendritic Au NCs were facilely prepared by a one-pot method at room temperature with the assistance of gemini surfactant.