Colloidal gold (Au) nanoparticles (NPs) deposition on silicon (Si) substrate is highly affected by the deposition technique and surface properties of the substrate. Spin-coating technique has been proven to be an efficient approach in terms of cost, time and maintaining the quality of the deposition. However, to prevent the agglomeration of NPs and obtain desirable density and distribution of NPs on the substrate, precise control of the spin-coating parameters is required. In this study colloidal Au NPs were spin-coated onto a modified, yet linker-free Si surface. By controlling the spinning speed, acceleration, dwelling time, and the volume of NPs colloidal solution, the density and distribution of the NPs on Si were optimized. Scanning electron microscope was used to investigate the NPs density in each step of the process. Results showed that the distribution of NPs on Si substrate is highly dependent on the spinning speed, duration, and acceleration rate as well as surface properties of Si substrate.
In this work, 10 nm gold nanoparticles (AuNPs) was successfully synthesized via seeded-growth method. The green chemically synthesis of this AuNPs becomes attractive because the growth process does not involve heat. Moreover, this technique has advantages of quick, simple, and low cost process. Sodium borohydrate (NaBH4) was used as a reducing agent while trisodium citrate was used as a source of OH- ions in the seed stage. Hydroxylamine hydrochloride (NH4.3H2O) was used as a slow reducing agent to enlarge 4 nm seeds to 10 nm AuNPs. A 4 ml AuNPs seed was the optimized volume to produce 10 nm AuNPs with great homogeneity and dispersity. A sharp peak of surface plasmon resonance (SPR) measurement at 517 nm proved that 10 nm AuNPs was successfully synthesized via this method. Optical properties of the seeds and grown AuNPs were analyzed using UV-Vis spectroscopy while size and surface morphology were observed using a transmission electron microscopy (TEM). Particle size distribution was measured using Zetasizer. 10 nm AuNPs was then conjugated with streptavidin and goat anti-human IgA. Depending on type of protein, 10 µg/ml of streptavidin and 11.2 µg/ml of goat anti-human IgA were required to conjugate with 10 nm AuNPs. The produced products had binding capability on lateral flow immunoassay (LFI). A few nanometer red-shifted absorption spectrum of 10 nm AuNPs conjugated protein revealed successful conjugation instead of agglomeration. 1% BSA was determined as the optimum concentration to stabilize 10 nm AuNPs conjugated biomolecules.
Anodisation of iron foil was done to produce anodic film with nanoporous structure. The effect of anodic voltage on the morphology of the anodic oxide formed was investigated. Anodic film formed on iron foil anodised at 10 V is rather compact no obvious pores. Pores can be detected on oxide anodised at 30 V despite not very uniform. For foil anodised at 50 V, 1.8 µm thick anodic layer which consisted of uniform circular pores is observed. This film was then annealed at 450°C for 3 h in air as to induce crystallinity. The annealed nanoporous film exhibits a light illuminated photocurrent of 0.45 mA in 1 M NaOH + H2O2 solution.
In this study, ZnO nanorods was formed on a seeded substrates prepared by thermal oxidation of Zn foil followed by hydrothermal reaction. ZnO seed was prepared via thermal oxidation process at 300°C for 10 minutes to form uniform circular nanosize grains that were suitable as a seeded template for the growth of ZnO nanorods via hydrothermal reaction. Several hydrothermal reaction parameters were studied; hydrothermal reaction temperature, ratio of zinc nitrate to hexamethylamine and pH. In hydrothermal reaction, the formation of ZnO nanorods occurs due to thermal degradation of hexamethylamine (HMT) which released hydroxyl ions that react with Zn ions in the precursor solution. Well aligned, ZnO nanorods with length of ~700 nm, base diameter of ~200 nm and top diameter of less than 30 nm needle-like structure were formed on seeded Zn substrate with concentration ratio of zinc nitrate to hexamethylamine 0.1M:0.1M, pH 6-7 at hydrothermal reaction temperature of 80°C
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.