Question Description:
"Colloidal gold nanoparticles were conjugated with oligonucleotides to create biorecognition nanomodules"
I want to know what is colloidal gold?Thank you
Answer:
A colloidal gold solution is a dispersed-phase gold sol with particles of l-150 nm in diameter. A colloidal gold solution is a gold sol with dispersed phase particles between l-150 nm in diameter, a multi-phase inhomogeneous system, and an orange to purplish-red color. The use of colloidal gold as a marker for immunohistochemistry began in 1971, Faulk et al. applied electron microscopy immunocolloid gold staining (IGS) to observe Salmonella, since then they combined colloidal gold with a variety of proteins. 1974 Romano et al. labeled colloidal gold on a second antibody (horse anti-human IgG), the establishment of the indirect immunocolloid gold staining. 1978 geoghega discovered the use of colloidal gold markers at the light microscopic level. This application of colloidal gold in immunochemistry is also known as immunogold. Afterwards, many scholars further proved that colloidal gold can adsorb proteins stably and rapidly, and the biological activity of proteins is not significantly changed. It can be used as a probe for the precise localization of cell surface and intracellular polysaccharides, proteins, polysaccharides, antigens, hormones, nucleic acids and other macromolecules, and can also be used for routine immunodiagnosis, immunohistochemical localization, and thus its application in clinical diagnosis and drug detection has been widely valued. Currently, immunogold staining (IGS) at the electron microscopic level, immunogold-silver staining (IGSS) at the light microscopic level, and spot immunogold staining at the naked eye level have become powerful tools for scientific research and clinical diagnosis.
Colloidal nature of colloidal gold particles in the size of 1 ~ 100nm, tiny gold particles stable, uniform, a single dispersion suspended in the liquid, colloidal gold solution. Colloidal gold thus has a variety of colloidal properties, especially on the sensitivity of the electrolyte. Electrolyte can destroy the peripheral permanent hydration layer of colloidal gold particles, thus breaking the stable state of the colloid, so that the dispersion of a single gold particles coalesce into large particles, and precipitate from the liquid. Certain proteins and other macromolecular substances have the role of protecting colloidal gold and strengthening its stability.
Colloid coloration of tiny particles of colloid red, but different sizes of colloid color has some differences. The smallest colloidal gold (2 ~ 5nm) is orange-yellow, medium-sized colloidal gold (10 ~ 20nm) is burgundy, larger particles of colloidal gold (30 ~ 80nm) is purple-red. According to this feature, the color of colloidal gold can be observed with the naked eye to roughly estimate the size of the gold particles. Over the past 10 years, colloidal gold labeling has developed into an important immunolabeling technology. Colloidal gold immunoassay in drug detection, biomedical and many other areas of research has been developed, and more and more attention by the relevant research areas. Light-absorbing colloidal gold has a single light-absorbing peak in the visible range, and the wavelength of this light-absorbing peak (λmax) is in the range of 510-550 nm, which varies with the size of colloidal gold particles. λmax of colloidal gold with large particles is biased towards long wavelengths, and vice versa for colloidal gold with small particles, and λmax of colloidal gold with small particles is biased towards short wavelengths, and λmax of colloidal gold with small particles is listed as some of the λmax of colloidal gold in Table 1.
Table The preparation and characterization of colloidal gold in the following four types of particle size. Preparation and properties of colloidal gold
Colloidal gold particle size (nm) 1% trisodium citrate added (ml)* Colloidal gold properties
Color λmax
16 2.00 Orange 518nm
24.5 1.50 Orange red 522nm
41 1.00 Red 525nm
71.5 0.70 Purple 535nm