6 buffers for the synthesis of gold nanoparticles and their characteristics
In recent years, due to the inertness and unique optical properties of precious metal nanoparticles, the demand for their biocompatibility and stability has been increasing. In this article, seven different synthesis methods are proposed to obtain gold nanoparticles by using common biological buffers. The results show that the size, shape, and monodispersity of the nanoparticles can vary according to the type of buffer used, because these buffers act as both a reducing agent and a stabilizer in each synthesis. Most of the nanoparticles synthesized using buffers show unique broad pH stability and good cell viability, without further modification. The synthesis details using different buffers are as follows.
Put 4 ml of 100 mM PIPES buffer and 1 ml of 20 mM HAuCl4 aqueous solution in 36 ml of deionized water and stir vigorously at 25°C. The solution turned dark pink within 1 minute, indicating that particles were formed, and the buffer was used as a reducing agent and a capping agent at the same time without heating or cooling.
Put 4 ml of 100 mM MES water buffer and 1 ml of 20 mM HAuCl4 aqueous solution in 36 ml of deionized water, and stir vigorously at 100° C. for 10 minutes. Then the dark pink solution was cooled while stirring to obtain gold nanoparticles. .
Mix 1 ml of 20 mM HAuCl4 aqueous solution with 36 ml of deionized water, and boil at 100°C for 5 minutes. Then, 4 ml of 0.1M TAPSO aqueous buffer was added to form particles within 30 seconds.
Mix 1 ml of 20 mM HAuCl4 aqueous solution with 36 ml of deionized water, and boil at 100°C for 5 minutes. Then, 4 ml of 0.5M TAPS aqueous buffer was added; the reaction lasted for 1 h.
Mix 1 ml of 20 mM HAuCl4 aqueous solution with 36 ml of deionized water, and boil at 100°C for 5 minutes. Then, 4 ml of 0.05M TES aqueous buffer was added, and the reaction was continued for 10 minutes.
Under vigorous stirring at 25°C, 1 ml of 20 mM HAuCl4 aqueous solution and 4 ml of 100 mM TEA buffer were placed in 36 ml of deionized water. The solution turned dark blue within 30 seconds, indicating particle formation.
Mix 1 ml of 20 mM HAuCl4 aqueous solution with 36 ml of deionized water, and boil at 100°C for 5 minutes. Then, 4 milliliters of 0.05M bicine aqueous buffer was added, and the reaction was continued for 1 minute.
Most spectra have a single absorption peak (λmax) in the visible light range from 530 to 550 nm, indicating that the size and shape of the nanoparticles are monodisperse. Experiments show that the gold nanoparticles formed by TAPS present a strong band near 585nm, TEA presents an irregular broadband, TAPS and TEA buffer have a wider absorption band for gold nanoparticles, and the absorption bands of MES and BTP are clearer. Due to the strong surface adsorption of PIPES buffer on the gold surface, it shows the greatest stability. However, the NPs synthesized using bicine, TES and TAPSO all formed precipitates in a short period of time.
When it comes to the chemiluminescent reagent Luminol, it is not unfamiliar to everyone and is commonly used in the field of criminal investigation to detect blood stains. Researchers have found that the principle of luminol luminescence can be used to detect specific substances in saliva, such as proteins, DNA, and related indicators of microorganisms, in order to determine physical conditions.