Preparation of Au-Ag Bimetals and Large-Size Porous Gold Nanostructured Materials

Gold, silver, and other precious metals are very important nonferrous metals and have been widely applied in fields such as electronics, medicine, metallurgy, pharmaceuticals, and transportation. Adjustable properties of precious metals are mainly attributed to controlled synthesis of precious metals by structure, size, composition, and morphology. Synthesis of binary metals focuses on coordination of physical and chemical properties of metal elements in components, with the aim to give full play to the advantages of the two metals. Gold (Au) and silver (Ag) have similar lattice constants, which provide important theoretical basis for obtaining the binary bimetallic nanostructure of the two metals by coreduction at room temperature. Ag–Au alloy was prepared at different molar ratios of Ag+/AuIII, and the bimetallic nanomaterials obtained had similar Ag/Au ratios to the molar ratio at reaction. This suggested that the bimetallic nanomaterials reacted completely, with the maximum average size in Ag90.1–Au9.9 and the minimum average size in Ag83.2–Au16.8 and Ag66.9–Au33.1. Due to the deficiency of conventional etching agents, the “regrowth etching” method was proposed in this study. Specifically, with AuI as the etching agent, the porous gold nanomaterials with the size of more than 300 nm were successfully prepared, achieving the regrowth etching effect and a good structural stability. According to the analysis based on the catalytic reduction reaction with p-nitrophenol, the properties of the large-size porous gold nanomaterials were related to the quantity and size of pores.

2021 Colin Garfield Fink Postdoctoral Summer Fellowship – Summary Report Luciferase – Functionalized 3D Highly Porous Gold-based Electrochemical Biosensors

Recent advances in electrochemical biosensors have focused on new materials and strategies to improve specificity, sensitivity, stability, and response time. Herein, we aim to develop an electrochemical biosensor device by modification of a screen-printed electrode (SPE) with highly porous Au nanostructures and a bioluminescence (BL)-producing enzyme (luciferase). This approach leverages the enhanced electrochemically active surface area and the mass transport effect and offers an alternative configuration for optical output from the enzyme. The BL presents an instantaneous measurement of enzyme activity and can be exploited to show that the enzyme is being electrochemically controlled (an ON-OFF switchable sensor).

Why Do Protein Crystals Grown With the Aid of Porous Materials Show Better Diffraction Quality?

Well-diffracting protein crystals are indispensable for X-ray diffraction analysis, which is still the most powerful method for structure-function studies of biomolecules. A promising approach to growing such crystals is by using porous nucleation-inducing materials. However, while protein crystal nucleation in pores has been thoroughly considered, little attention has been paid to the subsequent growth of the crystals. Although the nucleation stage is decisive, it is the subsequent growth of the crystals outside the pore that determines their diffraction quality. The molecular-scale mechanism of growth of protein crystals in and outside pores is here considered theoretically. Due to the metastable conditions, the crystals that emerge from the pores grow slowly, which is a prerequisite for better diffraction. This expectation has been corroborated by experiments carried out with several types of porous material, such as Bioglass (“Naomi’s Nucleant”), Buckypaper, porous gold and porous silicon. Protein crystals grown with the aid of Bioglass and Buckypaper yielded significantly better diffraction quality compared with crystals grown conventionally. In all cases, visually superior crystals are usually obtained. We furthermore conclude that heterogeneous nucleation of a crystal outside the pore is an exceptional case. Rather, the protein crystals nucleating inside the pores continue growing outside them.

Surface Acoustic Wave Biosensor with Laser-Deposited Gold Layer Having Controlled Porosity

Laser-deposited gold immobilization layers having different porosities were incorporated into love wave surface acoustic wave sensors (LW-SAWs). Variation of pulsed laser deposition parameters allows good control of the gold film morphology. Biosensors with various gold film porosities were tested using the biotin–avidin reaction. Control of the Au layer morphology is important since the biotin and avidin layer morphologies closely follow that of the gold. The response of the sensors to biotin/avidin, which is a good indicator of biosensor performance, is improved when the gold layer has increased porosity. Given the sizes of the proteins, the laser-deposited porous gold interfaces have optimal pore dimensions to ensure protein stability.