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Liquid metals have aroused interest in the scientific communities of electronics, engineering and biomedicine. In particular, the stabilization of liquid metal nanodroplets by surfactants and macromolecules has been investigated in the past extensively. Herein, we investigate the change in interfacial tension of the liquid metal Galinstan in contact with aqueous electrolytes upon addition of surfactants in aqueous solutions. We show that is governed by the chemical environment, the structure of the electric double layer (EDL) and the surfactant charge. In most environments a critical micelle concentration (CMC) can be determined, the value of which is in favorable agreement with literature values. Furthermore, based on the selective adsorption of the surfactant, the structure of the EDL is predicted and discussed, and the adsorption of surfactants is employed to mitigate liquid metal droplet coalescence. In this regard, the data suggests that the packing parameter, change in IFT upon surfactant addition and charge density of EDL are the main contributors for liquid metal droplet stability. [ABSTRACT FROM AUTHOR]

Colloidal stability of nanoparticles with particle sizes smaller than 100 nm is a critical issue for various research areas, including material science, electronics and biomedicine. We propose a facile, fast and cost-efficient method to increase the colloidal stability by simply adding organic molecules as ligands, which adsorb to the nanoparticle surface subsequently. Citric acid, oxalic acid, glutamic acid and propylamine were found to stabilize the nanodiamond (ND) particles with a mean diameter of approx. 30–100 nm. The charge of the particles could be controlled by the pH of the dispersions and by stabilizing with carboxylic acids or amino acids mentioned above. ND particles stabilized with citric acid and oxalic acid at a pH higher than 2.5 were negatively charged, while ND dispersions stabilized with glutamic acid were charged positively below a pH of 3.2. Furthermore, the stability of the dispersion was found to be dependent on the concentration of the stabilizing agent and the pH of the dispersion. Finally, we proposed the stabilizing mechanism of ND particles with propylamine. Glutamic acid and propylamine stabilized ND dispersions can be utilized for high seeding densities on negatively charged surfaces due to the amino-groups, which can be helpful for adsorption processes in electronics and material science. Due to the high biocompatibility, non-cytotoxicity and chemical inertness of ND particles, carboxylic acids and amino acids stabilized ND particles are envisaged to be useful in the biomedical field, i.e. bio-labels, drug delivery vehicles, and effective enterosorbent. [ABSTRACT FROM AUTHOR]

This study presents the synthesis and characterization of a novel glucose electrochemical biosensor based on gold nanoparticles/bovine serum albumin/Fe 3 O 4 (AuNPs/BSA/Fe 3 O 4 ) composite nanoparticles. The prepared magnetic composite nanoparticles consist of a BSA protein shell, providing biocompatible environment for enzyme immobilization. Furthermore, in situ immobilization of gold nanoparticles greatly enhances the performance of electron transfer. Using these composite nanoparticles, the model enzyme, glucose oxidase (GOx) was readily adsorbed to surface so as the GOx/AuNPs/BSA/Fe 3 O 4 electrochemical biosensor was developed. The electrochemical performance of the biosensor was characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry. Under the optimal preparation conditions, the resultant biosensor has a short response time of 0.8 s, an excellent sensitivity of 115.3 μA mM −1 cm −2 , and a linear dynamic range from 0.25 to 7.0 mM with a low detection limit of 3.54 μM (S/N = 3). The high sensitivity, good reproducibility and stability of the biosensor presented in this study show that the as-prepared AuNPs/BSA/Fe 3 O 4 composite nanoparticles are a promising material for the development and construction of biosensors. [ABSTRACT FROM AUTHOR]