Highly branched gold-copper nanostructures for non-enzymatic specific detection of glucose and hydrogen peroxide.

The development of highly sensitive and highly selective sensors for non-enzymatic glucose and hydrogen peroxide (H2O2) detection using gold-copper alloy nanoparticles (AuCu alloy NPs) is reported. The AuCu NPs are nanostructures with branches and can be used as an electrochemical catalyst. Series of AuCu alloy NPs with various metal ratios are synthesized through a coreduction reaction. The morphology of AuCu alloy NPs is altered from highly branched structures (nanourchin, nanobramble, nanostar, nanocrystal) to a spherical shape by increasing Au content in the synthesis reaction. Cu-rich AuCu nanobramble and Au-rich AuCu nanostar exhibit selective electrocatalysis behaviors toward electro-oxidation of glucose and electroreduction of H2O2, respectively. The AuCu nanobramble-based sensor holds great potential in glucose detection with a linear working range of 0.25 to 10 mM. The sensor possesses a sensitivity of 339.35 µA mM-1 cm-2, a limit of detection (LOD) of 16.62 µM, which is an acceptable selectivity and good stability. In addition, the AuCu nanostar-based sensor shows excellent electrochemical responses toward H2O2 reduction with good selectivity, reproducibility, and a short response time of about 2-3 s. The linear range for H2O2 determination is 0.05 to 10 mM, with LOD and sensitivity of 10.93 µM and 133.74 µA mM-1 cm-2, respectively. The good sensing performance is a result of the synergistic surface structure and atomic composition effects, which leads AuCu alloys to be a promising nanocatalyst for sensing both glucose and H2O2. Graphical abstract Schematic illustration presents the construction of gold-copper alloy nanoparticles (AuCu alloy NPs) on the surface of screen-printed carbon electrode (SPCE). The highly branched nanostructures of AuCu alloys with different surface structure and metal ratios give selective electrocatalysis behaviors. Cu-rich AuCu nanobramble-based sensor reveals prominent electrocatalytic activity for glucose detection. Au-rich AuCu nanostar-based sensor provides good electrochemical response for H2O2 detection.

Supramolecular self-assembled polymeric nanospheres based on hydrazino naphthalimide functionalised pillar[5]arene for long chain aldehyde detection.

A novel fluorescent sensor HNP5A is constructed consisting of bis-hydrazine naphthalimide decorated pillar[5]arene. Interestingly, this sensor possessed the potential for sensitive and selective detection of long-chain aldehydes, particularly nonanal (C9), and subsequently formed supramolecular pseudorotaxane polymeric nanoparticles inducing a strong fluorescence enhancement. In addition, this as-produced HNP5A⊂C9 exhibited an unexpected reduction of Ag+ to produce AgNPs in an aqueous system and the resulting AgNPs-HNP5A⊂C9 demonstrated a significant fluorescence enhancement under metal-enhanced fluorescence (MEF) behaviour.