Stimuli‐Responsive Biointerface Based on Polymer Brushes for Glucose Detection

The construction and characterization of a biosensor based on polymer brushes is reported. The use of polymer brushes combined with nanoparticles was applied to show its suitability as a biosensor platform – with glucose oxidase as an enzyme probe. The biosensor demonstrated a pH‐sensitive on‐off property, and it was further used to control or modulate the electrochemical responses. In terms of the kinetic behavior, we were able to show the changing in the kinetic parameters of glucose oxidase operating in “on” and “off” state of the polymer brushes. The performance of the bioelectrode was investigated by chronoamperometry, impedance electrochemistry and cyclic voltammetric techniques. At optimized experimental conditions the dynamic concentration range was 2.0 to 16.0 mmol L^?1 with a detection limit of 5.6×10–⁶ mol L^?1. The repeatability of current responses for injections of 5.0 mmol L^?1 glucose was evaluated to be 5.3 % (n=10). The resulting biosensor seemed to provide the enzymes with a biocompatible nanoenvironment as it sustained the enhanced enzyme activity for an extended time and promoted possible good electron transfer through the polymer brushes to the electrode.     

Hydrodesulfurization of thiophene over CoMo/AlMCM-41

In this paper the application of a series of CoMo/AlMCM-41 catalysts with different Si/Al ratios was studied in the model reaction of thiophene hydrodesulfurization. The results obtained showed good catalytic activity for the formation of H₂S, isobutene, 1-butene, n-butane, 2-trans-butene-and 2-cis-butene.     

Highly Sensitive Neurotransmitters Analysis at Platinum‐Ultramicroelectrodes Arrays

An easy way to determine norepinephrine (NE) in biological fluid using a platinum ultramicroelectrode array (Pt‐UMEAs) is described. Issues related to UME electrode surface treatment and characterizations are also addressed. At optimized experimental conditions the dynamic concentration range was 1.0 to 10.0 µmol L^?1 with a detection limit of 40.5 nmol L^?1. The repeatability of current responses for injections of 5 µmol L^?1 NE was evaluated to be 4.0 % (n=10). This approach obtained excellent sensitivity, a reliable calibration profile and stable electrochemical response for norepinephrine detection. The content of NE in urine samples without any preconcentration, purification, or pretreatment step, was successfully analyzed by the standard addition method using the Pt‐UMEAs.