Direct Electron Transfer of Cellobiose Dehydrogenase on Positively Charged Polyethyleneimine Gold Nanoparticles.

Invited for this month's cover is the group of Prof. Dr. Lo Gorton at Lund University, Sweden. The cover picture shows a biosensor for measuring lactose in dairy products. It consists of a gold electrode, onto which a layer of polyethyleneimine-capped gold nanoparticles is deposited. Read the full text of the article at 10.1002/cplu.201600453.

Direct Electron Transfer of Cellobiose Dehydrogenase on Positively Charged Polyethyleneimine Gold Nanoparticles.

Efficient conjugation between biomolecules and electrode materials is one of the main challenges in the field of biosensors. Cellobiose dehydrogenase (CDH) is a monomeric enzyme, which consists of two separate domains: one catalytic dehydrogenase domain (DHCDH ) carrying strongly bound flavin adenine dinucleotide (FAD) in the active site and a cytochrome domain (CYTCDH ) carrying a b-type heme connected by a flexible linker region. Herein, we report on the development of a lactose biosensor, based on direct electron transfer (DET) from CDH from Phanerochaete sordida (PsCDH) electrostatically attached onto polyethyleneimine-stabilized gold nanoparticles (PEI@AuNPs) used to cover a conventional polycrystalline solid gold disk electrode. PEI@AuNPs were synthesized in aqueous solution using PEI as reducing agent for AuIII and as stabilizer for the nanoparticles. The heterogeneous electron-transfer (ET) rate (ks ) for the redox reaction of immobilized PsCDH at the modified electrodes was calculated based on the Laviron theory and was found to be (39.6±2.5) s-1 . The proposed lactose biosensor exhibits good long term stability as well as high and reproducible sensitivity to lactose with a response time less than 5 s and a linear range from 1 to 100 µm.

New findings and the current controversies for water oxidation by a copper(ii)-azo complex: homogeneous or heterogeneous?

In this paper, new findings for the water-oxidizing activity of [(L)Cu(II)(NO3)], (L = (E)-3-(pyridin-2-yldiazenyl)naphthalen-2-ol (HL)) under both electro-water oxidation conditions and in the presence of cerium(iv) ammonium nitrate are reported.

Fabrication of a nonenzymatic glucose sensor using Pd-nanoparticles decorated ionic liquid derived fibrillated mesoporous carbon.

A novel nonenzymatic sensor was developed for glucose detection by the use of ionic liquid derived fibrillated mesoporous carbon (IFMC) decorated with palladium nanoparticles (PdNPs). PdNPs were uniformly decorated on IFMC and then the prepared nano-hybrid material (Pd@IFMC) was drop cast on the surface of a glassy carbon electrode to fabricate a glucose sensor. The prepared Pd@IFMC showed excellent electrocatalytic activity towards glucose oxidation. An oxidation peak at about +0.40 V vs. Ag|AgCl|KClsat was observed for glucose on the fabricated sensor in alkaline solution. The oxidation peak current intensity was linear towards glucose in the concentration range between 1 and 55 mM (R(2) = 0.9958) with a detection limit of 0.2 mM. The relative standard deviation (RSD) for repetitive measurements (n = 6) of 5 mM of glucose was of 5.3%. The fabricated sensor showed a number of great features such as ease of fabrication, wide linear range, excellent reproducibility, satisfactory operational stability and outstanding resistance towards interfering species such as ascorbic acid, uric acid, dopamine, fructose and chloride.