The indirect electrochemical detection and quantification of DNA through its co-adsorption with anthraquinone monosulphonate on graphitic and multi-walled carbon nanotube screen printed electrodes

Functional Protection of Exfoliated Black Phosphorus by Noncovalent Modification with Anthraquinone

Few and monolayer black phosphorus (phosphorene) is currently an intensively researched material. Shear exfoliated black phosphorus (BP_SE) nanosheets were functionalized with the redox active antraquinone (AQ) that can provide additional charge storage capacity. The noncovalent interaction of BP with AQ occurs due to van der Waals interactions. X-ray photoelectron spectroscopy results show that AQ coverage of BP_SE nanosheets led to a stabilization against BP_SE degradation. Electrochemistry of the BP_SE-AQ shows that AQ is stably anchored onto BP_SE and exhibits redox peaks stable for more than 100 cycles. The surface coverage by AQ on BP_SE is estimated to be 1.25 nmol AQ/mg BP and electron-transfer rate constant ( k_ET) of 33 s^-1. Furthermore, the proposed modification greatly increases the gravimetric capacitance of BP_SE-AQ with respect to the starting BP_bulk. Such coating of BP not only protects BP from degradation but also brings electroactive functionality to this two-dimensionally layered material.

3D Printed Microfluidic Device with Microporous Mn2O3-Modified Screen Printed Electrode for Real-Time Determination of Heavy Metal Ions

Fabricating portable devices for the determination of heavy metal ions is an ongoing challenge. Here, a 3D printing approach was adopted to fabricate a microfluidic electrochemical sensor with the desired shape in which the model for velocity profiles in microfluidic cells was built and optimized by the finite element method (FEM). The electrode in the microfluidic cell was a flexible screen-printed electrode (SPE) modified with porous Mn₂O₃ derived from manganese containing metal-organic framework (Mn-MOF). The microfluidic device presented superior electrochemical detection properties toward heavy metal ions. The calibration curves at the modified SPE for Cd(II) and Pb(II) covered two linear ranges varying from 0.5 to 8 and 10 to 100 μg L^-1, respectively. The limits of detection were estimated to be 0.5 μg L^-1 for Cd(II) and 0.2 μg L^-1 for Pb(II), which were accordingly about 6 and 50 times lower than the guideline values proposed by the World Health Organization. Furthermore, the microfluidic device was connected to iPad via a USB to enable real-time household applications. Additionally, the sensing system exhibited a better stability and reproducibility compared with traditional detecting system which offered a promising prospect for the detection of heavy metal ions especially in household and resource-limited occasions.

Bifunctional redox tagging of carbon nanoparticles

Despite extensive work on the controlled surface modification of carbon with redox moieties, to date almost all available methodologies involve complex chemistry and are prone to the formation of polymerized multi-layer surface structures. Herein, the facile bifunctional redox tagging of carbon nanoparticles (diameter 27 nm) and its characterization is undertaken using the industrial dye Reactive Blue 2. The modification route is demonstrated to be via exceptionally strong physisorption. The modified carbon is found to exhibit both well-defined oxidative and reductive voltammetric redox features which are quantitatively interpreted. The method provides a generic approach to monolayer modifications of carbon and carbon nanoparticle surfaces.