Imaging surface plasmon resonance for multiplex microassay sensing of mycotoxins

A prototype imaging surface plasmon resonance-based multiplex microimmunoassay for mycotoxins is described. A microarray of mycotoxin–protein conjugates was fabricated using a continuous flow microspotter device. A competitive inhibition immunoassay format was developed for the simultaneous detection of deoxynivalenol (DON) and zearalenone (ZEN), using a single sensor chip. Initial in-house validation showed limits of detection of 21 and 17 ng/mL for DON and 16 and 10 ng/mL for ZEN in extracts, which corresponds to 84 and 68 µg/kg for DON and 64 and 40 µg/kg for ZEN in maize and wheat samples, respectively. Finally, the results were critically compared with data obtained from liquid chromatography-mass spectrometry confirmatory analysis method and found to be in good agreement. The described multiplex immunoassay for the rapid screening of several mycotoxins meets European Union regulatory limits and represents a robust platform for mycotoxin analysis in food and feed sample

Surface engineered quantum dots in photoelectrochemistry and supramolecular assembly

This thesis demonstrates the power of chemical surface engineering in the design and fabrication of functional hybrid materials made of Quantum Dots. The small size of the QDs, in the range of 1 to 10 nm, and related stability in solution, require a careful consideration of a proper surface chemistry for the ligand shell. By a judicious choice of the coating one can remarkably influence the physicochemical and photophysical properties of the semiconductor nanocrystals as well as design and engineer new generations of advanced nanoscale materials. This work describes in detail the synthetic approaches to chemical surface functionalization of QDs with electroactive ligands, including ferrocenyl thiols and poly(ferrocenylsilanes), and with β-cyclodextrin (β-CD) ligands suitable for supramolecular host-guest assembly. These functional ligands are shown to be important components in the engineering of new types of QD hybrid materials. The influence of the electroactive ligands on the optical properties of QDs was investigated by spectroscopic and electrochemical methods. These investigations gave an important insight into the quenching mechanisms of QDs by ferrocene and to the fundamental electron transfer processes in hybrid materials composed of QDs and electro-active ligands. Additionally, ferrocene groups located on the QD surface were shown to be able to take part in host-guest complexation reactions with β-cyclodextrin in solution. This ability was useful in the phase transfer of hydrophobic nanoparticles between solvents of markedly different polarities. The complexation ability of β-CD-functionalized QDs and adamantyl dendrimers was exploited for the preparation of supramolecular multilayer structures on surfaces. Surface bound QDs were shown to be able to transduce optically the binding events to the β-CD cavity, a proof-of-principle for a sensor design. This thesis demonstrates that both FRET and ET can be used as the transduction mechanisms. Thus, proper surface design and engineering of QDs gives unique opportunities to obtain the new class of hybrid materials using numerous functionalization approaches and surface chemistries

Manipulating the monolayer : responsive and reversible control of colloidal inorganic nanoparticle properties

Funding: EPSRC EP/K016342/1; Leverhulme Trust: RPG-2015-042For a wide range of nanomaterials, surface-bound molecules play a central role in defining properties, and are key to integration with other components – be they molecules, surfaces, or other nanoparticles. Predictable and general methods for manipulating the surface monolayer are therefore crucial to exploiting this new region of chemical space. This review highlights limitations of the few established methods for controlling nanoparticle-bound molecular functionality, then focuses on emerging new strategies. In particular, approaches that can achieve stimuli-responsive and reversible modification of surface-bound molecules in colloidal solution are examined, with an emphasis on using these methods to control nanoparticle properties such as solvent compatibility, catalytic activity and cytotoxicity. Finally, the outstanding challenges and future potential for precisely controlled nanoparticle bound monolayers are discussed.Publisher PDFPeer reviewe

Reconfigurable Intelligent Surface MIMO Simulation using Quasi Deterministic Radio Channel Model

Reconfigurable Intelligent Surface (RIS) is a planar array that can control reflection and thus can implement the concept of partially controllable propagation environment. RIS received a lot of attention from industry and academia, but the majority of the researchers who study RIS-assisted systems use simple Rician model. Though it is suitable for theoretical analysis, stochastic Non Line-of-Sight (NLoS) component in Rician model does not account for the geometry of deployment. Furthermore, Rician model is not eligible to evaluate 3GPP standardization proposals. In this article we adapt the popular Quasi Deterministic Radio channel Generator (QuaDRiGa) for RIS-assisted systems and compare it against Rician model. The comparison shows that geometry-inconsistent NLoS Rician modeling results in higher estimated achievable rate. Our method, in contrast, inherits the advantages of QuaDRiGa: spatial consistency of Large Scale Fading, User Equipment mobility support as well as consistency between Large Scale and Small Scale Fading. Moreover, QuaDRiGa comes with calibrated scenario parameters that ensure 3GPP compatibility. Finally, the proposed method can be applied to any model or software originally designed for conventional MIMO, so every researcher can use it to build a simulation platform for RIS-assisted systems.Comment: 5 pages, 3 figures, submitted to IEEE ANTS 202