Electroactive monolithic μchip for electrochemically-responsive chromatography

The EMμ project’s focus is ultimately, the development of an electroactive monolith that can be incorporated into a microfluidic system for electroanalytical applications such as sensing and electrochemically-controlled extractions and separations. To date our have made several significant advances to achieving this end goal. Firstly a facile fabrication method which allows for the production of fully disposable, gasket–free thin–layer cells suitable for EMμ was developed. A polydimethylsiloxane (PDMS)–glass μchip, configured to house an electrochemical thin–layer flow cell is being used to electrochemically polymerise polyaniline (PANI) monoliths on-chip1. The feasibility of integrating macro–dimensioned, working electrodes into microfluidic channels being a critical first step of the EMμ project. This platform has been used for amperometric detection of ascorbic acid. Simultaneously inverse opal monolithic flow-through structures of conducting polymer have been achieved in microfluidic channels via the fabrication of polystyrene (PS) colloidal crystal templates and the subsequent electrochemical or chemical polymerisation of the polymer2. Currently the focus of EMμ is to build on the significant advances to date, to demonstrate electrochemically-responsive chromatography on μchip which will provide many advantages over solvent gradient-controlled chromatography. To achieve this, high back pressures on chip will be required and thus work to fabricate mechanically robust monoliths from electroactive conducting polymer is necessary. This is currently being examined via compositing with methacrylates which are an existing stationary phase polymer monolith material

The Preparation and Characterisation of Silver Nanomaterials and Their Application in Sensing Techniques

In this work the impact of nanomaterial, specifically silver nanostructures, on sensing techniques is investigated. The work can be divided in to three sections, preparation and characterisation of silver nanoparticles, their application as a nanocomposite based chemiresistor humidity sensing device and finally their application within the surface enhanced (resonance) Raman spectroscopy, SE(R)RS, technique. In the first study silver nanoparticles were prepared as aqueous colloidal dispersions. The colloids were of either a defined diameter (average diameter ~ 20 nm) with high silver loading or lower loaded colloids of tuneable morphology and hence optical properties. In a subsequent study the high load colloid when cast on platinum interdigital electrodes as a nanocomposite coating proved to be useful as a humidity sensor. The sensor gave a reversible, selective and rapid response which was proportional to humidity levels within the range of 10% RH to 60% RH. An investigation into the mechanism of the sensor’s response was conducted and the response was found to correlate well with a second order Langmuir adsorption model. The final study was multi faceted as it first determined the suitability of the tuneable colloids as SE(R)RS substrates using a number of probe molecules. A clear sensing trend was observed, where the Raman signal emitted was significantly enhanced by the addition of silver nanoparticles. This prompted an additional investigation where both colloids were again cast as films (fabricating alternative SERS substrates) to determine the degree outside factors could influence the enhancement seen by the SERS technique. The suitability of the SERS substrates in a real world application was investigated, with SERS being used to monitor the action mechanism of components of a commercially available volatile corrosion inhibitor

Optically clear superhydrophobic coatings

The overall performance of optical equipment and devices is ultimately dependent on their transparency. This is especially evident when such devices are constantly exposed to varying environmental conditions. Thus the development of a robust, transparent and self-cleaning coating is highly desirable. This work discusses the inherent difficulties in the design of transparent self-cleaning coatings. Describing hydrophobicity and the potential challenges the achievement of transparency can introduce. Before detailing the various established methods of characterisation of super hydrophobic surfaces and outlining some of the group’s preliminary results

Development of a Novel Humidity Sensor Based on a Polymer Silver Nanoparticle Composite

Humidity sensing is of particular concern for many industrial applications. Humidity sensors have typically been based on a reversible interaction between a polymer and water vapour. There is work published on gas sensors based on polymer gold nanoparticle composites, where the conductivity of the composite decreases on interaction with the gas. This happens because the swelling of the polymer which increases the electron hopping distance between the gold nanoparticles. The device in this work is a poly vinyl alcohol silver nanoparticle composite cast on an interdigital electrode array. On application of a dc bias, a current develops which is proportional to levels of humidity from 10% to 60%. The response is reversible and fast at room temperature. Details are provided of the synthesis, characterisation and use of the composite for humidity sensing. In addition the device forms the basis of a sensor for an array of gases

Carbon Nanomaterials and their application to Electrochemical Sensors: A review

Carbon has long been applied as an electrochemical sensing interface owing to its unique electrochemical properties. Moreover, recent advances in material design and synthesis, particularly nanomaterials, has produced robust electrochemical sensing systems that display superior analytical performance. Carbon nanotubes (CNTs) are one of the most extensively studied nanostructures because of their unique properties. In terms of electroanalysis, the ability of CNTs to augment the electrochemical reactivity of important biomolecules and promote electron transfer reactions of proteins is of particular interest. The remarkable sensitivity of CNTs to changes in surface conductivity due to the presence of adsorbates permits their application as highly sensitive nanoscale sensors. CNT-modified electrodes have also demonstrated their utility as anchors for biomolecules such as nucleic acids, and their ability to diminish surface fouling effects. Consequently, CNTs are highly attractive to researchers as a basis for many electrochemical sensors. Similarly, synthetic diamonds electrochemical properties, such as superior chemical inertness and biocompatibility, make it desirable both for (bio) chemical sensing and as the electrochemical interface for biological systems. This is highlighted by the recent development of multiple electrochemical diamond-based biosensors and bio interfaces

From the Laboratory to The Vineyard—Evolution of The Measurement of Grape Composition using NIR Spectroscopy towards High-Throughput Analysis

Compared to traditional laboratory methods, spectroscopic techniques (e.g., near infrared, hyperspectralimaging)provideanalystswithaninnovativeandimprovedunderstandingofcomplex issuesbydeterminingseveralchemicalcompoundsandmetabolitesatonce,allowingforthecollection of the sample “fingerprint”. These techniques have the potential to deliver high-throughput options for the analysis of the chemical composition of grapes in the laboratory, the vineyard and before or during harvest, to provide better insights of the chemistry, nutrition and physiology of grapes. Faster computers, the development of software and portable easy to use spectrophotometers and data analytical methods allow for the development of innovative applications of these techniques for the analyses of grape composition

From the Laboratory to The Vineyard—Evolution of The Measurement of Grape Composition using NIR Spectroscopy towards High-Throughput Analysis

Compared to traditional laboratory methods, spectroscopic techniques (e.g., near infrared, hyperspectralimaging)provideanalystswithaninnovativeandimprovedunderstandingofcomplex issuesbydeterminingseveralchemicalcompoundsandmetabolitesatonce,allowingforthecollection of the sample “fingerprint”. These techniques have the potential to deliver high-throughput options for the analysis of the chemical composition of grapes in the laboratory, the vineyard and before or during harvest, to provide better insights of the chemistry, nutrition and physiology of grapes. Faster computers, the development of software and portable easy to use spectrophotometers and data analytical methods allow for the development of innovative applications of these techniques for the analyses of grape composition

Computed tomography diagnosed cachexia and sarcopenia in 725 oncology patients: is nutritional screening capturing hidden malnutrition?

Background: Nutrition screening on admission to hospital is mandated in many countries, but to date, there is no consensus on which tool is optimal in the oncology setting. Wasting conditions such as cancer cachexia (CC) and sarcopenia are common in cancer patients and negatively impact on outcomes; however, they are often masked by excessive adiposity. This study aimed to inform the application of screening in cancer populations by investigating whether commonly used nutritional screening tools are adequately capturing nutritionally vulnerable patients, including those with abnormal body composition phenotypes (CC, sarcopenia, and myosteatosis). Methods: A prospective study of ambulatory oncology outpatients presenting for chemotherapy was performed. A detailed survey incorporating clinical, nutritional, biochemical, and quality of life data was administered. Participants were screened for malnutrition using the Malnutrition Universal Screening Tool (MUST), Malnutrition Screening Tool (MST), and the Nutritional Risk Index (NRI). Computed tomography (CT) assessment of body composition was performed to diagnose CC, sarcopenia, and myosteatosis according to consensus criteria. Results: A total of 725 patients (60% male, median age 64 years) with solid tumours participated (45% metastatic disease). The majority were overweight/obese (57%). However, 67% were losing weight, and CT analysis revealed CC in 42%, sarcopenia in 41%, and myosteatosis in 46%. Among patients with CT-identified CC, the MUST, MST, and NRI tools categorized 27%, 35%, and 7% of them as ‘low nutritional risk’, respectively. The percentage of patients with CT-identified sarcopenia and myosteatosis that were categorised as ‘low nutritional risk’ by MUST, MST and NRI were 55%, 61%, and 14% and 52%, 50%, and 11%, respectively. Among these tools, the NRI was most sensitive, with scores <97.5 detecting 85.8%, 88.6%, and 92.9% of sarcopenia, myosteatosis, and CC cases, respectively. Using multivariate Cox proportional hazards models, NRI score < 97.5 predicted greater mortality risk (hazard ratio 1.8, confidence interval: 1.2–2.8, P = 0.007). Conclusions: High numbers of nutritionally vulnerable patients, with demonstrated abnormal body composition phenotypes on CT analysis, were misclassified by MUST and MST. Caution should be exercised when categorizing the nutritional risk of oncology patients using these tools. NRI detected the majority of abnormal body composition phenotypes and independently predicted survival. Of the tools examined, the NRI yielded the most valuable information from screening and demonstrated usefulness as an initial nutritional risk grading system in ambulatory oncology patients