Browsing by Author "Chianella, Iva"

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    Adhesiveless bonding of wood - a review with a focus on wood welding
    (North Carolina State University, 2021-08-01) Gedara, Ajith K.A.; Chianella, Iva; Endrino, José L.; Zhang, Qi
    Most industrially used synthetic wood adhesives release formaldehyde, which is carcinogenic for humans. Adhesiveless bonding of wood can be achieved using heat treatment by either hot-pressing method, suitable mainly for wood particles and fibres or by wood welding. Welding of wood, which relies on the heat generated via friction, can be used for bonding two or more solid wood pieces together. The process can be carried out either by linear or rotational wood welding. This review first considers the manufacturing of binderless wood-based panels by hot-pressing. Then this is followed by an in-depth outlook of wood welding and its application in the wood industry. The effects of varying wood welding parameters, such as applied pressure, vibrational frequency and amplitude, holding pressure, holding time, welding time in linear wood welding, and relative diameter difference between the substrate and the dowel in rotational wood welding to obtain joints with optimal mechanical and physical properties is reviewed and discussed. Wood products made by heat treatment (hot-pressing and wood welding) are environmentally friendly, and the brief curing times needed for their manufacture represent a great advantage compared with the usage of wood adhesives to bind pieces of wood.
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    Biomimetic polymer reactor: design and modulation of novel tandem catalysts.
    (Cranfield University, 2021-09) Wei, Wenjing; Chianella, Iva; Thakur, Vijay Kumar; Koziol, Krzysztof
    Tandem catalysis can perform multi-step catalytic reactions in one-pot sequentially, which not only improves the efficiency of reactions significantly, but also decreases time, energy and the amounts of reagents needed. However, as there is always more than one active site (catalyst) in tandem reactors, it is critical to separate different sites and ensure each step is conducted individually. Moreover, it is often challenging to control the whole reaction processes due to the complexity of the systems. In this research, several bio-inspired catalytic reactors were proposed and developed to address the two challenges of site separation and smart control of tandem catalysis. First of all, the goal of sites separation has been achieved in this work through an enzyme-inspired molecularly imprinted polymer reactor MIP-Au-NP-BNPC and a core-shell structure catalytic nanoreactor AMPS@AM-Ag. Two molecularly imprinted cavities were created in MIP-Au-NP-BNPC. The different channels of the two catalytic sites in the reactor enabled different catalytic reactions to occur in different regions, resulting in the process of tandem reactions. As a result of the radial distribution of catalytic sites and mass transfer, the core-shell structure of AMPS@AM-Ag enabled the nanoreactor to perform different catalytic processes sequentially. Hence, the nanoreactor demonstrated the ability to conduct tandem catalysis with successful site separation. Then a biomimetic switch was introduced into the reactor to achieve the smart control of the catalytic process. Firstly, a new type of catalytic reactor consisting of a three-layer mussel-inspired polymer, MIP-AgPRS, was developed. The smart switchable layer composed of mussel-inspired self-healing copolymer was prepared between two MIP layers. This middle smart layer was able to react to different temperatures, permitting either simple or tandem reactions by closing and opening the access of the intermediate products. Secondly, a bilayer polymer reactor, DPR, composed of two different temperature-sensitive polymer layers was prepared. The two functional layers were not only able to respond to different specific temperatures, but each also contained different catalytic sites. Because of the two different phase transition processes of the two layers, the polymer reactor demonstrated to be able to perform simple/tandem catalysis in different temperature regions. As a result, this new type of bilayer polymer reactor was capable of achieving smart control of the tandem reactions. Finally, a three-layer switchable polymer reactor, PRS, with two MIP layers and a PNIPAM-PAM switchable layer in the middle was prepared. In an aqueous environment, when the temperature was low (lower than 47 °C), it exhibited an open access (hydrophilic condition), while when the temperature was high (higher than 47 °C), it became closed (hydrophobic condition). Furthermore, a comonomer (AM) was introduced in the middle layer with different ratios to adjust the responsive temperature range, enabling a more comprehensive range of practical uses. Therefore, a fast responsive and stable polymer reactor with self- controlled catalytic property was obtained. By preparing different types of new catalytic reactors, the research carried out here has shown the ability to achieve a smart control of the tandem catalysis while separating the catalytic sites effectively. Therefore, this study has highlighted new solutions to address the challenges present in tandem catalysis and has provided novel inspiration on how to exploit functional polymers while performing complicated catalytic reactions.
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    Black phosphorus: the rise of phosphorene in 2D materials applications
    (Elsevier, 2024-05-03) Mishra, Raghvendra Kumar; Sarkar, Jayati; Chianella, Iva; Goel, Saurav; Nezhad, Hamed Yazdani
    Few layers Black phosphorus (BP) and phosphorene are two-dimensional (2D) materials renowned for their adjustable bandgaps, high carrier mobility, and anisotropic conductivity, which make them highly promising for applications in the visible and infrared spectrum. The incorporation of these materials into polymer matrices has led to significant advancements in material science, resulting in nanocomposites with enhanced mechanical, electrical, and optical properties. This article provides a thorough analysis of BP/phosphorene polymer nanocomposites, including synthesis techniques (such as exfoliation methods) and manufacturing approaches. Advanced characterisation techniques are utilised to assess the structure, morphology, and properties of these composites. The article highlights the potential applications of these materials in energy storage (e.g., high-capacity batteries), flexible electronics (e.g., bendable displays), environmental sensing, and emerging biomedical fields such as targeted drug delivery. Furthermore, the article discusses potential solutions to tackle the challenges associated with the scalable, cost-effective production and ambient stability of BP/phosphorene, leveraging recent advancements in engineering research. The conclusion outlines future research directions, emphasising the importance of addressing persistent challenges through technological breakthroughs and exploring potential avenues for further advancement.
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    Borophene: a 2D wonder shaping the future of nanotechnology and materials science
    (Elsevier, 2024-05-10) Mishra, Raghvendra Kumar; Sarkar, Jayati; Verma, Kartikey; Chianella, Iva; Goel, Saurav; Nezhad, Hamed Yazdani
    Two-dimensional (2D) materials have attracted considerable research interest due to their precisely defined properties and versatile applications. In this realm, borophene - a single atomic sheet of boron atoms arranged in a honeycomb lattice - has emerged as a promising candidate. While borophenes were theoretically predicted to have unique structural, optical, and electronic properties, the experimental synthesis of crystalline borophene sheets was first demonstrated on metal substrates in 2015, marking a crucial milestone. Since then, research efforts have focused on controlling the synthesis of semiconducting borophene polymorphs and exploring their novel physical characteristics. This review aims to explore the potential of 2D materials, specifically borophene, in various technological fields such as batteries, supercapacitors, fuel cells, and more. The analysis emphasises meticulous scrutiny of synthesis techniques due to their fundamental importance in realising borophene's properties. Specifically, the high carrier mobilities, tuneable bandgaps, and exceptional thermal conductivity of borophene are highlighted. By providing a comprehensive outlook on the significance of borophene in advancing materials science and technologies, this review contributes to shaping the landscape of 2D material research.
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    A comparison of EIS and QCM nanoMIP-based sensors for morphine
    (MDPI, 2021-12-11) D’Aurelio, Roberta; Tothill, Ibtisam E.; Salbini, Maria; Calò, Francesca; Mazzotta, Elisabetta; Malitesta, Cosimino; Chianella, Iva
    In this work we have compared two different sensing platforms for the detection of morphine as an example of a low molecular weight target analyte. For this, molecularly imprinted polymer nanoparticles (NanoMIP), synthesized with an affinity towards morphine, were attached to an electrochemical impedance spectroscopy (EIS) and a quartz crystal microbalance (QCM) sensor. Assay design, sensors fabrication, analyte sensitivity and specificity were performed using similar methods. The results showed that the EIS sensor achieved a limit of detection (LOD) of 0.11 ng·mL−1, which is three orders of magnitude lower than the 0.19 µg·mL−1 achieved using the QCM sensor. Both the EIS and the QCM sensors were found to be able to specifically detect morphine in a direct assay format. However, the QCM method required conjugation of gold nanoparticles (AuNPs) to the small analyte (morphine) to amplify the signal and achieve a LOD in the µg·mL−1 range. Conversely, the EIS sensor method was labor-intensive and required extensive data handling and processing, resulting in longer analysis times (~30–40 min). In addition, whereas the QCM enables visualization of the binding events between the target molecule and the sensor in real-time, the EIS method does not allow such a feature and measurements are taken post-binding. The work also highlighted the advantages of using QCM as an automated, rapid and multiplex sensor compared to the much simpler EIS platform used in this work, though, the QCM method will require sample preparation, especially when a sensitive (ng·mL−1) detection of a small analyte is needed.
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    Computational modeling and molecular imprinting for the development of acrylic polymers with high affinity for bile salts
    (Elsevier Science B.V., Amsterdam., 2010-02-05T00:00:00Z) Yañez, Fernando; Chianella, Iva; Piletsky, Sergey A.; Concheiro, Angel; Alvarez-Lorenzo, Carmen
    This work has focused on the rational development of polymers capable of acting as traps of bile salts. Computational modeling was combined with molecular imprinting technology to obtain networks with high affinity for cholate salts in aqueous medium. The screening of a virtual library of 18 monomers, which are commonly used for imprinted networks, identified N-(3-aminopropyl)-methacrylate hydrochloride (APMA·HCl), N,N-diethylamino ethyl methacrylate (DEAEM) and ethyleneglycol methacrylate phosphate (EGMP) as suitable functional monomers with medium-to-high affinity for cholic acid. The polymers were prepared with a fix cholic acid:functional monomer mole ratio of 1:4, but with various cross- linking densities. Compared to polymers prepared without functional monomer, both imprinted and non-imprinted microparticles showed a high capability to remove sodium cholate from aqueous medium. High affinity APMA-based particles even resembled the performance of commercially available cholesterol-lowering granules. The imprinting effect was evident in most of the networks prepared, showing that computational modeling and molecular imprinting can act synergistically to improve the performance of certain polymers. Nevertheless, both the imprinted and non-imprinted networks prepared with the best monomer (APMA·HCl) identified by the modeling demonstrated such high affinity for the template that the imprinting effect was less important. The fitting of adsorption isotherms to the Freundlich model indicated that, in general, imprinting increases the population of high affinity binding sites, except when the affinity of the functional monomer for the target molecule is already very high. The cross-linking density was confirmed as a key parameter that determines the accessibility of the binding points to sodium cholate. Materials prepared with 9% mol APMA and 91% mol cross-linker showed enough affinity to achieve binding levels of up to 0.4 mmol g−1 (i.e., 170 mg g−1) under flow (1 mL min−1) of 0.2 mM sodium cholate s
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    Development of affinity sensors for Microcystin-LR based on a computationally designed molecularly imprinted polymer
    (Cranfield University, 2003-01) Chianella, Iva; Piletsky, Sergey A.; Chen, B.; Tothill, Ibtisam E.
    In this work the development of affinity sensors for the detection of microcystin-LR based on a computationally designed artificial receptor is presented. Microcystin-LR is a cyclic heptapeptide hepatotoxin produced by Cyanobacteria (aquatic organisms also known as blue-green algae), which during blooms period can release toxins in water. Clinical signs of hepatotoxicosis have been observed in domestic animals and livestock and recently also in humans. At present, analysis of these toxins is achieved largely using conventional, time consuming and expensive techniques such as chromatographic methods (HPLC, TLC) and immunoassay. Therefore, the necessity of an easy and inexpensive method of analysis such a biosensor is becoming urgent. In this work an artificial receptor for microcystin-LR was synthesised using a combined approach of molecular imprinting and computer modelling. A computer-aided rational design was applied to study microcystin-LRlmonomers interactions in order to find an optimal composition for the synthesis of the receptor. The optimised composition, suggested by computer modelling, consisted in 1 mol of2-acrylamido-2-methyl-propanesulfonic acid and 6 mol ofurocanic acid ethyl ester for 1 mol of template. This monomer composition was then used to synthesise a molecularly imprinted polymer (MIP) and an enzyme- linked competitive assay was developed to characterise the computational receptor. In the assay, computational MIP was able both to detect 0.1 ~g rl of microcystin-LR and to distinguish the analyte among analogues such as microcystin-YR, microcystin-RR and nodularin. The computationally designed receptor was then used as a sensing element for the construction of sensor devices. A MIP-based piezoelectric sensor, capable of detecting 35 ~g rl of toxin in water, was developed. In order to improve the system sensitivity, the computational polymer was also used as a material in solid-phase extraction (SPE) for samples pre-concentration. The receptor was able to pre-concentrate up to 1,000 fold tap water samples spiked with only 1 J.1g rl of toxin. By combining MIP-based SPE and piezoelectric sensor an improved system with a minimum detectable concentration of toxin of 0.35 ~g rl was achieved. Encouraging preliminary results were also obtained in developing a MIP-based electrochemical sensor.
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    Development of an impedimetric biosensor for lung cancer detection.
    (2018-06) Arabnejad, Mahdi; Tothill, Ibtisam E.; Chianella, Iva
    The promise of biosensors offering attractive features has kept the field active and growing. The aim is often to develop a device which is sensitive, specific, rapid, portable, cheap, and with the ability to capture an analyte in different matrices without cross-reactivity. The challenges increase when the aim is simultaneous multi-analyte detection on a single platform, without the need for complex procedures and expensive instruments. Such a system is invaluable in many clinical settings, where disease diagnosis and progression are multifactorial. Cancer is a good example of complex diagnosis requirements. This project is aimed at the development of biosensing platform to overcome the aforementioned problems and allow direct, simple analysis with the minimum of sample pre-treatment. The early detection of lung cancer has been chosen as there is no commercial biosensor available for detection of this disease and for lung cancer diagnosis multi-analyte recognition is necessary. This project presents the development of impedimetric and magnetic sensing platform for early detection of lung cancer via detecting the neuron-specific enolase (NSE) and carcinoembryonic antigen (CEA) which are known as potential lung cancer biomarkers. The sensing platform developed here comprises of magnetic manipulation, screen printed electrode (SPE), and magnetic nanobeads. The magnetic nanobeads (MBs) were functionalised with antibodies to fish the analyte from the sample, and to move them over the sensing area. Moreover, magnetic nanobeads were used to increase the chance of antigen-antibody complex formation. After cleaning the surface of electrodes with 50 mM KOH in 25% H₂O₂ (for 10 minutes), immunosensors were developed by immobilising the antibodies on the gold working electrode of SPEs through formation of self-assembled monolayer (SAM layer) due to its simplicity, stability, well-organised structure and low background noise. The optimised NSE immunosensor with 10 µg/ml of 10-7937 antibody was successfully tested to measure various concentrations of NSE protein (0 – 100 ng/ml) in both PBS buffer and 100 % serum using functionalised MBs with 2.4 mg/ml of 10-7938 antibody. The optimised sensor achieved detection limit of 0.18 ng/ml (R²= 0.9848) in buffer and 0.52 ng/ml (R² = 0.9977) in 100 % serum with via EIS with the use of 10 mM potassium ferri/ferrocyanide as a redox probe. The impedimetric CEA immunosensor was developed and optimised by use of 20 µg/ml of 12-140-01 antibody and was used to measure analyte with functionalised MBs with 2.4 mg/ml of 12-140-10 antibody. The CEA immunosensor was also able to measure various CEA concentrations (0 – 100 ng/ml) in both PBS buffer and 100 % serum in presence of 10 mM potassium ferri/ferrocyanide. The sensor achieved low limit of detection as 0.26 ng/ml (R² = 0.9924) and 0.76 ng/ml (R²= 0.9839) for CEA detection in buffer and 100 % serum, respectively. In conclusion, both immunosensors developed here, using EIS and the magnetic sensing platform, were capable of detecting their corresponding biomarkers in serum in relatively short time (40 minutes) and in the appropriate concentration range, as serum concentrations higher than 12.5 ng/ml and 7 ng/ml for NSE and CEA respectively can indicate presence of cancer. To the best of our knowledge, no one has reported a use of magnetic platform as the one developed in this thesis.
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    Development of electrochemical immunosensors for HER-1 and HER-2 analysis in serum for breast cancer patients
    (MDPI, 2023-03-07) Wignarajah, Shayalini; Chianella, Iva; Tothill, Ibtisam E.
    In this work, two human epidermal growth factor receptors, HER-1 and HER-2, were selected as biomarkers to enable the detection of breast cancer. Therefore, two biosensors were developed using gold sensor chips coupled with amperometric detection of the enzyme label horse radish peroxidase (HRP). The biosensors/immunosensors relied on indirect sandwich enzyme-linked immunosorbent assays with monoclonal antibodies (Ab) against HER-1 and HER-2 attached to the sensors to capture the biomarkers. Detection polyclonal antibodies followed by secondary anti-rabbit (for HER-1) and anti-goat (for HER-2) IgG antibody-HRP were then applied for signal generation. In buffer, the developed sensors showed limits of detections (LOD) of 1.06 ng mL−1 and 0.95 ng mL−1 and limits of quantification (LOQ) of 2.1 ng mL−1 and 1.5 ng mL−1 for HER-1 and HER-2, respectively. In 100% (undiluted) serum, LODs of 1.2 ng mL−1 and 1.47 ng mL−1 and LOQs of 1.5 ng mL−1 and 2.1 ng mL−1 were obtained for HER-1 and HER-2, respectively. Such limits of detections are within the serum clinical range for the two biomarkers. Furthermore, gold nanoparticles (AuNP) labelled with secondary anti-rabbit and anti-goat IgG antibody-HRP were then used to enhance the assay signal and increase the sensitivity. In buffers, LODs of 30 pg mL−1 were seen for both sensors and LOQs of 98 pg mL−1 and 35 pg mL−1 were recorded for HER-1 and HER-2, respectively. For HER-2 the AuNPs biosensor was also tested in 100% serum obtaining a LOD of 50 pg mL−1 and a LOQ of 80 pg mL−1. The HER-2 AuNP electrochemical immunosensor showed high specificity with very low cross-reactivity to HER-1. These findings demonstrate that the two developed sensors can enable early detection as well as monitoring of disease progression with a beneficial impact on patient survival and clinical outcomes.
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    Development of functionalized nanostructured polymeric membranes for water purification
    (Elsevier, 2016-04-24) Altintas, Zeynep; Chianella, Iva; Da Ponte, Gabriella; Paulussen, Sabine; Gaeta, Soccorso; Tothill, Ibtisam E.
    Pharmaceuticals specific molecularly imprinted polymers nanoparticles (MIPNPs) were synthesized and applied onto the polyvinylidene fluoride (PVDF) membranes previously subjected to the plasma treatment. Diclofenac-, metoprolol- and vancomycin-MIPs were applied onto the membranes and scanning electron microscopy was employed to visualize MIPNPs on the membrane. After functionalization of the membranes with target-specific MIPs the molecularly imprinted membranes (MIMs) affinity against their targets was evaluated using solid phase extraction (SPE) technique coupled with high performance liquid chromatography (HPLC). MIMs were used as filters to load the target solutions through employing a vacuum pump to evaluate the amount of pharmaceuticals in filtrate. Moreover, a comparative study was performed by comparing the efficiency of MIMs functionalized either by adsorption or covalent immobilization. The capacity analysis of MIPNPs by SPE–HPLC revealed 100%, 96.3%, and 50.1% uptake of loaded solution of metoprolol, diclofenac and vancomycin, respectively. MIMs showed 99.6% uptake with a capacity of 60.39 ng cm2 for metoprolol; 94.7% uptake with a capacity of 45.09 ng cm2 for diclofenac; and 42.6% uptake with a capacity of 16.9 ng cm2 for vancomycin. HPLC detection limits of targets were found as 3.7, 7.5 and 15 ng mL−1 for diclofenac, metoprolol and vancomycin respectively. A small scale pilot test was also conducted which indicates the promising future applications of the developed MIMs for high volume of filtrates especially in the case of the plasma-treated PVDF membranes prepared by covalent immobilization of the MIPs.
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    Development of nanomip based sensors for drugs of abuse detection.
    (2018-02) D'aurelio, Roberta; Tothill, Ibtisam E.; Chianella, Iva
    This work presents the development of portable, yet highly sensitive and specific, sensor based on NanoMIPs EIS for the detection of cocaine and morphine at trace levels (sub-ppm). The molecularly imprinted polymer nanoparticles (nanoMIPs) were synthesised as the sensing elements using solid-phase synthesis approach at the University of Leicester. Cocaine nanoMIPs and morphine nanoMIPs particle size (dH) were measured using Dynamic Light Scattering (DLS) and were found to be 168.80±68.73 nm and 170.09±54.75 nm for cocaine nanoMIP and morphine nanoMIP respectively, thus highlighting a small batch to batch variations. The nanoMIPs were then covalently attached to the conventional screen-printed electrode (SPE), thus yielding a nanoMIP EIS sensor. The Faradic Electrochemical Impedance Spectroscopy (EIS) was applied to detect the analyte binding events, having 10 mM [Fe (CN) 6]³⁻/⁴⁻ in MOPS (10 mM, pH 7.4) as redox couple solution. The EIS was recorded at a 0.12 V potential over the frequency range from 0.1 Hz to 50 kHz with a modulation voltage of 10 mV. The cocaine nanoMIP EIS sensor, fabricated onto SPE, was optimised and was able to detect cocaine hydrochloride (salt form) dissolved in 10 mM MOPS (pH 7.4) in the linear range of 0.1 – 50 ng mL⁻¹ (R²=0.984) and with a LOD equal to 0.24 ng mL⁻¹ . The optimisation studies on the surface blocking agents guaranteed the absence of cross-reactivity towards other drugs, such as morphine and other cocaine adulterants, such as levamisole, caffeine and, partially, mannitol. The optimised sensor and assay conditions were replicated using interdigitated electrode (IDE), achieving an LOD (2.5 ng mL⁻¹), which will requires further optimisation. Analogously, the morphine nanoMIP EIS sensor, fabricated onto SPE, was optimised and tested against morphine salt dissolved in MOPS (pH 7.4) (0.1 – 50 ng mL⁻¹). The sensor was able to detect morphine in the linear range of 0.1- 10 ng mL⁻¹ (R² = 0.977) and achieving a LOD as low as 0.109 ng mL⁻¹. The optimised sensor was replicated using IDE, placed in a custom-made 3D printed IDE cable holder. The sensor achieved an LOD of 0.114 ng mL⁻¹ in a linear range of 0.01 to 5 ng mL⁻¹. Furthermore, a QCM platform with a fully automated microfluidic system was employed in this work to develop a multiplexing nanoMIPs QCM sensor for cocaine and morphine detection. The morphine nanoMIPs and cocaine nanoMIPs were respectively immobilised on spot 1 and spot 2 of a QCM sensor chip. Due to the required QCM signal enhancement, morphine and cocaine were separately adsorbed onto 40 nm gold nanoparticles (AuNPs). Increasing concentration (250 ng mL⁻¹ to 50 µg mL⁻¹) of each drug conjugated AuNPs were prepared in PBS (pH 7.4) and injected onto the nanoMIP QCM sensor. The nanoMIPs QCM sensor was able to detect morphine-AuNPs and cocaine-AuNPs, without any detectable cross-reactivity events, with the respective LOD equal to 0.191 µg mL-¹and 0.360 µg mL⁻¹. The morphine-AuNPs and cocaine-AuNPs detection binding data were fitted to 1:1 Langmuir binding model and the average (±SD) values of the KD were equal to 0.647±0.340 µM and 0.225±0.197 µM respectively, thus providing insight on the affinity binding. All the nanoMIPs sensors developed in this work are cheap, easy-to-use and portable (in the case of EIS) screening methods for drugs of abuse detection, thus being a valuable competitor to the current on-site screening methods.
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    Development Of Novel Matrices For Biomolecule Immobilisation On Sensor Surfaces
    (Cranfield University, 2010) Kyprianou, Dimitris; Chianella, Iva; Piletsky, Sergey A.
    The development of a novel protocol for the covalent immobilisation of biomolecules containing primary amines using either polythiol compounds or novel, inexpensive and simple polymers is presented in this thesis. When developing biosensors, the method used for the immobilisation of the sensing elements is very important. The immobilisation needs to be fast, cheap and most importantly should not affect the biorecognition activity of the immobilised receptor. The chemistry used for the immobilisation is based on the well known reaction between primary amines and thioacetal groups, formed upon reaction of o-phthaldialdehyde (OPA) and thiol compounds. Initially the possibility to use this chemistry to immobilise receptors and develop biosensors was proved using commercially available polythiol compounds. Such compounds can be irreversibly adsorbed, creating self-assembling monolayers (SAMs), on noble metal transducer surfaces. These SAMs were immobilised on Biacore surface plasmon resonance (SPR) gold chips and then used to study kinetic of biomolecules interactions and to detect cells. A general protocol suitable for the immobilisation of enzymes and antibodies such as anti-prostate specific antigen (anti-PSA) and anti-Salmonella typhimurium antibody was optimised. Kinetic data were obtained for PSA binding to anti-PSA antibody and they were compared to the results obtained using commercially available Biacore chips, CM1. For Salmonella typhimurium cells, a detection limit of 5 × 106 cells ml-1 with minimal non-specific binding of other biomolecules was obtained. An interesting capability shown by these SAMs, in contrast with commercially available chips, was the opportunity to immobilise any proteins, even those with very low or high isoelectric points, pI. In addition protein immobilisation was achieved with a simple step, without requirement of any activation. These findings make this immobilisation technique a very promising alternative to peptide bond formation for amine coupling. Even though, the developed SAMs showed to be useful for certain type of applications (kinetic study and detection of very large analyte), it was clear that due to a combination of factors (e.g. limited and steric hindrance), they were not suitable for the development of biosensors good enough for practical applications. Therefore to overcome the drawbacks shown by polythiol SAMs, a novel 3-D polymer was developed. The main advantage of this polymer is the tridimensional (3D) network, which, after immobilisation, ensures the availability of a high percentage of receptor binding sites. As the polythiol SAMs, also the 3-D polymer contains thioacetal groups, which do not need any activation to react with primary amines in proteins. The novel 3-D polymer also contains thiol derivative groups (disulphide groups or thioethers) that promote self-assembling on metal surfaces. As before, the polymer was immobilised on SPR gold chips and the resulting layer was characterised using contact angle meter, atomic force microscopy (AFM) and ellipsometry. Contact angle demonstrated that the immobilisation of polymer on sensor surface produced a relatively hydrophobic surface. The thickness of polymer layer was determined by applying ellipsometry, whereas AFM showed the change of surface roughness after polymer attachment. A general protocol suitable for the immobilisation of BSA, enzymes and antibodies such as polyclonal anti-microcystin-LR and monoclonal anti-prostate specific antigen (anti-PSA) antibody was then optimised. The affinity characteristics of developed immunosensors were investigated in reaction with microcystin-LR, and PSA. The calculated detection limit for analytes depended on the properties of the antibodies. The detection limit for microcystin-LR was 10 ng ml and for PSA 0.05 ng ml. The 3-D polymer chips were stored for up to 2 months without any noticeable deterioration in their ability to react with proteins. The performance of 3-D polymer chips were also compared with commercially available Biacore chips, as CM5. The main advantages were found to be the low cost, the possibility to immobilise biomolecules at physiological pH (pH 7.4), the lack of any activation step for biomolecules immobilisation and the opportunity to immobilise proteins with very different pI (also very low pI). Despite the successful detection of PSA achieved in buffer (detection limit 0.05 ng ml-1) using 3-D polymer chips, the detection of proteins in serum resulted to be very challenging due to the complex nature of the matrix, which contains a high content of many different compounds. Different techniques were applied in order to reduce the non specific adsorption of serum on 3-D polymer sensors with antibodies immobilised on the surface. Satisfactory results were finally obtained by including the surfactant P20 into the measuring system. The detection of PSA in serum using 3-D polymer sensors, however, became possible only by switching from a direct detection to a ‘sandwich detection’. In this sandwich format, after injecting samples of PSA (prepared both in buffer or 20% serum) onto a specific antibody (capture-Ab, C-Ab) immobilised on the 3-D polymer surface, the analytical signal is recorded by injecting a second specific Ab (detection-Ab, prepared in PBS), which recognises a different epitope of the antigen. With this format, the analytical signal is recorded in absence of any complex matrix, avoiding interference from non specific adsorption. The detection limit for PSA, obtained using the sandwich immunosensor (developed on 3-D polymer chips) was 0.1 ng ml-1 in buffer and 5 ng ml-1 in 20% serum, which is very close to the sensitivity necessary for detection of the prostate biomarker in real samples. Therefore this study has demonstrated the opportunity to apply the novel 3-D polymer for development of biosensors suitable for applications in real samples.
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    Development of Polymeric Materials to Inhibit Bacterial Quorum Sensing
    (Cranfield University, 2014-07) Cavaleiro, Eliana Marisa dos Santos; Chianella, Iva; Duarte, Ana Sofia; Correia, António; University of Aveiro
    Bacterial infections are an increasing problem for human health. In fact, an increasing number of infections are caused by bacteria that are resistant to most antibiotics and their combinations. A new solution to fight bacteria and infectious diseases, without promoting antimicrobial resistance, is required. A promise strategy is the disruption or attenuation of bacterial Quorum Sensing (QS), a refined system that bacteria use to communicate. In a QS event, bacteria produce and release specific small chemicals, signal molecules - autoinducers (AIs) - into the environment. AIs regulate gene expression as a function of cell population density. Phenotypes mediated by QS (QS- phenotypes) include virulence factors, toxin production, antibiotic resistance and biofilm formation. In this work, two polymeric materials (linear polymers and molecularly imprinted nanoparticles) were developed and their ability to attenuate QS was evaluated. Both types of polymers should be able to adsorb bacterial signal molecules, limiting their availability in the extracellular environment, with expected disruption of QS. Linear polymers were composed by methyl methacrylate as backbone and itaconic acid or methacrylic acid as functional monomer. IA and MAA monomers were identified by computer modelling to have strong interactions with the AIs produced by Gram-negative bacteria. Cont/d.
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    Direct replacement of antibodies with molecularly imprinted polymer (MIP) nanoparticles in ELISA - development of a novel assay for vancomycin
    (American Chemical Society , 2013-09-03T00:00:00Z) Chianella, Iva; Guerreiro, Antonio R.; Moczko, Ewa; Caygill, J. S.; Piletska, Elena V.; Perez De Vargas Sansalvador, Isabel M.; Whitcombe, Michael J.; Piletsky, Sergey A.
    A simple and straightforward technique for coating microplate wells with molecularly imprinted polymer nanoparticles (nanoMIPs) to develop ELISA type assays is presented here for the first time. NanoMIPs were synthesized by a solid phase approach with immobilized vancomycin (template) and characterized using Biacore 3000, dynamic light scattering and electron microscopy. Immobilization, blocking and washing conditions were optimized in microplate format. The detection of vancomycin was achieved in competitive binding experiments with a HRP-vancomycin conjugate. The assay was capable of measuring vancomycin in buffer and in blood plasma within the range 0.001-70 nM with a detection limit of 0.0025 nM (2.5 pM). The sensitivity of the assay was three orders of magnitude better than a previously described ELISA based on antibodies. In these experiments nanoMIPs have shown high affinity and minimal interference from blood plasma components. Immobilized nanoMIPs were stored for 1 month at room temperature without any detrimental effects to their binding properties. The high affinity of nanoMIPs and the lack of a requirement for cold chain logistics make them an attractive alternative to traditional antibodies used in ELISA
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    Discovery and quantification of proteins of biological relevance through differential proteomics and biosensing
    (Cranfield University, 2012-04) Lonardoni, Francesco; Bossi, Alessandra; Chianella, Iva
    Medical diagnosis is the process of attempting to determine and/or identify a possible disease or disorder. This process is revealed by biomarkers, defined by The Food and Drug Administration (FDA) as “characteristics that are objectively measured and evaluated as indicators of normal biologic processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention”. The process of biomarker discovery has been boosted in the last years by proteomics, a research discipline that takes a snapshot of the entire wealth of proteins in an organism/ tissue/ cell/ body fluid. An implementation of the analysis methods can help in isolate proteins present in the low range of concentrations, such as biomarkers very often are. An established biomarker can further be measured with the help of biosensors, devices that can be employed in the point-of care diagnostics. This PhD thesis shows and discusses the results of three projects in the field of protein biomarkers discovery and quantification. The first project exploited proteomics techniques to find relevant protein markers for Intrauterine Growth Restriction (IUGR) in cordonal blood serum (UCS) and amniotic fluid (AF). A 14 proteins in UCS and 11 in AF were successfully identified and found to be differentially expressed. Molecularly Imprinted Polymers (MIPs) directed towards proteins and peptides containing phosphotyrosine were then produced, with the final goal of selectively extracting phosphopeptides from a peptide mixture. An alteration of the phosphorylation pattern is in fact often associated to important diseases such as cancer. The polymers were produced as nanoparticles, that were characterised with Dynamic Light Scattering (DLS) and Atomic Force Microscopy (AFM). A recipe was also tested for binding capacity towards phosphotyrosine. A Surface Plasmon Resonance (SPR) biosensor to quantify hepcidin hormone was finally produced. This is the major subject in iron homeostasis in vertebrates and marker of iron unbalance diseases. A calibration curve was made and affinity/kinetic parameters for the ligand employed were measured.
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    Does size matter? Study of performance of pseudo-ELISAs based on molecularly imprinted polymer nanoparticles prepared for analytes of different sizes
    (Royal Society of Chemistry, 2016-01-18) Cáceres, C.; Canfarotta, F.; Chianella, Iva; Pereira, E.; Moczko, Ewa; Esen, C.; Guerreiro, Antonio R.; Piletska, Elena V.; Whitcombe, Michael J.; Piletsky, Sergey A.
    The aim of this work is to evaluate whether the size of the analyte used as template for the synthesis of molecularly imprinted polymer nanoparticles (nanoMIPs) can affect their performance in pseudo-enzyme linked immunosorbent assays (pseudo-ELISAs). Successful demonstration of a nanoMIPs-based pseudo-ELISA for vancomycin (1449.3 g mol) was demonstrated earlier. In the present investigation, the following analytes were selected: horseradish peroxidase (HRP, 44 kDa), cytochrome C (Cyt C, 12 kDa) biotin (244.31 g mol) and melamine (126.12 g mol). NanoMIPs with a similar composition for all analytes were synthesised by persulfate-initiated polymerisation in water. In addition, core-shell nanoMIPs coated with polyethylene glycol (PEG) and imprinted for melamine were produced in organics and tested. The polymerisation of the nanoparticles was done using a solid-phase approach with the correspondent template immobilised on glass beads. The performance of the nanoMIPs used as replacement for antibodies in direct pseudo-ELISA (for the enzymes) and competitive pseudo-ELISA for the smaller analytes was investigated. For the competitive mode we rely on competition for the binding to the nanoparticles between free analyte and corresponding analyte-HRP conjugate. The results revealed that the best performances were obtained for nanoMIPs synthesised in aqueous media for the larger analytes. In addition, this approach was successful for biotin but completely failed for the smallest template melamine. This problem was solved using nanoMIP prepared by UV polymerisation in an organic media with a PEG shell. This study demonstrates that the preparation of nanoMIP by solid-phase approach can produce material with high affinity and potential to replace antibodies in ELISA tests for both large and small analytes. This makes this technology versatile and applicable to practically any target analyte and diagnostic field.
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    Evidence for some antimicrobial properties of English churchyard lichens
    (The Microbiology Society, 2023-06-20) Taylor, Judith A.; Fourie, Toscane; Powell, Mark; Chianella, Iva
    The emergence of multidrug-resistant bacteria has driven the need for novel antibiotics. Our investigations have focussed on lichens as they naturally produce a wide range of unique and very effective defence chemicals. The aim of this study was to evaluate some of the antimicrobial properties of ten common British churchyard lichens. The lichen material was sampled from ten species, namely Caloplaca flavescens, Diploicia canescens, Cladonia fimbriata, Psilolechia lucida, Lecanora campestris subsp. Campestris, Lecanora sulphurea, Pertusaria amara f.amara, Lepraria incana, Porpidia tuberculosa and Xanthoria calcicola. Crude acetone extracts of these lichens were tested against six bacteria (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Salmonela typhimurium, Listeria monocytogenes and Lactobacillus acidophilus ) and two fungi (Trichophyton interdigitale and Aspergillus flavus) by the disc-diffusion susceptibility test method. Extracts of Diploicia canescens, Psilolechia lucida, Lecanora sulphurea, Pertusaria amara and Lepraria incana showed clear inhibition of the Gram-positive bacteria tested (S. aureus, L. monocytogenes, L. plantarum). Diploicia canescens, Pertusaria amara and Lepraria incana extracts also inhibited the dermatophyte fungi tested. The Lepraria incana sample tested here was the only extract that showed activity against any of the Gram-negative bacteria tested; it showed inhibition of Pseudomnas aeruginosa. Overall, our results showed that crude extracts of Diploicia canescens and Pertusaria amara had the most potent antimicrobial activity of all the extracts tested. Our results are in general agreement with published findings elsewhere. The activity of the Porpidia tuberculosa margin sample being different from that of the main colony material was an interesting and new finding reported here for the first time.
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    Exploring transformative and multifunctional potential of MXenes in 2D materials for next-generation technology
    (Elsevier, 2024-04-26) Mishra, Raghvendra Kumar; Sarkar, Jayati; Verma, Kartikey; Chianella, Iva; Goel, Saurav; Nezha, Hamed Yazdani
    MXenes, a rapidly growing family of two-dimensional (2D) transition metal carbides, nitrides, or carbonitrides (Mn+1XnTx, where M is a transition metal, X is carbon, nitrogen, or both, and T represents surface functional groups), have captured the scientific community's interest due to their exceptional physicochemical properties and diverse technological applications. This comprehensive review explores the latest breakthroughs in MXene synthesis and characterisation, emphasising their multifaceted applications in energy storage, catalysis, sensing, and other cutting-edge domains. This review examines the most widely used MXene synthesis strategies, including selective etching and delamination, and highlight recent advancements in controlling surface terminations, composition, and morphology. The influence of these synthetic parameters on MXene properties is discussed in detail. Characterisation techniques, ranging from spectroscopic methods to electron microscopy, are essential for elucidating MXenes' structure-property relationships. Research into energy storage leverages MXenes' high electrical conductivity, large surface area, and chemical tunability. This has led to significant progress in the field. This paper presents research efforts focused on optimising MXenes for both battery and supercapacitor applications. Additionally, the catalytic prowess of MXenes, particularly in electrocatalysis and photocatalysis, is explored, emphasising their role in green energy technologies and environmental remediation. MXenes' remarkable sensitivity and selectivity make them promising candidates for sensing various gases, biomolecules, and ions, offering exciting possibilities in healthcare and environmental monitoring. Importantly, this review underscores the need for continued optimisation of MXene synthesis protocols to achieve large-scale production, enhanced stability, and precise control over properties across various fields.
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    Graphene nanoplatelets/barium titanate polymer nanocomposite fibril: a remanufactured multifunctional material with unprecedented electrical, thermomechanical, and electromagnetic properties
    (Wiley, 2023-09-25) Mishra, Raghvndra Kumar; Goel, Saurav; Chianella, Iva; Yazdani Nezhad, Hamed
    A novel, zero-waste and recycling plastic waste solution is introduced, to scalably produce graphene nanoplatelets/barium titanate (GNP/BaTiO3) polymer nanocomposite fibrils. A comprehensive investigation is performed to evaluate the compatible and non-compatible recycled polypropylene (PP)/polyethyleneterephthalate (PET) blends combined with functional (electrical, piezoelectric,and dielectric) materials for in-situ fibril production. The nanocompositefibrils made from recycled PP, PET and GNPs/BaTiO3 with high-aspect ratio disparity (400:1) are produced, which exhibit significantly enhanced electrical, thermomechanical, and electromagnetic characteristics. Single-screw extrusion is utilised to fabricate the fibrils with the in-situ fibril morphology of PET and GNPs/BaTiO3 leading to improved electrical conductivity. It is demonstrated that such fibril morphology restricts the chain mobility of polymer molecules, and ultimately increases viscosity and strain energy. Moreover, the study demonstrates a positive reinforcement effect from the utilisation of PET fibrils and GNPs/BaTiO3 in a PP matrix, dominated by the high-aspect ratio, stiffness, and thermal stability of GNPs/BaTiO3. Furthermore, it is observed that the mechanical properties and tension-bearing capacity of the PP are significantly improved by such incorporation. The study also demonstrates that the protection of the remanufactured nanocomposites against electromagnetic interference is significantly improved with the increasing GNPs/BaTiO3 content and the morphological transition from spherical to fibril-shaped PET.
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    Hollow silica nano and micro spheres with polystyrene templating: a mini-review
    (MDPI, 2022-12-01) Gurung, Siddharth; Gucci, Francesco; Cairns, Gareth; Chianella, Iva; Leighton, Glenn J. T.
    Synthesis of monodisperse hollow silica nanospheres, especially using a hard template route, has been shown to be successful, but a high yield is needed for this strategy to be used on an industrial scale. On the other hand, there is a research gap in the synthesis of hollow silica microspheres due to the popularity and easiness of the synthesis of silica nanospheres despite the larger spheres being beneficial in some fields. In this review, current trends in producing hollow silica nanospheres using hard templates, especially polystyrene, are briefly presented. Soft templates have also been used to make highly polydisperse hollow silica spheres, and complex designs have improved polydispersity. The effect of the main parameters on the coating is presented here to provide a basic understanding of the interactions between the silica and template surface in the absence or presence of surfactants. Surface charge, surface modification, parameters in the sol–gel method and interaction between the silica and templates need to be further improved to have a uniform coating and better control over the size, dispersity, wall thickness and porosity. As larger organic templates will have lower surface energy, the efficiency of the micro sphere synthesis needs to be improved. Control over the physical structure of hollow silica spheres will open up many opportunities for them to be extensively used in fields ranging from waste removal to energy storage.