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Potassium, sodium, and calcium are crucial electrolytes of human blood. Among the functions of the electrolytes are maintenance of osmotic pressure and water distribution in the various body fluid compartments, maintenance of the proper pH, regulation of the proper function of the heart and other muscles, involvement in oxidation-reduction or electron transfer reactions, and participation in catalysis as cofactors for enzymes. Therefore, abnormal levels of electrolytes may be either the cause or the consequence of a variety of disorders, and thus the determination of electrolytes in different body fluids in general and in whole human blood particularly is one of the most important functions of the clinical laboratory . Serum or plasma is the usual specimen employed for assay of potassium, sodium, and calcium but not whole human blood. This research intended to create a sensor-array capable of analysing potassium, sodium, and calcium ion-activity in whole human blood based on miniaturised ion-sensors and zero-current direct potentiometry. This research dealt with sensing-side of the sensor-array hoping for integration of these sensors with microelectronics or discrete parts based electronics in due time. Clinics use single electrodes for K+, Na+, and Ca2+ sensing in body fluids. However, single sensing is costly and in emergency cases time consuming as well. Therefore a portable, battery-operated cost- and time-effective sensor array is needed for multi-sensing of r, Na +, and Ca2 + either in emergency cases in field or for patient near bed-side measurement/monitoring. The approach of this thesis to the problem is as follows: This thesis has five phases, all equally important. The first phase, a theoretical phase, mainly deals with the determination of the technique which fits best with chemical sensors and integration with microelectronics, and the decision among many alternative chemicals, whether natural or man-made, available for multi-sensing realisation, by taking into account all the best efforts devoted to development of chemical-sensors. The second phase is the miniaturisation process of the electrochemical sensor-array, either ion-sensors or reference electrode, as much as possible. The third phase is multi-sensing application of the sensorarray for sensing K+, Na+, and ci+ with binary and mixed electrolytes and with artificial and whole human blood respectively, the fourth phase is the sensor-array response with only millilitre or microlitre volumes of whole human blood and the fifth phase is the integration of a sensor array with discrete, parts based, electronic circuitry. So, as a new application a disposable reference electrode has been realised which reasonably fits with the sensor array for the analysis of potassium, sodium, and calcium in whole human blood. Since all the single sensing of these cations have been realised by using a conventional reference electrode, either silver/silver chloride or calomel electrode, which is a bulky and expensive alternative, this research prepared, tested, and implemented a new disposable reference electrode for the sensor-array based on a poly (vinyl alcohol) matrix incorporating a proper amount of Kel. Having a successfully working miniaturised reference electrode, valinomycin, ETH 157, and ETH 1001 ionophores have been used as the selective materials for potassium, sodium, and calcium in whole human blood, respectively. Multisensing applications have only used solutions as testing medium whereas the work described in this thesis goes one step further and uses artificial and whole human blood with fairly reasonable responses.

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Cardiovascular mortality continues to be the leading cause of death in the United Kingdom, China and the United States. Many of these deaths occur suddenly, called sudden cardiac death (SCD), with the number of these events estimated from these three Countries to be over 1,500,000 annually. In the vast majority of documented cases, the SCD is directly caused by ventricular tachycardia (V1). Prediction of the presence of the VT is of great importance. It has been found by using signal averaging (SA) techniques that the appearance of micro signals, called ventricular late potentials (VLPs), is highly correlated with the appearance of VT or SCD. The VLPs are about 0.1% - 1% of the size of the normal ECG in most patients and are masked by various noise sources, so that they can not be seen from the standard electrocardiogram (ECG). The SA techniques, depending largly on averaging many beats, can only detect the microvolt signals that are strictly constant in duration, morphology and timing relative to the QRS complex amongst the considerable amounts of noise which are present The main disadvantage of the technique is that it cannot offer information from an individual beat, i.e. variations among the beats and individual beat information are lost when averaging. This information can be very important in the diagnosis of the development of many heart abnormalities, particularly arrhythmias. This thesis describes various techniques that have been developed for a real-time processing system, in which the system can detect VLPs at the body surface with beat-to-beat variations. One of the most important techniques is the use of adaptive filters to reduce the most disruptive noise -random noise. Clinical investigations have been carried out based on 14 normal and 20 abnormal pathological subjects to produce reproducible results on the developed system. The results show that the system can produce much more information than SA techniques for the prediction of VT.

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Investigations into silicate-substituted hydroxyapatite (Si-HA) were performed. The aqueous precipitation method produced phase pure Si-HA with modi cations to the method causing impurities in the material. A novel study using Raman spectroscopy followed the behaviour of the silicate ions and provided a new interpretation regarding silicate substitution. The silicate ions created interactions with hydroxyl ions, initially, which reduced upon sintering of the material. As the silicate ions do not behave inde- pendently in the HA structure initially, suggests that these interactions may contribute to the bioactivity of Si-HA. Also industrial aspects of Si-HA were investigated regarding the silicate reagent (TEOS). A small di erence of 1% in the percentage concentration of TEOS was not negligible and caused a decrease in the amount of silicate substituted into HA. Di erent brands and grades of TEOS did produce Si-HA with similar structural properties. Therefore, a variety of brands and grades of TEOS can be used and thus the most cost e ective choice can be made. The rst analytical investigations into the molecular arrangement of fully mineralised osteoarthritic (OA) and osteoporotic (OP) bone were performed through small angle neutron scattering (SANS) studies. This study provided a description for the molecular arrangement of collagen molecules, along the lateral plane, regarding the molecular di- ameter and the packing of these molecules into the bril by the development of a model based on SANS theory. The collagen molecules behave like a 2-dimensional liquid-like system. Through the development of the model, the rst written solution for the struc- ture factor for a system of hard-disks was stated. This study provided an understanding into how collagen molecules are arranged in OA and OP bone. Also, compositional studies iterated possible di erences between the organic content of OA and OP bone. Thus the organic content of bone may play a role in the bone disorders.

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Responsive biomedical materials span a plethora of applications in the biomedical field, from stents, hydrogels, degradable implants to drug delivery systems, and are in constant further development to give properties that ultimately improve the quality of life and prevent disease. In an effort to develop cell-interacting constructs we sought to synthesize polymers with bioresponsive and even “life-like” properties. By exploiting living polymerization techniques we aim to build self-assembled capsule-mimicking structures (i.e. vesicles) that can serve as prototype copycats of natural cell membranes. Also, we aim to establish a primitive communication platform of the artificial structures with their natural counterparts (i.e. bacterial cells) by using the “glyco-code” as a means of biochemical language. First, model thermoresponsive polymers are utilized that bear carbohydrate moieties to study polymer-cell interactions via multivalency and ligand-receptor interactions. The glycopolymers were found to induce bacterial aggregation of a specific bacterial strain through specific molecular recognition effects. In chapter three, block-copolymer vesicles are synthesized that comprise sugar groups on their coronae and also interact with bacteria through multiple specific ligand-receptor interactions. Also, molecular transport of a model dye from the vesicles to the bacterial cells is facilitated by discrete vesicle-bacteria complex formation. Chapter four explores the communication networks employed by bacterial cells, that is quorum sensing, and simple polymers are tested as molecular quorum quenchers that modulate the quorum sensing response of bacteria through autoinducers scavenging. Ultimately, we seek for an integrated platform to set up an “imitation game” where artificial entities, such as the polymer vesicles, can act as prototype cell-mimics that can actively intervene to the bacterial communication networks. Aspects of the principles and practical requirements to prove the concept are discussed in the final chapter.

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