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Mixed silica-calcite matrices were prepared by developing a "low" temperature (sol-gel) method in presence of several biocompatible polymers, thus providing samples with adequate porosity for the flow of biological fluids and also mechanically robust. In order to analyse and characterise the sample's microenvironments, the highly solvatochromic probe Nile red was used, which enabled the role of polymer addition upon local environmental effects in the host media to be elucidated. The polymers used were polyethylene glycol, polymethylmethacrylate and polyethylene. Each matrix was also characterized with respect to microstructure, morphology and pore size via the use of X-ray diffractometry and scanning electron microscopy. The results show that is was possible to obtain, in a controlled way, mixed silica-calcite matrices with a wide range of porosities (important if the material is to be used for scaffold or drug release applications, for example). The spectroscopic behaviour of Nile red when incorporated has confirmed the existence of distinct and specific local polarities within each type of matrix that may determine to a large extent the mechanism of interaction between these matrices and biological molecules.

The presence of a conducting metal surface is known to affect the emission of a fluorophore in its proximity. This can lead to an enhancement in its fluorescence intensity along with a decrease in the fluorescence lifetime. This phenomenon, sometimes known as metal enhanced fluorescence, has implications in the area of sensing and “lab on a chip” applications. Here controlled, localised use of metallic structures can be advantageous in enhancing the detection of a fluorescent signal. The sol–gel technique has been demonstrated as a useful method by which to produce a biocompatible material. The versatility of the reaction allows for the inclusion of metal ions, which can form metallic nanostructures permitting the potential enhancement of fluorescence to be exhibited. In this work we incorporate silver nitrate within silica sol–gel derived films produced using a simple procedure at relative low temperatures (close to ambient). A compact time-resolved fluorescence microscope equipped with a semiconductor laser was used to photoactivate the silver ions to form localised metallic structures within the films. Patterning was achieved by computer control of the microscope stage and using the laser in CW mode. The films were characterised using AFM and UV-vis spectroscopy to ascertain the presence of the photoactivated silver nanostructures. The effect of the presence of these structures was elucidated by studying the time-resolved fluorescence of FITC labelled bovine serum albumin adsorbed to the films, where a decrease in the lifetime of the FITC label was observed in the location of the nanostructures.

This paper reports the development and characterisation of a multipoint quasi-distributed optical fiber sensor for pH measurement. The system is based on a 170 m length of 200 μm core diameter plastic cladding silica fiber where sections of cladding have been removed and replaced with dye immobilised sol-gel glass to form sensing points. Evanescent wave excitation of a dye, immobilised within 2 mm long sections of cladding, enables the pH value of any spillage material to be determined by optical time domain reflectometry along the length of the fiber. The results suggest a spatial resolution of better than 2.5 meters for this fiber system and indicate that this arrangement could form the basis of a practical sensor/actuator system for chemical spillage, provided that suitable dye/analyte combinations are available.

A pH optical fibre chemical sensor with 16 sensing points located along a 200µm core PCS fibre is reported. The sensing points are 2 mm in length positioned between 2 m and 72 m apart.

It has been suggested that screening for impairment in early childhood may cause anxiety to parents. Using self-administered questionnaires, we studied the attitudes and concerns of parents of infants aged 6 months and 8-9 months. Parents were randomly allocated to one of two groups. One group completed the second questionnaire after the 8-month assessment routinely performed by health visitors, and the other group completed the second questionnaire before the assessment. We showed changes in attitude and concerns over the 2-3 month period, but these were not related to the assessment. It appeared that particular concerns and anxieties were not resolved by a recent contact with a health visitor, although a high proportion of mothers stated that they found the assessment reassuring. There was some evidence of a lack of appreciation, both of the purpose of the tests and of the implication of test failure. Screening tests performed by health visitors at an age of 8 months do not appear to generate undue anxiety in parents. However, as many of the tests used are of doubtful validity, a review of the purpose and content of this early health visitor assessment is needed.