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Immobilization techniques that preserve the activity of biomolecules have many potential applications. Mesoporous silica has been used to encapsulate a wide variety of biomolecules. In this particular work, MCM-41 silica has been used as a matrix for the immobilization of two important enzymes, HpbA and GOx. The enzyme 2-hydroxybiphenyl 3-monooxygenase (HpbA) is involved in the microbial degradation of 2-hydroxy and 2,2′-dihydroxybiphenyl, which occurs during the desulfurization of coal and petroleum, while Glucose oxidase (GOx) catalyzes the oxidation of β-D-glucose to δ-gluconolactone. The silica-enzyme hybrids were extensively characterized and the one with GOx was used for the construction of a biosensor.

Protein detection and characterization based on Broad-band Mach-Zehnder Interferometry is analytically outlined and demonstrated through a monolithic silicon microphotonic transducer. Arrays of silicon light emitting diodes and monomodal silicon nitride waveguides forming Mach-Zehnder interferometers were integrated on a silicon chip. Broad-band light enters the interferometers and exits sinusoidally modulated with two distinct spectral frequencies characteristic of the two polarizations. Deconvolution in the Fourier transform domain makes possible the separation of the two polarizations and the simultaneous monitoring of the TE and the TM signals. The dual polarization analysis over a broad spectral band makes possible the refractive index calculation of the binding adlayers as well as the distinction of effective medium changes into cover medium or adlayer ones. At the same time, multi-analyte detection at concentrations in the pM range is demonstrated.

Radiation is significantly involved in a number of common medical tests and procedures. Knowledge of issues concerned with ionizing radiation is, therefore, mandatory in clinical practice. Is there a way to access whether university-level educational programmes concerning medical physics suffice in covering the practical requirements or not? One of the key issues involved in the assessment of the above procedure, however, is how to make use of available technology in order to conduct the assessment as efficiently and as effectively as possible. In previous work, we devised a sample manual questionnaire aimed at retrieving information regarding the status of radiation awareness, but also investigated the feasibility of applying a robust methodology in the analysis of the results. In this paper, we extend the above mentioned methodology to other areas of MD activity and utilize the question ‘how familiar are MDs with radiation?’ as an example, in order to demonstrate the importance of health information management in the modern era of e-health. Three stages or aspects of information management are considered: (i) efficient online information collection, (ii) effective and robust analysis based on Web databases, and finally (iii) extraction of rules and knowledge using data mining techniques and home-made software that facilitates the retrieval of associations. The latter stage is then further exploited in order to design an improved and realistic plan for the process of continuous education of MDs and health professionals in general.

Miniaturized bioanalytical devices find wide applications ranging from blood tests to environmental monitoring. Such devices in the form of hand held personal laboratories can transform point-of-care monitoring provided miniaturization, multianalyte detection and sensitivity issues are successfully resolved. Optical detection in biosensors is superior in many respects to other types of sensing based on alternative signal transduction techniques, especially when both sensitivity and label free detection is sought. The main drawback of optical biosensing transducers relates to the unresolved manufacturability issues encountered when attempting monolithic integration of the light source. If the mature silicon processing technology could be used to monolithically integrate optical components, including light emitting devices, into complete photonic sensors, then the lab on a chip concept would materialize into a robust and affordable way. Here, we describe and demonstrate a bioanalytical device consisting of a monolithic silicon optocoupler properly engineered as a planar interferometric microchip. The optical microchip monolithically integrates silicon light emitting diodes and detectors optically coupled through silicon nitride waveguides designed to form Mach-Zehnder interferometers. Label free detection of proteins is demonstrated down to pM sensitivities.

Organo-silanes provide a suitable interface between the silicon-based transducers of various biosensing devices and the sensing proteins, immobilized through physical adsorption, as for (3-aminopropyl)triethoxysilane (APTES), or covalent binding, e.g. via protein amine groups to (3-glycidoxypropyl)trimethoxysilane (GOPS) modified surface. Immobilization of rabbit gamma globulins (RgG) to silicon nitride surfaces, modified either with APTES or GOPS, was examined as a function of incubation time using atomic force microscopy (AFM), angle-resolved X-ray photoelectron spectroscopy (ARXPS) and time of flight secondary ion mass spectrometry (ToF-SIMS). Multivariate technique of principal component analysis was applied to ToF-SIMS spectra in order to enhance sensitivity of immobilized RgG detection. Principal component regression shows a linear relationship with surface density determined rigorously from ARXPS following an organic bilayer approach, allowing for protein coverage quantification by ToF-SIMS. Taking it overall the surface immobilized amount of RgG is higher and develops faster on the surfaces silanized with APTES rather than with GOPS. Similar, although less distinct, difference is observed between the two surface types concerning the temporal evolution of average AFM height. The average height of protein overlayer correlates well with ARXPS and ToF-SIMS data expressed in terms of protein surface density. However, determined linear regression coefficients are distinctively higher for the surfaces modified with epoxy- rather than amino-silane, suggesting different surface density and conformation of the proteins immobilized through to covalent binding and physical adsorption.

Despite the advances in optical biosensors, the existing technological approaches still face two major challenges: the inherent inability of most sensors to integrate the optical sourc e in the transducer chip, and the need to specifically design the optical transducer per application. In this work, the development of a radical optoelectronic platform is demonstrated based on a monolithic optocoupler array fabricated by standard Si-technology and suitable for multi-analyte detection. The platform has been specifically designed biochemical sensing. In the all-silicon array of transducers, each optocoupler has its own excitation source, while the entire array share a common detector. The li ght emitting devices (LEDs) are silicon avalanche diodes biased beyond their breakdown voltage and emit in the VIS -NIR part of the spectrum. The LEDs are coupled to individually functionalized optical transducers that converge to a single detector for multiplexed operation. The integrated nature of the basic biosensor scheme and the ability to functionalize each transducer independently allows for the development of miniaturized optical transducers tailored towards multi -analyte tests. The monolithic arrays can be used for a plethora of bio/chemical interactions becoming thus a versatile analytical tool. The platform has been successfully applied in bioassays and binding in a real -time and label-free format and is currently being applied to ultra-sensitive food safety applications.

Routine monitoring of occupational radiation exposure is done primarily to demonstrate compliance with dose limits. Analysis of past and present dose records provides a useful tool in the management of institutional radiation safety programs. In this study, an analysis of annual dose records from 1995 to 2015 is performed with the data from a nuclear medicine department where both radionuclide treatment and diagnostic imaging are done at a large scale. All radiation employees in the department were educated on their own subjects and experienced in their duties. They have been receiving periodic trainings about radiation protection. In this way, the annual effective dose values are limited to the minimum. Large variation in the mean annual dose exists among the different occupational groups. Among the workers, technologists received the largest annual effective dose. The study evaluates differences in occupational exposure within this group of workers performing the same procedure, and the efficacy of safety protocols. Continuing education and optimization of working technics can help minimize the radiation exposure of the workers. Limits can be assured to remain well below the acceptable values by incorporating the mechanism of job rotations.

Chromium-51 (⁵¹Cr)-ethylene diamino tetraacetic acid plasma clearance is commonly used in glomerular filtration rate measurements. In the presence of additional radionuclides in plasma samples, glomerular filtration rate may be seriously underestimated and a correction of the crosstalk interference may be necessary. This type of correction is problematic in the case of gallium-67 (⁶⁷Ga) mainly because of the close vicinity of its 300 keV photopeak with that of the 320 keV photopeak of ⁵¹Cr. A novel method of calculating and removing the interfering ⁶⁷Ga counts within the ⁵¹Cr counting window, based on the different decay rates of the two radionuclides, is presented, requiring two series of sample counting in the ⁵¹Cr counting window only, separated by a 3-day interval. This method was developed to solve a clinical problem and then it was validated by a controlled ⁶⁷Ga contamination of plasma samples with known counts from ⁵¹Cr-ethylene diamino tetraacetic acid.

Objectives: A quality control program in intraoral radiographic equipment was conducted aiming to verify compliance with the latest legal requirements and to measure radiation dose in order to contribute to the establishment of appropriate diagnostic reference levels. Methods: This study was performed in 191 intraoral radiographic facilities in Northern Greece. The quality control program included visual inspection of the unit, registration of its characteristics, measurement and calculation of several radiological parameters, including entrance surface dose, and overall compliance with legislation requirements. Results: Most units (61.8%) were found to perform within their corresponding specifications. Exposure timer accuracy was the parameter that the dental units showed the poorest performance. Inadequate beam filtration was found in almost half of the older 50 kVp units. Entrance surface dose showed significant discrepancies, varying from 0.30 mGy to 16.09 mGy with a third quartile value of 3.37 mGy. Conclusions: A diagnostic reference level of 3.5 mGy is considered to be a realistic value for all intraoral equipment currently operating in Greece. However, for newly installed units, a value of 2.8 mGy is considered to be more appropriate. Dentomaxillofacial Radiology (2005) 34, 304‐307. doi: 10.1259/dmfr/38802780

A complete Mach-Zehnder interferometer monolithically integrated on silicon is presented and employed as a refractive index and bio-chemical sensor. The device consists of broad-band light sources optically coupled to photodetectors through monomodal waveguides forming arrays of Mach-Zehnder interferometers, all components being monolithically integrated on silicon through mainstream silicon technology. The interferometer is photonically engineered in a way that the phase difference of light travelling through the sensing and reference arms is approximately wavelength independent. Consequently, upon effective medium changes, it becomes feasible even with a broad-band source to induce sinusoidal-type of detector photocurrents similar to the classical monochromatic counterparts. The device is completed with its fluidic and interconnect components so that on chip interferometric measurements can be performed. Examples of refractive index and protein sensing are presented to establish the potential of the proposed device for real-time in situ monitoring applications. This is the only silicon device that has achieved complete on-chip interferometry.