Modeling of SAM Impedance Onto Gold and Silver Thin-Film Mass-Produced Electrodes and Their Use for Optimization of Lactic Acid Detection.

In this work, we demonstrate how an innovative, out-of-cleanroom customized CD/DVD fabrication process can be successfully used for mass production of biosensors with thin-film electrodes. We show that silver and gold electrodes can be used for impedimetric and voltammetric biosensing applications, both in presence and absence of a redox mediator. We modeled the redox/non-redox electrodes impedance through equivalent electrical circuits, and we evaluated their transfer function sensitivity with a one-factor-at-a-time approach. Using this approach, we introduced a new prediction method to find which equivalent electrical circuit elements contribute more to the transfer function variations, then we experimentally validated the predictions measuring the electrodes electrochemical impedance spectroscopy responses with relevant self-assembled monolayer molecules immobilized on them, i.e., MCH and DTSP. We also assess the silver electrodes long-term stability with impedance spectroscopy measurements over a period of 1200 hours, proving their possible use in point-of-care applications. Finally, we also prove that the sensors correctly perform in a practical case, i.e., as a lactic acid biosensor, by studying the optimization of the biosensor efficiency through different enzyme immobilization methods. By comparing lactate oxidase enzyme direct adsorption and covalent binding to DTSP self-assembling monolayers, we found that covalent binding to DTSP can boost the catalytic current of about 40% with respect to that obtained from the direct adsorption of the same enzyme concentration.

Enhancement and control of surface plasmon resonance sensitivity using grating in conical mounting configuration.

In this work we propose a method to enhance and control the angular sensitivity of a grating coupled surface plasmon resonance (GCSPR) sensor. We lighted a silver grating, mounted in conical configuration, with a laser source and we measured the transmittance of the grating as a function of the azimuthal angle. To evaluate the sensitivity, grating surface was functionalized with four different alkanethiol self assembled monolayers (SAM) and the correspondent azimuthal transmittance peak shifts were measured. The sensitivity control was performed by simply change the light incident angle. This method offers the possibility to design dynamic GCSPR sensor benches that can be used to amplify the SPR angle shift at any step of a biological detection process.

Development of a complete plasmonic grating-based sensor and its application for self-assembled monolayer detection.

This work presents an integrated plasmonic biosensing device consisting of a one-dimensional metallic lamellar grating designed to exploit extraordinary transmission of light toward an underlying silicon photodetector. By means of finite element simulations, the grating parameters have been optimized to maximize the light transmission variation induced by the functionalization of the gold nanostructures. An optimized grating was fabricated using an electron beam process and an optoelectronic test bench suitable for sample tests was developed. A clear difference in the grating transmitted light due to surface functionalization was observed in presence of TM polarized illumination.

Nucleation and growth of ZnO in organic solvents--an in situ study.

ZnO is a metal oxide material which possesses versatile properties and applications. Therefore, the target-oriented preparation of ZnO has become a major issue. Many preparation techniques involve bottom-up methods from precursor solutions. In the current contribution, a special precursor system is described that enables a fine-control of kinetic parameters for the nucleation and growth of ZnO in various organic solvents. A large variety of analytical techniques could be applied in an in situ fashion to probe for the ZnO formation at all times and all length scales. Among the analytical techniques are UV/vis, Raman, Fluorescence, X-ray absorption, 1H NMR-spectroscopy, dynamic light-scattering, and TEM. Three different regimes for nucleation and growth with different characteristics could be identified. Furthermore, the effect of different parameters on the resulting ZnO particle size was investigated.

A fully electronic sensor for the measurement of cDNA hybridization kinetics.

Ion sensitive field effect transistors (ISFET) are candidates for a new generation of fully electrical DNA sensors. To this purpose, we have modified ISFET sensors by adsorbing on their Si(3)N(4) surface poly-L-lysine and single (as well as double) stranded DNA. Once coupled to an accurate model of the oppositely charged layers adsorbed on the surface, the proposed sensor allows quantitatively evaluating the adsorbed molecules densities, as well as estimating DNA hybridization kinetics.

[Occupational contact dermatitis in metal workers and gender effect]. / Dermatiti professionali nei metalmeccanici ed effetto di genere.

Contact dermatitis is more frequent among women for anatomical reasons and for extraprofessional exposure to irritants and detergents during homeworks. In addition sensitisation to contact haptens is different in sexes. The aim of our work was to evaluate the association between patch test skin sensitizations and professional exposure to metals analyzing data for gender. Of the 15.217 patients patch tested for dermatitis, 678 were metalworkers. The statistical analysis revealed a significant association between dermatitis and sensitisation to nickel in professional exposed women (OR = 1.68; LC50% 1.11-6.50) while metal sensitisation (Cr.Ni and Co) was not relevant in men: for them a significant association between dermatitis and sensitisation was found to quaternium (OR = 3.91; LC95% 1.18-12.9), to mercaptobenzothiazole (OR = 2.69; LC50% 1.11-6.50) and to ethylendiamine dichloride (OR = 2.53; LC95% 1-6.41). The authors stress the need to evaluate patch test sensitisation considering gender effects.

[Incidence of occupational contact dermatitis in the province of Pordenone in the period of 1995-2000]. / Incidenza di dermatite da contatto professionale nella provincia di Pordenone nel periodo 1995-2000.

Occupational contact dermatitis (OCD) ranks first of all occupational diseases in many countries but few are epidemiological data on incidence of this disease. We studied 146 subjects with OCD in Pordenone area in the period 1994-2000. In 90.5% subjects the diagnosis was allergic contact dermatitis and in 9.5% urticaria. Nickel sulfate was the most common sensitizer (14.7%), followed by latex (13.2%) and potassium dichromate (11.6%). Occupational groups at risk were mechanics (51.4%), health service workers (19.9%) and construction workers (7.5%). The incidence rate was 10.8 cases per 10,000 health service workers per year, 8 cases per 10,000 hairdressers and barbers per year, 4.1 cases per 10,000 construction workers per year and 1.9 cases per 10,000 mechanics per year.

Risk factors for nosocomial sepsis in newborn intensive and intermediate care units.

UNLABELLED: A multicentre prospective study was performed to estimate the incidence of hospital infections and to identify the most relevant risk factors for sepsis in a large and unselected population of high-risk newborns. The study involved 49 neonatal intensive care units and 17 neonatal intermediate care units in Italy. Newborns were followed up from admittance to the units until discharge. Data on demographics and clinical characteristics, exposure to the principal invasive procedures, and onset of infectious complications were prospectively collected. Only infections developing after 48 h from admittance to the unit were recorded. A multiple logistic regression was performed to identify which factors were independently associated with sepsis. Among the 8263 newborns included in the analysis, the incidence of infected newborns was 14.4 per 100 newborns and 0.9/100 days of stay. The incidence of infections was 19.1/100 newborns and 1.2/100 days of stay. Sepsis represented 15.4% of all infections (incidence 2.9/100 newborns and 0.2/100 days of stay). The following factors were independently associated with sepsis: umbilical catheterization, both through the vein and the artery for more than 5 days; mechanical ventilation for more than 5 days; necrotizing enterocolitis; birth weight equal to or less than 2500 g; nasogastric tube; total parenteral nutrition; and transfer from other hospitals. Umbilical catheters accounted for the highest proportion of sepsis (62%), followed by arterial catheters (31%), nasopharyngeal cannulae (26%), tracheal cannulae (20%), and nasal cannulae (20%). The population attributable risk for the other procedures was less than 10%. CONCLUSION: This study demonstrates that in a large and unselected newborn population, several host factors and invasive procedures are independently associated with an increased risk of sepsis. After adjustment for clinical severity, intravascular catheterization and assisted ventilation were found to be responsible for a considerable proportion of observed sepsis. They should therefore be considered as priorities for interventions, aimed both at reducing unnecessary use and promoting more strict compliance with aseptic practices.

Prevention of perinatally transmitted hepatitis B virus infection by hepatitis B immunoglobulin immunoprophylaxis: an account of 201 newborn babies of hepatitis Bs antigen carrier mothers.

Of 5,327 pregnant women who were screened between July 1981 and July 1983, 5.2% were found to be hepatitis Bs antigen (HBsAg) carriers. This high percentage of carriers accentuates the importance of vertical transmission of hepatitis B virus in our area. In view of this we sought to verify the effectiveness of hyperimmune immunoglobulins in the prevention of infection. We studied 201 babies born to HBsAg-positive mothers. These babies had regular checkups until 12 months of age. One hundred forty-nine received prophylactic hyperimmune globulin (two to seven doses according to risk ranking), while 52 did not. A higher percentage of infection was found in the babies who had no prophylaxis (25%) than in the babies who had prophylaxis (7.4%). Furthermore, hepatitis appeared earlier (from the 2nd to the 6th month) in the babies who had no prophylaxis than in the babies who had prophylaxis (from the 9th to the 12th month). No infection was observed during prophylaxis or up to 6 months.