m-DOPA addition in MAPLE immobilization of lipase for biosensor applications

Matrix Assisted Pulsed Laser Evaporation (MAPLE) is a thin film deposition technique which uses a pulsed laser beam impinging, inside a high vacuum chamber, on a frozen target containing the guest molecules in a volatile matrix to induce fast "evaporation" of the matrix, and ejection of the guest molecules. Lipase, an enzyme acting as a catalyst in hydrolysis of lipids, is widely used in biosensors for detection of triglycerides in blood serum. A key action to this purpose is lipase immobilization on a substrate. In a recent paper, we have shown that MAPLE technique is able to deposit lipase on a substrate in an active form. Here we show that addition to the guest/matrix target of a small amount of m-DOPA (3-(3,4-dihydroxyphenyl)-2-methyl-l-alanine) in order to improve adhesion and protect lipase secondary structure, also allows the lowering the laser pulse energy required for matrix evaporation and therefore the risk of damaging the enzyme. Keywords: MAPLE, Lipase, m-DOPA, Biosensor

Development of a Multiparametric Lidar with the depolarization sensor

The topic of this work was the design, the realization and the calibration of the depolarization sensor added in the Napoli Lidar (Light Detection and Ranging) system. In addition a complete rebuilding of the receiving system was operated, and a new characterization of all the components of the apparatus was done. From the advent of Lidar technology in 1970 the study of the composition of the atmosphere gets a speed up. Lidar is an active sensor that sends into the atmosphere a short laser pulse and measures the elastic and Raman shifted optical backscattered power from molecules and aerosols. From the delay of the received pulse, the position of the scattering elements is obtained. Analyzing the backscattered radiation some important optical properties of the atmospheric aerosols can be derived: backscattering and extinction coefficients, position and altitude of the layers, colour index and so on. In this context, a depolarization-sensitive Lidar can help to characterize the particle’s shape. The discrimination of the shape of the aerosols is very important, for example to distinguish the phase of the clouds (ice-clouds are strongly asymmetric scatterers while low clouds are made by spherical water’s drops) and the type of aerosols (Saharan dust is constituted by non-spherical particles while urban aerosols by little spherical particles). The depolarization measurements can be performed by using a linearly polarized laser source and a hardware configuration of the receiving system including two channels detecting simultaneously the backscattered radiation in the parallel and orthogonal direction with respect to the laser beam. The total depolarization ratio, due both to molecular and aerosol contributions, is simply the calibrated ratio of the orthogonal signal to the parallel one. So, a key question to obtain high quality depolarization measurements is performing a good calibration of the Lidar system. In this work different calibration techniques were analyzed by simulating lidar signals in different atmospheric conditions. In Napoli the sensor was realized and then calibrated while in Potenza the depolarization sensor was only calibrated. These two systems were calibrated with different techniques, due to different apparatus conditions. My scientific activity was spent for the most in the Atomic and Laser Applications Laboratory in Physics Department of University Federico II of Napoli. A period of three months was also spent in C.N.R.-I.S.A.C.(Istituto di Scienze Atmosferiche e Climatiche), in Bologna, where some theoretical models about the atmospheric dynamic were developed. Two months period was also spent in C.N.R.-I.M.A.A. (Istituto di Metodologie per l’Analisi Ambientale- Tito Scalo-Potenza), working under the supervision of Dr. Gelsomina Pappalardo

Liquid Crystal Polymer Composite Materials for LCDs

Digital displays nowadays play an essential and ubiquitous role in everyday life, and, in several applications, flexibility (i.e., the possibility to bend the device) or, at least, bending capability (i.e., the possibility to manufacture devices on a curved surface) is desirable or required. Polymer-dispersed liquid crystals (PDLCs) and other liquid crystal/polymer compounds are an interesting class of composite materials for the realization of flexible displays, since they couple the electrooptical properties of liquid crystals to the mechanical properties of polymers and can take full advantage from electronic properties of conducting copolymers. In this chapter, we will briefly discuss preparation techniques and then illustrate the working principle corresponding to different liquid crystal configurations (nematic, chiral, smectic, ferroelectric, holographic) with some examples

Polarization Lidar Calibration Techniques and Sensitivity Analysis

Calibrated lidar measurements of linear depolarization ratio provide highly reliable information to discriminate between spherical and non-spherical particles in the atmosphere and to distinguish between liquid and solid phase clouds. In this paper three different calibration techniques are described. For each technique a sensitivity analysis is performed and the different contributions to the total error are evaluated. The stability of atmosphere, the laser source polarization degree, the accuracy of polarization alignment and the background radiation are taken into account in the simulated depolarization measurements. The influence of these parameters and the choice of calibration range and calibration height are studied also. Two calibration techniques were experimentally validated by more than 28 calibration measurements in nearly 5 months. Furthermore aerosol depolarization measurements taken after the calibration are presented

Biosensor Applications of MAPLE Deposited Lipase

Matrix Assisted Pulsed Laser Evaporation (MAPLE) is a thin film deposition technique derived from Pulsed Laser Deposition (PLD) for deposition of delicate (polymers, complex biological molecules, etc.) materials in undamaged form. The main difference of MAPLE technique with respect to PLD is the target: it is a frozen solution or suspension of the (guest) molecules to be deposited in a volatile substance (matrix). Since laser beam energy is mainly absorbed by the matrix, damages to the delicate guest molecules are avoided, or at least reduced. Lipase, an enzyme catalyzing reactions borne by triglycerides, has been used in biosensors for detection of β-hydroxyacid esters and triglycerides in blood serum. Enzymes immobilization on a substrate is therefore required. In this paper we show that it is possible, using MAPLE technique, to deposit lipase on a substrate, as shown by AFM observation, preserving its conformational structure, as shown by FTIR analysis

Lipase immobilization for catalytic applications obtained using fumed silica deposited with MAPLE technique

tLipases are enzymes used for catalyzing reactions of acylglycerides in biodiesel production from lipids,where enzyme immobilization on a substrate is required.Silica nanoparticles in different morphologies and configurations are currently used in conjunction withbiological molecules for drug delivery and catalysis applications, but up to date their use for triglycerideshas been limited by the large size of long-chain lipid molecules.Matrix assisted pulsed laser evaporation (MAPLE), a laser deposition technique using a frozen solu-tion/suspension as a target, is widely used for deposition of biomaterials and other delicate molecules.We have carried out a MAPLE deposition starting from a frozen mixture containing fumed silica and lipasein water. Deposition parameters were chosen in order to increase surface roughness and to promote theformation of complex structures. Both the target (a frozen thickened mixture of nanoparticles/catalyst inwater) and the deposition configuration (a small target to substrate distance) are unusual and have beenadopted in order to increase surface contact of catalyst and to facilitate access to long-chain molecules.The resulting innovative film morphology (fumed silica/lipase cluster level aggregation) and the lipasefunctionality (for catalytic biodiesel production) have been studied by FESEM, FTIR and transesterificationtests

MAPLE deposition of silica nanoparticles for lipase immobilization

Lipases are enzymes used for catalyzing reactions of acylglycerides in biodiesel production from lipids, where enzyme immobilization on a substrate is required. Silica nanoparticles in different morphologies and configurations are currently used in conjunction with biological molecules for drug delivery and catalysis applications, but up to date their use for triglycerides has been limited by the large size of long-chain lipid molecules. MAPLE (Matrix Assisted Pulsed Laser Evaporation), a laser deposition technique using a frozen solution/suspension as target, is widely used for deposition of biomaterials and other delicate molecules. We have carried out a MAPLE deposition starting from a frozen mixture containing fumed silica and lipase in water. Deposition parameters were chosen in order to increase surface roughness and to promote the formation of complex structures. Both the target (a frozen thickened mixture of nanoparticles/catalyst in water) and the deposition configuration (a small target to substrate distance) are unusual and have been adopted in order to increase surface contact of catalyst and to facilitate access to long-chain molecules. The resulting innovative film morphology (fumed silica/lipase cluster level aggregation) and the lipase functionality (for catalytic biodiesel production) have been studied by FESEM, FTIR and transesterification tests

EARLINET correlative measurements for CALIPSO: first intercomparison results

A strategy for European Aerosol Research Lidar Network (EARLINET) correlative measurements for Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) has been developed. These EARLINET correlative measurements started in June 2006 and are still in progress. Up to now, more than 4500 correlative files are available in the EARLINET database. Independent extinction and backscatter measurements carried out at high-performance EARLINET stations have been used for a quantitative comparison with CALIPSO level 1 data. Results demonstrate the good performance of CALIPSO and the absence of evident biases in the CALIPSO raw signals. The agreement is also good for the distribution of the differences for the attenuated backscatter at 532 nm ((CALIPSO-EARLINET)/EARLINET (%)), calculated in the 1–10 km altitude range, with a mean relative difference of 4.6%, a standard deviation of 50%, and a median value of 0.6%. A major Saharan dust outbreak lasting from 26 to 31 May 2008 has been used as a case study for showing first results in terms of comparison with CALIPSO level 2 data. A statistical analysis of dust properties, in terms of intensive optical properties (lidar ratios, Ångström exponents, and color ratios), has been performed for this observational period. We obtained typical lidar ratios of the dust event of 49 ± 10 sr and 56 ± 7 sr at 355 and 532 nm, respectively. The extinction-related and backscatter-related Ångström exponents were on the order of 0.15–0.17, which corresponds to respective color ratios of 0.91–0.95. This dust event has been used to show the methodology used for the investigation of spatial and temporal representativeness of measurements with polar-orbiting satellites.Peer ReviewedPostprint (published version