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  • Open access
  • 74 Reads
Biocompatible Temperature nanosensors based on Titanium dioxide

The measurement of temperature is of fundamental importance in a huge scale of applications, from nanomedicine, where the early detection of tumorous cells is an essential requirement, to microelectronics and microcircuits1. Optical sensors with a micro/nano-spatial resolution can be used for temperature determination within a biological frame. Within this contest, Raman spectroscopy2 is particularly interesting: the inelastic scattering of light, has the advantage of a contactless measurement and exploits the temperature-dependence of intensities in the spectrum (which originates from the vibrational population), by observing the intensity ratio of anti-Stokes and Stokes signals. Titanium Dioxide can be regarded as a potential optical material for the temperature detection in biological samples, thanks to its high biocompatibility, already demonstrated in literature3, and to its strong Raman scattering signal. It presents multiple well-defined Raman peaks at lower Raman shifts, which is appealing for a Raman based thermometry. The aim of the present work is the realization of biocompatible optical thermometers, with a sub-micrometric spatial resolution, made of Titanium dioxide. Raman measurements have been performed on Anatase powder using 488, 568 and 647.1 nm excitation lines of the CW Ar/Kr ion laser. The laser beam is focalized through a microscope on the sample, kept at defined temperature using a temperature controller. The Stokes and anti-Stokes scattered light is analysed through a triple monochromator and detected by a liquid nitrogen cooled CCD camera. Raw data are analysed and Raman spectrum parameters – like area, intensity, frequency position and width of the peak - are calculated. Preliminary results showed that good reliable temperatures can be obtained to characterize the local temperature, through Raman technique.

  1. M Quintanilla and LM Liz-Marzan (2018), Nano Today, 19, 126.
  2. R L McCreery, Raman spectroscopy for chemical analysis, Vol. 225. John Wiley and Sons, 2005.
  3. ZF Yin, L Wu HG Yang and YH Su PCCP (2013), 15(14), 4844.
  • Open access
  • 214 Reads
A Novel Low-cost Method for Fabrication of 2D Multi-electrode Array (MEA) to Evaluate Functionality of Neuronal Cells

In this paper, a fabrication method for two-dimensional multi-electrode arrays (MEAs) using inexpensive material and method is proposed. The focus in this work is on the design and fabrication of 2D Microelectrode arrays (MEAs) using metallic electrodes on a silica substrate. Titanium/Gold multi-electrode arrays containing 60 electrodes with optimized metal thicknesses and 30 μm diameter, covered with thin modified SU-8 insulator layer as biocompatible material have been designed and manufactured using the standard photolithography-based microfabrication method. The utilization of affordable and more accessible materials and simpler techniques can be mentioned as the distinct point of the proposed method. Using these multi-electrode arrays, it is possible to either record or stimulate cells by accessing multiple sites of cell tissues and collect signals from the sources around each electrode simultaneously. Precisely adjusting the size, distance, and the number of microelectrodes causes the high measurement selectivity and reliability which has been taken into account in the design of the microelectrodes. In this study, by implementing the proposed system, we manufactured a preliminary representative MEA and the bio-compatibility of the manufactured MEA is going to be evaluated by neural cells, obtained from rat cortices. The main aim of this study is comparison of our inexpensive strategy with other approaches.

  • Open access
  • 142 Reads
A fluorescence-based POCT device for immunosuppressant-drug monitoring in transplanted patient

In the treatment of transplanted patients, therapeutic drug monitoring represents one of the most crucial aspects for the identification of the correct dosage of immunosuppressants, aiming to ensure the appropriate medical treatment and to avoid the rejection of the transplanted organ. Since only protein-unbound (free) drugs can cross membranes and bind to receptors to produce the required pharmacological effect, free drug concentrations (2-8% for immunosuppressive drugs) are more closely related to efficacy and also to toxicity compared to plasma, serum or whole blood concentrations, better reflecting the clinical outcome. At this aim, a novel point of care testing (POCT) optical device for the detection of blood immunosuppressant free fraction in transplanted patients was designed and tested, with the body interface constituted by an intravascular microdialysis catheter (MicroEye®), which provides the dialysate as clinical sample. The work was undertaken in the framework of the EU project NANODEM (NANOphotonic DEvice for Multiple therapeutic drug monitoring). The benefit of this device will be an optimized dosage of the therapeutic drugs to support patient management in a clinical environment. Calibration curves for cyclosporine A (CyA) and mycophenolic acid (MPA) in dialysis perfusate (20% Lipofundin) were obtained with limit of detection for CyA and MPA of 0.48 ng/mL and 0.79 ng/mL, respectively.

  • Open access
  • 114 Reads
Microfluidic portable device for pathogens 'rapid SERS detection

So far, in some of our previous works we have managed to rapid (within minutes) identify and discriminate pathogens by using SERS spectroscopy with
a single cell sensitivity. Having a more user friendly and robust system, which could be used not only by experts, would be the next step.
In order to meet our goal, we developed an experimental setup, including an in-house built microfluidic device followed by the optimization of SERS detection of common bacterial pathogens by using the developed device. The main components of the system are: a microfluidic flow-cell coupled to a syringe pump mediated-flow system, and a portable Raman spectrometer for SERS detection of pathogens immobilized in the flow cell. Inside the microfluidic channel of the flow cell, a silver spot was generated under laser irradiation for further use as SERS active substrate for detection. The silver spot can be washed and reused for a different pathogen from one experiment to another. The total analysis time was reduced to less than 15 min.

Considering the optimized experimental parameters for detection and its easy-to-use dedicated software, this portable microfluidic device has been tested in our lab and is ready to be transferred in other research/clinical premises for further use when necessary.

  • Open access
  • 70 Reads
Development of new catalytic material for accurate detection of biological biomarkers related to most common Non-communicable diseases
Published: 02 November 2020 by MDPI in The 1st International Electronic Conference on Biosensors session Posters

Presently, long-lasting health disorders represent a significant health problem in developing countries. Further, epidemiological trends associated with lifestyle habits, suggests that chronic conditions trend not to slow down all over the world. Hence, reliable analytical techniques to manage chronic health conditions like diabetes-mellitus, cardiovascular diseases, neurodegenerative diseases, among other non-communicable diseases (NCD), is of paramount importance [1].

The electrochemical biosensor is a pivotal technique for low analyte concentration detection, aiming for a swift and accurate diagnosis/therapy, to deal with the various health conditions. Though, the performance of electro-biosensors heavily depends on the catalytic activity of the material used as biosensor transducer. As a result, nanomaterials are widely used on the electrode surface owing to their unique physicochemical characteristics, like the high surface area to volume ratio, which renders their convenient features for biosensing heterogeneous catalysts [2].

Nowadays, silver nanoparticles (AgNPs) are used in numerous biomedical applications, such as therapeutic purposes or as catalytic material in the electrochemical analysis. Notwithstanding AgNP's health benefits impact, conventional methods used in their synthesis, are far from healthy, with scientific researchers pursuit for eco-friendly alternatives without health-hazardous chemicals [3].

One of the most used alternatives is plant-assisted synthesis, where, phytochemicals of the genus Lamiaceae Plectranthus proving to be a remarkable reducing and stabilizing agent of well-dispersed metal nanoparticles [4].

Aim of the current study is the design of a skilled approach for the provision of Plectranthus-assisted AgNPs, pointing their application as high-performance catalytic material in a sensitive biosensor for NCD

  • Open access
  • 183 Reads
Deployment and comparison of a low-cost high-sensitivity concentration meters using micro-optical resonators
, ,

Micro-optical resonators have been introduced as sensors in many applications for a wide number of variable types of stimuli due to their very high resolution, high sensitivity and high quality factor. In this paper a novel micro-optical sensor was designed and tested as a concentration meter for chemical composition of a solution. The micro-optical resonator used is based on whispering gallery mode (WGM). This phenomenon appears when a tapered single mode laser carrying micro-optical fiber is evanescently coupled with a polymeric or silica micro-optical resonator. The presented sensor shows the change in concentration by experiencing a change in its morphology due to the varied viscosity of its environment. The variation of concentrations or fluid contents results in a change between the radii of the micro-optical resonator. With varied chemical composition and concentration in the tested sample varied infinitesimally small morphological changes are detected. The change in the resonators shape is read as a WGM shift in the resonance transmission spectrum which is interpreted using a technique called cross-correlation which compares the output across time to display the shift which is later translated into distinct concentration levels. The proposed exceptionally low cost sensors were able to detect change at very high resolutions allowing better sensitivity along with wider range of variation. Experimental work for detection of ranges of concentrations of variable type of contaminants is presented.

  • Open access
  • 137 Reads
Nanomaterials-modified screen-printed electrodes: a powerful platform for sensor and biosensor set-up.
Published: 02 November 2020 by MDPI in The 1st International Electronic Conference on Biosensors session Posters

The use of nanomaterials in sensor and biosensor field is one of the hottest topics today in analytical chemistry. The advantage of using nanomaterials leads to sensors characterized by high sensitivity, stability, and an improved repeatability1. Screen-printed electrodes (SPEs) are recognized as successful sensor platforms in modern electroanalytical chemistry due to their low background, wide potential window, cost-effectiveness, and easiness of surface modification. This last property allows modifying the screen-printed electrodes (SPEs) with several nanomaterials such as carbon nanotubes, graphene, nanoparticles, graphene nanoplates (GNPs)2, etc3,4.

In this work, a comparative study using these devices (SPEs) modified with different nanomaterials via drop-casting procedure is reported (Figure 1). Moreover, the modified SPEs have been morphologically and electrochemically characterized. The research activity carried out for the development of sensors and biosensors based on SPEs modified with nanomaterials will be presented. Among the different feasible applications, the use of these nano-engineered biosensors for uric acid quantification based on SPEs modified with carbon nanotubes (bare or functionalized) and graphene nanoplatelets (GNPs) will be introduced. Significant improvements in analytical parameters have been obtained, when using nano-modified SPEs with respect to biosensors based on bare SPEs. Limit of detection (LOD), linear range and Km (Michaelis-Menten Constant) undergo remarkable ameliorations (LOD going from 48 μM to 12 μM, linear range from 0.05-2 mM to 0.02-5 mM and Km from 0.43 to 1.31 mM for bare and -CO2H MWNT based biosensors, respectively).

Figure1 Schematic representation of nanomaterial-modified SPE: a) by drop casting and then used to set up a biosensor, b) enzyme immobilization. Electrochemical measurements can be performed using portable instrumentation (c).

  • Open access
  • 133 Reads
Biosensors for cellulose-biosed materials in cultural heritage: case studies
, , ,
Published: 02 November 2020 by MDPI in The 1st International Electronic Conference on Biosensors session Posters

New methodologies for the characterization of chemical composition and the monitoring of cleaning processes of paper and wood artifacts are based on tuned electrochemical sensors based on screen printed electrodes (SPE) coupled with a portable instrumentation1,2. Electrochemical biosensors, based on enzymes, have been successfully applied in many fields from environment to medicine, from foods to pharmaceuticals but the use of them in the cultural heritage field is still an almost unexplored world. Many of these biosensors are well suitable to be used for the characterization of several important materials used in cultural heritage such as paper, paintings, textiles, metals or glass, with the aim of determining their composition, health state and/or the effectiveness of conservation or restoration interventions. Opportune biosensors could be indeed applied to determine both inorganic than organic compounds present as components, pollutants or degradation products of artworks. In this work, several application of sensors coupled with hydrogel is presented to underline the potentiality of these tools in cultural heritage.

  1. Mazzuca, C., Carbone, M., Cancelliere, R., Prati, S., Sciutto, G., Mazzeo, R., Tositti, L., Regazzi, R., Mostacci, D., Micheli, L. (2018) A new analytical approach to characterize the effect of γ-ray sterilization on wood Microchemical Journal, 143, pp. 493-502. DOI: 10.1016/j.microc.2018.08.001
  2. 18) Micheli, L., Mazzuca, C., Palleschi, A., Palleschi G. (2016) Development of a diagnostic and cleaning tool for paper artworks: a case of study Microchemical Journal, 126, 32-41 DOI: 10.1016/j.microc.2015.11.052

  • Open access
  • 133 Reads
An ultra-sensitive biosensor to investigate Random Telegraph Noise in human breast cancer cells

Breast cancer is a leading cause of death in women worldwide and yet its pathophysiology is poorly understood. Although single-cell studies have highlighted the contribution of membrane depolarisation to the proliferation of breast cancer, dynamic signalling at a network level has not been extensively researched. It is urgent therefore to decode the intercellular signalling patterns linked to metastasis, particularly at a cell cohort level. This paper introduces a novel strategy for conducting such recordings on highly metastatic MDA-MB-231 cells, via an ultra-low noise biosensor based on a large electrode area which maximises the Helmholtz double-layer capacitance. The extracellular sensitivity of our biosensor allows, for the first time, the detection of pA level Random Telegraph Signal (RTS) noise superimposed with an omnipresent 1/f noise. The RTS noise is validated and modelled using a Markov chain. The analysis of slow cooperative potentials across the large area electrode suggests the involvement of cohort calcium signalling, and the 1/f noise analysis suggests a strong contribution of resting membrane noise. Overall, this work shows the potential of the new recording platform and statistical analysis for better understanding and predicting the underlying signalling mechanisms of metastatic breast cancer cells. In future, this platform could highlight the effects of compounds, or drugs, on the underlying activity of cancer cell cohorts in a clinical setting.

  • Open access
  • 91 Reads
Indication of the coronavirus model particles using a nanowire biosensor
, , , , , , , , , ,

In early 2020, the world health organization (WHO) announced the coronavirus pandemic COVID-19.
According to the WHO, one of the most important factors in containing infection is the use of laboratory diagnostics. Thus, the development of new more sensitive and rapid methods of coronavirus indication and the study of its properties is an actual problem.
The goal of the research: - to study the method of indication of virus-like coronavirus particles (CVP) using a nanowire biosensor.
We used biosensors – n-channel silicon nanowire field-effect transistors (Si-NW FET) and non-pathogenic CVP based on vesicular stomatitis virus. In experiments, the concentration of CVP was changed in the range from 10-18 to 10-13 M. The CVP contained the surface protein S of the SARS-CoV-2 coronavirus on their surface. Specific antibodies to CVP were obtained based on the m396 antibody interacting with SARS.
In the process of biosensor preparation, the surface of its nanowire in the first version was modified with antibodies and APTES chemical reagent, in the second version-only with antibodies.
Directly in the process of indication, 1 ml of CVP suspension was applied to the surface of the nanowire with a pipette and the current in the source-drain circuit of the transistor was registered.

- antibody + CVP complexes at the interface with the surface of the nanowire modulate the current of the field-effect transistor;
- CVP have a positive electric charge at the interface " nanowire surface - viral suspension»;
- antibody + CVP complexes have a negative electric charge at the interface section " nanowire surface -- viral suspension»;
- the sensitivity of the biosensor is about 10-18 M;
- the display time was 200-300 seconds.