Search

In today's medicine, the celerity of the bio-assays analysis is crucial for the timely selection of the appropriate therapy and hence its effectiveness, especially in case of diseases characterized by the late onset of symptoms. In this paper, a lens-less fiber optics-based fluorescence sensor designed for the measurement of labeled bio-assays is presented and its potential for the early diagnosis of sepsis via C-reactive protein (CRP) detection is demonstrated. The sensor performance results from the combination of two key elements: a planar antenna that redirects fluorescence the marker emission and an automated fiber-based optical system for multi-spot analysis. First, the working principle of the device is demonstrated with a well-established antibody–antigen format (immunoglobulin IgG/anti-IgG assay), reporting more than one order of magnitude enhanced limit of detection (LOD) and limit of quantification (LOQ) for the planar antenna with respect to a standard glass substrate. The prototype is then tested against a sample mimicking a realistic case, prepared with commercially available human serum, showing a LOD and LOQ in the clinical range of interest (0.0015 μg/mL and 0.005 μg/mL, respectively) for the investigation of the sepsis biomarker CRP. These results validate the developed prototype as a simple and easy-to-operate device, compatible with standardized micro-well arrays, and potentially suitable for POC applications. [ABSTRACT FROM AUTHOR]

Optical fiber sensors, thanks to their compactness, fast response and real-time measurements, have a large impact in the fields of life science research, drug discovery and medical diagnostics. In recent years, advances in nanotechnology have resulted in the development of nanotools, capable of entering the single cell, resulting in new nanobiosensors useful for the detection of biomolecules inside living cells. In this paper, we provide an application of a nanotip coupled with molecular beacons (MBs) for the detection of DNA. The MBs were characterized by hybridization studies with a complementary target to prove their functionality both free in solution and immobilized onto a solid support. The solid support chosen as substrate for the immobilization of the MBs was a 30 nm tapered tip of an optical fiber, fabricated by chemical etching. With this set-up promising results were obtained and a limit of detection (LOD) of 0.57 nM was reached, opening up the possibility of using the proposed nanotip to detect mRNAs inside the cytoplasm of living cells. [ABSTRACT FROM AUTHOR]

Abstract: A novel method to detect the active form of NF-κB, a transcription factor regulating a battery of inflammatory genes and playing a fundamental role in the development of numerous pathological states, has been developed. In the present work, we used fluorescence resonance energy transfer (FRET) to study DNA–protein binding interaction taking place between double-strand (ds) DNA immobilized in a glass capillary wall and p50 proteins. For this purpose, we developed a regenerable FRET-based system comprising of a single-strand (ss) DNA with auto-complementary sequence that is end-labeled with Cy5 dye and is highly specific for p50 proteins. The proteins were labeled with a Black Hole Quencher (BHQ-3) to be used as FRET pair. The interaction of p50/p50 homodimer active form with its DNA binding site was demonstrated by both electrophoretic mobility shift assays and FRET studies. These preliminary results demonstrated the feasibility of the FRET-based DNA technique to detect the active form of NF-κB protein with 90% detection efficiency. In addition, we show that the system is stable and highly regenerable. [Copyright &y& Elsevier]

Severe infection and sepsis are a common, expensive, and frequently fatal conditions in critically ill patients. The sepsis diagnosis is not trivial, since it is an extremely complex chain of events involving inflammatory and anti-inflammatory processes, cellular reactions, and circulatory disorders. For these reasons, delay in diagnosis and initiation of drug treatments have shown to be crucial for this pathology. Moreover, a multitude of biomarkers has been proposed, many more than for other pathologies. In order to select optimal treatments for the highly heterogeneous group of sepsis patients and to reduce costs, novel multiplexed tools that better characterize the patient and his or her specific immune response are highly desired. In order to achieve the fundament of drastically improved multi-analyte detection and to attain low limits of detection in diagnostics, the area of point-of-care testing (POCT) technology is developing quickly, leading to the production of instruments, the reliability of which is continuously increasing. For this purpose, a selection of two biomarkers—C-reactive protein (CRP) and neopterin (NP)—was studied in this paper and a fluorescence-based integrated optical system, suitable for future POCT applications, was implemented that is capable of performing the simultaneous measurement of the two different biomarkers in replicate. A limit of detection of 10 and 2.1 µg L−1 was achieved for CRP and NP spiked in commercially available human serum, respectively. Moreover, measurements on both biomarkers were also performed on serum samples collected from septic patients. [ABSTRACT FROM AUTHOR]

Invited for this month's cover are collaborators from four different Italian research groups, three at the National Research Council (ICCOM, IFAC, and ISOF) and one at the University of Florence. The cover picture shows a representative cartoon of engineered 1D carbon nanomaterials and their effective surface decoration with (bio)molecules and fluorescent markers. Read the full text of the article at [ABSTRACT FROM AUTHOR]

Abstract: An optical platform for point of care testing (POCT) application is developed. The core of the platform is a miniaturised polymethylmetacrylate (PMMA) chip, that consists of two pieces of PMMA that have been custom-machined to produce flow channels, 500μm in width and 400μm in height, through which the analysed sample flows. Thanks to the fluorescence anisotropy, a large fraction of the fluorescence emitted by the sensing layer immobilised on the bottom of the PMMA cover travels along the thickness of the PMMA cover itself up to its end-face and it is collected by a plastic optical fibre connected to a photodetector. The potential of the optical chip is investigated with a sandwich assay for the C-reactive protein, one of the markers for inflammatory diseases. The assay covers the working range from 0.1 to 50mgL−1 with a limit of detection of 0.004mgL−1. Different combinations of capture and target antibodies were carefully investigated in order to achieve the best performances in terms of sensitivity and unspecific adsorption. [Copyright &y& Elsevier]

Abstract Filtering strategies are a crucial aspect for signal detection in many fluorescence based systems such as chemical and/or biochemical sensors. Here we present the design, fabrication and characterization of a new waveguide absorption filter capable of maximizing the fluorescence signal collection thanks to its high numerical aperture. The comparison in terms of performance with an interference filter demonstrates how this new type of absorption filter still works well even when the fluorescence light forms large incidence angles with the perpendicular at the filter input face, a condition for which any other filtering strategy fails. Finally, as a proof of concept, a preliminary fluorescence measurement carried out on an IgG - anti IgG bioassay shows the potentiality of our absorbing waveguide filter in comparison to that of the interference one. The use of such filtering strategy can improve and simplify the fluorescence signal detection in several fields of sensing application, from Point of Care Testing to environmental monitoring. [ABSTRACT FROM AUTHOR]