label-free determination of aflatoxin M1 levels in milk through a WLRS immunosensor

A miniaturized optical immunosensor based on White Light Reflectance Spectroscopy (WLRS) for the rapid and label-free detection of aflatoxin M1 (AFM1) in milk samples has been developed. WLRS sensing system consists of the measurement set-up and the biochip. The first encompasses the reflection probe, the light source, and the spectrometer, while the latter is a Si chip with a SiO2 layer on top where an AFM1-bovine serum albumin conjugate has been immobilized. The assay was performed by running mixtures of rabbit polyclonal anti-AFM1 antibody with the calibrators or the samples, followed by reaction with biotinylated anti-rabbit IgG antibody and streptavidin. The assay cycle was completed in 25 min, the limit of detection was 6 pg/mL, and the linear working range extended from 0.012 to 2.0 ng/mL. The assay was repeatable (intra-and inter-assay coefficients of variation ranged from 2.1 to 6.3% and 3.5 to 8.2%, respectively) and accurate (percent recovery values ranged from 92.5 to 110%). AFM1 could be detected with the immunosensor developed in both processed and unprocessed milk of different animal species without any dilution. The excellent analytical characteristics and the small instrument size make the proposed sensor suitable for accurate low-cost AFM1 determination in milk samples at the point-of-need.
D.Tsounidi, G. Koukouvinos, P. Petrou, K. Misiakos, G. Zisis, D. Goustouridis, I. Raptis, S. E. Kakabakos Sens. Act. B 282 104(2019) “Rapid and sensitive label-free determination of aflatoxin M1 levels in milk through a White Light Reflectance Spectroscopy immunosensor”

FR-ES, the Entry System for Film characterization

A new product, FR-ES is released. FR-ES is a compact entry level tool that is designed to provide an excellent performance in terms of characterization of coatings. It can be employed in a wide range of diverse applications, such as: Film thickness, Refractive Index, Color, Transmittance, Reflectance, and many more.

There are three configurations available:

  • VIS/NIR (370-1020nm,
  • NIR-N1 (850-1050nm),
  • NIR (900-1700nm).

The tool can be accompanied by a wide range of Accessories, such as: Filters to block light at certain spectral regimes, FR-Mic for measurements at very small areas, Manual stage, 25x25mm, 100x100mm or 200x200mm Film/Cuvette Holder for Absorbance / Transmittance and chemical concentration measurements, Integration Spheres for diffuse & total reflectance

For more information please contact our sales team at: sales@thetametrisis.com

Multiplexed mycotoxins determination employing WLRS and SiO2 areas of different thickness

Biosensing through White Light Reflectance Spectroscopy (WLRS) is based on monitoring the shift of interference spectrum due to the binding reactions occurring on top of a thin SiO2 layer deposited on a silicon chip. Multianalyte determinations were possible through scanning of a single sensor chip on which multiple bioreactive areas have been created. Nonetheless, the implementation of moving parts increased the instrumentation size and complexity and limited the potential for on-site determinations. Thus, in this work, a new approach, which is based on patterning the sensor surface to create areas with different SiO2 thickness, is developed and evaluated for multi-analyte determinations with the WLRS set-up. The areas of different thickness can be interrogated by a single reflection probe placed on a fixed position over the chip and the reflection spectrum recorded is deconvoluted to the spectra corresponding to each area allowing the simultaneous monitoring of the bioreactions taking place at each one of them. The combination of different areas thickness was optimized using chips with two areas for single analyte assays. The optimum chips were then used for the simultaneous determination of two mycotoxins, aflatoxin B1 and fumonisin B1. A competitive immunoassay format was followed employing immobilization of mycotoxin-protein conjugates onto the SiO2 of different thickness. It was found that the dual-analyte assays had identical analytical characteristics with the respective single-analyte ones. The detection limits achieved were 0.05 ng/mL for aflatoxin B1 and 1.0 ng/mL for fumonisin B1, with dynamic ranges extending up to 5.0 and 50 ng/mL, respectively. The sensor was also evaluated for the determination of the two mycotoxins in whole grain samples (wheat and maize). The extraction protocol was optimized and recoveries ranging from 85 to 115% have been determined. Due to lack of moving parts, the novel multi-analyte format is expected to considerably facilitate the built-up of a portable device for determination of analytes at the point-of-need.
V. Anastasiadis, G. Koukouvinos, P.S. Petrou, A. Economou, M. Harjanne, P. Heimala, D. Goustouridis, I. Raptis, S.E. Kakabakos Biosens. Bioelectron. 153 112035(2020) “Multiplexed mycotoxins determination employing white light reflectance spectroscopy and silicon chips with silicon oxide areas of different thickness”

FR-Monitor v3.1 Release

The version 3.1 of FR-Monitor software was released on January 2nd, 2015

FR-Monitor, is our software for the control of all modules in FR-tool series and for the measurement of thickness(es) and optical properties of film stacks. FR-Monitor was considerably upgraded and reached v3.1. In this version, certain new features and improvements were added, a small fraction of which are:

  • Calibration with spectralon
  • Updated GUI
  • Updated Referencing method
  • Extended Materials Database both in terms of materials and optical properties models
  • Updated Color coding

FR-Monitor v3.1 is available for download for both 32- and 64-bit operating systems to all our customers.

For more information please contact the technical support at: techsupport@thetametrisis.com

FR-Monitor v2.5 Release

The version 2.5 of FR-Monitor software was released on January 2nd, 2014

FR-Monitor, is our software for the control of all modules in FR-tool series and for the measurement of thickness(es) and optical properties of film stacks. FR-Monitor was considerably upgraded and reached v2.5. In this version, certain new features and improvements were added, a small number of a small fraction of which are:

  • The TRUST fitting algorithm was added
  • The Lorenz model for the calculation of refractive index of thin and thick layers
  • Updated Referencing method
  • Extended Materials Database both in terms of materials and optical properties models
  • New Color coding for the various graphs

FR-Monitor v2.5 is available for download for both 32- and 64-bit operating systems to all our customers.

For more information please contact the technical support at: techsupport@thetametrisis.com

FR-pOrtable tool release

ThetaMetrisis introduce the FR-pOrtable tool: the USB-powered tool for accurate film characterization at the Point of Need at unbeatable price
Thanks to its unique design, FR-pOrtable is the only really portable and handheld spectroscopic reflectance tool in the market. FR-pOrtable integrates a radically designed hybrid light source, combining LED’s and incandescent bulb, which covers the 360nm – 1050nm spectral range and has very long-time & stable optical power. With FR-pOrtable the user can characterize any film or stack of films in the 25nm to 90μm thickness range, either in the lab environment or at the field becoming a truly Point of Need (PoN) tool.

Some of its unique features are:
– Small size, saving expensive lab space
– Really portable and handheld.
– No need for power supply. It draw power from the USB connection to the PC
– Low weight (600gr without the stage)
– Transmission & Absorption measurements (option)
– Large sample stage (up to 15x15cm samples)
– Adjustable distance between the sample and the probe. Thick samples can be accommodated.
– Two years of warranty
– Unbeatable price