FIgure 19 - uploaded by Arun Bhunia
Content may be subject to copyright.
4 Interoferometric setup of FTIR. When infrared photons from light sources enter the Michelson interferometer unit, which is then split and directed toward fixed and moving mirror, they are recombined to the sample chamber in the sample holder unit.
Source publication
Citations
... Optically transparent pH sensing films fabricated by the ISAM technique have additional unique properties, as they can be conformal and multifunctional [6]. Such thin films based sensors whose properties allow use over a wide range of temperatures are well sought after in the food industry [12] as well as for remote accessible locations. ...
There are numerous applications for thin films based chemical pH sensors, in such areas as biomedical, military, environmental, food, and consumer products. pH sensitive films fabricated through the ionic self-assembled monolayers technique were made of polyelectrolyte polyallylamine hydrochloride and the water-soluble organic dye molecule Direct Yellow 4. The films were monitored in various environmental conditions and for selected periods, at temperatures varying between −13.7 and 46.2 °C. Absorbance measurements and atomic force microscopy performed before and after thermal treatment indicate that for optimized thickness and composition the films maintain their functionality and are not affected by long-term exposure at these temperatures.
... Biosensor platforms have been used for detection of foodborne pathogens, including fiber optic, surface plasmon resonance (SPR), Raman, Fourier transformed infrared (FTIR) spectroscopy, flow cytometry, and impedance-based microfluidic devices (Bae and Bhunia, 2013;Bhunia, 2014;Bisha and Brehm-Stecher, 2009;Cho et al., 2015a;Najafi et al., 2014;Sharma and Mutharasan, 2013;Velusamy et al., 2010). Here we employed a forward light scattering sensor, BARDOT (bacterial rapid detection using optical scattering technology) for detection of colonies of target pathogens. ...
The bottleneck for accurate detection of foodborne pathogens is separation of target analytes from complex food matrices. Currently used sample preparation methods are cumbersome, arduous and lengthy; thus, a user-friendly system is desirable. A hand-held sample preparation system designated pathogen enrichment device (PED) was built that contains a growth chamber, filters, and an ion exchange cartridge to deliver bacteria directly onto the detection platforms. Escherichia coli O157:H7, Salmonella enterica and Listeria monocytogenes were used as model pathogens. Spinach, ground beef, hotdogs, and eggs were used as model foods to evaluate PED performance, and results were compared with traditional bag enrichment method. Bacterial cells were inoculated at 1, 10, 100CFU/g of sample and enriched in PED using appropriate pathogen-specific selective enrichment broths. The bacterial cell counts in both PED and stomacher-bag were comparable and the pH in PED-recovered cell suspension was close to neutral whereas the pH of cell suspension in the stomacher-bag was slightly acidic. The bacterial recovery from the PED was 95-100% and were directly detected by lateral-flow immunoassay (LFIA), quantitative PCR (qPCR) and light scattering sensor with sample-to-result time of 8-24h with a detection limit of 1CFU/g. In qPCR, the amplified PCR products appeared in 4-5 cycles earlier with PED-enriched cultures compared to the cultures enriched in stomacher-bag. The hand-held PED proved to be a one-step procedure for enrichment and recovery of homogenous particle-free bacterial cells for detection using immunological, molecular or biosensor-based platforms.
Copyright © 2015. Published by Elsevier B.V.
... Nano/biosensor approaches Nano/biosensor platforms employ a combination of biological recognition molecules and physicochemical transducers in order to produce an electronic signal proportional to the interaction of a specific analyte with the sensor [23,43,44]. The biorecognition molecules (antibodies, aptamers, bacteriophages or their tail proteins, enzymes, antimicrobial peptides, host cell receptors and nucleic acid probes) provide specificity [45][46][47][48]. ...
... These platforms could possibly be used directly against food without preculturing or on culture-enriched samples [53]. Spectral-based sensors, such as light-scattering sensors [59], hyperspectral imaging [51] and Raman spectroscopy [73], are suitable for the real-time or near-real-time detection of pathogens, since they are highly sensitive, have no requirement for a pathogen-specific probe, maintain the integrity of target pathogens, are fast (requiring seconds to minutes) and are highly specific [44]. Furthermore, biosensor platforms amenable to automation that can also be configured for multipathogen and multisample screening could provide low-cost sample testing [53]. ...
ABSTRACT Foodborne pathogens pose serious public health risks. Rapid, accurate technologies to detect a low number of target cells (1 cell/25-325 g sample) and microbial toxins are in demand in order to assess product safety in hours to up to 1 day. Varied pathogen loads and the complexity of food present a major challenge. Current culture methods, while accurate, are lengthy. New methods, using brief culturing and detection kits (antibody based, nucleic acid amplification or nano/biosensors) or a culture-independent approach coupled with nucleic acid amplification, traditionally used for viruses/parasites, can be used to obtain results in hours. A strategic approach involving two-step, rapid, high-throughput screening to rule out negatives followed by a confirmatory test could accomplish product testing in 1 h to 1 day.
