Lateral flow assays (LFA) for detection of pathogenic bacteria: A small point-of-care platform for diagnosis of human infectious diseases.

Up-to-date diagnostics is globally improved by point-of-care testing (POCT) analysis and bedside research works. Development in POCT analysis has been provided mostly by forward-looking engineering technology for biosensing and sensing assessments. Lately, lateral flow assays (LFAs) have attracted a lot of interest as a result of their noteworthy benefits including cost-effectiveness, better portability, being operator friendly and rapid detection. This technique has been employed broadly for monitoring diverse biomarkers linked to ultrasensitive detection of pathogenic bacteria, ecological monitoring, consumer protection, and infectious diseases. LFA analyses established on qualitative and optical outcomes have boosted the objectivity and data efficiency of the assessments. Therefore, developing novel methods with the capability of providing reliable and quantitative information regarding a target analyte in a model and preserving the qualities of LFAs is of great necessity. In this review, the main principles of LFAs, challenges, and prospects for more development in this field in sensing pathogenic bacteria have been summarized. Subsequently, visually-read LFAs improvement to further progressive platforms have been explored by considering the prospects of this very flexible method for ultrasensitive detection of pathogenic bacteria. In addition, novel labeling methodologies, electrochemical and optical transducers are described. Also, recent developments in these detection methods elements in combination with other considered approaches have been highlighted.

Recent advances in surface plasmon resonance biosensors for microRNAs detection.

miRNAs are a large family of non-coding RNAs which play important roles in translational and post-transcriptional regulation of gene expression and biological processes. Abnormal expression of miRNAs is related to the initiation and progression of different diseases which make them be promising candidates for early medical diagnostics. Thus, accurate detection of miRNAs has great significance for disorder diagnosis. Nevertheless, their intrinsic characteristics such as short sequence, low concentration and sequence homology challenge routine techniques. The detection assays need to be extremely sensitive and selective in small value of intricate RNA samples. Biosensor-based strategies have emerged as potential alternatives to conventional methods in miRNA quantification. The surface plasmon resonance (SPR), an optical biosensor, possessing various advantages including excellent reliability, selectivity and reproducibility represents a wide range of applications in real-time monitoring of biomolecular interactions and detection of biological and chemical analytes with label-based or label free form. Various signal amplification methods can overcome the limitation of SPR methods for detection of small molecules, making it suitable for clinical diagnosis. This review discusses main concepts and performance characteristics of SPR biosensor. Mainly, it focuses on newly emerged enhanced SPR biosensors towards high-throughput and ultrasensitive screening of miRNAs using labeling processes with focusing on the future application in biomedical research and clinical diagnosis. Actually, label-based signal amplification strategies of SPR platforms including nanoparticle enhancement, supersandwich assembly, streptavidin/biotin complex, antibody amplification, enzymatic reactions, triplex structure formation and catalytic hairpin assembly are discussed. Finally label free detection of miRNAs and advantages of SPR-based method was presented.

Does Delayed Excretion of Therapeutic 131I-MIBG Interfere with a 123I-MIBG Diagnostic Scan 6 Weeks After the Therapy?

131I-metaiodobenzylguanidine (131I-MIBG) is a theranostic agent useful for treatment of neuroendocrine malignancies. In this case, a child with a Curie score of 21 was administered 17.871 GBq (483 mCi) of 131I-MIBG. The elimination half-life progressively increased from 23 h to 77 h during the 11 d that the patient was hospitalized for radiation isolation. Six weeks after the posttherapy scan, a survey with an ion-chamber device yielded readings of 0.3 µSv/h (0.03 mR/h) on contact with spinal regions that had shown increased uptake on the scan. A planar image obtained using the 131I setting and a high-energy collimator did not demonstrate any focal uptake. 123I-MIBG was administered, and the 24-h scan was of diagnostic quality, without degradation from the remaining 131I-MIBG. Additional study is needed on whether the Curie score affects elimination of 131I-MIBG and on whether the period of hospitalized radiation isolation needs to be extended.

On-Capillary Surface-Enhanced Raman Spectroscopy: Determination of Glutathione in Whole Blood Microsamples.

Oxidative stress monitoring in the neonatal period supports early outcome prediction and treatment. Glutathione (GSH) is the most abundant antioxidant in most cells and tissues, including whole blood, and its usefulness as a biomarker has been known for decades. To date, the available methods for GSH determination require laborious sample processing and the use of sophisticated laboratory equipment. To the best of our knowledge, no tools suitable for point-of-care (POC) sensing have been reported. Surface-enhanced Raman spectroscopy (SERS), performed in a microvolume capillary measurement cell, is proposed in this study as a robust approach for the quantification of GSH in human whole blood samples. The use of a silver colloid allowed a highly selective signal enhancement for GSH providing analytical enhancement factors of 3 to 4 orders of magnitude. A highly accurate determination of GSH in whole blood samples with recoveries ranging from 99 to 107% and relative standard deviations less than or equal to 18% were achieved by signal normalization with the intensity of an isotopically labeled internal standard. GSH concentrations were retrieved within 4 min using small-volume blood samples (2 µL). The developed procedure was applied to the analysis of blood of 20 healthy adults and 36 newborns, obtaining comparable results between literature and those found by SERS and a reference method. The characteristics of this novel tool are suitable for its implementation in a portable optical sensor device enabling POC testing of oxidative stress levels in newborns.

Pancreatic uptake and radiation dosimetry of 6-[18F]fluoro-L-DOPA from PET imaging studies in infants with congenital hyperinsulinism.

METHODS: After injecting 25.6 ± 8.8 MBq (0.7 ± 0.2 mCi) of 18F-Fluoro-L-DOPA intravenously, three static PET scans were acquired at 20, 30, and 40 min post injection in 3-D mode on 10 patients (6 male, 4 female) with congenital hyperinsulinism. Regions of interest (ROIs) were drawn over several organs visible in the reconstructed PET/CT images and time activity curves (TACs) were generated. Residence times were calculated using the TAC data. The radiation absorbed dose for the whole body was calculated by entering the residence times in the OLINDA/EXM 1.0 software. RESULTS: The mean residence times for the 18F-Fluoro-L-DOPA in the liver, lungs, kidneys, muscles, and pancreas were 11.54 ± 2.84, 1.25 ± 0.38, 4.65 ± 0.97, 17.13 ± 2.62, and 0.89 ± 0.34 min, respectively. The mean effective dose equivalent for 18F-Fluoro-L-DOPA was 0.40 ± 0.04 mSv/MBq. The CT scan used for attenuation correction delivered an additional radiation dose of 5.7 mSv. The organs receiving the highest radiation absorbed dose from 18F-Fluoro-L-DOPA were the urinary bladder wall (2.76 ± 0.95 mGy/MBq), pancreas (0.87 ± 0.30 mGy/MBq), liver (0.34 ± 0.07 mGy/MBq), and kidneys (0.61 ± 0.11 mGy/MBq). The renal system was the primary route for the radioactivity clearance and excretion. CONCLUSIONS: The estimated radiation dose burden from 18F-Fluoro-L-DOPA is relatively modest to newborns.

Determination of non-steroidal anti-inflammatory drugs in water and urine using selective molecular imprinted polymer extraction and liquid chromatography.

A selective solid-phase extraction was employed for the improvement of the determination of non-steroidal anti-inflammatory drugs (NSAIDs) in continental water and urine samples. Ketoprofen, naproxen, diclofenac, and ibuprofen were selected as target analytes due to they are the most frequently administered and consumed NSAIDs. These compounds were extracted using molecular imprinted polymers and determined by liquid chromatography with diode array (DAD), and tandem-mass spectrometry (MS-MS) detectors. Performance of DAD and MS-MS detectors was evaluated throughout this study. The obtained limits of quantification, after a 50-fold preconcentration solid-phase extraction, varied from 20 to 30µgL-1 for DAD, and from 0.007 to 0.017µgL-1 for MS-MS for both types of sample matrixes. Quantitative recoveries were found for blank-samples spiked at different NSAIDs concentration levels, ranging from 0.05 to 10mgL-1 for urine and from 0.5 to 500µgL-1 for water. The proposed methodology was applied for the determination of NSAID residues in urine of prescribed individuals, and continental waters.

Current air quality analytics and monitoring: a review.

This review summarizes the different tools and concepts that are commonly applied in air quality monitoring. The monitoring of atmosphere is extremely important as the air quality is an important problem for large communities. Main requirements for analytical devices used for monitoring include a long period of autonomic operation and portability. These instruments, however, are often characterized by poor analytical performance. Monitoring networks are the most common tools used for monitoring, so large-scale monitoring programmes are summarized here. Biomonitoring, as a cheap and convenient alternative to traditional sample collection, is becoming more and more popular, although its main drawback is the lack of standard procedures. Telemonitoring is another approach to air monitoring, which offers some interesting opportunities, such as ease of coverage of large or remote areas, constituting a complementary approach to traditional strategies; however, it requires huge costs.

Modified locally weighted--partial least squares regression improving clinical predictions from infrared spectra of human serum samples.

Locally weighted partial least squares regression (LW-PLSR) has been applied to the determination of four clinical parameters in human serum samples (total protein, triglyceride, glucose and urea contents) by Fourier transform infrared (FTIR) spectroscopy. Classical LW-PLSR models were constructed using different spectral regions. For the selection of parameters by LW-PLSR modeling, a multi-parametric study was carried out employing the minimum root-mean square error of cross validation (RMSCV) as objective function. In order to overcome the effect of strong matrix interferences on the predictive accuracy of LW-PLSR models, this work focuses on sample selection. Accordingly, a novel strategy for the development of local models is proposed. It was based on the use of: (i) principal component analysis (PCA) performed on an analyte specific spectral region for identifying most similar sample spectra and (ii) partial least squares regression (PLSR) constructed using the whole spectrum. Results found by using this strategy were compared to those provided by PLSR using the same spectral intervals as for LW-PLSR. Prediction errors found by both, classical and modified LW-PLSR improved those obtained by PLSR. Hence, both proposed approaches were useful for the determination of analytes present in a complex matrix as in the case of human serum samples.

FTIR-determination of sterols from the red alga Asparagopsis armata: Comparative studies with HPLC.

An analytical procedure was developed for the determination of the total amount of sterols in the red alga Asparagopsis armata, globally determined as cholesterol, which is the major sterol contained in red algae. Samples, previously saponified with KOH were preconcentrated on DSC-18 solid phase cartridges (SPE) and eluted with dichloromethane stabilized with beta-amylene. Fourier transform infrared (FTIR) spectrometry was employed for selective detection at 1049cm(-1) with a baseline established between 1000 and 1079cm(-1). The results were compared to those obtained by high performance liquid chromatography (HPLC). The concentration obtained in actual samples from alga was 3.37% (w/w) by FTIR and 3.30% (w/w) by HPLC, showing a good comparability between the two methods.

Non-chromatographic speciation of toxic arsenic in fish.

A rapid, sensitive and economic method has been developed for the direct determination of toxic species of arsenic present in fish and mussel samples. As(III), As(V), dimethylarsinic acid (DMA), and monomethylarsonic acid (MMA) were determined by hydride generation-atomic fluorescence spectrometry using a series of proportional equations without the need of a chromatographic previous separation. The method is based on the extraction of arsenic species from fish through sonication with HNO(3) 3moll(-1) and 0.1% (m/v) Triton and washing of the solid phase with 0.1% (m/v) EDTA, followed by direct measurement of the corresponding hydrides in four different experimental conditions. The limit of detection of the method was 0.62ngg(-1) for As(III), 2.1ngg(-1) for As(V), 1.8ngg(-1) for MMA and 5.4ngg(-1) for DMA, in all cases expressed in terms of sample dry weight. The mean relative standard deviation values (R.S.D.) in actual sample analysis were: 6.8% for As(III), 10.3% for As(V), 8.5% for MMA and 7.4% for DMA at concentration levels from 0.08mgkg(-1) As(III) to 1.3mgkg(-1) DMA. Recovery studies provided percentages greater than 93% for all species in spiked samples. The analysis of SRM DORM-2 and CRM 627 certified materials evidenced that the method is suitable for the accurate determination of arsenic species in fish.

A portable and low cost equipment for flow injection chemiluminescence measurements.

A compact, reliable and low cost flow injection chemiluminescence system is described. The flow system consists of a set of solenoid micro-pumps that can dispense reproductive micro-volumes of solutions. The luminometer was based on a coiled cell constructed from polyethylene tubing that was sandwiched between two large area photodiodes. The whole equipment costs about US$ 750 and weights ca. 3 kg. Equipment performance was evaluated by measuring low concentrations of hydrogen peroxide by oxidation of luminol and for the determination of ammonium, based on its inhibition of the luminescence provided by the reaction of luminol and sodium hypochlorite. Linear responses were achieved within 1.0-80 micromol L(-1) H(2)O(2) and 0.6-60 micromol L(-1) NH(4)(+) with detection limits estimated as 400 nmol L(-1) H(2)O(2) and 60 nmol L(-1) NH(4)(+) at the 99.7% confidence level. Coefficients of variation were 1.0 and 1.8%, estimated for 20 micromol L(-1) H(2)O(2) and 15 micromol L(-1) NH(4)(+) (n=20), respectively. Reagent consumption of 55 microg luminol, effluent volume of 950 microL per determination and sampling rate of 120 samples per hour were also achieved.

Rapid on-line sample dissolution assisted by focused microwave radiation for silicate analysis employing flame atomic absorption spectrometry: iron determination.

An on-line automated flow injection system with microwave-assisted sample digestion was used to perform silicate rock dissolution in acid medium for iron determination. For this purpose, a continuous flow system was built up by using an automatic flow injection analysis (FIA) system coupled to a flame atomic absorption spectrometer (FAAS), including a focused microwave oven unit. Inside the microwave cavity was inserted a polytetrafluoroethylene (PTFE) reactor coil (300cm length and 0.8mm i.d.) where the dissolution takes place. Chemical and flow variables as well as iron determination parameters were studied. In the flow system, a slurry of the rock sample (50mg in 200ml of acid mixture HF+HCl+HNO(3)) is pumped through the reaction coil and the microwaves are turned on. After elapsed the time required to complete the sample dissolution, the mixture is pumped again in order to fill the sampling loop (500mul). Then, by changing the valve position, a water carrier stream pushes the sample solution through the flame atomic absorption spectrometer nebulizer. To achieve an accurate determination of the rock certified materials, the slurry sample was irradiated during 210s at 90W power. Working in that condition, a detection limit of 0.80mugml(-1) (which corresponds to an Fe(2)O(3) content of 0.46%) and an analytical throughput of 10h(-1) were achieved. The relative standard deviation (R.S.D.) of the method varied between 1 and 11% when applied to the rock certified materials.