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Biomedicines Apr 2021This work demonstrates the quantitative assay of cardiac Troponin I (cTnI), one of the key biomarkers for acute cardiovascular diseases (the leading cause of death...
This work demonstrates the quantitative assay of cardiac Troponin I (cTnI), one of the key biomarkers for acute cardiovascular diseases (the leading cause of death worldwide) using the fluorescence-based sandwich immune reaction. Surface plasmon coupled emission (SPCE) produced by non-radiative coupling of dye molecules with surface plasmons being excitable via the reverse Kretschmann format is exploited for fluorescence-based sandwich immunoassay for quantitative detection of cTnI. The SPCE fluorescence chip utilizes the gold (2 nm)-silver (50 nm) bimetallic thin film, with which molecules of the dye Alexa 488 (conjugated with detection antibodies) make a near field coupling with the plasmonic film for SPCE. The experimental results find that the SPCE greatly improves the sensitivity via enhancing the fluorescence signal (up to 50-fold) while suppressing the photo-bleaching, permitting markedly enhanced signal-to-noise ratio. The limit of detection of 21.2 ag mL (atto-gram mL) is obtained, the lowest ever reported to date amid those achieved by optical technologies such as luminescence and label-free optical sensing techniques. The features discovered such as ultrahigh sensitivity may prompt the presented technologies to be applied for early diagnosis of cTnI in blood, particularly for emergency medical centers overloaded with patients with acute myocardial infarction who would suffer from time-delayed diagnosis due to insufficient assay device sensitivity.
PubMed: 33919217
DOI: 10.3390/biomedicines9050448 -
Nature Communications Mar 2021Optical evanescent sensors can non-invasively detect unlabeled nanoscale objects in real time with unprecedented sensitivity, enabling a variety of advances in...
Optical evanescent sensors can non-invasively detect unlabeled nanoscale objects in real time with unprecedented sensitivity, enabling a variety of advances in fundamental physics and biological applications. However, the intrinsic low-frequency noise therein with an approximately 1/f-shaped spectral density imposes an ultimate detection limit for monitoring many paramount processes, such as antigen-antibody reactions, cell motions and DNA hybridizations. Here, we propose and demonstrate a 1/f-noise-free optical sensor through an up-converted detection system. Experimentally, in a CMOS-compatible heterodyne interferometer, the sampling noise amplitude is suppressed by two orders of magnitude. It pushes the label-free single-nanoparticle detection limit down to the attogram level without exploiting cavity resonances, plasmonic effects, or surface charges on the analytes. Single polystyrene nanobeads and HIV-1 virus-like particles are detected as a proof-of-concept demonstration for airborne biosensing. Based on integrated waveguide arrays, our devices hold great potentials for multiplexed and rapid sensing of diverse viruses or molecules.
Topics: Biosensing Techniques; HEK293 Cells; Humans; Interferometry; Limit of Detection; Nanoparticles; Nanotechnology; Signal Processing, Computer-Assisted
PubMed: 33785760
DOI: 10.1038/s41467-021-22271-4 -
Electroanalysis Sep 2020A sensitive detection of extremely toxic phenylpyrazole insecticide, 'Fipronil' is presented. Currently, the advancement of approaches for the detection of insecticides...
A sensitive detection of extremely toxic phenylpyrazole insecticide, 'Fipronil' is presented. Currently, the advancement of approaches for the detection of insecticides at low concentrations with less time is important for environmental safety assurance. Considering this fact, an effort has been made to develop an electrospun CoZnO nanofiber (NF) based label-free electrochemical system for the detection of fipronil. The CoZnO NF were characterized using different techniques including field emission scanning electron microscopy (FE-SEM), Energy Dispersive X-Ray Analysis (EDX), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and Raman Spectroscopy. Based on the experimental results, the proposed platform displayed a linear response for fipronil in the attogram/mL range despite the multiple interfering agents. The sensitivity of the device was found to be 3.99 Kῼ (g/ml) cm. Limit of detection (LOD) and limit of quantification (LOQ) were calculated and found to be 112 ag mL and 340 ag mL respectively. Further, this proposed sensor will be implemented in the fields for the rapid and proficient detection of the real samples.
PubMed: 33456276
DOI: 10.1002/elan.202000051 -
Langmuir : the ACS Journal of Surfaces... Jan 2021Bacterial endotoxin detection is an essential safety requisite in biomedical, food, and pharmaceutical industries. Endotoxin in a sufficient concentration on entering...
Bacterial endotoxin detection is an essential safety requisite in biomedical, food, and pharmaceutical industries. Endotoxin in a sufficient concentration on entering the human bloodstream causes detrimental effects such as septic shock, which can lead to death. Hence, the sensitive and selective detection of endotoxin also known as lipopolysaccharide (LPS) is of paramount importance. Herein, a layer-by-layer (LBL) assembly of gold-chitosan nanocomposite (CGNC)-poly(acrylic acid) (PAA)-polymyxin B (PmB) on gold (Au) electrode is employed for the sensitive and selective detection of endotoxin. The surface electric charge studies using dynamic contact mode electrostatic force microscopy (DC-EFM) revealed the successful formation of each layer on the Au electrode. The polycationic PmB is a specific bioreceptor of LPS, which binds with high affinity to the anionic groups of the carbohydrate portions of LPS molecules and facilitates the selective electrochemical detection. This surface modification method presented a sensitive and selective detection of endotoxin down to the attogram level.
PubMed: 33356305
DOI: 10.1021/acs.langmuir.0c02852 -
Journal of Microbiological Methods Jul 2020Paper-based nucleic acid testing techniques are increasingly in demand. Hence, we have developed a simple and cheap paper fluidic device to detect multiple gene targets...
Paper-based nucleic acid testing techniques are increasingly in demand. Hence, we have developed a simple and cheap paper fluidic device to detect multiple gene targets in Leptospira. Fluidic channels of the penta-clover device are drawn using a correction pen on Whatman filter paper 1. The fluid blocks the pores of the paper, avoiding leakage and ensuring the equal flow of sample to the reaction pads. The target genes are amplified by performing Loop-Mediated Isothermal Amplification (LAMP) with dry reaction components. Thecolor change of leuco crystal violetallows real-time monitoring of a positive amplification. The difference in color intensity is captured with a smartphone and analyzed using image processing software. The device amplifies the target within 15 min, detects the pathogen at a concentration as low as 50 attogram μL, detects Leptospira in blood samples without prior treatment and differentiates the Leptospira species even after 21 days of storage at room temperature.
Topics: Humans; Leptospira; Leptospirosis; Molecular Diagnostic Techniques; Nucleic Acid Amplification Techniques; Paper; Sensitivity and Specificity
PubMed: 32473300
DOI: 10.1016/j.mimet.2020.105962 -
ACS Sensors Apr 2020As the use of nanoparticles is expanding in many industrial sectors, pharmaceuticals, cosmetics among others, flow-through characterization techniques are often required...
As the use of nanoparticles is expanding in many industrial sectors, pharmaceuticals, cosmetics among others, flow-through characterization techniques are often required for in-line metrology. Among the parameters of interest, the concentration and mass of nanoparticles can be informative for yield, aggregates formation or even compliance with regulation. The Suspended Nanochannel Resonator (SNR) can offer mass resolution down to the attogram scale precision in a flow-through format. However, since the readout has been based on the optical lever, operating more than a single resonator at a time has been challenging. Here we present a new architecture of SNR devices with piezoresistive sensors that allows simultaneous readout from multiple resonators. To enable this architecture, we push the limits of nanofabrication to create implanted piezoresistors of nanoscale thickness (∼100 nm) and implement an algorithm for designing SNRs with dimensions optimized for maintaining attogram scale precision. Using 8-in. processing technology, we fabricate parallel array SNR devices which contain ten resonators. While maintaining a precision similar to that of the optical lever, we demonstrate a throughput of 40 000 particles per hour-an order of magnitude improvement over a single device with an analogous flow rate. Finally, we show the capability of the SNR array device for measuring polydisperse solutions of gold particles ranging from 20 to 80 nm in diameter. We envision that SNR array devices will open up new possibilities for nanoscale metrology by measuring not only synthetic but also biological nanoparticles such as exosomes and viruses.
Topics: Gold; Microfluidic Analytical Techniques; Nanoparticles
PubMed: 32233476
DOI: 10.1021/acssensors.0c00394 -
Nanoscale Sep 2019The breathing modes of single suspended gold nanoplates have been examined by transient absorption microscopy. These vibrational modes show very high quality factors...
The breathing modes of single suspended gold nanoplates have been examined by transient absorption microscopy. These vibrational modes show very high quality factors which means that their frequencies can be accurately measured. Measurements performed before and after removing the organic layer that coats the as synthesized nanoplates show significant increases in frequency, which are consistent with removal of a few nm of organic material from the nanoplate surface. Experiments were also performed after depositing polymer beads on the sample. These measurements show a decrease in frequency in the region of the beads. This implies that adding a localized mass to the nanoplate hybridizes the vibrational normal modes, creating a new breathing mode which has a maximum amplitude at the bead. The nanoplate resonators have a mass sensing detection limit of ca. 10 attograms, which is comparable to the best results that have been achieved with plasmonic nanoparticles.
PubMed: 31453600
DOI: 10.1039/c9nr05940g -
Clinical Infectious Diseases : An... Apr 2020Treatment of subarachnoid neurocysticercosis (NCC) is complicated, and assays that can guide treatment are not widely available. The reproducibility and scalability of...
A Novel, Highly Sensitive Quantitative Polymerase Chain Reaction Assay for the Diagnosis of Subarachnoid and Ventricular Neurocysticercosis and for Assessing Responses to Treatment.
BACKGROUND
Treatment of subarachnoid neurocysticercosis (NCC) is complicated, and assays that can guide treatment are not widely available. The reproducibility and scalability of molecular-based biomarkers would be of great use.
METHODS
The Taenia solium genome was mined and primers and probes were designed to target repeats with the highest coverage; the most sensitive, specific, and efficient repeat (TsolR13) was selected for clinical testing. We tested 46 plasma samples and 36 cerebral spinal fluid (CSF) samples taken from patients with subarachnoid or ventricular disease using quantitative polymerase chain reaction (qPCR).
RESULTS
The analytic sensitivity of TsolR13 was 97.3% at 240 attograms (ag) of T. solium genomic DNA and 100% analytic specificity. The clinical sensitivity in detecting active subarachnoid or ventricular disease in symptomatic patients was 100% in CSF and 81.3% in plasma. The predictive ability to distinguish active from cured disease was better for CSF (94.4% of those cured had negative qPCR results) than for plasma (86.7% of those cured tested negative). Some subjects also had plasma DNA detectable intermittently for years after being cured. Overall, the test performance was equivalent to T. solium antigen detection.
CONCLUSIONS
A qPCR test for the detection of the highly repetitive Tsol13 sequence has been developed and shown to be highly sensitive and specific for NCC, but also useful as a test of cure in CSF and for the definitive diagnosis of NCC in plasma.
Topics: Animals; Antigens, Helminth; Enzyme-Linked Immunosorbent Assay; Humans; Neurocysticercosis; Polymerase Chain Reaction; Reproducibility of Results; Sensitivity and Specificity; Taenia solium
PubMed: 31232448
DOI: 10.1093/cid/ciz541 -
Analytical Chemistry Jun 2019Simultaneous detection of multiple constituents in the characterization of state-of-the-art nanomaterials is an elusive topic to a majority of the analytical techniques...
Simultaneous detection of multiple constituents in the characterization of state-of-the-art nanomaterials is an elusive topic to a majority of the analytical techniques covering the field of nanotechnology. Optical catapulting (OC) and optical trapping (OT) have recently been combined with laser-induced breakdown spectroscopy (LIBS) to provide single-nanoparticle resolution and attogram detection power. In the present work, the multielemental capabilities of this approach are demonstrated by subjecting two different types of nanometric ferrite particles to LIBS analysis. Up to three metallic elements in attogram quantities are consistently detected within single laser events. Individual excitation efficiency for each species is quantified from particle spectra showing an exponential correlation between photon production and the energy of the upper level of the monitored atomic line. Moreover, a new sampling strategy based in skimmer-like 3D printed cones that allows for thin dry nanoparticle aerosols to be formed via optical catapulting is introduced. Enhanced sampling resulted in an increase of the sampling throughput by facilitating stable atmospheric-pressure optical trapping of individual particles and spectroscopic chemical characterization within a short timeframe.
PubMed: 31074601
DOI: 10.1021/acs.analchem.9b01579 -
Journal of Chromatography. A Sep 2019The application of two-dimensional liquid chromatography (2D-LC) is gradually growing also in the area of metabolite profiling and identification. The current...
The application of two-dimensional liquid chromatography (2D-LC) is gradually growing also in the area of metabolite profiling and identification. The current contribution describes a heartcut 2D-UHPLC configuration that is applied in support of drug metabolism studies in development. The setup applies four LC columns: two analytical UHPLC columns to perform the first and second dimension separations, which are both preceded by a short HPLC column operated as trapping column. The first HPLC column allows a significant online preconcentration by large volume injection. The second short HPLC column is placed between the first and second dimension columns and enables the selection of orthogonal conditions in the second dimension independent of the first dimension making the heartcutting 2D approach more generic. The value of the setup was demonstrated with selective ultraviolet chromatograms obtained for the two major hydroxylated metabolites of atorvastatin separating them from a very high biological background, originating from an injection of 4 mL feces extract, by heartcut 2D-LC. In a second application, the main metabolite of imipramine was baseline separated from some minor metabolites that were co-eluting in the first dimension, allowing accurate and sensitive quantification. A quantification limit in the attogram/mL range was achieved thanks to the injection of 200 mL diluted urine, corresponding to 100 mL urine on column.
Topics: Animals; Atorvastatin; Chemistry Techniques, Analytical; Chromatography, High Pressure Liquid; Dogs; Feces; Humans; Imipramine; Pharmaceutical Preparations; Urine
PubMed: 31047660
DOI: 10.1016/j.chroma.2019.04.064