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Analytical Chemistry Jan 2018In this contribution, completely different from traditional probes based on molecular host-guest interaction, crystal level interaction was proposed as an ultrasensitive...
In this contribution, completely different from traditional probes based on molecular host-guest interaction, crystal level interaction was proposed as an ultrasensitive design strategy for molecule detection. In such a strategy, crystal-guest interaction triggered rapid crystal disaggregation to gain great signal change, far more efficient than molecule scale coupling. Highly ordered pyrene methanol (PM) crystal was self-assembled with hydrogen bond chain and π-π stacking force. Its {011} surface can be destabilized by methamphetamine hydrochlorate (MA, heavily used illicit drug) selectively and efficiently. The detection limit was improved to an amazing attogram level (5.4 ag/mL, 29.1 fM), 9 orders of magnitude lower than the best reported host-guest result.
PubMed: 29237262
DOI: 10.1021/acs.analchem.7b04783 -
Physical Review Letters Mar 2022We propose a search for low mass dark matter particles through momentum recoils caused by their scattering from trapped, nanometer-scale objects. Our projections show...
We propose a search for low mass dark matter particles through momentum recoils caused by their scattering from trapped, nanometer-scale objects. Our projections show that even with a modest array of femtogram-mass sensors, parameter space beyond the reach of existing experiments can be explored. The case of smaller, attogram-mass sensors is also analyzed-where dark matter can coherently scatter from the entire sensor-enabling a large enhancement in the scattering cross-section relative to interactions with single nuclei. Large arrays of such sensors have the potential to investigate new parameter space down to dark matter masses as low as 10 keV. If recoils from dark matter are detected by such sensors, their inherent directional sensitivity would allow an unambiguous identification of a dark matter signal.
PubMed: 35333080
DOI: 10.1103/PhysRevLett.128.101301 -
Analytical Chemistry Sep 2014Molecular diagnostics based on the polymerase chain reaction (PCR) offer rapid and sensitive means for detecting infectious disease, but prohibitive costs have impeded...
Molecular diagnostics based on the polymerase chain reaction (PCR) offer rapid and sensitive means for detecting infectious disease, but prohibitive costs have impeded their use in resource-limited settings where such diseases are endemic. In this work, we report an innovative method for transforming a desktop computer and a mobile camera phone--devices that have become readily accessible in developing countries--into a highly sensitive DNA detection system. This transformation was achieved by converting a desktop computer into a de facto thermal cycler with software that controls the temperature of the central processing unit (CPU), allowing for highly efficient PCR. Next, we reconfigured the mobile phone into a fluorescence imager by adding a low-cost filter, which enabled us to quantitatively measure the resulting PCR amplicons. Our system is highly sensitive, achieving quantitative detection of as little as 9.6 attograms of target DNA, and we show that its performance is comparable to advanced laboratory instruments at approximately 1/500th of the cost. Finally, in order to demonstrate clinical utility, we have used our platform for the successful detection of genomic DNA from the parasite that causes Chagas disease, Trypanosoma cruzi, directly in whole, unprocessed human blood at concentrations 4-fold below the clinical titer of the parasite.
Topics: Cell Phone; Chagas Disease; Coloring Agents; DNA, Protozoan; Electrophoresis, Polyacrylamide Gel; Humans; Microcomputers; Polymerase Chain Reaction; Software; Trypanosoma cruzi
PubMed: 25223929
DOI: 10.1021/ac5022419 -
Light, Science & Applications Jan 2016High-throughput small-molecule assays play essential roles in biomedical diagnosis, drug discovery, environmental analysis, and physiological function research....
High-throughput small-molecule assays play essential roles in biomedical diagnosis, drug discovery, environmental analysis, and physiological function research. Nanoplasmonics holds a great potential for the label-free detection of small molecules at extremely low concentrations. Here, we report the development of nanoplasmonic paper (NP-paper) for the rapid separation and ultrasensitive detection of mixed small molecules. NP-paper employs nanogap-rich silver nanoislands on cellulose fibers, which were simply fabricated at the wafer level by using low-temperature solid-state dewetting of a thin silver film. The nanoplasmonic detection allows for the scalable quantification and identification of small molecules over broad concentration ranges. Moreover, the combination of chromatographic separation and nanoplasmonic detection allows both the highly sensitive fluorescence detection of mixed small molecules at the attogram level and the label-free detection at the sub-nanogram level based on surface-enhanced Raman scattering. This novel material provides a new diagnostic platform for the high-throughput, low-cost, and label-free screening of mixed small molecules as an alternative to conventional paper chromatography.
PubMed: 30167113
DOI: 10.1038/lsa.2016.9 -
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 -
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 -
Nano Letters Sep 2015Operation of nanomechanical devices in liquid has been challenging due to the strong viscous damping that greatly impedes the mechanical motion. Here we demonstrate an...
Operation of nanomechanical devices in liquid has been challenging due to the strong viscous damping that greatly impedes the mechanical motion. Here we demonstrate an optomechanical microwheel resonator integrated in microfluidic system that supports low-loss optical resonances at near-visible wavelength with quality factor up to 1.5 million, which allows the observation of the thermal Brownian motion of the mechanical mode in both air and water environment with high signal-to-background ratio. A numerical model is developed to calculate the hydrodynamic effect on the device due to the surrounding water, which agrees well with the experimental results. With its very high resonance frequency (170 MHz) and small loaded mass (75 pg), the present device has an estimated mass sensitivity at the attogram level in water.
PubMed: 26226184
DOI: 10.1021/acs.nanolett.5b02388 -
Journal of Helminthology Nov 2015Schistosomiasis is a disease caused by parasitic flatworms of the genus Schistosoma, whose diagnosis has limitations, such as the low sensitivity and specificity of...
Polymerase chain reaction for the amplification of the 121-bp repetitive sequence of Schistosoma mansoni: a highly sensitive potential diagnostic tool for areas of low endemicity.
Schistosomiasis is a disease caused by parasitic flatworms of the genus Schistosoma, whose diagnosis has limitations, such as the low sensitivity and specificity of parasitological and immunological methods, respectively. In the present study an alternative molecular technique requiring previous standardization was carried out using the polymerase chain reaction (PCR) for the amplification of a 121-bp highly repetitive sequence for Schistosoma mansoni. DNA was extracted from eggs of S. mansoni by salting out. Different conditions were standardized for the PCR technique, including the concentration of reagents and the DNA template, annealing temperature and number of cycles, followed by the determination of the analytical sensitivity and specificity of the technique. Furthermore, the standardized PCR technique was employed in DNA extracted, using Chelex®100, from samples of sera of patients with an immunodiagnosis of schistosomiasis. The optimal conditions for the PCR were 2.5 mm MgCl2, 150 mm deoxynucleoside triphosphates (dNTPs), 0.4 μm primers, 0.75 U DNA polymerase, using 35 cycles and an annealing temperature of 63°C. The analytical sensitivity of the PCR was 10 attograms of DNA and the specificity was 100%. The DNA sequence was successfully detected in the sera of two patients, demonstrating schistosomiasis transmission, although low, in the community studied. The standardized PCR technique, using smaller amounts of reagents than in the original protocol, is highly sensitive and specific for the detection of DNA from S. mansoni and could be an important tool for diagnosis in areas of low endemicity.
Topics: Animals; DNA Primers; DNA, Helminth; Endemic Diseases; Humans; Polymerase Chain Reaction; Repetitive Sequences, Nucleic Acid; Schistosoma mansoni; Schistosomiasis mansoni; Sensitivity and Specificity; Venezuela
PubMed: 25141275
DOI: 10.1017/S0022149X14000595 -
Scientific Reports Nov 2016We have designed a versatile and sensitive liquid chromatographic (LC) system, featuring a monolithic trap column and a very narrow (10 μm ID) fused silica open...
We have designed a versatile and sensitive liquid chromatographic (LC) system, featuring a monolithic trap column and a very narrow (10 μm ID) fused silica open tubular liquid chromatography (OTLC) separation column functionalized with C-groups, for separating a wide range of molecules (from small metabolites to intact proteins). Compared to today's capillary/nanoLC approaches, our system provides significantly enhanced sensitivity (up to several orders) with matching or improved separation efficiency, and highly repeatable chromatographic performance. The chemical properties of the trap column and the analytical column were fine-tuned to obtain practical sample loading capacities (above 2 μg), an earlier bottleneck of OTLC. Using the OTLC system (combined with Orbitrap mass spectrometry), we could perform targeted metabolomics of sub-μg amounts of exosomes with 25 attogram detection limit of a breast cancer-related hydroxylated cholesterol. With the same set-up, sensitive bottom-up proteomics (targeted and untargeted) was possible, and high-resolving intact protein analysis. In contrast to state-of-the-art packed columns, our platform performs chromatography with very little dilution and is "fit-for-all", well suited for comprehensive analysis of limited samples, and has potential as a tool for challenges in diagnostics.
Topics: Animals; Axin Protein; Breast Neoplasms; Chromatography, Liquid; Exosomes; Female; Humans; Hydroxycholesterols; Mice; Peptides; Proteomics; Reproducibility of Results; Sensitivity and Specificity; Tandem Mass Spectrometry
PubMed: 27897190
DOI: 10.1038/srep37507 -
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