1,720,984 research outputs found
Detection and Characterization of Bacterial Biofilms and Biofilm-Based Sensors
Full text linkMicrobial biofilms have caused serious concerns in healthcare, medical, and food industries because of their intrinsic resistance against conventional antibiotics and cleaning procedures and their capability to firmly adhere on surfaces for persistent contamination. These global issues strongly motivate researchers to develop novel methodologies to investigate the kinetics underlying biofilm formation, to understand the response of the biofilm with different chemical and physical treatments, and to identify biofilm-specific drugs with high-throughput screenings. Meanwhile microbial biofilms can also be utilized positively as sensing elements in cell-based sensors due to their strong adhesion on surfaces. In this perspective, we provide an overview on the connections between sensing and microbial biofilms, focusing on tools used to investigate biofilm properties, kinetics, and their response to chemicals or physical agents, and biofilm-based sensors, a type of biosensor using the bacterial biofilm as a biorecognition element to capture the presence of the target of interest by measuring the metabolic activity of the immobilized microbial cells. Finally we discuss possible new research directions for the development of robust and rapid biofilm related sensors with high temporal and spatial resolutions, pertinent to a wide range of applications
Multiplexed Opto-Microfluidic Biosensing: Advanced Platform for Prostate Cancer Detection
Full text linkCancer stands as a prominent global cause of mortality, necessitating early detection to augment survival rates and alleviate economic burdens on healthcare systems. In particular, prostate cancer (PCa), impacting 1.41 million men globally in 2020, accentuates the demand for sensitive and cost-effective detection methods beyond traditional prostate-specific antigen (PSA) testing. While clinical techniques exhibit limitations, biosensors emerge as compact, user-friendly alternatives to traditional laboratory approaches. However, existing biosensors predominantly concentrate on PSA detection, prompting the necessity for advancing toward multiplex sensing platforms. This study introduces a compact opto-microfluidic sensor featuring a substrate of gold nanospikes, fabricated via electrodeposition, for enhanced sensitivity. Embedded within a microfluidic chip, this nanomaterial enables the precise and concurrent measurement of PSA, alongside two complementary PCa biomarkers, matrix metalloproteinase-2 (MMP-2) and anti-α-methylacyl-CoA racemase (anti-AMACR) in diluted human plasma, offering a comprehensive approach to PSA analysis. Taking advantage of the localized surface plasmon resonance principle, this biosensor offers robustness and sensitivity in real sample analysis without the need for labeling agents. With the limit of detection at 0.22, 0.37, and 0.18 ng/mL for PSA, MMP-2, and anti-AMACR, respectively, this biosensing platform holds promise for point-of-care analysis, underscoring its potential impact on medical diagnostics
Nanoplasmonic multiplex biosensing for COVID-19 vaccines
Full text linkThe ongoing emergence of severe acute respiratory syndrome caused by the new coronavirus (SARS-CoV-2) variants requires swift actions in identifying specific antigens and optimizing vaccine development to maximize the humoral response of the patient. Measuring the specificity and the amount of antibody produced by the host immune system with high throughput and accuracy is critical to develop timely diagnostics and therapeutic strategies. Motivated by finding an easy-to-use and cost-effective alternative to existing serological methodologies for multiplex analysis, we develop a proof-of-concept multiplex nanoplasmonic biosensor to capture the humoral response in serums against multiple antigens. Nanoplasmonic sensing relies on the wavelength shift of the localized surface plasmon resonance (LSPR) peak of gold nanostructures upon binding interactions between the antibodies and the immobilized antigens. Here the antigens are first immobilized on different sensing areas by using a mono-biotinylation system based on the high affinity interaction between biotin and streptavidin. We then validate the multiplex platform by detecting the presence of 3 monoclonal antibodies against 3 antigens (2 different hemagglutinins (HAs) from influenza viruses, and the SARS-CoV-2 Spike RBD (receptor binding domain)). We also measure the humoral response in murine sera collected before and after its immunization with the SARS-CoV-2 Spike protein, in good agreement with the results obtained by the ELISA assay. Our nanoplasmonic assays have successfully demonstrated multiple serum antibody profiling, which can be further integrated with microfluidics as an effective high throughput screening platform in future studies for the ongoing SARS-CoV-2 vaccine development
Detection of antibodies against SARS-CoV-2 spike protein by gold nanospikes in an opto-microfluidic chip
Full text linkThe ongoing global pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to active research in its associated diagnostics and medical treatments. While quantitative reverse transcription polymerase chain reaction (qRT-PCR) is the most reliable method to detect viral genes of SARS-CoV-2, serological tests for specific antiviral antibodies are also important as they identify false negative qRT-PCR responses, track how effectively the patient's immune system is fighting the infection, and are potentially helpful for plasma transfusion therapies. In this work, based on the principle of localized surface plasmon resonance (LSPR), we develop an opto-microfluidic sensing platform with gold nanospikes, fabricated by electrodeposition, to detect the presence and amount of antibodies specific to the SARS-CoV-2 spike protein in 1 mu L of human plasma diluted in 1 mL of buffer solution, within similar to 30 min. The target antibody concentration can be correlated with the LSPR wavelength peak shift of gold nanospikes caused by the local refractive index change due to the antigen-antibody binding. This label-free microfluidic platform achieves a limit of detection of similar to 0.08 ng/mL (similar to 0.5 pM), falling under the clinical relevant concentration range. We demonstrate that our opto-microfluidic platform offers a promising point-of-care testing tool to complement standard serological assays and make SARS-CoV-2 quantitative diagnostics easier, cheaper, and faster
Sensing Dynamically Evolved Short‐Range Nanomechanical Forces in Fast‐Mutating Single Viral Spike Proteins
Full text linkUnderstanding changes in the mechanical features of a single protein from a mutated virus while establishing its relation to the point mutations is critical in developing new inhibitory routes to tackle the uncontrollable spread of the virus. Addressing this, herein, the chemomechanical features of a single spike protein are quantified from alpha, beta, and gamma variants of SARS‐CoV‐2. Integrated amplitude‐modulation atomic force microscopy is used with dynamic force–distance curve (FDC) spectroscopy, in combination with theoretical models, to quantify Young's modulus, stiffness, adhesion forces, van der Waals forces, and the dissipative energy of single spike proteins. These obtained nanomechanical properties can be correlated with mutations in the individual proteins. Therefore, this work opens new possibilities to understand how the mechanical properties of a single spike protein relate to the viral functions. Additionally, single‐protein nanomechanical experiments enable a variety of applications that, collectively, may build up a new portfolio of understanding protein biochemistry during the evolution of viruses
Measuring the Radius of Gyration and Intrinsic Flexibility of Viral Proteins in Buffer Solution Using Small-Angle X‑ray Scattering
Full text linkMeasuring structural features of proteins dispersed in
buffer solution,
in contrast to crystal form, is indispensable in understanding morphological
characteristics of the biomolecule in a native environment. We report
on the structure and apparent viscosity of unfolded α and β
variants of SARS-CoV-2 spike proteins dispersed in buffer solutions.
The radius of gyration of the β variant is found to be larger
than that of the α variant, while the ab initio computation
of one of the possible particle-like bodies is consistent with the
small-angle X-ray scattering (SAXS) profiles resembling a conformation
similar to the three-dimensional structure of the folded state of
the corresponding α and β spike variant. However, a smaller
radius of gyration with respect to the predicted folded state of 2.4
and 2.7 is observed for both α and β variants, respectively.
Our work complements the structural characterization of spike proteins
using cryo-electron microscopy techniques. The measurement/analysis
discussed here might be useful for quick and cost-effective evaluation
of several protein structures, let alone mutated viral proteins, which
is useful for drug discovery/development applications
Evaporation driven smart patterning of microparticles on a rigid-soft composite substrate
No full textLabel-Free Detection of Gliadin in Food by Quartz Crystal Microbalance-Based Immunosensor
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