Fluorescence Immunoassay of Prostate-Specific Antigen Using 3D Paddle Screw-Type Devices and Their Rotating System.

In this paper, we present a sensitive and highly reproducible fluorescence immunosensor for detecting PSA in human serum. A unique feature of this study is that it uses creatively designed paddle screw-type devices and their custom-made rotating system for PSA immunoassay. The paddle screw devices were designed to maximize the surface-to-volume ratio over which the immunoassay reaction could occur to improve detection sensitivity.

Isolation and Characterization of Exosomes from Cancer Cells Using Antibody-Functionalized Paddle Screw-Type Devices and Detection of Exosomal miRNA Using Piezoelectric Biosensor.

Exosomes are small extracellular vesicles produced by almost all cell types in the human body, and exosomal microRNAs (miRNAs) are small non-coding RNA molecules that are known to serve as important biomarkers for diseases such as cancer. Given that the upregulation of miR-106b is closely associated with several types of malignancies, the sensitive and accurate detection of miR-106b is important but difficult. In this study, a surface acoustic wave (SAW) biosensor was developed to detect miR-106b isolated from cancer cells based on immunoaffinity separation technique using our unique paddle screw device.

Simultaneous Detection of Exosomal microRNAs Isolated from Cancer Cells Using Surface Acoustic Wave Sensor Array with High Sensitivity and Reproducibility.

We present a surface acoustic wave (SAW) sensor array for microRNA (miRNA) detection that utilizes photocatalytic silver staining on titanium dioxide (TiO) nanoparticles as a signal enhancement technique for high sensitivity with an internal reference sensor for high reproducibility. A sandwich hybridization was performed on working sensors of the SAW sensor array that could simultaneously capture and detect three miRNAs (miRNA-21, miRNA-106b, and miRNA-155) known to be upregulated in cancer. Sensor responses due to signal amplification varied depending on the concentration of synthetic miRNAs.

Detection of cyanide and sulfide ions by different mechanisms using a fluorescent chemical sensor containing a fluorophore and a potential ligand for metal complexes.

Here, we present a fluorescent chemical sensor for the simultaneous detection of CN and S ions, which are highly toxic to humans and the environment. When the BPMA-Flu-Cu complex comprising BPMA-Flu, a fluorophore combined with Cu, was used, the fluorescence was turned off. However, the fluorescence was turned on again by the addition of CN and S ions.

A QCM immunosensor employing signal amplification strategies by enlarging the size of nanoparticles using gold or silver staining.

We present quartz crystal microbalance (QCM) immunosensors for the detection of alpha-fetoprotein (AFP) in a human serum immunoassay with high sensitivity. In this study, we employed three types of signal amplification strategies using size enlargement and/or increase in mass of gold and titanium dioxide nanoparticles. Since the basic principle of the QCM sensor is to measure the change in resonance frequency according to the mass change caused by the molecular interactions on the sensor surface, we were able to quantitatively analyze AFP by sandwich immunoassay using gold or titanium dioxide nanoparticles conjugated with anti-AFP detection antibodies and the subsequent three signal amplification techniques in a similar manner.

Quartz crystal microbalance cardiac Troponin I immunosensors employing signal amplification with TiO nanoparticle photocatalyst.

A sensitive and highly reproducible cardiac troponin I (cTnI) immunoassay in human serum is a challenging research goal for researchers studying biosensors because cTnI can undergo proteolysis and various modifications in blood. Furthermore, the reproducible detection of cTnI at very low concentrations is also required for diagnosing acute myocardial infarction. Here, we present sensitive and highly reproducible quartz crystal microbalance (QCM) immunosensors for the detection of cTnI in human serum.

Sensitive detection of microRNA using QCM biosensors: sandwich hybridization and signal amplification by TiO nanoparticles.

MicroRNA-21 (miR-21) is known to act as an important biomarker for cancer, in that its up-regulation is closely related to several types of malignant tumor. Sensitive and accurate detection of miR-21 using a biosensor is highly challenging. In this study, sensitive and selective detection technology for miR-21 molecules using a quartz crystal microbalance (QCM) biosensor was developed.

QCM sensing of miR-21 by formation of microRNA-DNA hybrid duplexes and intercalation on surface-functionalized pyrene.

MicroRNAs (miRNAs) are small non-coding RNA molecules that serve as important biomarkers for a variety of diseases such as cancer and vascular disease. However, sensitive and accurate detection of miR-21 is very challenging in that up-regulation of miR-21 is highly associated with several types of malignant tumors. Here, quartz crystal microbalance (QCM) biosensors were developed for sensitive and specific detection of miR-21 through formation of miR-21-DNA hybrid duplexes and non-specific intercalation of surface-modified pyrene molecules.

Sensitivity and reproducibility improvements in a human plasma immunoassay with removal of clotting factors.

Interferences in human plasma immunoassay are severe challenge that affects the sensitivity and reproducibility of the assay. The clotting factor fibrinogen is a negatively charged protein and is one of the most common sources of interference in immunoassays, and its removal increases the sensitivity and reproducibility. Here, we present a highly sensitive and reproducible method for the detection of prostate specific antigen (PSA) in human plasma immunoassays.

Highly sensitive piezoelectric immunosensors employing signal amplification with gold nanoparticles.

We present a quartz crystal microbalance (QCM) immunosensor for highly sensitive detection of prostate-specific antigen (PSA) in a human serum immunoassay. In particular, in this study, we employed signal amplification using and enlarging gold nanoparticles. Because QCM measures the change of resonance frequency according to the mass change occurring on the sensor surface, we could quantitatively analyze PSA based on a tremendous increase in mass by sandwich immunoassay using AuNP-conjugated anti-PSA-detecting antibody enhanced with subsequent gold staining.

Strategic Approaches for Highly Selective and Sensitive Detection of Hg Ion Using Mass Sensitive Sensors.

Here we present a quartz crystal microbalance (QCM) sensor for the highly selective and sensitive detection of Hg ion, a toxic chemical species and a hazardous environmental contaminant. Hg ion can be quantitatively measured based on changes in the resonance frequency of QCM following mass changes on the QCM sensor surface. The high selectivity for Hg ion in this study can be obtained using a thymine-Hg-thymine pair, which is more stable than the adenine-thymine base pair in DNA.

Catalytic Deacetylation of p-Nitrophenyl Thioacetate by Cyanide Ion and Its Sensor Applications.

We demonstrated a simple and rapid deacetylation reaction of p-nitrophenyl thioacetate by cyanide ion. This reaction is caused by the strong nucleophilic tendency of the cyanide ion to the electrophilic substrate and has been previously reported as the most common method for detecting cyanide ions. Tetrabutylammonium cyanide and sodium cyanide can be used as sources of cyanide ions for catalytic deacetylation reactions.

Efficient and accurate analysis of microRNA using a specific extension sequence.

We present here on an innovative assay for detecting miRNAs using a uniquely designed specific extension sequence that provides high efficiency and accuracy. This assay consists of poly(A) tailing and reverse transcription followed by real-time PCR. In the first step of this reaction, target miRNAs are poly(A) tailed by poly(A) polymerase followed by cDNA synthesis using poly(T) adaptors.

Real-time qRT-PCR assay for the detection of miRNAs using bi-directional extension sequences.

Highly specific detection of miRNAs was performed using a novel bi-directional extension (BDE) assay. After reverse transcription, the cDNA was hybridized to a uniquely designed specific BDE sequence; this cDNA-BDE hybrid forms the PCR template. The PCR template was amplified in a SYBR Green-based quantitative real-time PCR.

Simultaneous capture and in situ analysis of circulating tumor cells using multiple hybrid nanoparticles.

Using hybrid nanoparticles (HNPs), we demonstrate simultaneous capture, in situ protein expression analysis, and cellular phenotype identification of circulating tumor cells (CTCs). Each HNP consists of three parts: (i) antibodies that bind specifically to a known biomarker for CTCs, (ii) a quantum dot that emits fluorescence signals, and (iii) biotinylated DNA that allows capture and release of CTC-HNP complex to an in-house developed capture & recovery chip (CRC). To evaluate our approach, cells representative of different breast cancer subtypes (MCF-7: luminal; SK-BR-3: HER2; and MDA-MB-231: basal-like) were captured onto CRC and expressions of EpCAM, HER2, and EGFR were detected concurrently.

A centrifugally actuated point-of-care testing system for the surface acoustic wave immunosensing of cardiac troponin I.

A fully automated point-of-care testing (POCT) system with a surface acoustic wave (SAW) immunosensor was developed for rapid and sensitive detection of cardiac troponin I (cTnI) in body fluid (plasma and whole blood). The assay, based on gold nanoparticle sandwich immunoassay and subsequent gold staining, was performed on the SAW immunosensor packaged inside a disposable microfluidic cartridge. The entire fluidic process, including plasma separation, reagent transport, metering, and mixing, was carried out by controlling the centrifugal force acting on the rotating cartridge and laser-irradiated ferrowax microvalves.

A trachea-inspired bifurcated microfilter capturing viable circulating tumor cells via altered biophysical properties as measured by atomic force microscopy.

Circulating tumor cells (CTCs), though exceedingly rare in the blood, are nonetheless becoming increasingly important in cancer diagnostics. Despite this keen interest and the growing number of potential clinical applications, there has been limited success in developing a CTC isolation platform that simultaneously optimizes recovery rates, purity, and cell compatibility. Herein, a novel tracheal carina-inspired bifurcated (TRAB) microfilter system is reported, which uses an optimal filter gap size satisfying both 100% theoretical recovery rate and purity, as determined by biomechanical analysis and fluid-structure interaction (FSI) simulations.

Highly efficient assay of circulating tumor cells by selective sedimentation with a density gradient medium and microfiltration from whole blood.

Isolation of circulating tumor cells (CTCs) by size exclusion can yield poor purity and low recovery rates, due to large variations in size of CTCs, which may overlap with leukocytes and render size-based filtration methods unreliable. This report presents a very sensitive, selective, fast, and novel method for isolation and detection of CTCs. Our assay platform consists of three steps: (i) capturing CTCs with anti-EpCAM conjugated microbeads, (ii) removal of unwanted hematologic cells (e.

Continuous labeling of circulating tumor cells with microbeads using a vortex micromixer for highly selective isolation.

Circulating tumor cells (CTCs) are identified in transit within the blood stream of cancer patients and have been proven to be a main cause of metastatic disease. Current approaches for the size-based isolation of CTCs have encountered technical challenges as some of the CTCs have a size similar to that of leukocytes and therefore CTCs are often lost in the process. Here, we propose a novel strategy where most of the CTCs are coated by a large number of microbeads to amplify their size to enable complete discrimination from leukocytes.

A rapid and facile signal enhancement method for microcantilever-based immunoassays using the agglomeration of ferromagnetic nanoparticles.

A rapid and facile signal enhancement method for detecting alpha-fetoprotein (AFP) was developed using the magnetic agglomeration of ferromagnetic nanoparticles and microcantilever sensors. The resonance frequency and deflection of the cantilevers were found to be more than 10-fold greater than that before physical agglomeration of the free nanoparticles around the magnetized nanoparticles.

SSA-MOA: a novel CTC isolation platform using selective size amplification (SSA) and a multi-obstacle architecture (MOA) filter.

Circulating tumor cells (CTCs) have gained increasing attention as physicians and scientists learn more about the role these extraordinarily rare cells play in metastatic cancer. In developing CTC technology, the critical criteria are high recovery rates and high purity. Current isolation methods suffer from an inherent trade-off between these two goals.

Sensitive and simultaneous detection of cardiac markers in human serum using surface acoustic wave immunosensor.

We present a rapid and sensitive surface acoustic wave (SAW) immunosensor that utilizes gold staining as a signal enhancement method. A sandwich immunoassay was performed on sensing area of the SAW sensor, which could specifically capture and detect cardiac markers (cardiac troponin I (cTnI), creatine kinase (CK)-MB, and myoglobin). The analytes in human serum were captured on gold nanoparticles (AuNPs) that were conjugated in advance with detection antibodies.

A visible light-induced photocatalytic silver enhancement reaction for gravimetric biosensors.

We have developed a novel microgravimetric immunosensor using a WO(3) nanoparticle-modified immunoassay and a silver enhancement reaction. When the nanoparticles in silver ion solution (i.e.

Electrochemical detection of DNA mutations on a PNA-modified electrode utilizing a single-stranded DNA specific endonuclease.

Utilizing a peptide nucleic acid (PNA)-modified electrode and a single-stranded DNA specific endonuclease, a novel electrochemical method to identify DNA mutations has been developed and represents a totally new strategy for the electrochemical diagnosis of human genetic mutations.