A fluorescent probe based on fluorescein displays excellent selectivity and sensitivity for cysteine its application bio-imaging is described.

Mercury severely damages the environment and human health, particularly when it accumulates in food chain. Methods for colorimetric detection of Hg2+ have increasingly been developed over past decade because progress nanotechnology. However, limits (LODs) these methods are mostly either comparable to or higher than allowable maximum level (10 nM) drinking water set by US Environmental Protection Agency. In this study, we report a single Au nanoparticle (AuNP)-based assay solution. AuNPs...

Janus droplets with complex compositions and morphologies were fabricated by co-solvent evaporation driven liquid–liquid phase separation.

Quantifying carbohydrate-protein (ligand-receptor) interactions is important to understand diverse biological processes and develop new diagnostic therapeutic methods. We an approach quantitatively study by Au nanoparticle localized surface plasmon resonance (LSPR) peak position shift at the single particles level. Unlike previous techniques for particle LSPR spectral imaging, only first-order streak of individual needed extract a spectrum, which has great potential increase throughput 500...

Photobleaching and spectral diffusion (blue shift) of quantum dots at the solid/liquid interface are suppressed by adding mercaptoethylamine.

The key factor of realizing super-resolution optical microscopy at the single-molecule level is to separately position two adjacent molecules. An opportunity independently localize target molecules provided by intermittency (blinking) in fluorescence a quantum dot (QD) under condition that blinking each emitter can be recorded and identified. Herein we develop spectral imaging based color nanoscopy which capable determining QD multicolor complex through tracking first-order spectrum, thus,...

Digital multiplexed homogeneous immunoassay is supposed to have the advantages of high sensitivity, analytical throughput, small sampling errors, and low consumption. We present a spectral imaging-based multiplex, homogenous by counting sandwich-structured immunocomplexes in form quantum dot (QD) aggregates. As proof concept, method was utilized detect two tumor biomarkers: carcino-embryonic antigen (CEA) α-fetoprotein (AFP). The immunocomplex induced CEA contained QD 655 585 were recognized...

The development of multiplexed immunoassays is impeded by the difficulty in distinguishing labeled immunocomplexes from free probes and nonspecifically bound probes. Here, we attempted to overcome this issue counting core–satellite-structured simultaneously using dark-field fluorescence microscopy. tumor biomarkers carcinoembryonic antigen (CEA), α-fetoprotein (AFP), prostate-specific (PSA) were chosen as model targets. Gold nanoparticles (AuNPs) with diameters 70 nm coated detection...

Abstract A simple method was developed for injecting a sample on cross‐form microfluidic chip by means of hydrostatic pressure combined with electrokinetic forces. The generated simply adjusting the liquid level in different reservoirs without any additional driven equipment such as pump. Two dispensing strategies using floating injection and gated injection, coupled loading, were tested. fluorescence observation verified feasibility loading separation mixture fluorescein sodium salt...

Core–shell quantum dots suffer from photobleaching by light at wavelengths longer than their emission wavelengths. That is, QD can be triggered photons with low energies that are insufficient to pump electrons into the conduction band. The most probable reason is pumped a surface state and then nonradiatively decayed as in conventional photobleaching.

We developed a single-molecule homogeneous immunoassay by counting spatially "overlapping" two-color quantum dots (QD) under wide-field fluorescence microscope. QD 655 with red and 565 green were modified capture detection antibodies, respectively. A antibody-modified conjugated corresponding antigen molecule to form "sandwich" immunocomplex. The could not be distinguished from the fluorescent microscopy because distance between them was smaller than resolution of an optical microscope...

Plasmonic resonance energy transfer (PRET) from a Au nanosphere (AuNS) to quantum dot (QD) is discovered at the single particle level. A homogenous immunoassay based on this PRET verified using prostate specific antigen (PSA) as an example. The limit of detection PSA determined be 0.2 fM.

Developing highly sensitive and selective assays for monitoring heparin levels in blood is required during after surgery. In previous studies, electrostatic interactions are exploited to recognize changes light signal intensity used sense heparin. the present study, we developed a quantum dot (QD) aggregation-based detection strategy quantify When cationic micelles fluorescence QDs modified with anti-thrombin III (AT III) added into sample solution, AT III-QDs, which specifically bind...

Quantum dot (QD)-based digital immunoassays play an important role in ultrasensitive biomarker detection. However, the requirement of objective with a high numerical aperture (NA) limits application this immunoassay. Here, high-quality imaging massive single-QDs was achieved by combination air (20×/0.4 NA) and liquid-immersed microspheres (150 μm, n = 2.2). The signal-to-noise ratio comparable to that 100×/1.4 NA oil objective. Digital analysis prostate-specific antigen (PSA) performed...

A novel sample injection method for chip CE was presented. This uses hydrostatic pressure, generated by emptying the waste reservoir, loading and electrokinetic force dispensing. The performed on a double-cross microchip. One cross, created separation channels, is used formation of plug. Another formed controlling plug control. By varying electric field in channel, volume can be linearly adjusted. Hydrostatic pressure takes advantage its ease generation microfluidic chip, without any...

We present an evaporation-driven miniaturized liquid fuel cell with high power density and portability simultaneously.

Amplification-free digital immunoassays (DIAs) typically utilize optical nanoparticles to enhance single immunocomplex molecule detection. The efficiency and uniformity of transferring the from a bulk solution solid surface determine limit detection (LOD) accuracy DIAs. Previous methods suffer issues like low efficiency, nonuniform distribution, particle aggregation. Here, we present novel technique named synergistic sedimentation Brownian motion suppression dehydration transfer (SynSed) for...

A laser-induced fluorescence imaging method was developed to simultaneously measure flow velocities in the middle and near wall of a channel with particles or single molecules, by selectively switching from wide field excitation mode evanescent wave mode. Fluorescent microbeads diameter 175 nm were used calibrate system, collisions walls directly observed. The main at 275 bottom measured. measured molecules two positions microchannel consistent calculated value based on Poiseuille theory...