A flexible nanoparticle-based sulfate assay is demonstrated in which the positively-charged gold nanoparticles (cysteamine-AuNPs) act as indicator. The aggregation of cysteamine-AuNPs is selectively induced by sulfate, which allows the rapid colorimetric sensing of sulfate without any precipitant, sample preparation and specific instruments. In this work, the cysteamine-AuNPs probe has been suc...

A chemiluminescence enzyme immunoassay based on magnetic microparticles (MmPs-CLEIA) was developed to evaluate serum α-fetoprotein (AFP) in parallel with traditional colorimetric enzyme-linked immunosorbent assay (ELISA). A systematic comparison between the MmPs-CLEIA and colorimetric ELISA concluded that the MPs-CLEIA exhibited fewer dosages of immunoreagents, less total assay time, and better...

A new application of gold nanoparticles (AuNPs) as a colorimetric method for gene detection of α-thalassemia 1 (SEA deletion) is reported here for the first time. This technique is based on color changes from salt-induced aggregation of un-hybridized nanogold probes after hybridization with the target DNA. Specific DNA probes were synthesized, thiol modified and conjugated on the surface of AuN...

The development of a green and facile strategy for synthesizing high stable gold nanoparticles (AuNPs) is still highly challenging. Additionally, the main problems regarding AuNPs based colorimetric sensors are their poor selectivity and low sensitivity, as well their tendency to aggregate during their synthesis and sensing process. Herein, we present an in-situ reduction strategy to synthesize...

A simple colorimetric immunoassay system, based on the peroxidase mimicking activity of Fe3O4 magnetic nanoparticles (MNPs), has been developed to detect clinically important antigenic molecules. MNPs with ca. 10 nm in diameter were synthesized and conjugated with specific antibodies against target molecules, such as rotaviruses and breast cancer cells. Conjugation of the MNPs with antibodies (...

There is an urgent need to build digital image databases with adequate colorimetric accuracy for museums, achieves and libraries. Traditional colorimetric imaging suffers from the possibilities of metameric problem, while spectral imaging can facilitate accurate tristimulus estimation and possibilities for spectral reconstruction of each pixel. Spectral image archives can be used to render accu...

A facile, ultrasensitive, and selective sensor strip utilizing 4-amino-3-penten-2-one (fluoral-p) functionalized electrospun polyacrylonitrile (PAN) (PAN/fluoral-p) nanofibrous membranes has been successfully developed for naked-eye colorimetric assay of formaldehyde. The sensor strips presented a significant reflectance decreasing band at 417 nm which induced a vivid color change from white to...

Colorimetric sensing, which transduces environmental changes into visible color changes, provides a simple yet powerful detection mechanism that is well-suited to the development of low-cost and low-power sensors. A new approach in colorimetric sensing exploits the structural color of photonic crystals (PCs) to create environmentally-influenced color-changeable materials. PCs are composed of pe...

The detection of environmental mercury (Hg) contamination requires complex and expensive instruments and professional technicians. We present a simple, sensitive, and portable Hg2+ detection system based on a smartphone and colorimetric aptamer nanosensor. A smartphone equipped with a light meter app was used to detect, record, and process signals from a smartphone-based microwell reader (MR S-...

Rapid and sensitive detection methods are in urgent demand for the screening of extensively used organophosphorus pesticides and highly toxic nerve agents for their neurotoxicity. In this study, we developed a novel Fe(3)O(4) magnetic nanoparticle (MNP) peroxidase mimetic-based colorimetric method for the rapid detection of organophosphorus pesticides and nerve agents. The detection assay is co...