Highly sensitive and specific detection of human papillomavirus type 16 using CRISPR/Cas12a assay coupled with an enhanced single nanoparticle dark-field microscopy imaging technique.

Human papillomavirus (HPV) is a prevalent sexually transmitted pathogen associated with cervical cancer. Detecting high-risk HPV (hr-HPV) infections is crucial for cervical cancer prevention, particularly in resource-limited settings. Here, we present a highly sensitive and specific sensor for HPV-16 detection based on CRISPR/Cas12a coupled with enhanced single nanoparticle dark-field microscopy (DFM) imaging techniques.

Homogeneous immunoassay utilizing fluorescence resonance energy transfer from quantum dots to tyramide dyes deposited on full immunocomplexes.

There is an urgent need for homogeneous immunoassays that offer sufficient sensitivity for routine clinical practice. In this study, we have developed a highly sensitive, fluorescence resonance energy transfer (FRET)-based homogeneous immunoassay. Unlike previous FRET-based homogeneous immunoassays, where acceptors were attached to antibody molecules located far from the donor, we employed acceptors to label the entire sandwich-structured immunocomplex, including two antibodies and one antigen.

Corrigendum: Contactless and robust dielectric microspheres-assisted surface-enhanced Raman scattering sensitivity improvement for anthrax biomarker detection.

[This corrects the article DOI: 10.3389/fchem.2022.

Contactless and robust dielectric microspheres-assisted surface-enhanced Raman scattering sensitivity improvement for anthrax biomarker detection.

This report presents a contactless and robust dielectric microspheres (DMs)-assisted surface enhanced Raman scattering (SERS) enhancement method to improve SERS detection sensitivity detection sensitivity. DMs that could focus and collect light were embedded within the polydimethylsiloxane (PDMS) film to avoid direct contact with the analytical solution and improve detection reliability. The as prepared DMs embedded PDMS (DMs-PDMS) film was integrated with a microfluidic technique to enhance the SERS signal of a liquid substrate.

The Arsenic-Binding Aptamer Cannot Bind Arsenic: Critical Evaluation of Aptamer Selection and Binding.

An arsenic-binding aptamer named Ars-3 was reported in 2009, and it has been used for detection of As(III) in more than two dozen papers. In this work, we performed extensive binding assays using isothermal titration calorimetry, various DNA-staining dyes, and gold nanoparticles. By carefully comparing Ars-3 and a few random control DNA sequences, no specific binding of As(III) was observed in each case.

Adsorption of Arsenite on Gold Nanoparticles Studied with DNA Oligonucleotide Probes.

Gold nanoparticles (AuNPs) have been extensively used for detecting arsenite, As(III). Many methods rely on a DNA aptamer that claimed to bind specifically to inorganic arsenic. In these cases, the focus was on arsenic binding to the aptamer, while the potential interactions between As(III) and the AuNP surface were ignored.

synthesis of low-cost and large-scale flexible metal nanoparticle-polymer composite films as highly sensitive SERS substrates for surface trace analysis.

Surface-enhanced Raman spectroscopy (SERS) has been one of the most promising analytical tools. Despite many efforts in the design of SERS substrates, it remains a great challenge for creating a general flexible substrate that could detect analytes on diverse objects. Herein, we report our attempt to address this issue by developing a facile and versatile method capable of generating silver/gold nanoparticles on the surface of a cellulose acetate (CA) polymer in a simple, cheap, practical, and capping agent-free way.

A Single-Molecule Homogeneous Immunoassay by Counting Spatially "Overlapping" Two-Color Quantum Dots with Wide-Field Fluorescence Microscopy.

We developed a single-molecule homogeneous immunoassay by counting spatially "overlapping" two-color quantum dots (QD) under a wide-field fluorescence microscope. QD 655 with red fluorescence and QD 565 with green fluorescence were modified with capture and detection antibodies, respectively. A capture antibody-modified QD 655 and a detection antibody-modified QD 565 were conjugated by a corresponding antigen molecule to form a "sandwich" immunocomplex.

Visual and colorimetric determination of HO and glucose based on citrate-promoted HO sculpturing of silver nanoparticles.

Isotropic silver nanoparticles (iAg NPs) can be easily prepared at low costs, have a low electrochemical potential and high extinction coefficient. An effective colorimetric assay for HO is reported here based on the finding that HO can induce the shape transformation of citrate-capped iAg NPs with the help of citrate. The substantial shape variation affords an apparent surface plasmon resonance (SPR) shift, accompanied by a vivid color change from light yellow to mauve.

Sensing Active Heparin by Counting Aggregated Quantum Dots at Single-Particle Level.

Developing highly sensitive and highly selective assays for monitoring heparin levels in blood is required during and after surgery. In previous studies, electrostatic interactions are exploited to recognize heparin and changes in light signal intensity are used to sense heparin. In the present study, we developed a quantum dot (QD) aggregation-based detection strategy to quantify heparin.

Viscosity based droplet size controlling in negative pressure driven droplets generator for large-scale particle synthesis.

The poor control and regulation of droplets limit the applications of negative pressure driven droplet generator (NPDDG). Here, we present a simple method to control droplet size in NPDDG via varying the oil viscosity. Depending on the infinite intersolubility of high viscous mineral oil and low viscous hexadecane, we obtain a series of oils with kinematic viscosities linearly varied from 4.

A self-driven miniaturized liquid fuel cell.

We present a miniaturized fuel cell driven by an evaporation pump. The prototype cell shows a net peak current density of 22 mA cm and a net power density of 10.2 mW cm, both of which are the highest net values among passive-driven micro-fuel cells.

Fabrication of Janus droplets by evaporation driven liquid-liquid phase separation.

We present a universal and scalable method to fabricate Janus droplets based on evaporation driven liquid-liquid phase separation. In this work, the morphologies and chemical properties of separate parts of the Janus droplets can be flexibly regulated, and more complex Janus droplets (such as core-shell Janus droplets, ternary Janus droplets, and multiple Janus droplets) can be constructed easily.

Single Gold Nanoparticle-Based Colorimetric Detection of Picomolar Mercury Ion with Dark-Field Microscopy.

Mercury severely damages the environment and human health, particularly when it accumulates in the food chain. Methods for the colorimetric detection of Hg(2+) have increasingly been developed over the past decade because of the progress in nanotechnology. However, the limits of detection (LODs) of these methods are mostly either comparable to or higher than the allowable maximum level (10 nM) in drinking water set by the US Environmental Protection Agency.

Counting quantum dot aggregates for the detection of biotinylated proteins.

We develop a method to quantify the quantum dots (QDs) in QD aggregates in aqueous solution by recording the entire process of blue shifting and photobleaching under continuous illumination and utilize this method to detect the biotinylated proteins based on counting the degree of aggregation (DOA).

In situ formation of phosphorescent molecular gold(I) cluster in a macroporous polymer film to achieve colorimetric cyanide sensing.

A highly phosphorescent molecular Au(I) cluster capable of rapid, sensitive, and selective detection of cyanide has been successfully fabricated. The origin of the outstanding sensing performance of the molecular Au(I) cluster toward cyanide is justified by X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) analyses. The response mechanism employed with the molecular Au(I) cluster and the cost-effectiveness in cyanide detection affords several key sensor features, making this molecular Au(I) cluster-based sensor unique compared to other cyanide sensing schemes.

Template-free synthesis of renewable macroporous carbon via yeast cells for high-performance supercapacitor electrode materials.

The urgent need for sustainable development has forced material scientists to explore novel materials for next-generation energy storage devices through a green and facile strategy. In this context, yeast, which is a large group of single cell fungi widely distributed in nature environments, will be an ideal candidate for developing effective electrode materials with fascinating structures for high-performance supercapacitors. With this in mind, herein, we present the first example of creating three-dimensional (3D) interpenetrating macroporous carbon materials via a template-free method, using the green, renewable, and widespread yeast cells as the precursors.

Engineering natural materials as surface-enhanced Raman spectroscopy substrates for in situ molecular sensing.

Surface-enhanced Raman spectroscopy (SERS) is a powerful analytical tool. However, its applications for in situ detection of target molecules presented on diverse material surfaces have been hindered by difficulties in rapid fabricating SERS-active substrates on the surfaces of these materials through a simple, low-cost, and portable approach. Here, we demonstrate our attempt to address this issue by developing a facile and versatile method capable of in situ generating silver nanoparticle film (SNF) on the surfaces of both artificial and natural materials in a simple, cheap, practical, and disposable manner.

Fluorescent silver nanoclusters for user-friendly detection of Cu2+ on a paper platform.

The development of a user-friendly sensing platform for the detection of Cu(2+) in water is necessary as there are wide concerns due to the substantial impact of Cu(2+) on human health, environmental monitoring, and so on. Motivated by this, we report a fluorescent silver nanoclusters (AgNCs)-based sensor for the detection of Cu(2+). These water-soluble AgNCs, as a new class of fluorescent probes, were synthesized by using azobenzene modified poly(acrylic acid) (MPAA) as templates.

Dual modal in vivo imaging using upconversion luminescence and enhanced computed tomography properties.

In vivo upconversion luminescence (UCL) imaging, exhibiting favorable characteristics such as high photostability, no blinking, sharp emission lines, and long lifetimes, is recognized as the excellent and significant photoluminescence imaging for the future. To develop the imaging system with high visual sensitivity and tissue penetration, the functional molecules with X-ray computed tomography (CT) contrast were grafted onto upconversion nanoparticles to obtain β-NaYF(4):18% Yb(3+),2%Er(3+)@SiO(2)-I/PEG (UCNPs@SiO(2)-I/PEG) nanoprobes. These nanoprobes are water-soluble, have low cytotoxicity, and possess excellent UCL and remarkable CT contrast.

Dual-emission fluorescent silica nanoparticle-based probe for ultrasensitive detection of Cu2+.

An effective dual-emission fluorescent silica nanoparticle-based probe has been constructed for rapid and ultrasensitive detection of Cu(2+). In this nanoprobe, a dye-doped silica core served as a reference signal, thus providing a built-in correction for environmental effects. A response dye was covalently grafted on the surface of the silica nanoparticles through a chelating reagent for Cu(2+).