Optical encoding with shaped DAM-1 molecular sieve particles

Multiplexed molecular detection using encoded microparticles and nanoparticles

Signal-encoded microparticles and nanoparticles have been used to label many reactions simultaneously for target identification in assays, and thus are an indispensable part of multiplex technologies. With the increasing demand for multiplexed molecular detection, encoded particles have evolved from pattern encoding to signal-intensity encoding, and also from signal-molecule encapsulation to signal-molecule tagging. The fabrication and utilization of such nano- and microparticles should advance multiplexed analysis. This short review focuses on how these encoded particles work and briefly touches on their applications in multiplexed molecular detection.

A microfluidic concentration-gradient droplet array generator for the production of multi-color nanoparticles

A microfluidic concentration-gradient droplet array generator (CDrAG) with parallel multi-channels and multi-layers was developed with 64 outlet channels producing 33 droplet gradient concentrations. A droplet production rate of 5 × 10(4) min(-1) was obtained, and the RSD value of droplet diameters in 64 groups is 5.5% (n = 64). Using the concentration gradient droplet array as parallel microreactors, 33 Au/Ag ratio nanoparticles were synthesized. The absorption spectra of the Au/Ag nanoparticles shifted from the spectrum of pure gold to one of pure silver. This demonstrates the CDrAG platform's promising potential to produce specific nanoparticle barcodes for high-throughput screening in chemistry, biology and a broad range of life science applications.

Encoded silica colloidal crystal beads as supports for potential multiplex immunoassay

We developed a new kind of suspension array for multiplexed immunoassays using silica colloidal crystal beads (SCCBs) as coding carriers. The monodisperse and size-controlled SCCBs were fabricated by a microfluidic device. Calcination was employed to improve the mechanical stability and lower the fluorescent background of the SCCBs. Immobilization of protein molecules on the surface of the SCCBs through chemical bonds was studied, and the modification condition was optimized to increase the detection sensitivity. Results indicated that the SCCBs as supports were more sensitive (0.92 ng/mL IgG) than the glass beads (27 ng/mL IgG) and the planar carriers (140 ng/mL IgG). A multiplex immunoassay showed the flexibility and feasibility of SCCBs array in clinical applications.

Multifunctional layer-by-layer coating of digitally encoded microparticles

In the field of medical diagnostics there is a growing need for inexpensive, accurate, and quick "multiplexing" assays. By making use of encoded microparticles, such assays allow simultaneous determination of the presence of several analytes in a biological sample. The microparticles under investigation in this study are encoded by writing a digital dot or bar code in their central plane. This study evaluates to what extent a "multifunctional" coating can be applied around the digitally encoded microparticles by the layer-by-layer (LbL) technology. We show that a LbL coating containing CrO2 nanoparticles allows (a) an optimal (optical) readout of the dot and bar codes, (b) a perfect orientation of the microparticles, necessary to be able to read the code, and (c) an optimal coupling of capture probes to the surface of the microparticles.

Optical fiber-based sensors: application to chemical biology

Optical fibers have been used to develop sensors based on nucleic acids and cells. Sensors employing DNA probes have been developed for various genomics applications and microbial pathogen detection. Live cell-based sensors have enabled the monitoring of environmental toxins, and have been used for fundamental studies on populations of individual cells. Both single-core optical fiber sensors and optical fiber sensor arrays have been used for sensing based on nucleic acids and live cells.

Nanoparticle coding: size-based assays using atomic force microscopy

Described herein is a novel strategy for the construction and interrogation of an assay platform based on (1) the size encoding of labeled nanoparticles; (2) the high imaging resolution of atomic force microscopy; and (3) evaporatively driven self-assembly of dense nanoparticle layers. This strategy employs two different sized nanoparticles that couple in the presence of a target analyte. In this example, one set of particles is a few hundred nanometers in size and acts as a capture substrate, while a second set of smaller particles serve as the analyte label. Thus, by forming an evaporatively assembled layer from a mixture of the two particle dispersions, the imaged size of the smaller particles when bound to the larger capture particles identifies the presence of the analyte. This letter demonstrates the feasibility of our bar-code strategy by concept tests using the binding specificity of biotin-modified silica nanoparticles (300-nm diameter) with streptavidin-labeled gold nanoparticles (10-nm diameter). The potential to extensively multiplex this assay strategy is briefly discussed.