No abstract

Rapid and sensitive diagnosing hematological infections based on the separation and detection of pathogenic bacteria in the patient's blood is a significant challenge. To address this, we herein present a new barcodes technology that can simultaneously capture and detect multiple types of pathogenic bacteria from a complex sample. The barcodes are poly (ethylene glycol) (PEG) hydrogel inverse opal particles with characteristic reflection peak codes that remain stable during bacteria capture on their surfaces. As the spherical surface of the particles has ordered porous nanostructure, the barcodes can provide not only more surface area for probe immobilization and reaction, but also a nanopatterned platform for highly efficient bioreactions. In addition, the PEG hydrogel scaffold could decrease the non-specificity adsorption by its anti-adhesive effect, and the decorated aptamer probes in the scaffolds could increase the sensitivity, reliability, and specificity of the bacteria capture and detection. Moreover, the tagged magnetic nanoparticles in the PEG scaffold could impart the barcodes with controllable movement under magnetic fields, which can be used to significantly increase the reaction speed and simplify the processing of the bioassays. Based on the describe barcodes, it was demonstrated that the bacteria could be captured and identified even at low bacterial concentrations (100 CFU mL) within 2.5h, which is effectively shortened in comparison with the "gold standard" in clinic. These features make the barcodes ideal for capturing and detecting multiple bacteria from clinical samples for hematological infection diagnostics.

The development of a highly sensitive platform for multiplex circulating microRNAs (miRNAs) detection is important for clinical diagnosis. Here, a new type of porous hydrogel encapsulated photonic crystal (PhC) barcodes is presented with integrated rolling circle amplification (RCA) strategy for multiplex miRNA quantification. As the surrounding porous hydrogel shells of the PhC barcodes are interconnected inverse opal structure with hydrophilic scaffolds, they can provide homogeneous water surrounding for the miRNA targets reaction and RCA. The encapsulated PhC cores of the barcodes can offer stable diffraction peaks for encoding different miRNAs and their RCAs during the detection. By integrating the advantages of PhC barcodes and RCA, it is demonstrated that the technology shows acceptable accuracy and detection reproducibility for the rapid quantification of lowabundance miRNAs, with the limits of detection of 20 fM. Thus, the proposed porous hydrogel encapsulated PhC barcodes provide a new platform for the multiplex quantification of low-abundance targets for practical applications.

With the increasing demand for multiplex and high-throughput analysis of large numbers of biomolecules, multiplex technology becomes a promising tool for carrying out thousands of individual reactions at the same time for large-scale biological analysis. Among current technologies, suspension arrays based on appropriate barcode particles have been popularly used in multiplex bioassays of many research fields with the ability of unique encoding, such as in the clinical, medicinal, nutritional, and environmental fields. Besides the unique form of barcode, these particles have higher flexibility, better sensitivity, and faster reaction kinetics. In this review, we present some examples of typical barcode particles that are divided into different groups depending on how they are encoded and their applications in multiplex bioassays for different targets such as proteins, DNA and RNA sequences, and cells. The bioassays for monitoring food safety, drug research, and clinical diagnosis are also described.

Barcodes-based suspension array have for demonstrated values in multiplex assay of tumor markers. Photonic barcodes which are encoded by their characteristic reflection peaks are the important supports for suspension array due to their stable code, low fluorescent background and high surface-volume ratio. Attempts to develop this technology tend to improve the function of the photonic barcodes. Here, we present a new type of hybrid hydrogel photonic barcodes for efficient multiplex assays. This photonic barcodes are hybrid inverse opal hydrogel composed of poly(ethylene glycol) diacrylate (PEG-DA) and agarose. The polymerized PEG-DA hydrogel could guarantee the stabilities of the inverse opal structure and its resultant code, while the agarose could offer active chemical groups for the probe immobilization and homogeneous water surrounding for the bioassay. In addition, the interconnected pores inverse opal structure could provide channels for biomolecules diffusing and reaction into the voids of barcodes. These features imparted the hybrid hydrogel photonic barcodes with limits of detection (LOD) of 0.78ng/mL for carcinoembryonic antigen (CEA) and 0.21ng/mL for α-fetoprotein (AFP), respectively. It was also demonstrated that the proposed barcodes showed acceptable accuracy and detection reproducibility, and the results were in acceptable agreement with those from common clinic method for the detections of practical clinical samples. Thus, our technique provides a new platform for simultaneous multiplex immunoassay.