Rewritable remote encoding and decoding of miniature multi-bit magnetic tags for high-throughput biological analysis

CdSe/ZnS quantum dot-encoded maleic anhydride-grafted PLA microspheres prepared through membrane emulsification for multiplexed immunoassays of tumor markers

Early diagnosis of tumor markers is of great importance for the successful treatment of cancer. As a high-throughput and high-sensitivity detection technology, liquid suspension biochips based on quantum dot (QD) encoded microspheres have been widely used in the immunodetection of tumor markers. In this work, maleic anhydride grafted PLA (PLA-MA) microspheres based on quantum dot encoding were used as carriers for liquid phase suspension biochips for the immunoassay of tumor markers. PLA-MA fluorescent beads are prepared by embedding CdSe/ZnS quantum dots in PLA-MA using Shirasu porous glass (SPG) membrane emulsification technology, which has high fluorescence intensity, good stability, and good dispersion. Fluorescent immunoassays on dipsticks found that PLA-MA microspheres have high biological activity and good stability, which is conducive to immunoassays. Based on this, using the characteristics of CdSe/ZnS quantum dots and flow cytometry, monochromatic and two-color coding methods were developed, and 9 distinguishable coding beads were prepared. The results showed that PLA-MA fluorescent microspheres exhibited good biocompatibility, stable coding signals, low background noise, and low detection limits when performing quaternary immunoassays on tumor markers CA125, CA199, CA724, and CEA by CdSe/ZnS QD-encoded PLA-MA microsphere binding flow cytometry.

Precisely Encoded Barcodes through the Structure-Fluorescence Combinational Strategy: A Flexible, Robust, and Versatile Multiplexed Biodetection Platform with Ultrahigh Encoding Capacities

With the rapid development of suspension array technology, microbeads-based barcodes as the core element with sufficient encoding capacity are urgently required for high-throughput multiplexed detection. Here, a novel structure-fluorescence combinational encoding strategy is proposed for the first time to establish a barcode library with ultrahigh encoding capacities. Based on the never revealed transformability of the structural parameters (e.g., porosity and matrix component) of mesoporous microbeads into scattering signals in flow cytometry, the enlargement of codes number has been successfully realized in combination with two other fluorescent elements of fluorescein isothiocyanate isomer I (FITC) and quantum dots (QDs). The barcodes are constructed with precise architectures including FITC encapsulated within mesopores and magnetic nanoparticles as well as QDs immobilized on the outer surface to achieve the ultrahigh encoding level of 300 accompanied with superparamagnetism. To the best of knowledge, it is the highest record of single excitation laser-based encoding capacity up to now. Moreover, a ten-plexed tumor markers bioassay based on the tailored-designed barcodes has been evaluated to confirm their feasibility and effectiveness, and the results indicate that the barcodes platform is a promising and robust tool for practical multiplexed biodetection.

Suspension arrays based on nanoparticle-encoded microspheres for high-throughput multiplexed detection

Spectrometrically or optically encoded microsphere based suspension array technology (SAT) is applicable to the high-throughput, simultaneous detection of multiple analytes within a small, single sample volume. Thanks to the rapid development of nanotechnology, tremendous progress has been made in the multiplexed detecting capability, sensitivity, and photostability of suspension arrays. In this review, we first focus on the current stock of nanoparticle-based barcodes as well as the manufacturing technologies required for their production. We then move on to discuss all existing barcode-based bioanalysis patterns, including the various labels used in suspension arrays, label-free platforms, signal amplification methods, and fluorescence resonance energy transfer (FRET)-based platforms. We then introduce automatic platforms for suspension arrays that use superparamagnetic nanoparticle-based microspheres. Finally, we summarize the current challenges and their proposed solutions, which are centered on improving encoding capacities, alternative probe possibilities, nonspecificity suppression, directional immobilization, and "point of care" platforms. Throughout this review, we aim to provide a comprehensive guide for the design of suspension arrays, with the goal of improving their performance in areas such as multiplexing capacity, throughput, sensitivity, and cost effectiveness. We hope that our summary on the state-of-the-art development of these arrays, our commentary on future challenges, and some proposed avenues for further advances will help drive the development of suspension array technology and its related fields.

The Scanning TMR Microscope for Biosensor Applications

We present a novel tunnel magnetoresistance (TMR) scanning microscope set-up capable of quantitatively imaging the magnetic stray field patterns of micron-sized elements in 3D. By incorporating an Anderson loop measurement circuit for impedance matching, we are able to detect magnetoresistance changes of as little as 0.006%/Oe. By 3D rastering a mounted TMR sensor over our magnetic barcodes, we are able to characterise the complex domain structures by displaying the real component, the amplitude and the phase of the sensor’s impedance. The modular design, incorporating a TMR sensor with an optical microscope, renders this set-up a versatile platform for studying and imaging immobilised magnetic carriers and barcodes currently employed in biosensor platforms, magnetotactic bacteria and other complex magnetic domain structures of micron-sized entities. The quantitative nature of the instrument and its ability to produce vector maps of magnetic stray fields has the potential to provide significant advantages over other commonly used scanning magnetometry techniques.

A composite element bit design for magnetically encoded microcarriers for future combinatorial chemistry applications

A composite element (CE) bit design for magnetically encoded microcarriers provides an increased coercivity range for longer bit codes as well as significant improvements to encoding density, reliability and read-out.