Expanding the codes: The development of density-encoded hydrogel microcarriers for suspension arrays

Water-stable perovskite-silica nanocomposites for encoded microbeads construction and multiplexed detection

All-inorganic lead halide perovskite nanocrystals exhibiting bright luminescence have great potential as fluorescence elements for optical encoding. However, their limited stability in water hinders the application in biosensing. In this study, novel optical encoded microbeads based on CsPbX3 (X = Cl, Br) nanocrystals are developed and applied in bead-based suspension arrays for the first time. Through the in-situ crystallization of CsPbX3 nanocrystals within mesoporous silica nano-templates (MSNs), accompanied by mesopores collapse after sintering, CsPbX3@MSNs (X3M) nanocomposites with uniform morphology and stable fluorescence intensity in aqueous solutions for up to 50 days are obtained. By assembling X3M with microspheres to form a host-guest structure, an optical encoding microbead (MX3M) library is established by varying the X3M ratio, halide composition, and the size of host microspheres, which can be easily decoded under multi-channel flow cytometer. As a result, MX3M exhibits outstanding capacity for specific target capture and negligible nonspecific absorption performance in the multiplex nucleic acid detection of respiratory viruses, with a low limit of detection (10 copies/rxn). This result highlights the tremendous potential of MX3M encoded microbeads constructed based on CsPbX3 nanocrystals for multiplexed bioassays.

Magnetic quantum dots barcodes using Fe3O4/TiO2 with weak spectral absorption in the visible region for high-sensitivity multiplex detection of tumor markers

Magnetic quantum dot (QD) barcode holds great potential for automatic suspension array and rapid point-of-care detection since it enables simultaneous target encoding, enrichment and separation. However, a serious obstacle to enhancing the encoding capacity of magnetic QD microbeads (MBs) is the fluorescence quenching of magnetic nanoparticles (MNPs) to quantum dots (QDs) in the visible wavelength range due to the broad and strong optical absorption spectrum of MNPs. Here, we report Fe₃O₄/TiO₂ core/shell MNPs and CdSe/ZnS QDs for the construction of dual-function magnetic QD barcodes. Fe₃O₄/TiO₂ MNPs can significantly inhibit fluorescence quenching because the weak absorption of visible light by the TiO₂. The two-dimension barcode library of 30 magnetic QD barcodes was constructed based on Fe₃O₄/TiO₂ MNPs and CdSe/ZnS QDs. Moreover, the magnetic QD barcodes showed high sensitivity for the multiplex detection of four tumor markers, cancer antigen 125 (CA125), cancer antigen 199 (CA199), alpha-fetoprotein (AFP), and neuron specific enolase (NSE) with detection limits of 0.89 KU/L, 0.72 KU/L, 0.05 ng/mL, and 0.15 ng/mL, respectively. This bifunctional magnetic QD barcodes are promising for automatic high-sensitivity multiplex bioassay.

Production and Utility of Extracellular Vesicles with 3D Culture Methods

In recent years, extracellular vesicles (EVs) have emerged as promising biomarkers, cell-free therapeutic agents, and drug delivery carriers. Despite their great clinical potential, poor yield and unscalable production of EVs remain significant challenges. When using 3D culture methods, such as scaffolds and bioreactors, large numbers of cells can be expanded and the cell environment can be manipulated to control the cell phenotype. This has been employed to successfully increase the production of EVs as well as to enhance their therapeutic effects. The physiological relevance of 3D cultures, such as spheroids, has also provided a strategy for understanding the role of EVs in the pathogenesis of several diseases and to evaluate their role as tools to deliver drugs. Additionally, 3D culture methods can encapsulate EVs to achieve more sustained therapeutic effects as well as prevent premature clearance of EVs to enable more localised delivery and concentrated exosome dosage. This review highlights the opportunities and drawbacks of different 3D culture methods and their use in EV research.