Compact Magneto‐Fluorescent Colloids by Hierarchical Assembly of Dual‐Components in Radial Channels for Sensitive Point‐of‐Care Immunoassay

Abstract

Exploring signal amplification strategies to enhance the sensitivity of lateral flow immunoassay (LFIA) is of great significance for point-of-care (POC) testing of low-concentrated targets in the field of in vitro diagnostics. Here, a highly-sensitive LFIA platform using compact and hierarchical magnetofluorescent assemblies as both target-enrichment substrates and optical sensing labels is demonstrated. The large-pored dendritic templates are utilized for high-density incorporation of both superparamagnetic iron oxide nanoparticles (IOs) and quantum dots (QDs) within the vertical channels. The hierarchical structure is built via affinity-driven assembly of IOs and QDs from organic phase with silica surface and mercapto-organosilica intermediate layer, respectively. The sequential assembly with central-radial channels enables 3D loading of dual components and separately controlling of discrete functionalities. After the alkyl-organosilica encapsulation and silica sealing, the composite spheres exhibit high stabilities and compatibility with LFIA for procalcitonin (PCT) detection. With the assistance of liquid-phase antigen-capturing, magnetic enrichment, and fluorescence-signal amplification, a limit of detection of 0.031 ng mL −1 for PCT is achieved with a linear range from 0.012 to 10 ng mL −1 . The current LFIA is robust and validated for PCT detection in real serum, which holds great diagnostic significance for precise guidance of antibiotic therapy with POC manner.

Ultrasensitive Competitive Lateral Flow Immunoassay with Visual Semiquantitative Inspection and Flexible Quantification Capabilities

“…The surface carboxylation caused a prominently decrease of the Zeta potential to −67.9 mV, which was further altered to −24.1 mV owing to the subsequent antibody conjugation on the nanoparticle surface. 43,46 Optimization of Loading AuNPs on dSiO 2 . How to maximize the loading content of AuNPs in the assembly while maintaining the intrinsic plasmonic feature of the building blocks is of particular significance.…”

“…41 Our group has employed dSiO 2 colloids as a carrier to assemble magnetic and optical units controllably for enhancing the sensitivity of LFIA. 42,43 In this work, a new CLFIA with flexible readout was fabricated for ENR detection using compact three-dimensional AuNPs assemblies as nanolabels. The nanolabels (designated as iSAS) are prepared from assembly of hydrophobic AuNPs with the dSiO 2 affiliative supports, followed by silica encapsulation, surface functionalization, and antibody conjugation (Scheme 1A).…”

Recent Advances in Silica-Nanomaterial-Assisted Lateral Flow Assay

“…Furthermore, they also optimized the QD size to balance the loading amount and quantum yields [ 58 ], and the LOD of CPR was further lowered to 5 pg mL −1 . Liang et al loaded both QDs and iron oxide nanoparticles into DMSNs for procalcitonin detection [ 59 ]. Here, iron oxide nanoparticles were used for magnetic separation.…”

Hue Recognition Competitive Fluorescent Lateral Flow Immunoassay for Aflatoxin M1 Detection with Improved Visual and Quantitative Performance

“…On the other hand, it is better to transform the heterogeneous solid–liquid immunoreaction on the strip to the homogeneous solution reaction, thus favoring both the immune-binding kinetics and the target analyte pre-concentration via magnetic separation. Although some dual-component hybrids and multilayer assembly strategies have been reported to prepare magneto-fluorescent structures for highly sensitive immunoassay, − the compatibility of incorporated units still needs to be improved.…”