Single-Nanoparticle Differential Immunoassay for Multiplexed Gastric Cancer Biomarker Monitoring

Abstract

Precision medicine demands the best application of multiple unambiguous biomarkers to bring uniform decisions in disease prognosis. The remarkable development of heterogeneous immunoassay greatly promotes precision medicine when combined with the biomarker combination strategy. Nevertheless, the cumbersome washing steps in heterogeneous immunoassay have inevitably compromised the accuracy because of the sample losses and nature change of the matrix, challenging the further exploration of a more facile and lower limit-of-detection analysis. The new methodologies with high throughputs and specificity are never out of date to provide simultaneous evaluations and uniform decisions on multiple analytes through a simple process. Herein, we propose a new wash-free immunoassay, named differential assay, for multiplexed biomarker monitoring. The method is based on counting the number difference of unbound nanoparticle tags before and after immunoreactions from a solid support (i.e., magnetic microsphere) by single-particle inductively coupled plasma mass spectrometry (sp-ICP-MS), discarding the tedious washing steps. We primarily explore the proof-of-concept proposal within two types (sandwich and competitive assay), demonstrating the good feasibility for further facile clinical practice. To provide efficient multiplexed evaluations, we synthesized PtNPs with four diameters and screened the most suitable size for efficient differential immunoassay. The wash-free strategy was successfully utilized in simultaneous serological biomarker (CA724, CA199, and CEA) evaluation, with results in good accordance with those measured by the clinical routine method. Potentially, the proposed differential bioassay can be regarded as a more facile and valuable tool in malignancy prognosis and cancer recurrence monitoring.

Digital detection of proteins

“…Two recent publications have used mass spectrometry to count single labels in bead-based immunoassays, one approach based on TSA 142 and one using gold and silver nanoparticles. 143…”

Single-Molecule Protein Analysis by Centrifugal Droplet Immuno-PCR with Magnetic Nanoparticles

“…Ultrasensitive detection of proteins in complex biological media is crucial for medical diagnostics, biomarker discovery, drug development, etc . For example, in neurodegenerative disorders, such as Parkinson’s disease (PD) and Alzheimer’s disease (AD), protein biomarkers often exist in extremely low levels in the peripheral blood due to the blood–brain barrier. − Quantitative measurements of these biomarkers can be challenging using conventional methods, such as the enzyme-linked immunosorbent assay (ELISA) or chemiluminescence. − As a result, current clinical diagnostics of neurodegenerative diseases rely heavily on medical imaging and pathological analysis instead of molecular profiling. − …”

Construction of Magnetic Core–Large Mesoporous Satellite Immunosensor for Long‐Lasting Chemiluminescence and Highly Sensitive Tumor Marker Determination

“…[3][4][5] Therefore, it is of great significance to develop efficient and accurate detection methods for CEA. Currently, various techniques have been developed for the detection of CEA, such as inductively coupled plasma mass spectrometry, [6] colorimetry, [7] electrochemistry, [8] chemiluminescence (CL), [9] fluorescence, [10] electrochemistry, [11] surface enhanced Raman scattering, [12] and enzyme-linked immunosorbent assay (ELISA). [13] CL has been widely recognized as a rapid and highly sensitive technique with the advantages of high signal-to-noise ratio and wide detection range.…”