Development of homogeneous plasmonic potency assay using gold nanoparticle immunocomplexes

Development of a multiplexing potency assay using upconverting nanoparticles-based luminescence resonance energy transfer

A homogeneous particle-based immunoassay using upconverting nanoparticles (UCNPs) has been developed for multiplexing potency analysis of two different therapeutic monoclonal antibodies (mAbs) in a fixed-combination formulation.The UCNP, considered as the best donor lumiphore for luminescence resonance energy transfer (LRET), offers long lasting excitation state and increased signal-to-noise (S/N) ratio due to low autofluorescence effect and light scattering from near infrared (NIR) excitation. In this study, the dose-response curves for each therapeutic mAb were generated using two distinct UCNPs. This proof-of-concept LRET-based immunoassay demonstrated a novel approach for increasing testing throughput and analyzing the potency of mixed therapeutic mAbs in co-formulated products.

Label-Free, Rapid and Facile Gold-Nanoparticles-Based Assay as a Potential Spectroscopic Tool for Trastuzumab Quantification

Monoclonal antibody-based immunotherapy is one of the pillars of cancer treatment. However, for an efficient and personalized approach to the therapy, a quantitative evaluation of the right dose for each patient is required. In this study, we developed a simple, label-free, and rapid approach to quantify Trastuzumab, a humanized IgG1 monoclonal antibody used against human epidermal growth factor receptor 2 (HER2), overexpressed in breast cancer patients, based on localized surface plasmon resonance (LSPR). The central idea of this work was to use gold nanoparticles (AuNPs) as plasmonic scaffolds, decorated with HER2 binders mixed with oligo-ethylene glycol (OEG) molecules, to tune the surface density of the attached macromolecules and to minimize nonspecific binding events. Specifically, we characterized and optimized a self-assembled monolayer of mixed alkylthiols terminated with nitrilotriacetic acid (NTA), and OEG3 as a spacing ligand to achieve both excellent dispersibility and high reliability in protein immobilization. The successful immobilization of histidine-tagged HER2 (His-tagged HER2) on NTA via cobalt (II) chelates was demonstrated, confirming the fully functional attachment of the proteins to the AuNP surface. The proposed design demonstrates the capability of producing a clear readout that enables the transduction of a Trastuzumab/HER2 binding event into optical signals based on the wavelength shifts in LSPR, which allowed for detecting clinically relevant concentrations of Trastuzumab down to 300 ng/mL in the buffer and 2 µg/mL in the diluted serum. This strategy was found to be fast and highly specific to Trastuzumab. These findings make the present platform an auspicious tool for developing affordable bio-nanosensors.