Multivalent Antibody–Nanoparticle Conjugates To Enhance the Sensitivity of Surface-Enhanced Raman Scattering-Based Immunoassays

Abstract

Multivalent immunoprobes can improve the sensitivity of biosensors because increased valency can strengthen the binding affinity between the receptor and target biomolecules. Here, we report surface-enhanced Raman scattering (SERS)-based immunoassays using multivalent antibody-conjugated nanoparticles (NPs) for the first time. Multivalent antibodies were generated through the ligation of Fab fragments fused with Fc-binding peptides to immunoglobulin G. This fabrication method is easy and fast because of the elimination of heterologous protein expression, high degrees of antibody modifications, and covalent chemical ligation steps. We constructed multivalent antibody−NP conjugates (MANCs) and employed them as SERS immunoprobes. MANCs improved the sensitivity of SERS-based immunoassays by 100 times compared to standard antibody−NP conjugates. MANCs will increase the feasibility of practical SERS-based immunoassays.

Targeted immuno-antiretroviral HIV therapeutic approach to provide dual protection and boosts cellular immunity: A proof-of-concept study

“…The observed enhanced binding affinity of xfR5-D+T NP (Table 2) could be attributed to the multi-valent interaction strengthening the binding affinity between the target biomolecules on the NP and the receptors on cell-surface (39). Previous theoretical calculation has illustrated that mAb conjugated to NP via flexible PEG spacers, could result in ten mAb/receptor complex formation per one NP interacting with respective receptor-expressing cells (39), although, one naïve xfR5 mAb in solution could only bind/block one CCR5 molecule per cell (32) (Supplementary figure 1). Therefore, based on the above theoretical assumption, the xfR5-D+T NP was expected to elucidate 10-times higher affinity than the naive xfR5 mAb.…”

Advances in Antibody Preparation Techniques for Immunoassays of Total Aflatoxin in Food

“…In addition, antibody engineering can lead to better genetically engineered antibodies such as recombinant antibody fragment of antigen binding (Fab) [ 66 ] and multivalent antibodies [ 67 ]. Although the preparation and application of these antibodies is theoretical with technical testing, this area is a key new direction of antibody research.…”

Troponin Aptamer on an Atomically Flat Au Nanoplate Platform for Detection of Cardiac Troponin I

“…Atomically flat surfaced nanomaterials have been interfaced with various kinds of systems, improving nano-devices remarkably [17][18][19][20][21][22][23]. For the development of high-performance biosensors, it is important to prepare bioactive surfaces that can provide the maximized functionality of bioreceptors [23].…”

“…For the development of high-performance biosensors, it is important to prepare bioactive surfaces that can provide the maximized functionality of bioreceptors [23]. Well-ordered bioreceptors on atomically flat surfaces can exhibit improved affinity and specificity toward target species, thus they can be important building blocks in the realization of high-performance biological sensors [17][18][19][20][21][22]. To obtain an extremely sensitive and selective cTnI sensor, we combined an advanced bioreceptor of cTnI with an atomically flat Au (111) surface of a nanoplate.…”

“…To obtain an extremely sensitive and selective cTnI sensor, we combined an advanced bioreceptor of cTnI with an atomically flat Au (111) surface of a nanoplate. Previously, our group reported that the single-crystalline Au nanoplates have ultraflat and ultraclean surfaces [17] and thus biomolecules could be uniformly immobilized on the atomically flat Au nanoplates [17][18][19]. Additionally, aptamers, oligonucleic acids with high affinity and specificity toward target molecules, have been considered as outstanding bioreceptors because they have the beneficial properties of rapid production, high stability, and easy functionalization [4,5,24].…”