Streptavidin-Coated Au Nanoparticles Coupled with Biotinylated Antibody-Based Bifunctional Linkers as Plasmon-Enhanced Immunobiosensors

Abstract

The localized surface plasmon resonance (LSPR) effect of aggregating gold nanoparticles (AuNPs) has facilitated the development of colorimetric biosensors that can potentially be employed on site. We have developed an effective strategy to enhance the LSPR color-change signal by decoupling target detection and signal generation steps during immunobiosensing. The biosensor consists of streptavidin-coated AuNPs coupled with biotinylated antibacteria antibody as bifunctional linkers (BLs). While a BL can function both as an immunoreactor to bind to the target and as a cross-linker to aggregate AuNPs, its cross-linking function is largely limited when it binds with the target. We investigated the effect of number density (D n ) of AuNPs on the LSPR signal enhancement and the attendant improvement in detection sensitivity and rapidity of our biosensor by changing the particle size (5 to 50 nm diameter) when holding the absorbance of the AuNPs solution constant (Abs = 0.4 at 10× dilution). The performance enhancement of the biosensor was demonstrated by detecting a model target, streptavidin, and two bacteria, Escherichia coli and Legionella pneumophila. The results show that when Abs is held constant, the systems with lower D n but larger particles perform better. Therefore, our visual biosensing system can be suitably composed to maximize the limit of detection and rapidity.

The Biotin–Avidin Interaction in Biotinylated Gold Nanoparticles and the Modulation of Their Aggregation

“…Yield: 240 mg (84%). 1 (7). A solution of 6 (240 mg, 0.47 mmol, 1 eq) was stirred in the presence of activated molecular sieves in anhydrous DMF (8 mL) for 30 min, then a solution of 3 (269 mg, 0.705 mmol, 1.5 eq) in anhydrous DMF (3 mL) was added, followed by DIPEA (98 µL, 0.56 mmol, 1.2 eq) and the reaction was heated at 70 • C for 2 days.…”

“…However, the multivalent interactions at play enable the formation of complex aggregation patterns. The problem has been addressed under specific conditions or by focusing on how this interaction may be exploited to govern specific targeting [7][8][9][10][11][12][13]. The most accurate investigation carried out so far on this issue was performed by Pérez-Luna using streptavidin and biotinylated nanoparticles [14].…”

“…It presented conditions leading to nanoparticle aggregation and pointed out the relevance of slow kinetics in the disaggregation process. Most of the studies aim at exploiting the practical application of the biotin/avidin interaction as in immuno-biosensing [4]; other biological application [5], such as in targeted delivery [6]; or were devoted to control the interaction between different types of gold nanosystems like nanorods [7,8] or nanosystems presenting different geometries [10]. A thorough analysis on how the biotin-(strept)avidin binding may control both the interaction of biotinylated nanosystems with the protein and how this may affect the crosslinking of the system is, however, still well deserved.…”

Nanohole-boosted electron transport between nanomaterials and bacteria as a concept for nano–bio interactions

“…The rapid colonization of pathogenic bacteria and large amounts of toxic metabolites cause local tissue necrosis or systemic infection 4 , and the design of approaches for effectively combating pathogenic bacteria is a tricky global problem 5 , 6 . Unfortunately, natural antimicrobials present unstable chemical properties, exert a limited antibacterial effect, and exhibit obvious drug resistance 7 , 8 .…”

Gold Nanoparticles Functionalized with Angiogenin for Wound Care Application

“…In the case of gold nanoparticles, physical interactions may depend on three concurrent effects: (i) ionic attraction between the negatively charged citrate capped-AuNPs and the positively charged groups of the molecules; (ii) hydrophobic interactions; (iii) dative binding between the gold conducting electrons and amino acid sulfur atoms. On the other hand, chemical interactions can take place through: (i) Au-S bonds with thiol groups; (ii) bifunctional linkers and (iii) adapter molecules like streptavidin and biotin [ 41 , 42 , 43 ].…”