Surfactant-Free Vapor-Phase Synthesis of Single-Crystalline Gold Nanoplates for Optimally Bioactive Surfaces

Abstract

We report the surfactant-free vapor-phase synthesis of atomically flat and ultraclean gold nanoplates. These gold nanoplates can offer optimally functional surfaces through the immobilization of molecules without unspecific adsorption and defect, which could be quite valuable for diverse applications including biomedical sensing, plasmonics, molecular electronics, electrochemistry, etc. The ultraflat, ultraclean, and single-crystalline nanostructures, including gold nanoparticles (NPs), gold nanowires (NWs), gold nanobelts, and gold nanoplates, are stereoepitaxially grown on a substrate with a specific orientation. Moreover, the nanostructures can be selectively synthesized by experimental conditions and locations of the substrate. The geometry and orientation of the nanostructures show strong correlations, suggesting a growth process of seed NPs → NWs → nanobelts → nanoplates. This synthetic process can be explained by the mechanism in which the height-to-width ratio of gold nanostructures is determined by the ratio of the atom-supply rate by direct impingement to the atom-supply rate by surface diffusion. We finely tuned the shapes (NPs, NWs, nanobelts, or nanoplates) and sizes (from several micrometers to hundreds of micrometers) of the gold nanostructures by adjusting the deposition flux. Crucially, the surfactant-free and atomically flat gold nanoplates could be optimally bioactive surfaces. We substantially decreased the nonspecific binding of avidin by immobilizing the biotinylated molecules onto the gold nanoplates. Compared with thermally deposited gold films, the single-crystalline gold nanoplates showed a 100 times lower detection limit in the recognition of the biotin−avidin interaction. We anticipate that the gold nanoplates will bring us one-step closer to the realization of ideal biomolecular sensors because the several bioactive gold surfaces can be prepared by immobilizing various biological molecules onto the gold nanoplates.

Intra-nanogap controllable Au plates as efficient, robust, and reproducible surface-enhanced Raman scattering-active platforms

“…As starting materials, single-crystalline Au nanoplates are prepared according to a previous report. 28 The prepared Au nanoplates and AgI powder are placed in a glass reaction tube, and then the reaction tube is put in the horizontal quartz tube furnace system. Next, the furnace system is heated under a ow of Ar gas at a rate of 150 standard cubic centimeters per minute (sccm).…”

“…The ultra-at, ultraclean, and single-crystalline Au nanoplates were employed as starting nanomaterials. 28 The Au nanoplates were transformed to single-crystalline AuAg alloy nanoplates aer reaction with AgI in the vapor phase. We investigated the alloy formation mechanism and thus can control the composition of alloy nanoplates accurately.…”

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].…”