Long-Standing Stability of Silver Nanorod Array Substrates Functionalized Using a Series of Thiols for a SERS-Based Sensing Application

Abstract

Silver nanorod (AgNR) array substrates were fabricated using an oblique angle thermal evaporation technique; their long-term stability, surface uniformity and reproducibility, which are primary requirements for their widespread realistic application and commercialization, were assessed using surface-enhanced Raman scattering (SERS) spectroscopy. The nanorod surfaces were functionalized using a series of organic thiols, which range from hydrophilic to hydrophobic, to mimic various conditions that often arise during detection of hydrophilic/phobic analytes in a realistic application field. A group of these functionalized substrates was stored in ambient laboratory atmosphere; another in light minimized, moisture-free vacuum; while another was stowed carefully and neatly in water to mimic realistic conditions. The effects of these storing conditions were studied. A surfactant was added to the water to maintain consistent surface wetting in the third group. SERS spectra of nanorod substrates prior to functionalization were also recorded to investigate the effect of adventitious carbonaceous contaminants. A meticulous systematic study on the reproducibility of SERS signals was carried out: spot-to-spot, substrate-to-substrate, batch-to-batch, day-to-day. The relative standard deviation (RSD) shown by the SERS signals acquired from various spots of a single substrate was less than 3%, which is very similar to the only account reported so far, in which RSD is reported as 2%. The wetting behavior of these thiol functionalized AgNR substrates are investigated using static contact angle measurements. The functionalized substrates have exhibited excellent long-standing stability over a period of six months when stored appropriately; hence, they are highly suitable for mass production towards realistic application.

Facing Challenges in Real-Life Application of Surface-Enhanced Raman Scattering: Design and Nanofabrication of Surface-Enhanced Raman Scattering Substrates for Rapid Field Test of Food Contaminants

“…Furthermore, for analytes with no affinity for gold or silver or are highly hydrophobic, surface modification is commonly employed to attract target molecules to the SERS substrate via hydrophobic interactions, such as an alkanethiol self-assembled monolayer. − On the basis of the strong Au–S bonds, a monolayer of alkanethiol can be easily assembled on the substrates, in order to entrap hydrophobic targets. Compared with unmodified SERS substrate, a lower LOD can often be achieved for these modified SERS substrates, as shown in Table .…”

Insight into the fabrication and perspective of dendritic Ag nanostructures

“…It is very important to control the size, shape and distribution of the Ag nanoparticles (AgNPs) to systematically investigate their antibacterial, catalytic and electro-optical properties and new applications. Numerous of synthetic routes has been developed for fabricating various Ag NPs, such as wires [8,9], rods [10,11], triangular plates [12], cubes [13][14][15], polyhedrons [16], dendrites [17,18], etc. Dendritic Ag NPs have hierarchical branches and leaves as shown in Figure 1.…”

Structure‐Based Varieties of Polymeric Nanocarriers and Influences of Their Physicochemical Properties on Drug Delivery Profiles

“…Nanobiotechnology has become an integral part of daily life and essential in sectors like healthcare, beauty products, and food industry. [ 35 , 36 , 37 , 38 ] According to European Medicines Agency, nanotechnology serves as interface in translating fundamental findings of biology to their applications in healthcare. [ 39 ] Nanocarriers can overcome various limitations, which are otherwise faced by conventional delivery carriers, and accomplish superior biodistribution, efficient intra‐cellular trafficking, and organelle specific targeting.…”