A functionalization-free plasmonic hole-sphere nanogap SERS platform for reliable on-site analysis and oxide-state
Minjun Kim1, Damun Heo2, Sung Yoon Cho3
1Institute of Quantum Systems, Chungnam National University, Deajeon, 34134, Republic of Korea. myjeon@cnu.ac.kr.
None:
Developing plasmonic nanogaps via simple, lithography-free methods is essential for advancing practical surface-enhanced Raman spectroscopy (SERS) sensors. Here, we present a functionalization-free, lithography-free plasmonic hole-sphere nanogap (HSNG) platform, enabling sensitive differentiation of oxidation states at trace levels. The HSNG structure, fabricated by straightforward thermal annealing and metal deposition, achieves highly uniform nanogaps (signal deviation <15%), resulting in a strong (∼108) and uniform Raman enhancement. The fully metal-coated nanocavity structure eliminates background interference, significantly enhancing the analytical reliability in complex environmental samples. Using this platform, we demonstrated the ability to distinguish trace concentrations of As3+ and As5+, which were difficult to distinguish with conventional gold nanoparticles due to low signal intensity, at the on-site analysis level. Remarkably, reliable oxidation state identification remains possible even under reduced spectral resolution, ensuring compatibility with simplified detection setups such as bandpass filters or smartphone-based spectrometers. This HSNG-based SERS platform provides a scalable, accessible, and field-applicable approach to chemical sensing, readily extendable to the detection of diverse environmental contaminants.
Related Concept Videos
Functional Classification of Joints
The functional classification of joints is determined by the amount of mobility between the adjacent bones. Joints are functionally classified as a synarthrosis or immobile joint, an amphiarthrosis or slightly moveable joint, or as a diarthrosis, a freely moveable joint. Fibrous and cartilaginous joints can be functionally classified as either synarthroses or amphiarthroses, whereas all synovial joints are classified as diarthroses.
Synarthrosis
An...
Reliability and Validity
Oxidation Numbers
Detection of Black Holes
Their closest cousins are neutron stars, which are composed almost entirely of neutrons packed against each other, making them extremely dense. A neutron star has the same mass as the Sun but its diameter is only a few kilometers. Therefore, the escape velocity from their surface is close to the speed of light.
Not until the 1960s, when the first neutron...
Classification of Titrimetric Analysis Based on Reaction Types
Titrations between an acid and a base lead to neutralization reactions that form...
Pyruvate Oxidation
First, the enzyme pyruvate dehydrogenase removes the carboxyl group from pyruvate and releases it as carbon dioxide. The stripped molecule is then oxidized and releases electrons, which are then picked up by NAD+...
![Quantitative SERS Detection of Uric Acid via Formation of Precise Plasmonic Nanojunctions within Aggregates of Gold Nanoparticles and Cucurbit[n]uril](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F61682.jpg&w=3840&q=50)

