Highly Sensitive, Robust, and Recyclable TiO2/AgNP Substrate for SERS Detection

Pure metallic 1T phase Sc-doped MoS2 Fusilli morphology for ultra-sensitive SERS detection

Surface-enhanced Raman spectroscopy (SERS) offers great potential for sensitive molecular detection in fields ranging from environmental science to healthcare diagnostics, but its efficacy is limited by the low enhancement factors and sensitivity of semiconductor substrates. In this study, we synthesized scandium-doped 1T-phase molybdenum disulfide (Sc-doped 1T-MoS2) substrates and measured their performance against standard 2H-phase molybdenum disulfide (2H-MoS2) and undoped 1T-MoS2. Here, the substrate-analyte molecule interaction was amplified by doping metallic MoS2 with Sc, which resulted in a notable rise in SERS enhancement for non-metal-sulfide semiconductor materials. The modified 0.4Sc-MoS2 substrate not only maintains the metal-like conductivity and stability inherent to the 1 T phase but also significantly enhances SERS sensitivity. The doped substrates demonstrated significantly improved SERS enhancement factors and reduced detection limits to 5.3 × 10-5 M for aspartame (APM) and 5.0 × 10-9 M for thiabendazole (TBZ). To validate and understand the mechanism behind these phenomena, density functional theory (DFT) calculations have been used to study the interaction of methylene blue (MB) molecules with xSc-MoS2, 2H-MoS2 and 1T-MoS2. Our findings not only improve the understanding of physicochemical interactions within Raman-enhancing substrates but also pave the way for developing high-performance semiconductor-based substrates for Raman spectroscopy. This advancement is a critical step toward the practical implementation of these materials in a wide range of sensing applications.

Breaking Barriers: Exploring Neurotransmitters through In Vivo vs. In Vitro Rivalry

Neurotransmitter analysis plays a pivotal role in diagnosing and managing neurodegenerative diseases, often characterized by disturbances in neurotransmitter systems. However, prevailing methods for quantifying neurotransmitters involve invasive procedures or require bulky imaging equipment, therefore restricting accessibility and posing potential risks to patients. The innovation of compact, in vivo instruments for neurotransmission analysis holds the potential to reshape disease management. This innovation can facilitate non-invasive and uninterrupted monitoring of neurotransmitter levels and their activity. Recent strides in microfabrication have led to the emergence of diminutive instruments that also find applicability in in vitro investigations. By harnessing the synergistic potential of microfluidics, micro-optics, and microelectronics, this nascent realm of research holds substantial promise. This review offers an overarching view of the current neurotransmitter sensing techniques, the advances towards in vitro microsensors tailored for monitoring neurotransmission, and the state-of-the-art fabrication techniques that can be used to fabricate those microsensors.

Capillary Tube Surface-Enhanced Raman Scattering Substrate and High-Sensitivity Molecule Detection

Surface-enhanced Raman scattering (SERS) greatly improves molecule sensitivity compared with ordinary Raman spectroscopy. To excite and detect SERS efficiently, we fabricated glass-made microcapillary tubes decorated with silver nanoparticles inside them. The capillary tubes work as sample containers, where the required sample volume is in the order of a few nanoliters. The capillary tubes also play the role of optical waveguides. The tubes guide the excitation laser light through them so that the light illuminates whole silver nanoparticles inside the tubes at once. The tubes guide the SERS light to the tube end efficiently. The decoration of silver nanoparticles inside the tubes was performed by the silver mirror reaction. By making the tubes thinner and longer, highly sensitive SERS spectroscopy can be achieved. Our method would be a powerful tool for high-sensitivity molecule detection where the sample volume and concentration are extremely low.

Ag Nanoparticles Decorated CuO@RF Core-Shell Nanowires for High-Performance Surface-Enhanced Raman Spectroscopy Application

Vertical-aligned CuO nanowires have been directly fabricated on Cu foil through a facile thermal oxidation process by a hotplate at 550 °C for 6 h under ambient conditions. The intermediate layer of resorcinol-formaldehyde (RF) and silver (Ag) nanoparticles can be sequentially deposited on Cu nanowires to form CuO@RF@Ag core-shell nanowires by a two-step wet chemical approach. The appropriate resorcinol weight and silver nitrate concentration can be favorable to grow the CuO@RF@Ag nanowires with higher surface-enhanced Raman scattering (SERS) enhancement for detecting rhodamine 6G (R6G) molecules. Compared with CuO@Ag nanowires grown by ion sputtering, CuO@RF@Ag nanowires exhibited a higher SERS enhancement factor of 5.33 × 10⁸ and a lower detection limit (10^-12 M) for detecting R6G molecules. This result is ascribed to the CuO@RF@Ag nanowires with higher-density hot spots and surface-active sites for enhanced high SERS enhancement, good reproducibility, and uniformity. Furthermore, the CuO@RF@Ag nanowires can also reveal a high-sensitivity SERS-active substrate for detecting amoxicillin (10^-10 M) and 5-fluorouracil (10^-7 M). CuO@RF@Ag nanowires exhibit a simple fabrication process, high SERS sensitivity, high reproducibility, high uniformity, and low detection limit, which are helpful for the practical application of SERS in different fields.