Plasmonic Titanium Nitride Nanohole Arrays for Refractometric Sensing.

Group IVB metal nitrides have attracted great interest as alternative plasmonic materials. Among them, titanium nitride (TiN) stands out due to the ease of deposition and relative abundance of Ti compared to those of Zr and Hf metals. Even though they do not have Au or Ag-like plasmonic characteristics, they offer many advantages, from high mechanical stability to refractory behavior and complementary metal oxide semiconductor-compatible fabrication to tunable electrical/optical properties. In this study, we utilized reactive RF magnetron sputtering to deposit plasmonic TiN thin films. The flow rate and ratio of Ar/N2 and oxygen scavenging methods were optimized to improve the plasmonic performance of TiN thin films. The stoichiometry and structure of the TiN thin films were thoroughly investigated to assess the viability of the optimized operation procedures. To assess the plasmonic performance of TiN thin films, periodic nanohole arrays were perforated on TiN thin films by using electron beam lithography and reactive ion etching methods. The resulting TiN periodic nanohole array with varying periods was investigated by using a custom microspectroscopy setup for both reflection and transmission characteristics in various media to underline the efficacy of TiN for refractometric sensing.

Plasmonic Magnesium Nanoparticles Are Efficient Nanoheaters.

Understanding and guiding light at the nanoscale can significantly impact society, for instance, by facilitating the development of efficient, sustainable, and/or cost-effective technologies. One emergent branch of nanotechnology exploits the conversion of light into heat, where heat is subsequently harnessed for various applications including therapeutics, heat-driven chemistries, and solar heating. Gold nanoparticles are overwhelmingly the most common material for plasmon-assisted photothermal applications; yet magnesium nanoparticles present a compelling alternative due to their low cost and superior biocompatibility. Herein, we measured the heat generated and quantified the photothermal efficiency of the gold and magnesium nanoparticle suspensions. Photothermal transduction experiments and optical and thermal simulations of different sizes and shapes of gold and magnesium nanoparticles showed that magnesium is more efficient at converting light into heat compared to gold at near-infrared wavelengths, thus demonstrating that magnesium nanoparticles are a promising new class of inexpensive, biodegradable photothermal platforms.

Nanoplasmonic biosensors: Theory, structure, design, and review of recent applications.

Nanoplasmonic biosensing shows an immense potential to satisfy the needs of the global health industry - low-cost, fast, and portable automated systems; highly sensitive and real-time detection; multiplexing and miniaturization. In this review, we presented the theory of nanoplasmonic biosensing for popular detection schemes - SPR, LSPR, and EOT - and underline the consideration for nanostructure design, material selection, and their effects on refractometric sensing performance. Later, we covered the bottom-up and top-down nanofabrication methods for nanoplasmonic biosensors. Subsequently, we reviewed the recent examples of nanoplasmonic biosensors over a wide range of clinically relevant analytes in the diagnosis and prognosis of a wide range of diseases and conditions such as biomarker proteins, infectious bacteria, viral agents. Finally, we discussed the challenges of nanoplasmonic biosensing toward clinical translation and proposed strategic avenues to be competitive against current clinical detection methods. Hopefully, nanoplasmonic biosensing can realize its potential through successful demonstrations of clinical translation in the upcoming years.

Aptamer and nanomaterial based FRET biosensors: a review on recent advances (2014-2019).

Fluorescence resonance energy transfer, one of the most powerful phenomena for elucidating molecular interactions, has been extensively utilized as a biosensing tool to provide accurate information at the nanoscale. Numerous aptamer- and nanomaterial-based FRET bioassays has been developed for detection of a large variety of molecules. Affinity probes are widely used in biosensors, in which aptamers have emerged as advantageous biorecognition elements, due to their chemical and structural stability. Similarly, optically active nanomaterials offer significant advantages over conventional organic dyes, such as superior photophysical properties, large surface-to-volume ratios, photostability, and longer shelf life. In this report (with 175 references), the use of aptamer-modified nanomaterials as FRET couples is reviewed: quantum dots, upconverting nanoparticles, graphene, reduced graphene oxide, gold nanoparticles, molybdenum disulfide, graphene quantum dots, carbon dots, and metal-organic frameworks. Tabulated summaries provide the reader with useful information on the current state of research in the field. Graphical abstract Schematic representation of a fluorescence resonance energy transfer-based aptamer nanoprobe in the absence and presence of a given target molecule (analyte). Structures are not drawn to their original scales.