The burgeoning field of nanotechnology aims to create and deploy nanoscale structures, devices, and systems with novel, size-dependent properties and functions. The nanotechnology revolution has sparked radically new technologies and strategies across all scientific disciplines, with nanotechnology now applied to virtually every area of research and development in the US and globally. NanoFlorida was founded to create a forum for scientific exchange, promote networking among nanoscientists, encourage collaborative research efforts across institutions, forge strong industry-academia partnerships in nanoscience, and showcase the contributions of students and trainees in nanotechnology fields. The 2019 NanoFlorida International Conference expanded this vision to emphasize national and international participation, with a focus on advances made in translating nanotechnology. This review highlights notable research in the areas of engineering especially in optics, photonics and plasmonics and electronics; biomedical devices, nano-biotechnology, nanotherapeutics including both experimental nanotherapies and nanovaccines; nano-diagnostics and -theranostics; nano-enabled drug discovery platforms; tissue engineering, bioprinting, and environmental nanotechnology, as well as challenges and directions for future research.

We demonstrate a simple three-step gold thin-film sample preparation process to enhance the morphology and lithographic precision using helium ion based direct-writing. The procedure includes metal deposition, heat treatment and template stripping, which produce smooth monocrystalline gold grains with sizes up to 500 nm and an average surface roughness of 0.267 nm. By using a helium ion microscope, we can fabricate structures with feature sizes less than 20 nm in a 100 nm thick gold film with high-quality sidewalls. We demonstrate the efficacy of this technique by producing high-quality double nanohole (DNH) nanoapertures for single nanoparticle trapping in a single grain of 100 nm thick gold. This procedure can be applied to a wide range of antenna geometries and features that need to be fabricated producing optical and or electronic devices.

This paper presents simulation results for double nanohole and inverted bowtie nanoapertures optimized to resonate in the short-wave infrared regime (1050 nm and 1550 nm). These geometries have shown great promise for trapping nanoparticles with applications in optical engineering, physics, and biology. Using a finite element analysis tool, we found that the outline length for inverted bowtie nanoapertures in a 100 nm thick gold film with a 20 nm gap dimension having an optimized transmission resonance for 1050 nm and 1550 nm optical wavelengths is 106.5 nm and 188.5 nm, respectively. With the same gap size, the radii of the circles for the double nanohole nanoapertures are 72 nm and 128 nm. The near-field enhancements of the two structures are almost the same, while the double nanohole geometries have a 20% larger full width at half-maximum than the inverted bowtie. Next, by studying the effect of changing the inner radii of the inverted bowtie corners, we found that the difference between 2 nm and 6 nm corner radii can blue-shift the optical resonance by up to 45 nm. As a result of not having any inner corners, the double nanohole structure requires less precise fabrication and therefore could potentially have a higher successful yield of nanoapertures during the manufacturing process. Lastly, we will show experimental results that confirm the optical resonance of the nanoapertures at 1550 nm. These results will enable better performance and signal-to-noise ratio in nanoaperture trapping for the short-wave infrared wavelength regime.

Recent advances in single-molecule techniques have led to new discoveries in analytical chemistry, biophysics, and medicine. Understanding the structure and behavior of single biomolecules provides a wealth of information compared to studying large ensembles. However, developing single-molecule techniques is challenging and requires advances in optics, engineering, biology, and chemistry. In this paper, we will review the state of the art in single-molecule applications with a focus over the last few years of development. The advancements covered will mainly include light-based in vitro methods, and we will discuss the fundamentals of each with a focus on the platforms themselves. We will also summarize their limitations and current and future applications to the wider biological and chemical fields. This article is categorized under: Laboratory Methods and Technologies > Imaging Laboratory Methods and Technologies > Macromolecular Interactions, Methods Analytical and Computational Methods > Analytical Methods.

Remarkable breakthroughs have established the functionality of graphene and carbon nanotube transistors as replacements to silicon in conventional computing structures, and numerous spintronic logic gates have been presented. However, an efficient cascaded logic structure that exploits electron spin has not yet been demonstrated. In this work, we introduce and analyse a cascaded spintronic computing system composed solely of low-dimensional carbon materials. We propose a spintronic switch based on the recent discovery of negative magnetoresistance in graphene nanoribbons, and demonstrate its feasibility through tight-binding calculations of the band structure. Covalently connected carbon nanotubes create magnetic fields through graphene nanoribbons, cascading logic gates through incoherent spintronic switching. The exceptional material properties of carbon materials permit Terahertz operation and two orders of magnitude decrease in power-delay product compared to cutting-edge microprocessors. We hope to inspire the fabrication of these cascaded logic circuits to stimulate a transformative generation of energy-efficient computing.

Nanoaperture optical tweezers are emerging as useful label-free, free-solution tools for the detection and identification of biological molecules and their interactions at the single molecule level. Nanoaperture optical tweezers provide a low-cost, scalable, straight-forward, high-speed and highly sensitive (SNR ∼ 33) platform to observe real-time dynamics and to quantify binding kinetics of protein-small molecule interactions without the need to use tethers or labeling. Such nanoaperture-based optical tweezers, which are 1000 times more efficient than conventional optical tweezers, have been used to trap and isolate single DNA molecules and to study proteins like p53, which has been claimed to be in mutant form for 75% of human cancers. More recently, nanoaperture optical tweezers have been used to probe the low-frequency (in the single digit wavenumber range) Raman active modes of single nanoparticles and proteins. Here we review recent developments in the field of nanoaperture optical tweezers and how they have been applied to protein-antibody interactions, protein-small molecule interactions including single molecule binding kinetics, and protein-DNA interactions. In addition, recent works on the integration of nanoaperture optical tweezers at the tip of optical fiber and in microfluidic environments are presented.

We demonstrate the first optical trapping of a single free-solution, untethered, unlabeled macrophage using a double nanohole aperture trap and furthermore collected its Raman vibrational spectra using our new two photon EAR technique.

We demonstrate the trapping of single 20 and 40 nm polystyrene spheres at the cleaved end of a fiber optic with a double nanohole aperture in gold and without any microscope optics. An optical transmission increase of 15% indicates a trapping event for the 40 nm particle, and the jump is 2% for the 20 nm particle. This modular technique can be used to replace those used with current optical trapping setups that require complicated free space optics and frequent calibration, with one that is modular and requires no free space optics. This simple arrangement with the potential for fiber translation is of interest for future biosensor and optical nano-pipette devices.

Colloidal quantum dots, viruses, DNA and all other nanoparticles have acoustic vibrations that can act as ‘fingerprints’ to identify their shape, size and mechanical properties, yet high-resolution Raman spectroscopy in this low-energy range has been lacking. Here, we demonstrate extraordinary acoustic Raman (EAR) spectroscopy to measure the Raman-active vibrations of single isolated nanoparticles in the 0.1–10 cm −1 range with ∼0.05 cm −1 resolution, to resolve peak splitting from material anisotropy and to probe the low-frequency modes of biomolecules. EAR employs a nanoaperture laser tweezer that can select particles of interest and manipulate them once identified. We therefore believe that this nanotechnology will enable expanded capabilities for the study of nanoparticles in the materials and life sciences.

The nanoplasmonic properties of apertures in metal films have been studied extensively; however, we have recently discovered surprising new features of this simple system with applications to super-focusing and super-scattering. Furthermore, apertures allow for optical tweezers that can hold onto particles of the order of 1 nm; I will briefly highlight our work using these apertures to study protein - small molecule interactions and protein - DNA binding.

Recently, self-assembled monolayers (SAMs) have been used for plasmonic rulers to measure the nonlocal influence on the Au nanoparticle - metal film resonance wavelength shift and probe the ultimate field enhancement. Here we examine the influence of surface roughness on this plasmonic ruler in the nonlocal regime by comparing plasmonic resonance shifts for as-deposited and for ultra-flat Au films. It is shown that the resonance shift is larger for ultra-flat films, suggesting that there is not the saturation from nonlocal effects previously reported for the spacer range from 0.7 nm to 1.6 nm. We attribute the previously reported saturation to the planarization of the as-deposited films by thinner SAMs, as measured here by atomic-force microscopy. This work is of interest both in probing the ultimate limits of plasmonic enhancement with SAMs for applications in Raman and nonlinear optics, but also in the study of SAMs planarization as a function surface roughness.

Double nanohole (DNH) laser tweezers can optically trap and manipulate objects such as proteins, nanospheres, and other nanoparticles; however, precise fabrication of those DNHs has been expensive with low throughput. In this work, template stripping was used to pattern DNHs with gaps as small as 7 nm, in optically thick Au films. These DNHs were used to trap streptavidin as proof of operation. The structures were processed multiple times from the same template to demonstrate reusability. Template stripping is a promising method for high-throughput, reproducible, and cost efficient fabrication of DNH apertures for optical trapping.

We have developed a NSOM technique that can map both the near optical field and the optical force using an atomic force microscope. This technique could be very useful for characterizing MEMs/NEMs devices, plasmonic nanoantennas, nano-photonic devices and biologically active substrates. Unlike conventional NSOM techniques that rely on an aperture fabricated on the end of an AFM tip to collect the optical signal this apertureless technique uses a lockin amplifier locked to the AFM tip vibrational frequency, to correlate the amplitude modulation of the back reflected optical signal to the strength of the optical field. And since we are not limited by the fabrication of an aperture the spatial resolution of the map is limited only by the size of a sharp AFM tip which for metallic coated tips can have a radius of curvature of 10 to 20 nm. For optical force mapping the incident laser is modulated and the lock-in amplifier is used to correlate the amplitude modulation of the vibrating AFM tip to strength of the optical gradient force. And in this way one can get a very accurate mapping of both the optical force and the optical field for any substrate of interest as long as it can be back illuminated. Lastly with an electrically monolithic substrate it is possible to correlate the amplitude modulation of the tunneling current to the optical field and obtain a spatial mapping that has a resolution of an STM, about 1 nm or maybe less.

The loss in optical antennas can affect their performance for their practical use in many branches of science such as biological and solar cell applications. However the big question is that how much loss is due to the joule heating in the metals. This would affect the efficiency of solar cells and is very important for single photon detection and also for some applications where high heat generation in nanoantennas is desirable, for example, payload release for cancer treatment. There are few groups who have done temperature measurements by methods such as Raman spectroscopy or fluorescence polarization anisotropy. The latter method, which is more reliable than Raman spectroscopy, requires the deposition of fluorescent molecules on the antenna surface. The molecules and the polarization of radiation rotate depending upon the surface temperature. The reported temperature measurement accuracy in this method is about 0.1 degrees C. Here we present a method based on thermo-reflectance that allows better temperature accuracy as well as spatial resolution of 500 nm. Moreover, this method does not require the addition of new materials to the nanoantenna. We present the measured heat dissipation from bull's-eye nanoantennas and compare them with 3D simulation results.

A laser can be thought of as an optical cavity with two mirrors within which light bounces back and forth many times. Because the optical mode is strongly coupled to the cavity, a slight change to either mirror can cause a change to the cavity and to the operation of the laser. Increasing the interaction strength between changes to the mirror and the cavity can lead to interesting operational methods for the laser. Recently developed fabrication techniques have made it possible to integrate metallic nanostructures with lasers, creating a hybrid device with applications in the medical, communication, commercial, and defense fields. Using an optical antenna creates an area of very high electric-field concentration; by placing one of these antennas in close proximity to the laser cavity, the antenna can perturb this area, influencing the whole cavity mode. We will show that by modulating the laser mode by interacting it with the near field of the antenna, one can perform the following: determine the near-field and optical force profiles of different antenna geometries, frequency modulate a laser, amplitude modulate a laser, and detect biomolecules with high sensitivity. With the development of nanofabrication techniques, optical antennas can be made and further explored in the visible region of the optical spectrum. These antennas are similar to radio frequency (RF) antennas in that they are structures that are designed to be resonant with specific wavelengths through both their geometrical and material properties as well as their external surroundings. Though both RF and optical antennas have the same basic goal of controlling radiation patterns, there is an important difference. RF antennas are designed to optimize far-field characteristics in order to obtain better transmission and reception of signals, while optical antennas are designed to optimize the near-field characteristics, in order to, for example, create a spot size that is smaller than the wavelength of incoming light. The different operating wavelengths of these antennas also impose an orders-of-magnitude size mismatch between the two classes of antennas.