A critical challenge arising during a surgical procedure for tumor removal is the determination of tumor margins. Gold nanorods (GNRs) conjugated to epidermal growth factor receptors (EGFR) (GNRs-EGFR) have long been used in the detection of cancerous cells as the expression of EGFR dramatically increases once the tissue becomes cancerous. Optical techniques for the identification of these GNRs-EGFR in tumor are intensively developed based on the unique scattering and absorption properties of the GNRs. In this study, we investigate the distribution of the GNRs in tissue sections presenting squamous cell carcinoma (SCC) to evaluate the SCC margins. Air scanning electron microscopy (airSEM), a novel, high resolution microscopy is used, enabling to localize and actually visualize nanoparticles on the tissue. The airSEM pictures presented a gradient of GNRs from the tumor to normal epithelium, spread in an area of 1 mm, suggesting tumor margins of 1 mm. Diffusion reflection (DR) measurements, performed in a resolution of 1 mm, of human oral SCC have shown a clear difference between the DR profiles of the healthy epithelium and the tumor itself.

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Entangled-photon-pair interaction (EPPI) with matter is a key element in many suggested quantum-light applications and an enhancement of this interaction is of great importance. In this paper, we suggest and investigate the use of metallic nanoparticles (MNPs), with their exceptional capability of light-matter coupling at their localized surface plasmon resonance, for a potential enhancement of EPPI. We specifically investigate second-harmonic generation and theoretically estimate the rate of EPPI with MNPs using measurements with classical-light. We perform a simple measurement based on approximating the optical-setup factor G, of hyper-Rayleigh scattering. Experimental results, obtained for solutions of silver NPs (SNPs) with different densities, show a hyperpolarizability of about 10 esu . 24-[ ] The results indicate that the use of SNPs can indeed be advantageous for EPPI, with an estimated three orders-of magnitude enhancement of the hyperpolarizability, relative to the best organic molecules. However, we show that further optimization of the SNPs should be carried out to enlarge their EPPI crosssection even more.

Early diagnosis of disease onset requires sensor systems that detect multiple disease-related processes within the body. However, major obstacles must be surmounted for in vivo sensor use, including size, biocompatibility, sensitivity, and selectivity. As an initial study, here we fabricated a multidimensional gold nanorod (GNR)-based bio-barcode sensing array for sensitive and selective detection of biological events. The sensor comprises an array of gold nanocavities and GNRs that are bound to the array as well as to fluorescein via bio-barcode peptides. Exposure of the sensor to peptide-specific enzymes as inputs led to bio-barcode cleavage, which produced distinct optical-based output, that is, changes in fluorescence lifetime and surface plasmon resonance. The sensor showed sensitivity and selectivity to each biomarker input alone, as well as simultaneous distinguishable responses to their combination. By performing AND, OR, and XOR operations at the sensing system level, the biological events can be simply detected. This GNR-based bio-barcode sensor, incorporating plasmonic and fluorescent-enhancing nanotechnologies, is versatile and adaptable and thus has the potential to enable detection of a wide range of biomarkers to provide complex and advanced detection capabilities that have not been previously possible.

Nanoplasmonic biosensors incorporating noble metal nanocavity arrays are widely used for the detection of various biomarkers. Gold nanorods (GNRs) have unique properties that can enhance spectroscopic detection capabilities of such nanocavity-based biosensors. However, the contribution of the physical properties of multiple GNRs to resonance enhancement of gold nanocavity arrays requires further characterization and elucidation. In this work, we study how GNR aspect ratio (AR) and surface area (SA) modify the plasmonic resonance spectrum of a gold triangular nanocavity array by both simulations and experiments. The finite integration technique (FIT) simulated the extinction spectrum of the gold nanocavity array with 300 nm periodicity onto which the GNRs of different ARs and SAs are placed. Simulations showed that matching of the GNRs longitudinal peak, which is affected by AR, to the nanocavity array’s spectrum minima can optimize signal suppression and shifting. Moreover, increasing SA of the matched GNRs increased the spectral variations of the array. Experiments confirmed that GNRs conjugated to a gold triangular nanocavity array of 300 nm periodicity caused spectrum suppression and redshift. Our findings demonstrate that tailoring of the GNR AR and SA parameters to nanoplasmonic arrays has the potential to greatly improve spectral variations for enhanced plasmonic biosensing.