Probing Temperature-Induced Plasmonic Nonlinearity: Unveiling Opto-Thermal Effects on Light Absorption and Near-Field Enhancement.

Precise measurement and control of local heating in plasmonic nanostructures are vital for diverse nanophotonic devices. Despite significant efforts, challenges in understanding temperature-induced plasmonic nonlinearity persist, particularly in light absorption and near-field enhancement due to the absence of suitable measurement techniques. This study presents an approach allowing simultaneous measurements of light absorption and near-field enhancement through angle-resolved near-field scanning optical microscopy with iterative opto-thermal analysis. We revealed gold thin films exhibit sublinear nonlinearity in near-field enhancement due to nonlinear opto-thermal effects, while light absorption shows both sublinear and superlinear behaviors at varying thicknesses. These observations align with predictions from a simple harmonic oscillation model, in which changes in damping parameters affect light absorption and field enhancement differently. The sensitivity of our method was experimentally examined by measuring the opto-thermal responses of three-dimensional nanostructure arrays. Our findings have direct implications for advancing plasmonic applications, including photocatalysis, photovoltaics, photothermal effects, and surface-enhanced Raman spectroscopy.

Defocused imaging-based quantification of plasmon-induced distortion of single emitter emission.

Optical properties of single emitters can be significantly improved through the interaction with plasmonic structures, leading to enhanced sensing and imaging capabilities. In turn, single emitters can act as sensitive probes of the local electromagnetic field surrounding plasmonic structures, furnishing fundamental insights into their physics and guiding the design of novel plasmonic devices. However, the interaction of emitters in the proximity to a plasmonic nanostructure causes distortion, which hinders precise estimation of position and polarization state and is one of the reasons why detection and quantification of molecular processes yet remain fundamentally challenging in this era of super-resolution. Here, we investigate axially defocused images of a single fluorescent emitter near metallic nanostructure, which encode emitter positions and can be acquired in the far-field with high sensitivity, while analyzing the images with pattern matching algorithm to explore emitter-localized surface plasmon interaction and retrieve information regarding emitter positions. Significant distortion in defocused images of fluorescent beads and quantum dots near nanostructure was observed and analyzed by pattern matching and finite-difference time-domain methods, which revealed that the distortion arises from the emitter interaction with nanostructure. Pattern matching algorithm was also adopted to estimate the lateral positions of a dipole that models an emitter utilizing the distorted defocused images and achieved improvement by more than 3 times over conventional diffraction-limited localization methods. The improvement by defocused imaging is expected to provide a way of enhancing reliability when using plasmonic nanostructure and diversifying strategies for various imaging and sensing modalities.

Efficacy and Safety of Tenofovir Disoproxil Orotate in Chronic Hepatitis B Patients Previously Treated with Tenofovir Disoproxil Fumarate: Multicenter, Open-Label, Prospective Study.

BACKGROUND/AIM: We aimed to demonstrate the efficacy and safety of tenofovir disoproxilorotate (TDO) compared with that of tenofovir disoproxil fumarate (TDF) in patients with chronic hepatitis B. METHODS: This multicenter, open-label, prospective clinical trial (KCT0004185) was conducted to evaluate the efficacy and safety of TDO on switching from TDF for 24 weeks in virologically suppressed chronic hepatitis B patients. The primary efficacy endpoint was the maintenance of virologic response. Safety was assessed by evaluating major adverse events, changes in renal function, and occurrence of hepatocellular carcinoma (HCC). RESULTS: TDO treatment was not inferior in terms of virological response when compared with that on TDF treatment, with a noninferiority margin of -10% (risk difference, -3.17%; 95% confidence interval, -7.5%-1.15%). The biological response of TDO was also comparable to that of TDF, with no significant difference in the proportion of patients with normalized alanine transaminase levels. After 24 weeks of treatment, hepatitis B core-related antigen (HBcrAg) significantly decreased to a mean titer of 3.91 log U/mL from 4.15 log U/mL at baseline (p = 0.01). There were no cases of grade 3 or higher adverse events and HCC. The mean estimated glomerular filtration rate increased from 91.09 mL/min to 93.34 mL/min (p = 0.056), and the mean serum level of phosphorus increased from 3.33 mg/dL to 3.44 mg/dL (p = 0.045), suggesting improvement in renal function with TDO treatment. CONCLUSION: In patients with chronic hepatitis B, the efficacy of TDO was noninferior to that of TDF, with a significant decrease in the HBcrAg titer and improved renal function.

Effectiveness of high curvature segmentation on the curved flexible surface plasmon resonance.

In this report, we explore a segmentation-based approach for the calculation of surface plasmon resonance (SPR) on the curved surface with high curvature by modeling it as a contiguous array of finite segments. The approach would significantly facilitate the calculation with good accuracy because of the inherent nature that transfer matrix analysis can be used. Using the segmentation model, resonance characteristics at SPR were obtained as the curvature radius was varied. For validation of the segmentation, resonance wavelength (λSPR), reflectance at resonance (RSPR), and resonance width (δλSPR) were compared with the finite element method in the parallel and perpendicular light incidence. It was found that the results from the segmentation were in excellent agreement, λSPR in particular, while RSPR and δλSPR under parallel incidence showed disparity between the two models due to the short segmentation. Resonance of curved surface on the rigid and flexible substrate was compared and the overall trend was found to be almost identical. The segmentation is expected to provide a simple, fast, and efficient way for studying plasmonic devices with high curvature in flexible and wearable applications.

Curvature effects on flexible surface plasmon resonance biosensing: segmented-wave analysis.

We investigate the effect of surface curvature on characteristics of flexible surface plasmon resonance biosensors. For simplified analysis, segmentation-based approximation of curved substrates has been conducted in a range of curvature radius |r| > 225 µm in the parallel and perpendicular light incidence with respect to the surface. The results suggest that resonance characteristics in general broaden with increased curvature due to larger momentum dispersion, the effect of which appears more prominent and direct in the parallel light incidence. Resonance shifts as a result of biosensing, such as DNA immobilization and hybridization, overall decrease with curvature and perpendicular incidence is more robust with a curvature change. The approach was extended to multi-curvature structure and finds significant fluctuation of resonance shift for parallel light incidence. The study can be of profound importance for plasmonic devices using flexible substrates and in fiber-based in vivo applications.

Long-term outcomes of two rescue therapies in lamivudine-refractory patients with chronic hepatitis B: combined lamivudine and adefovir, and 1-mg entecavir.

BACKGROUND/AIMS: Adefovir (ADV) and lamivudine (LAM) combination therapy (ADV+LAM) has been a useful option for patients with LAM-resistant (LAM-r) chronic hepatitis B (CHB). However, the long-term outcomes of LAM+ADV and 1-mg entecavir (ETV) rescue therapies have still been limited. The aim of this study was to determine the long-term outcomes of these two rescue therapies. METHODS: Sixty patients with LAM-r CHB underwent rescue therapy with LAM+ADV (n=36) or 1-mg ETV (n=24). We determined the duration of rescue therapy, timing and type of mutation, undetectable serum hepatitis B virus (HBV) DNA by PCR (lower limitation of detection, < 140 copies/mL), biochemical response (alanine aminotransferase < 40 IU/mL), and the incidence of hepatitis B virus e antigen (HBeAg) seroconversion and virologic breakthrough. RESULTS: Baseline characteristics did not differ between the two therapy groups. The duration of rescue therapy was 56 months (range, 14-100 months) in the ADV+LAM group and 42 months (range, 12-73 months) in the ETV group (P=0.036). The cumulative rates of HBV DNA undetectability and HBeAg seroconversion up to 6 years were 88.6% and 43.0%, respectively, in the ADV+LAM group, and 45.8% and 31.8% in the ETV group. The rate of virologic breakthrough and resistance was 14.4% in the ADV+LAM group and 71.9% in the ETV group (P=0.001). CONCLUSIONS: Combination of LAM and ADV therapy for up to 6 years achieved modest rates of virological suppression and resistance. ETV is not an optimal therapy because the risk of viral breakthrough to ETV increases over time.