Carbon nanodots (CNDs) are featured with a wide range of light absorption and excitationdependent fluorescence. The emission enhancement of CNDs is of great interest for the development of nanophotonics. Although the phenomenon of plasmon-enhanced fluorescence for quantum dots and molecular dyes has been well investigated, rarely has it been reported for CNDs. In this work, a series of plasmonic nanoslit designs were fabricated and utilized for immobilization of CNDs in nanoslits and examination of the best match for plasmonic fluorescence enhancement of CNDs. In concert, to better understand the plasmonic effect on the enhancement, the surface optical field is measured with or without CND immobilization using a hyperspectral imaging system as a comparison, and a semianalytical model is conducted for a quantitative analysis of surface plasmon generation under the plane-wave illumination. Both the fluorescence and surface reflection light intensity enhancement are demonstrated as a function of nanoslit width and are maximized at the 100 nm nanoslit width. The analysis of surface plasmon-exciton coupling of CNDs in the nanoslit area suggests that the enhancement is primarily due to plasmonic light trapping for increased electromagnetic field and plasmoninduced resonance energy transfer. This study suggests that incorporating CNDs in the plasmonic nanoslits may provide a largely enhanced CND-based photoemission system for optical applications.

The light-induced property of photosystem I (PSI) has been utilized to convert solar energy to electrical energy in photoelectrochemical cells.Here we provide new results on the relationship between surface plasmon generation (SPG) efficiency of nanoslits and the experimentally obtained photocurrent by immobilizing PSI on the gold nanoslit electrode surfaces regarding different nanoslit widths. The photocurrent increases with the increment of SPG efficiency. This finding can be attributed to the phenomenon of plasmon−exciton coupling effect on the PSI in the nanoslits. The enhancement of photocurrent generation is discussed on the basis of plasmonic light trapping and plasmon-induced resonance energy transfer.

A bimetallic (Ag/Au) nanoslit film is reported on surface plasmon (SP) generation and refractive index (RI) sensitivity. These were compared to gold devices in transmission surface plasmon resonance (tSPR). The bimetallic films have a primary resonant peak that shifts with periodicity and correlates well with Finite-Difference Time-Domain (FDTD) simulation studies. The SPR of bimetallic nanoslit structures is analyzed via a semianalytical model. The model enables decomposition and quantitative analysis of SP generation at the aperture under plane-wave illumination. The nanostructured, metallic, thin films provide flexibility to integrate with microfluidics, allowing for simplified instrumentation and alignment. Calculation and experimentation demonstrate that bimetallic films afford an increase in RI sensitivity due to the addition of silver along with the biocompatibility of gold. The Ag/Au films were found to be non-diffusing, long-term stable (over several months), and provided an increase in sensitivity (about 53/RIU) over gold equivalents.[a] T.

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Carbon nanodots are fascinating candidates for the field of biomedicine, in applications such as bioimaging and drug delivery. However, the nuclear penetrability and process are rarely studied and lack understanding, which limits their applications for drug carriers, single-molecule detection and live cell imaging. In this study, we attempt to examine the uptake of CNDs in cells with a focus on the potential nuclear penetrability using enhanced dark-field microscopy (EDFM) associated with hyperspectral imaging (HSI) to quantitatively determine the light scattering signals of CNDs in the cells. The effects of both CND incubation time and concentration are investigated, and plausible nuclear penetration involving the nuclear pore complex (NPC) is discussed. The experimental results and an analytical model demonstrate that the CNDs’ uptake proceeds by a concentration-dependent three-stage behavior and saturates at a CND incubation concentration larger than 750 µg/mL, with a half-saturated concentration of 479 μg/mL. These findings would potentially help the development of CNDs’ utilization in drug carriers, live cell imaging and other biomedical applications.