Surface Plasmon Field-Enhanced Raman Scattering Co-Excited by P-Polarized and S-Polarized Light Based on Waveguide-Coupled Surface Plasmon Resonance Configuration.

We constructed a waveguide-coupled surface plasmon resonance (WCSPR) structure to enhance Raman scattering. In this structure, P-polarized and S-polarized incident lasers can simultaneously coexcite the evanescent field, thereby further enhancing Raman scattering. This configuration is a five-phase Kretschmann resonance setup that consists of a SF10 prism/inner Ag film/SiO film/outer Ag film/water structure.

Preparation and characterisation of linalool oil-in-water starch-based Pickering emulsions and the effects of the addition of cellulose nanocrystals on their stability.

Creaming could be generated during storage of the starch-based Pickering emulsions. And cellulose nanocrystals in the solution are usually dispersed by relatively strong mechanical force, otherwise they may appear in the form of aggregates. In this work, we investigated the effects of cellulose nanocrystals on the stability of the starch-based Pickering emulsions.

Tuning Organic Microcrystal Morphologies through Crystal Engineering Strategies toward Anisotropic Optical Waveguide.

The construction of organic optoelectronic materials with desirable size and morphology remains a challenge now. Crystal engineering strategies (polymorphs and cocrystals) provide convenience for tailoring molecular packing and further controlling the growth morphology and photofunctionality of materials. Herein, we prepare polymorphic 2D plate crystals and 3D microhelixes by assembly of a cyanostilbene derivative (2-(3',5'-bis(trifluoromethyl)-biphenyl-4-yl)-3-(4-(pyridin-4-yl)phenyl)acrylonitrile, CF-CN-Py).

Single-Cell Oxidative Stress Events Revealed by a Renewable SERS Nanotip.

A nanotip sensitive to reactive oxygen species (ROS) and NAD/NADH (oxidized/reduced forms of nicotinamide adenine dinucleotide) was designed and prepared to identify the redox events in a single living cell by surface-enhanced Raman scattering (SERS) spectroscopy. The nanotips were prepared by the one-step laser-induced Ag growth and deposition. A redox-reversible Raman reporter, 4-mercaptophenol (4-MP), was employed for the nanotip decoration along with the Ag deposition.

Long-Range Surface Plasmon Resonance Configuration for Enhancing SERS with an Adjustable Refractive Index Sample Buffer to Maintain the Symmetry Condition.

We propose a method to maintain the symmetry condition of the refractive index with respect to a dielectric buffer layer for a long-range surface plasmon resonance (LRSPR) configuration. The symmetry condition was maintained by changing the concentration of the ethylene glycol aqueous solution (sample buffer layer) to match the refractive index of the MgF film. Maintenance of the symmetry condition is necessary for exciting the LRSPR mode and increasing the electric field intensity near the film.

Plasmon-Enhanced Four-Wave Mixing Imaging for Microdroplet-Based Single-Cell Analysis.

A high-throughput single-cell analytical technique based on the microdroplet array integrated with the plasmon-enhanced-four-wave mixing (PE-FWM) imaging was developed, which is applicable for the highly sensitive and automatic assessment of the surface receptors of cells. The metal nanoprobes were prepared by simply decorating metal nanoparticles with capturing molecules (antibody or molecules with surface identification function). Owing to the multifrequency selection of lasers via resonating their plasmonic bands, these metal nanoprobes are highly recognizable under the FWM imaging and display high photostability above fluorescent dyes.

A two-photon fluorescence, carbonized polymer dot (CPD)-based, wide range pH nanosensor: a view from the surface state.

A green-emitting, low-toxicity carbonized polymer dot (CPD) with a high fluorescence quantum yield was synthesised by a simple hydrothermal method, and has been applied as a three-mode pH indicator and the pH readouts involve the intensity ratio of the absorption bands, the single-photon fluorescence, and the two-photon fluorescence (TPF) signals. The pH sensing mechanism of this CPD is dependent on the hydrogen ion regulation on its surface states, which is evidenced for the first time by transient spectroscopy. The rich surface states of this CPD allow a wider pH-responsive range relative to other carbon nanodot-based pH nanosensors.

Deep Red Emissive Carbonized Polymer Dots with Unprecedented Narrow Full Width at Half Maximum.

Development of high-performance carbon dots (CDs) with emission wavelength longer than 660 nm (deep red emission) is critical in deep-tissue bioimaging, yet it is still a major challenge to obtain CDs with both narrow full width at half maximum (FWHM) and high deep red/near-infrared emission yield. Here, deep red emissive carbonized polymer dots (CPDs) with unprecedented FWHM of 20 nm are synthesized. The purified CPDs in dimethyl sulfoxide (DMSO) solution possess quantum yield (QY) as high as 59% under 413 nm excitation, as well as recorded QY of 31% under 660 nm excitation in the deep red fluorescent window.

Solvation-Enhanced Intermolecular Charge Transfer Interaction in Organic Cocrystals: Enlarged C-C Surface Close Contact in Mixed Packing between PTZ and TCNB.

The mixed π-π packing of the donor (D) and acceptor (A) molecules is the highlighting feature of the intermolecular interactions following charge transfer (CT) issues in organic cocrystal systems. There is an inverse relationship between the D-A interplanar distance and the intermolecular CT interaction. However, the D-A C-C surface close contact (relative areas) on the intermolecular CT interactions in organic cocrystal systems is rarely investigated.

Remarkable pressure-induced emission enhancement based on intermolecular charge transfer in halogen bond-driven dual-component co-crystals.

A series of two-component co-crystals driven by IN interactions based on the bipyridine (BIPY) chromophore with one among three different co-former building blocks, iodopentafluorobenzene (IPFB), 1,4-diiodotetrafluorobenzene (DITFB) and 1,3,5-trifluoro-2,4,6-triiodobenzene (IFB), were prepared and analysed via infared spectroscopy and single-crystal X-ray diffraction. By comparing the IN distances in the co-crystal structures, we found that the higher the -F ratio in the building blocks the closer the contact of the IN bond, enhancing the intermolecular interactions in these co-crystals as well. That is, the positive electrostatic potential on the iodine atom(s) in the co-formers was enhanced by the presence of strong electron-withdrawing groups.

Investigation of supramolecular interaction in 4, 4'-bipyridine crystal by hydrostatic pressure spectroscopies.

The luminescence and structural changes of 4, 4'-bipyridine in the crystal and powder forms under the effect of high pressure applied by a diamond anvil cell has been investigated through the fluorescence and Raman spectroscopies. In its single crystal structure, the 4, 4'-bipyridine molecules are paralleled arranged with the identifiable CH⋯N and π⋯π interactions among molecules. However, in the powder form, these intermolecular interactions nearly diminish.

Design of Metal-Free Polymer Carbon Dots: A New Class of Room-Temperature Phosphorescent Materials.

Polymer carbon dots (PCDs) are proposed as a new class of room-temperature phosphorescence (RTP) materials. The abundant energy levels in PCDs increase the probability of intersystem crossing (ISC) and their covalently crosslinked framework structures greatly suppress the nonradiative transitions. The efficient methods allow the manufacture of PCDs with unique RTP properties in air without additional metal complexation or complicated matrix composition.

Note: A portable Raman analyzer for microfluidic chips based on a dichroic beam splitter for integration of imaging and signal collection light paths.

An integrated and portable Raman analyzer featuring an inverted probe fixed on a motor-driving adjustable optical module was designed for the combination of a microfluidic system. It possesses a micro-imaging function. The inverted configuration is advantageous to locate and focus microfluidic channels.

Note: Mobile micro-Raman analyzer integrated with a lab-on-a-chip.

A mobile micro-Raman microfluidic analyzer was designed and built for label-free, nondestructive, fingerprint detection of samples on microfluidic chip systems. It mainly includes an optical module (including the Raman detection system and the microscopic imaging system), 3-axis stages with step motors and other auxiliary circuits. The setup of the analyzer was designed with fully considering the characters of the microfluidics system.