Tailoring Fluorescence-Phosphorescence Emission with a Single Nanocavity.

Realizing the dual emission of fluorescence-phosphorescence in a single system is an extremely important topic in the fields of biological imaging, sensing, and information encryption. However, the phosphorescence process is usually in an inherently "dark state" at room temperature due to the involvement of spin-forbidden transition and the rapid non-radiative decay rate of the triplet state. In this work, we achieved luminescent harvesting of the dark phosphorescence processes by coupling singlet-triplet molecular emitters with a rationally designed plasmonic cavity. The achieved Purcell enhancement effect of over 1000-fold allows for overcoming the triplet forbidden transitions, enabling radiation enhancement with selectable emission wavelengths. Spectral results and theoretical simulations indicate that the fluorescence-phosphorescence peak position can be intelligently tailored in a broad range of wavelengths, from visible to near-infrared. Our study sheds new light on plasmonic tailoring of molecular emission behavior, which is crucial for advancing research on plasmon-tailored fluorescence-phosphorescence spectroscopy in optoelectronics and biomedicine.

Rapid Point-of-Care Assay by SERS Detection of SARS-CoV-2 Virus and Its Variants.

Addressing the spread of coronavirus disease 2019 (COVID-19) has highlighted the need for rapid, accurate, and low-cost diagnostic methods that detect specific antigens for SARS-CoV-2 infection. Tests for COVID-19 are based on reverse transcription PCR (RT-PCR), which requires laboratory services and is time-consuming. Here, by targeting the SARS-CoV-2 spike protein, we present a point-of-care SERS detection platform that specifically detects SARS-CoV-2 antigen in one step by captureing substrates and detection probes based on aptamer-specific recognition. Using the pseudovirus, without any pretreatment, the SARS-CoV-2 virus and its variants were detected by a handheld Raman spectrometer within 5 min. The limit of detection (LoD) for the pseudovirus was 124 TU µL-1 (18 fM spike protein), with a linear range of 250-10,000 TU µL-1. Moreover, this assay can specifically recognize the SARS-CoV-2 antigen without cross reacting with specific antigens of other coronaviruses or influenza A. Therefore, the platform has great potential for application in rapid point-of-care diagnostic assays for SARS-CoV-2.

Advanced plasmonic technologies for multi-scale biomedical imaging.

The use of imaging technologies has been critical in deciphering biological phenomena, structures, and mechanisms across a wide range of spatial scales. The spatial resolution of traditional imaging modalities cannot meet the needs of high-precision research and diagnosis in biomedical fields. Plasmon resonance is the light-matter interaction that allows localizing far-field radiation in the near field with an intense electromagnetic field, enhancing the nanometric ablation, elastic/inelastic scattering of the adsorbate, and photoluminescence of the fluorophore nearby. Further, plasmon resonance scattering of nanoparticles can sensitively indicate the local environmental changes. This is accomplished by combining the spatially resolved capability with molecular spectrometry techniques such as Raman, infrared, fluorescence, etc., leading to a series of excellent imaging techniques to interrogate diverse biological processes from the tissue to subcellular level. In this tutorial review, we first provide the fundamental aspects of plasmonics. Then we give a systematic discussion of the working principle of these plasmon-based imaging techniques with an emphasis on the achievable spatial resolutions: surface-enhanced Raman spectroscopy (micrometre to nanometre), tip-enhanced ablation and ionization mass spectrometry (submicrometre), scattering-type scanning near-field optical microscopy (nanometre), tip-enhanced Raman spectroscopy (nanometre), tip-enhanced fluorescence spectroscopy (nanometre), and plasmon/molecular ruler microscopy (nanometre to angstrom). We also review the recent developments of the bioimaging applications of these techniques and expect that the plasmon-based techniques will not only pave a new way to decipher mysteries in life sciences but also hold great potential to be extended from fundamental research studies to real-life biomedical applications.

Shell-Isolated Nanoparticle-Enhanced Electrochemiluminescence.

Enhanced electrochemiluminescence (ECL) aims to promote higher sensitivity and obtain better detection limit. The core-shell nanostructures, owing to unique surface plasmon resonance (SPR) enabling distance-dependent strong localized electromagnetic field, have attracted rising attention in enhanced ECL research and application. However, the present structures usually with porous shell involve electrocatalytic activity from the metal core and adsorption effect from the shell, which interfere with practical SPR enhancement contribution to ECL signal. Herein, to exclude the interference and unveil exact SPR-enhanced effect, shell-isolated nanoparticles (SHINs) whose shell gets thicker and becomes pinhole-free are developed by modifying pH value and particles concentration. Furthermore, allowing for the distribution of hotspots and stronger enhancement, excitation intensity and ECL reaction layer thickness are mainly investigated, and several types of SHINs-enhanced ECL platforms are prepared to fabricate distinct hotspot distribution via electrostatic attraction (submonolayer) and a layer-by-layer deposition method (monolayer). Consequently, the strongest enhancement up to ≈250-fold is achieved by monolayer SHINs with 10 nm shell, and the platform is applied in a "turn-off" mode sensing for dopamine. The platform provides new guidelines to shell preparation, interface engineering and hotspots fabrication for superior ECL enhancement and analytical application with high performance.

Manipulating the light-matter interactions in plasmonic nanocavities at 1 nm spatial resolution.

The light-matter interaction between plasmonic nanocavity and exciton at the sub-diffraction limit is a central research field in nanophotonics. Here, we demonstrated the vertical distribution of the light-matter interactions at ~1 nm spatial resolution by coupling A excitons of MoS2 and gap-mode plasmonic nanocavities. Moreover, we observed the significant photoluminescence (PL) enhancement factor reaching up to 2800 times, which is attributed to the Purcell effect and large local density of states in gap-mode plasmonic nanocavities. Meanwhile, the theoretical calculations are well reproduced and support the experimental results.

A New Approach for Quantitative Surface-Enhanced Raman Spectroscopy through the Kinetics of Chemisorption.

Surface enhanced Raman spectroscopy (SERS) is a non-destructive, highly sensitive, and rapid analytical tool, which has been widely used in different fields, especially for trace quantities of analyte. However, using SERS for reliable quantitative sample analysis is still a great challenge. Herein, a new approach to quantitative SERS analysis at nanostructured substrates that does not require an internal standard or well-ordered nanostructured SERS substrates is developed. This method is based on the kinetics of chemisorption, that is, on a homogeneous surface, the time taken for adsorption of an adsorbate (adenine or melamine) to reach equilibrium negatively correlates with the concentration of the adsorbate. Quantitative analysis is achieved by using in situ SERS to acquire the adsorption profile of the adsorbate and enabling the adsorption equilibrium time to be calculated. There is excellent correlation between the adenine and melamine SERS response over adsorption equilibrium time with concentration, and the correlation coefficients are 0.9906 and 0.9682, respectively. Moreover, milk sample spiked with the melamine is also studied, and the standard recovery rate is 106%. This work demonstrates a novel, non-destructive, and cost-effective quantitative SERS detection technique, which can broaden applications across multiple fields.

Plasmonic Core-Shell Nanoparticle Enhanced Spectroscopies for Surface Analysis.

Probing the properties and components of reactive surfaces is crucial for illustrating reaction mechanisms. However, common surface analysis techniques are restricted to in situ acquisition of surface information at the molecular scale in the human environment and industrial catalysis processes. Plasmonic spectroscopies are promising tools to solve this problem. This Feature is intended to introduce the plasmonic core-shell nanoparticle enhanced spectroscopies for qualitatively and quantitatively analyzing surface trace species. Four different working modalities are designed for meeting varied needs, involving in situ surface species detection, catalytic process monitoring, labeled sensing, and dual mode analysis. These newly developed plasmonic spectroscopies show great potential not only in fundamental research but also in practical applications.

Molecular Insight of the Critical Role of Ni in Pt-Based Nanocatalysts for Improving the Oxygen Reduction Reaction Probed Using an In Situ SERS Borrowing Strategy.

PtNi alloy catalysts have excellent catalytic activity and are considered some of the most promising electrocatalysts capable of replacing pure Pt for the oxygen reduction reaction (ORR). For PtNi alloys, Ni-doping can improve performance by changing the electronic and structural properties of the catalyst surface and its interaction with reaction intermediates. However, to date there is no direct spectral evidence detecting or identifying the effect of Ni on the ORR in PtNi alloy catalysts. Herein, we introduce a surface-enhanced Raman spectroscopic (SERS) "borrowing" strategy for investigating ORR processes catalyzed by Au@PtNi nanoparticles (NPs). The bond vibration of adsorbed peroxide intermediate species (*OOH) was obtained, and the effect of Ni on the interaction between surface Pt and *OOH was studied by varying the Ni content in the alloy. The frequency of the *OOH spectral band has an obvious red-shift with increasing Ni content. Combined with density functional theory (DFT) calculations, we show that Ni-doping can optimize *OOH surface binding on the Pt surface, achieving more efficient electron transfer, thus improving the ORR rate. Notably, these results evidence the SERS borrowing strategy as an effective technique for in situ observations of catalytic processes.

Rapid and Quantitative Detection of Aflatoxin B1 in Grain by Portable Raman Spectrometer.

Many foodstuffs are extremely susceptible to contamination with aflatoxins, in which aflatoxin B1 is highly toxic and carcinogenic. Therefore, it is crucial to develop a rapid and effective analytical method for detecting and monitoring aflatoxin B1 in food. Herein, a surface-enhanced Raman spectroscopic (SERS) method combined with QuEChERS (quick, easy, cheap-effective, rugged, safe) sample pretreatment technique was used to detect aflatoxin B1. Sample preparation was optimized into a one-step extraction method using an Au nanoparticle-based solution (Au sol) as the SERS detection substrate. An affordable portable Raman spectrometer was then used for rapid, label-free, quantitative detection of aflatoxin B1 levels in foodstuffs. This method showed a good linear log relationship between the Raman signal intensity of aflatoxin B1 in the 1-1000 µg L-1 concentration range with a limit of detection of 0.85 µg kg-1 and a correlation coefficient of 0.9836. Rapid aflatoxin B1 detection times of ∼10 min for wheat, corn, and protein feed powder samples were also achieved. This method has high sensitivity, strong specificity, excellent stability, is simple to use, economical, and is suitable for on-site detection, with good prospects for practical application in the field of food safety.

Probing Electric Field Distributions in the Double Layer of a Single-Crystal Electrode with Angstrom Spatial Resolution using Raman Spectroscopy.

The electrical double layer (EDL) is the extremely important interfacial region involved in many electrochemical reactions, and it is the subject of significant study in electrochemistry and surface science. However, the direct measurement of interfacial electric fields in the EDL is challenging. In this work, both electrochemical resonant Raman spectroscopy and theoretical calculations were used to study electric field distributions in the EDL of an atomically flat single-crystal Au(111) electrode with self-assembled monolayer molecular films. This was achieved using a series of redox-active molecules containing the 4,4'-bipyridinium moiety as a Raman marker that were located at different precisely controlled distances away from the electrode surface. It was found that the electric field and the dipole moment of the probe molecule both directly affected its Raman signal intensity, which in turn could be used to map the electric field distribution at the interface. Also, by variation of the electrolyte anion concentration, the Raman intensity was found to decrease when the electric field strength increased. Moreover, the distance between adjacent Raman markers was ∼2.1 Å. Thus, angstrom-level spatial resolution in the mapping of electric field distributions at the electrode-electrolyte interface was realized. These results directly evidence the EDL structure, bridging the gap between the theoretical and experimental understandings of the interface.

[Treatment of spine metastases by open decompression, microwave ablation combined with open vertebroplasty and pedicle screw rod system].

OBJECTIVE: To evaluate the preliminary clinical effective of open decompression, microwave ablation combined with open vertebroplasty and pedicle screw rod system in the treatment of spine metastases. METHODS: The clinical data of 12 patients with spine metastases were retrospectively analyzed, they were treated with open decompression, microwave ablation combined with open vertebroplasty and pedicle screw rod system between January 2014 and January 2016. Six males and 6 females were included, aged from 30 to 75 years old with an average of 55.6 years. There were 5 cases with spine metastases from lung cancer, 2 from breast cancer, 2 from thyroid cancer, 2 from renal cancer and 1 from liver cancer. Sevencases were thoracic metastases and 5 cases were lumbar metastases. Tomita score were mainly arranging from 3 to 6 points. According to ASIA neurologic grading system, 3 patients were grade C, 1 was grade D, 8 were grade E. Preoperative VAS score was 8.3±0.4. VAS was used to evaluate the clinical effect at 1, 3, 6 months after operation and final follow-up. RESULTS: All operations were successful and the amount of blood loss during surgery was 500 to 2 050 ml (average of 850 ml), operation time was 3.5 to 5.5 h (average of 4.5 h). There was no nerve root injury during surgery. Cerebrospinal fluid leakage occurred in 3 cases after surgery, which were healed after conservative treatment. Superficial infection of the incision occurred in 2 cases, which were healed after dressing change. There was one case of pulmonary infection. No deep infection, lower limb thrombosis or other complications were found. All 12 patients were followed up for 9 -40 months with an average of 28.6 months. The clinical symptoms of all patients were significantly improved, and the motor function of the lower limbs was recovered to varying degrees. According to ASIA grade, 2 cases of grade C were improved to grade B;1 case of grade C did not recover significantly;1 case of grade D was improved to grade E. One patient died of primary liver cancer 10 months after surgery. Local tumor recurrence occurred in 1 patient during follow up period. The VAS scores were 2.7±0.6, 2.5±0.4, 2.6±0.5, and 2.5±0.5 at 1, 3, 6 months after surgery and at final follow-up, which were significantly improved compared with the score before surgery(P<0.05). CONCLUSION: Open decompression, microwave ablation combined with open vertebroplasty and pedicle screw rod system in the treatment of spine metastases show some effects, with less intraoperative blood loss, shorter operation time, significant postoperative pain relief, and low tumor recurrence rate.

In situ Raman study of the photoinduced behavior of dye molecules on TiO2(hkl) single crystal surfaces.

In dye-sensitized solar cells (DSSCs), the TiO2/dye interface significantly affects photovoltaic performance. However, the adsorption and photoinduced behavior of dye molecules on the TiO2 substrate remains unclear. Herein, shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) was used to study the adsorption and photoinduced behavior of dye (N719) molecules on different TiO2(hkl) surfaces. On TiO2(001) and TiO2(110) surfaces, the in situ SHINERS and mass spectrometry results indicate S[double bond, length as m-dash]C bond cleavage in the anchoring groups of adsorbed N719, whereas negligible bond cleavage occurs on the TiO2(111) surface. Furthermore, DFT calculations show the stability of the S[double bond, length as m-dash]C anchoring group on three TiO2(hkl) surfaces in the order TiO2(001) < TiO2(110) < TiO2(111), which correlated well with the observed photocatalytic activities. This work reveals the photoactivity of different TiO2(hkl) surface structures and can help with the rational design of DSSCs. Thus, this strategy can be applied to real-time probing of photoinduced processes on semiconductor single crystal surfaces.

Dual-vortex-assisted matrix solid-phase dispersion coupled with isotope-dilution ultrahigh-performance liquid chromatography-high resolution mass spectrometry for the rapid determination of parabens in indoor dust samples.

A reliable and straightforward method was developed for the rapid determination of nine parabens (methyl-, ethyl-, propyl-, butyl-, isopropyl-, isobutyl-, pentyl-, hexyl-, and benzyl-parabens) in indoor dust by a mortar/pestle-free and column-free dual-vortex-assisted matrix solid-phase dispersion (DVA-MSPD) technique. After that, they were determined by isotope-dilution ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-qTOF-MS, or called UHPLC-HRMS) and operating in negative electrospray ionization mode. Optimization of the DVA-MSPD was done using Box-Behnken Design along with response surface methodology. Validation was done by measuring and calculating selectivity, limits of detection (LOD), limits of quantitation (LOQs), precision and trueness (accuracy) of intra- and inter-day analysis. The LOQs of the method ranged from 0.9 to 2.8 ng/g. High precisions for both intra- and inter-day analysis were obtained ranging from 1 to 8%. Excellent trueness (or mean extraction recovery) varied from 93 to 104%. The DVA-MSPD combined with isotope-dilution UHPLC-qTOF-MS was successfully applied to determine parabens in indoor dust samples from office rooms and private houses, and the total concentrations ranged from 55 to 686 ng/g.

[Extensively Porous-coated Distal Fixation Long Stem Prosthesis for Unstable Proximal Femur Fracture with Complex Hip Disease].

OBJECTIVES: To evaluate the clinical results of femoral proximal fracture with complex hip diseases using an uncemented extensively porous-coated long femoral stems. METHODS: 15 cases of femoral proximal fracture with complex hip diseases treated with the uncemented extensively porous-coated long femoral stem were retrospectively reviewed. All patients were followed up at 1, 3, 6, 12 months in the first year postoperatively and once a year from the second year on.Radiological evaluations were conducted using the related criteria, including anteropostierior radiograph of pelvis, anteropostierior and lateral radiograph of proximal femur, and flat tomography of lower limbs.The bone union of the femur fracture, the fixation of prosthesis, and periprosthetic bone loss were evaluated by above-mentioned radiography.The subsidence of femoral prosthesis was compared between 1 month postoperatively and the last follow-up. Complications during the follow-up period was recorded.Clinical outcomes were assessed with Harris Hip Score the last follow-up, including excellent (90-100), good (80-89), moderate (70-79) and bad (<70). RESULTS: The average follow-up period was (45.5±21.7) months. All fractures were united at mean 12.6 weeks. There were no femoral stem subsidence and evidence of loosening both radiologically and clinically. The reconstructive offset for femoral fracture was 35.8 mm, while the contralateral offset was 34.8 mm. The average Harris Hip Score was 89.5 at the last follow-up. Moreover, no loosening, dislocation or infection were observed. CONCLUSIONS: Total hip arthroplasty with extensively porous-coated long femoral stem provides a good fracture stability that promotes fracture healing and offers a successful solution for femoral proximal fracture with complex hip diseases.