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1.
Article in Chinese | WPRIM (Western Pacific) | ID: wpr-971287

ABSTRACT

OBJECTIVE@#To investigate whether 3D-printed artificial vertebral body can reduce prosthesis subsidence rate for patients with cervical chordomas, through comparing the rates of prosthesis subsidence between 3D printing artificial vertebral body and titanium mesh for anterior spinal reconstruction after total spondylectomy.@*METHODS@#This was a retrospective analysis of patients who underwent surgical treatment for cervical chordoma at our hospital from March 2005 to September 2019. There were nine patients in the group of 3D artificial vertebral body (3D group), and 15 patients in the group of titanium mesh cage (Mesh group). The patients' characteristics and treatment data were extracted from the medical records, including age, gender, CT hounsfield unit of cervical vertebra and surgical information, such as the surgical segments, time and blood loss of surgery, frequency and degree of prosthesis subsidence after surgery. Radiographic observations of prosthesis subsidence during the follow-up, including X-rays, CT, and magnetic resonance imaging were also collected. SPSS 22.0 was used to analysis the data.@*RESULTS@#There was no significant difference between the two groups in gender, age, CT hounsfield unit, surgical segments, time of surgery, blood loss of posterior surgery and total blood loss. Blood loss of anterior surgery was 700 (300, 825) mL in 3D group and 1 500 (750, 2 800) mL in Mesh group (P < 0.05). The prosthesis subsidence during the follow-up, 3 months after surgery, there was significant difference between the two groups in mild prosthesis subsidence (P < 0.05). The vertebral height of the 3D group decreased less than 1 mm in eight cases (no prosthesis subsidence) and more than 1 mm in one case (mild prosthesis subsidence). The vertebral height of the Mesh group decreased less than 1 mm in five cases (no prosthesis subsidence), and more than 1 mm in eight cases (mild prosthesis subsidence). Two patients did not have X-rays in 3 months after surgery. There was a statistically significant difference between the two groups in the prosthesis subsidence rate at the end of 12 months (P < 0.01). The vertebral height of eight cases in the 3D group decreased less than 1 mm (no prosthesis subsidence) and one case more than 3 mm (severe prosthesis subsidence). Four of the 15 cases in the Mesh group decreased less than 1 mm (no prosthesis subsidence), two cases more than 1 mm (mild prosthesis subsidence), and nine cases more than 3 mm (severe prosthesis subsidence). There was a statistically significant difference between the two groups in the prosthesis subsidence rate at the end of 24 months (P < 0.01). The vertebral height of seven cases in the 3D group decreased less than 1 mm (no prosthesis subsidence), one case more than 3 mm (severe prosthesis subsidence), and one case died with tumor. One case in the Mesh group decreased less than 1 mm (no prosthesis subsidence), one case more than 1 mm (mild prosthesis subsidence), 11 case more than 3 mm (severe prosthesis subsidence), one case died with tumor and one lost the follow-up. Moreover, at the end of 12 months and 24 months, there was significant difference between the two groups in severe prosthesis subsidence rate (P < 0.01).@*CONCLUSION@#3D-printed artificial vertebral body for anterior spinal reconstruction after total spondylectomy for patients with cervical chordoma can provide reliable spinal stability, and reduce the incidence of prosthesis subsidence after 2-year follow-up.


Subject(s)
Humans , Chordoma/surgery , Retrospective Studies , Vertebral Body , Titanium , Cervical Vertebrae/surgery , Printing, Three-Dimensional , Spinal Fusion/methods , Treatment Outcome
2.
Acta Physiologica Sinica ; (6): 27-35, 2023.
Article in Chinese | WPRIM (Western Pacific) | ID: wpr-970103

ABSTRACT

This study was designed to investigate the cardiovascular effects of sulfur dioxide (SO2) in the caudal ventrolateral medulla (CVLM) of anesthetized rats and its mechanism. Different doses of SO2 (2, 20, 200 pmol) or artificial cerebrospinal fluid (aCSF) were injected into the CVLM unilaterally or bilaterally, and the effects of SO2 on blood pressure and heart rate of rats were observed. In order to explore the possible mechanisms of SO2 in the CVLM, different signal pathway blockers were injected into the CVLM before the treatment with SO2 (20 pmol). The results showed that unilateral or bilateral microinjection of SO2 reduced blood pressure and heart rate in a dose-dependent manner (P < 0.01). Moreover, compared with unilateral injection of SO2 (2 pmol), bilateral injection of 2 pmol SO2 produced a greater reduction in blood pressure. Local pre-injection of the glutamate receptor blocker kynurenic acid (Kyn, 5 nmol) or soluble guanylate cyclase (sGC) inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, 1 pmol) into the CVLM attenuated the inhibitory effects of SO2 on both blood pressure and heart rate. However, local pre-injection of nitric oxide synthase (NOS) inhibitor NG-Nitro-L-arginine methyl ester (L-NAME, 10 nmol) only attenuated the inhibitory effect of SO2 on heart rate but not blood pressure. In conclusion, SO2 in rat CVLM has cardiovascular inhibitory effects, and its mechanism is related to the glutamate receptor and NOS/cGMP signal pathways.


Subject(s)
Animals , Rats , Heart Rate , Sulfur Dioxide , Blood Pressure , Cyclic GMP , Receptors, Glutamate
3.
Article in Chinese | WPRIM (Western Pacific) | ID: wpr-965808

ABSTRACT

Objective To explore the radiation shielding optimization plan for a medical proton cyclotron developing and commissioning building at various commissioning stages. Methods According to the maximum source termsat different commissioning stages, we used the empirical formula to estimate the instantaneous dose rate at the point of interest outside the shield of the building, and optimized the building’s shielding ateach commissioning stage. Results When adding 1.0 m mobile concrete shielding blocks (“blocks” below) each to wall 3 and wall 4 at the cyclotron commissioning stage, 1.0 m blocks to wall 4 and 1.25 m blocks to wall 5 at the beam transport line commissioning stage, and 1.0 m blocks to wall 9 and 0.4 m blocks to the ceiling at the simulated treatment room commissioning stage, the dose rates at the points of interest outside the shield could meet the dose rate limit requirements. Conclusion The application of mobile concrete shielding blocks not only meets the shielding requirements, but also has economical and space-saving advantages, conforming to the principle of shielding optimization. This can be an approach to the optimization of radiation shielding for high-energy particle accelerators or similar scientific projects.

4.
Eur J Med Chem ; 191: 112134, 2020 Apr 01.
Article in English | MEDLINE | ID: mdl-32088493

ABSTRACT

11ß-hydroxysteroid dehydrogenase type 1 (11ß-HSD1) is a key metabolic enzyme that catalyzing the intracellular conversion of inactive glucocorticoids to physiologically active ones. Work over the past decade has demonstrated the aberrant overexpression of 11ß-HSD1 contributed to the pathophysiological process of metabolic diseases like obesity, type 2 diabetes mellitus, and metabolic syndromes. The inhibition of 11ß-HSD1 represented an attractive therapeutic strategy for the treatment of metabolic diseases. Therefore, great efforts have been devoted to developing 11ß-HSD1 inhibitors based on the diverse molecular scaffolds. This review focused on the structural features of the most important 11ß-HSD1 inhibitors and categorized them into natural products derivatives and synthetic compounds. We also briefly discussed the optimization process, binding modes, structure-activity relationships (SAR) and biological evaluations of each inhibitor. Moreover, the challenges and directions for 11ß-HSD1 inhibitors were discussed, which might provide some useful clues to guide the future discovery of novel 11ß-HSD1 inhibitors.


Subject(s)
11-beta-Hydroxysteroid Dehydrogenase Type 1/antagonists & inhibitors , Biological Products/pharmacology , Drug Development , Enzyme Inhibitors/pharmacology , Metabolic Diseases/drug therapy , 11-beta-Hydroxysteroid Dehydrogenase Type 1/metabolism , Animals , Biological Products/chemistry , Enzyme Inhibitors/chemistry , Humans , Metabolic Diseases/metabolism , Molecular Structure
5.
Article in English | WPRIM (Western Pacific) | ID: wpr-878348

ABSTRACT

Objective@#We aimed to compare the clinical and radiological outcomes of midline lumbar fusion (MIDLF) versus minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) in patients with degenerative spondylolisthesis and/or stenosis in L4-L5 two years after surgery.@*Methods@#Consecutively treated patients with lumbar pathology who underwent MIDLF ( @*Results@#The mean operative time and hematocrit (HCT, Day 1) were significantly shorter and lower in MIDLF cases (174 min @*Conclusion@#MIDLF is comparable to MI-TLIF at L4-5 in clinical outcomes and fusion rates, and the results verified the meaningful advantage of using MIDLF for the elderly with osteoporosis.


Subject(s)
Aged , Female , Humans , Male , Middle Aged , Lumbar Vertebrae/surgery , Retrospective Studies , Spinal Fusion/methods , Treatment Outcome
6.
Article in Chinese | WPRIM (Western Pacific) | ID: wpr-773246

ABSTRACT

As a topical plaster developed by modern pharmaceutical technology based on traditional Tibetan medicine,Cheezheng Xiaotong Tiegao has functions of promoting blood circulation,relieving swelling and relieving pain. Since its introduction in 1993,it has been widely used in the treatment of various types of acute and chronic musculoskeletal pain and various types of spinal,joint and soft tissue diseases. In order to better standardize the clinical application and improve the clinical efficacy of Cheezheng Xiaotong Tiegao,the research and development work of the Experts consensus statement on Cheezheng Xiaotong Tiegao in clinical practice was officially launched on October 19,2017,upon approval from China Association of Chinese Medicine. In this paper,main R&D process and related technical links for the experts consensus on Cheezheng Xiaotong Tiegao would be summarized,which will help the various medical workers understand,master and apply more accurately,and also provide reference for the development of experts consensus on clinical application of other topical Chinese medicines.


Subject(s)
Humans , Administration, Topical , China , Consensus , Medicine, Tibetan Traditional , Pain , Pain Management
7.
Nanoscale ; 10(42): 19684-19691, 2018 Nov 01.
Article in English | MEDLINE | ID: mdl-30328878

ABSTRACT

Chiral cysteine-directed assemblies of Au@Ag core-shell nanocrystals (CSNCs) and Au/Ag nanorods with end-to-end (ETE) and side-by-side (SBS) configurations are fabricated and used to explore the definitive factors affecting the chiral response. The interaction between cysteine and metallic nanoparticles leads to intense and widely tunable plasmonic circular dichroism (PCD) ranging from a near-infrared (NIR) to ultraviolet (UV) regime. More importantly, it was observed that, in Ag nanorod and CSNC samples with varied aspect ratios, the ETE assembled patterns exhibit much larger PCD enhancement than SBS assemblies in an l/d-cysteine solvent environment. Very surprisingly, such a giant PCD response in these assemblies is completely different from that of the Au nanorod assembly case as reported earlier. Experimental and theoretical studies reveal that the interplay between the local field enhancement and backaction, triggered by the geometric configuration differentia of covered achiral CTAB molecules on Ag and Au surfaces, plays a crucial role in chiral response variances and leads to geometry-dependent optical activities. This work not only sheds light on understanding the relationship between the configuration of plasmonic nanostructure assemblies and geometry-manipulated circular dichroism, but also paves the way for predictive design of plasmonic biosensors or other nanodevices with controllable optical activities from the UV to the NIR light range.

8.
ACS Nano ; 12(10): 9913-9921, 2018 Oct 23.
Article in English | MEDLINE | ID: mdl-30153416

ABSTRACT

A precision photoreduction technology for the ultrafast high-precision light-controlled growth of silver nanoparticles for printing plasmonic color images is presented. Ultraviolet (UV) patterns with about a million pixels are generated to temporally and spatially regulate the photoreduction of silver salts to precisely create around a million clusters of distinct silver nanoparticles on a titanium dioxide (TiO2)-capped quartz substrate. The silver nanoparticle-TiO2-quartz structure exhibits a Fano-like reflection spectrum, whose spectral dip can be tuned by the dimension of the silver nanoparticles for plasmonic color generation. This technology allows the one-step production of multiscale engineered large-area plasmonic substrates without the use of either nanostructured templates or additional nanofabrication processes and thus offers an approach to plasmonic engineering for a myriad of applications ranging from structural color decoration to plasmonic microdevices and biosensors.

9.
Adv Mater ; 30(35): e1801772, 2018 Aug.
Article in English | MEDLINE | ID: mdl-30024062

ABSTRACT

The development of a new nanolithographic strategy, named scanning nanowelding lithography (SNWL), for the one-step fabrication of arbitrary high-aspect-ratio nanostructures of metal is reported in this study. Different from conventional pattern transfer and additive printing strategies which require subtraction or addition of materials, SNWL makes use of a sharp scanning tip to reshape metal thin films or existing nanostructures into desirable high-aspect-ratio patterns, through a cold-welding effect of metal at the nanoscale. As a consequence, SNWL can easily fabricate, in one step and at ambient conditions, sub-50 nm metal nanowalls with remarkable aspect ratio >5, which are found to be strong waveguide of light. More importantly, SNWL outweighs the existing strategies in terms of the unique ability to erase the as-made nanostructures and rewrite them into other shapes and orientations on-demand. Taking advantages of the serial and rewriting capabilities of SNWL, the smart information storage-erasure of Morse codes is demonstrated. SNWL is a promising method to construct arbitrary high-aspect-ratio nanostructure arrays that are highly desirable for biological, medical, optical, electronic, and information applications.

10.
Inorg Chem ; 57(14): 8200-8204, 2018 Jul 16.
Article in English | MEDLINE | ID: mdl-29939734

ABSTRACT

The influence of plasmonic effect on the upconversion emission characteristics of Yb3+-Er3+-Tm3+ tridoped ß-NaYF4 hexagonal microrods is studied. Upconversion spontaneous emission can be improved by 10 times if the microrod is deposited on an Ag-coated substrate. The enhancement is also dependent on the emission wavelength and the polarization of the excitation source. Furthermore, upconversion lasing is supported by the geometry of the microrods via the formation of whispering gallery modes. The corresponding excitation threshold can also be reduced by 50% through the influence of plasmonic effect, the coupling between the whispering gallery modes and the surface plasmonic resonance modes.

11.
Small ; 14(30): e1800870, 2018 Jul.
Article in English | MEDLINE | ID: mdl-29943418

ABSTRACT

Plasmonic metal nanostructures are widely used as subwavelength light concentrators to enhance light harvesting of organic solar cells through two photophysical effects, including enhanced local electric field (ELEF) and antenna-amplified light scattering (AALS), while their adverse quenching effect from surface energy transfer (SET) should be suppressed. In this work, a comprehensive study to unambiguously distinguish and quantitatively determine the specific influence and contribution of each effect on the overall performance of organic solar cells incorporated with Ag@SiO2 core-shell nanoparticles (NPs) is presented. By investigating the photon conversion efficiency (PCE) as a function of the SiO2 shell thickness, a strong competition between the ELEF and SET effects in the performance of the devices with the NPs embedded in the active layers is found, leading to a maximum PCE enhancement of 12.4% at the shell thickness of 5 nm. The results give new insights into the fundamental understanding of the photophysical mechanisms responsible for the performance enhancement of plasmonic organic solar cells and provide important guidelines for designing more-efficient plasmonic solar cells in general.

12.
ACS Nano ; 12(7): 6492-6503, 2018 Jul 24.
Article in English | MEDLINE | ID: mdl-29924592

ABSTRACT

Charge transport plays an important role in defining both far-field and near-field optical response of a plasmonic nanostructure with an ultrasmall built-in nanogap. As the gap size of a gold core-shell nanomatryoshka approaches the sub-nanometer length scale, charge transport may occur and strongly alter the near-field enhancement within the molecule-filled nanogap. In this work, we utilize ultrasensitive surface-enhanced Raman spectroscopy (SERS) to investigate the plasmonic near-field variation induced by the molecular junction conductance-assisted electron transport in gold nanomatryoshkas, termed gap-enhanced Raman tags (GERTs). The GERTs, with interior gaps from 0.7 to 2 nm, are prepared with a wet chemistry method. Our experimental and theoretical studies suggest that the electron transport through the molecular junction influences both far-field and near-field optical properties of the GERTs. In the far-field extinction response, the low-energy gap mode predicted by a classical electromagnetic model (CEM) is strongly quenched and hence unobservable in the experiment, which can be well explained by a quantum-corrected model (QCM). In the near-field SERS response, the optimal gap size for maximum Raman enhancement at the excitation wavelength of 785 nm (633 nm) is about 1.35 nm (1.8 nm). Similarly, these near-field results do not tally with the CEM calculations but agree well with the QCM results where the molecular junction conductance in the nanogap is fully considered. Our study may improve understanding of charge-transport phenomena in ultrasmall plasmonic molecular nanogaps and promote the further development of molecular electronics-based plasmonic nanodevices.

13.
Adv Mater ; 30(22): e1707237, 2018 May.
Article in English | MEDLINE | ID: mdl-29665110

ABSTRACT

"Fata Morgana" or "Mirage" phenomena have long been captivated as optical illusions, which actually relies on gradient-density air or vapor. Man-made optical illusions have witnessed significant progress by resorting to artificially structured metamaterials. Nevertheless, two long-standing challenges remain formidable: first, exotic parameters (negative or less than unity) become inevitable; second, the signature of original object is altered to that of a virtual counterpart. It is thus not able to address the holy grail of illusion per se, since a single virtual object still exposes the location. In this study, those problems are successfully addressed in a particular setup-illusion thermotics, which identically mimics the exterior thermal behavior of an equivalent reference and splits the interior original heat source into many virtual signatures. A general paradigm to design thermal illusion metadevices is proposed to manipulate thermal conduction, and empower robust simultaneous functions of moving, shaping, rotating, and splitting heat sources of arbitrary cross sections. The temperature profile inside the thermal metadevice can mislead the awareness of the real location, shape, size, and number of the actual heat sources. The present concept may trigger unprecedented development in other physical fields to realize multiple functionalized illusions in optics, electromagnetics, etc.

14.
Talanta ; 182: 38-48, 2018 May 15.
Article in English | MEDLINE | ID: mdl-29501167

ABSTRACT

Surface functionalization is an effective strategy in the precise control of electronic surface states of two-dimensional materials for promoting their applications. In this study, based on the strong coordination interaction between the transition-metal centers and N atoms, the surface functionalization of few-layer MoS2 nanosheets was successfully prepared by liquid phase exfoliation method in N, N-dimethylformamide (DMF), 1-methyl-2-pyrrolidinone, and formamide. The cytotoxicity of surface-functionalized MoS2 nanosheets was for the first time evaluated by the methylthiazolyldiphenyl-tetrazoliumbromide assays. An electrochemical sensor was constructed based on glass carbon electrode (GCE) modified by MoS2 nanosheets obtained in DMF, which exhibits relatively higher sensitivity to Cd2+ detection and lower cytotoxicity against MCF-7 cells. The mechanisms of surface functionalization and selectively detecting Cd2+ were investigated by density functional theory calculations together with various spectroscopic measurements. It was found that surface-functionalized MoS2 nanosheets could be generated through Mo-N covalent bonds due to the orbital hybridization between the 5 s orbitals of Mo atoms and the 2p orbitals of N atoms of the solvent molecules. The high selectivity of the sensor is attributed to the coordination reaction between Cd2+ and O donor atoms of DMF adsorbed on MoS2 nanosheets. The robust anti-interference is ascribed to the strong binding energy of Cd2+ and O atoms of DMF. Under the optimum conditions, the electrochemical sensor exhibits highly sensitive and selective assaying of Cd2+ with a measured detection limit of 0.2 nM and a linear range from 2 nM to 20 µM.

16.
Article in Chinese | WPRIM (Western Pacific) | ID: wpr-708147

ABSTRACT

This paper describes the status and uses of the National Radiation Safety Management System of Nuclear Technology Utilization ( NRSMS) and the purpose and significance of radioactive source safety oversight informatization. The emphasis is on the analysis of the current status, the summary of accomplishments and the identification of potential problems. It concluded with providing possible suggestions about radioactive source safety oversight informatization in China for use as reference for the management of radioactive source safety in China.

17.
Article in Chinese | WPRIM (Western Pacific) | ID: wpr-941680

ABSTRACT

OBJECTIVE@#To investigate the treatment strategy for subcutaneous fistula secondary to cerebrospinal fluid leakage (CSFL) in thoracic spinal stenosis (TSS) cases.@*METHODS@#In the study, 186 CSFL cases diagnosed with TSS and operated in general spine group of Department of Orthopedics, Peking University Third Hospital from January 2005 to December 2014 were retrospectively reviewed, of which eleven had subcutaneous fistula secondary to CSFL and were regularly followed up. Treatment strategy for subcutaneous fistula depended on the severity of CSFL and the recovery rate of thoracic myelopathy. Japanese Orthopedic Association (JOA) score was utilized to evaluate the neurologic status of these patients preoperatively and postoperatively. Statistical analysis was conducted between preoperative and postoperative JOA scores.@*RESULTS@#All of the 11 patients were regularly followed up for at least 24 months. Six of them had ossification of the posterior longitudinal ligament (OPLL) combined with ossification of ligamentum flavum (OLF), all of them undertook "cave-in" 360° circumferential decompression of the spinal cord with instrumentation. Five cases had OLF only, and received En bloc resection of lamina and OLF and fixation. The follow-up period ranged from 30 months to 131 months, and averaged at (85±34) months. Preoperative symptoms lasted from 3 months to 8 years, and the median was 18 months. Drainages were placed for 2-6 days, and averaged at (4.2±1.1) days. Ten cases appeared with fever during the perioperative period, the maximum body temperature was (37.3-39.7) °C. Prolonged antibiotics were applied in two cases with high fever. Ten cases were treated with conservative methods, CSFL were completely absorbed during the follow-up time, of which compressive dressing was utilized in 8 cases, and punctures combined with compressive dressing were used in 2 cases. For only 1 case, conservative therapy failed and reoperation was required because of neurological deterioration arising from CSF pseudocyst. For these 11 cases, preoperative JOA score arose from (3.8±1.6) preoperatively to (8.9±1.2) at the end of the final follow-up, the recovery rate was 70.8%. No infection of wound or central nerve system were noticed, and neither were unhealing wound.@*CONCLUSION@#Most TSS cases with subcutaneous fistula secondary to CSFL could be cured by conservative methods, and reoperation is required only if myelopathy caused by cerebrospinal fluid pseudocyst is identified.


Subject(s)
Humans , Cerebrospinal Fluid Leak/complications , Decompression, Surgical , Fistula/etiology , Retrospective Studies , Spinal Cord Diseases , Spinal Stenosis/complications , Thoracic Vertebrae , Treatment Outcome
18.
ACS Nano ; 11(3): 3067-3080, 2017 03 28.
Article in English | MEDLINE | ID: mdl-28291332

ABSTRACT

Metal-film-coupled nanoparticles with subnanometer particle-film gaps possess an ultrasmall mode volume, responsible for a variety of intriguing phenomena in plasmonic nanophotonics. Due to the large radiative loss associated with dipolar coupling, however, the plasmonic-film-coupled nanocavities usually feature a low-quality factor, setting an ultimate limit of the increased light-matter interaction strength. Here, we demonstrate a plasmonic nanocavity composed of a metal-film-coupled nanoparticle dimer, exhibiting a significantly improved quality factor. Compared to a silica-supported dimer, the spectral line width of the nanocavity plasmon resonance is reduced by a factor of ∼4.6 and is even smaller than its monomer counterpart (∼30% reduction). Comprehensive theoretical analyses reveal that this pronounced resonance narrowing effect can be attributed to intense film-mediated plasmon hybridization between the bonding dipolar and quadrupolar gap modes in the dimer. More importantly, the invoking of the dark quadrupole resonance leads to a giant photoluminescence intensity enhancement (∼200 times) and dramatic emission line-width narrowing (∼4.6 times), compared to the silica-supported dimer. The similar spectral characteristics of the measured plasmonic scattering and photoluminescence emission indicate that the radiative decay of the coupled plasmons in the nanocavity is the origin of the observed photoluminescence, consistent with a proposed phenomenological model. Numerical calculations show that the intensity enhancement is mainly contributed by the dimer-film gap rather than the interparticle gap. These findings not only shed more light on the hybridized interaction between plasmon modes but also deepen the understanding of photoluminescence emission in coupled plasmonic nanostructures.

19.
Light Sci Appl ; 6(5): e16217, 2017 May.
Article in English | MEDLINE | ID: mdl-30167245

ABSTRACT

Lanthanide-doped upconversion nanocrystals (UCNCs) have recently become an attractive nonlinear fluorescence material for use in bioimaging because of their tunable spectral characteristics and exceptional photostability. Plasmonic materials are often introduced into the vicinity of UCNCs to increase their emission intensity by means of enlarging the absorption cross-section and accelerating the radiative decay rate. Moreover, plasmonic nanostructures (e.g., gold nanorods, GNRs) can also influence the polarization state of the UC fluorescence-an effect that is of fundamental importance for fluorescence polarization-based imaging methods yet has not been discussed previously. To study this effect, we synthesized GNR@SiO2@CaF2:Yb3+,Er3+ hybrid core-shell-satellite nanostructures with precise control over the thickness of the SiO2 shell. We evaluated the shell thickness-dependent plasmonic enhancement of the emission intensity in ensemble and studied the plasmonic modulation of the emission polarization at the single-particle level. The hybrid plasmonic UC nanostructures with an optimal shell thickness exhibit an improved bioimaging performance compared with bare UCNCs, and we observed a polarized nature of the light at both UC emission bands, which stems from the relationship between the excitation polarization and GNR orientation. We used electrodynamic simulations combined with Förster resonance energy transfer theory to fully explain the observed effect. Our results provide extensive insights into how the coherent interaction between the emission dipoles of UCNCs and the plasmonic dipoles of the GNR determines the emission polarization state in various situations and thus open the way to the accurate control of the UC emission anisotropy for a wide range of bioimaging and biosensing applications.

20.
Angew Chem Int Ed Engl ; 56(5): 1283-1288, 2017 01 24.
Article in English | MEDLINE | ID: mdl-28004466

ABSTRACT

Detailed understanding of the interaction between a chiral molecule and a noble metal surface is essential to rationalize and advance interfacial self-assembly of amino acids and metal-mediated anchoring of proteins. Here we demonstrate that individual Au@Ag core-shell nanocuboids can serve as a plasmonic reporter of an extended helical network formed among chemisorbed cysteine molecules, through generating an interband absorption enhanced, Ag-surface-exclusive circular dichroism (CD) band in the UV region. The observed unusual, strong CD response in the hybrid Au@Ag-cysteine system can be used to probe in real time conformational evolution and structural rearrangement of biomolecules in general and also monitor the interfacial interaction between a metal surface and an adsorbed molecule, opening up the possibility of using Ag nanostructures as promising stereochemically attuned nanosensors.

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