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1.
Mol Pharm ; 21(2): 661-676, 2024 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-38175819

RESUMO

Oral squamous cell carcinoma (OSCC) accounts for nearly 90% of oral and oropharyngeal cancer cases and is characterized by high mortality and poor prognosis. RNA-based gene therapies have been developed as an emerging option for cancer treatment, but it has not been widely explored in OSCC. In this work, we developed an efficient siRNA cationic micelle DOTAP-mPEG-PCL (DMP) by self-assembling the cationic lipid DOTAP and monomethoxy poly(ethylene glycol)-poly(ε-caprolactone) (mPEG-PCL) polymer. We tested the characteristics and transformation efficiency of this micelle and combined DMP with siRNA targeting STAT3 and TGF-ß to evaluate the antitumor effect and bone invasion interfering in vitro and in vivo. The average size of the DMP was 28.27 ± 1.62 nm with an average zeta potential of 54.60 ± 0.29 mV. The DMP/siRNA complex showed high delivery efficiency, with rates of 97.47 ± 0.42% for HSC-3. In vitro, the DMP/siSTAT3 complex exhibited an obvious cell growth inhibition effect detected by MTT assay (an average cell viability of 25.1%) and clonogenic assay (an average inhibition rate of 51.9%). Besides, the supernatant from HSC-3 transfected by DMP/siTGF-ß complexes was found to interfere with osteoclast differentiation in vitro. Irrespective of local or systemic administration, DMP/siSTAT3+siTGF-ß showed antitumor effects and bone invasion inhibition in the OSCC mice mandibular invasion model according to tumor volume assays and Micro-CT scanning. The complex constructed by DMP cationic micelles and siSTAT3+siTGF-ß represents a potential RNA-based gene therapy delivery system for OSCC.


Assuntos
Carcinoma de Células Escamosas , Ácidos Graxos Monoinsaturados , Neoplasias de Cabeça e Pescoço , Neoplasias Bucais , Compostos de Amônio Quaternário , Camundongos , Animais , Micelas , RNA Interferente Pequeno/genética , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/terapia , Carcinoma de Células Escamosas de Cabeça e Pescoço , Neoplasias Bucais/genética , Neoplasias Bucais/terapia , Polietilenoglicóis , Poliésteres , Linhagem Celular Tumoral
2.
Small ; 19(1): e2204959, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36372545

RESUMO

The self-assembly of peptidyl virus-like nanovesicles (pVLNs) composed of highly ordered peptide bilayer membranes that encapsulate the small interfering RNA (siRNA) is reported. The targeting and enzyme-responsive sequences on the bilayer's surface allow the pVLNs to enter cancer cells with high efficiency and control the release of genetic drugs in response to the subcellular environment. By transforming its structure in response to the highly expressed enzyme matrix metalloproteinase 7 (MMP-7) in cancer cells, it helps the siRNA escape from the lysosomes, resulting in a final silencing efficiency of 92%. Moreover, the pVLNs can serve as reconfigurable "Trojan horse" by transforming into membranes triggered by the MMP-7 and disrupting the cytoplasmic structure, thereby achieving synergistic anticancer effects and 96% cancer cell mortality with little damage to normal cells. The pVLNs benefit from their biocompatibility, targeting, and enzyme responsiveness, making them a promising platform for gene therapy and anticancer therapy.


Assuntos
Nanopartículas , Neoplasias , Sistemas de Liberação de Medicamentos/métodos , Metaloproteinase 7 da Matriz , RNA Interferente Pequeno/genética , Linhagem Celular Tumoral , Peptídeos/química , Nanopartículas/química , Neoplasias/tratamento farmacológico
3.
Int J Mol Sci ; 24(5)2023 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-36902471

RESUMO

The pathophysiology of Alzheimer's disease is thought to be directly linked to the abnormal aggregation of ß-amyloid (Aß) in the nervous system as a common neurodegenerative disease. Consequently, researchers in many areas are actively looking for factors that affect Aß aggregation. Numerous investigations have demonstrated that, in addition to chemical induction of Aß aggregation, electromagnetic radiation may also affect Aß aggregation. Terahertz waves are an emerging form of non-ionizing radiation that has the potential to affect the secondary bonding networks of biological systems, which in turn could affect the course of biochemical reactions by altering the conformation of biological macromolecules. As the primary radiation target in this investigation, the in vitro modeled Aß42 aggregation system was examined using fluorescence spectrophotometry, supplemented by cellular simulations and transmission electron microscopy, to see how it responded to 3.1 THz radiation in various aggregation phases. The results demonstrated that in the nucleation aggregation stage, 3.1 THz electromagnetic waves promote Aß42 monomer aggregation and that this promoting effect gradually diminishes with the exacerbation of the degree of aggregation. However, by the stage of oligomer aggregation into the original fiber, 3.1 THz electromagnetic waves exhibited an inhibitory effect. This leads us to the conclusion that terahertz radiation has an impact on the stability of the Aß42 secondary structure, which in turn affects how Aß42 molecules are recognized during the aggregation process and causes a seemingly aberrant biochemical response. Molecular dynamics simulation was employed to support the theory based on the aforementioned experimental observations and inferences.


Assuntos
Doença de Alzheimer , Doenças Neurodegenerativas , Humanos , Radiação Terahertz , Peptídeos beta-Amiloides/química , Fragmentos de Peptídeos/química , Estrutura Secundária de Proteína
4.
Plant Cell Rep ; 41(8): 1751-1761, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35748890

RESUMO

KEY MESSAGE: Ketocarotenoids were synthesized successfully in Camelina sativa seeds by genetic modification without using a traditional selection marker genes. This method provided an interesting tool for metabolic engineering of seed crops. Camelina sativa (L.) Crantz is an important oil crop with many excellent agronomic traits. This model oil plant has been exploited to accumulate value-added bioproducts using genetic manipulation that depends on antibiotic- or herbicide-based selection marker genes (SMG), one of the major concerns for genetically modified foods. Here we reported metabolic engineering of C. sativa to synthesize red ketocarotenoids that could serve as a reporter to visualize transgenic events without using a traditional SMG. Overexpression of a non-native ß-carotene ketolase gene coupled with three other carotenogenous genes (phytoene synthase, ß-carotene hydroxylase, and Orange) in C. sativa resulted in production of red seeds that were visibly distinguishable from the normal yellow ones. Constitutive expression of the transgenes led to delayed plant development and seed germination. In contrast, seed-specific transformants demonstrated normal growth and seed germination despite the accumulation of up to 70-fold the level of carotenoids in the seeds compared to the controls, including significant amounts of astaxanthin and keto-lutein. As a result, the transgenic seed oils exhibited much higher antioxidant activity. No significant changes were found in the profiles of fatty acids between transgenic and control seeds. This study provided an interesting tool for metabolic engineering of seed crops without using a disputed SMG.


Assuntos
Brassicaceae , Sementes , Brassicaceae/genética , Carotenoides/metabolismo , Engenharia Metabólica , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismo , Sementes/metabolismo
5.
Langmuir ; 36(46): 13735-13742, 2020 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-33175547

RESUMO

Supramolecular nanocatalysts were designed for asymmetric reactions through the self-assembly process of a bio-organometallic molecule, ferrocene-l-prolinamide (Fc-CO-NH-P). Fc-CO-NH-P could self-assemble into versatile nanostructures in water, including nanospheres, nanosheets, nanoflowers, and pieces. In particular, the self-assembled nanoflowers exhibited a superior specific surface area, high stability, and delicate three-dimensional (3D) chiral catalytic active sites. The nanoflowers could serve as heterogeneous catalysts with an excellent catalytic performance toward direct aldol reactions in aqueous solution, achieving both high yield (>99%) and stereoselectivity (anti/syn = 97:3, ee% >99%). This study proposed a significant strategy to fabricate supramolecular chiral catalysts, serving as a favorable template for designing new asymmetric catalysts.

6.
Appl Opt ; 59(10): C31-C41, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32400563

RESUMO

Properly interpreting lidar (light detection and ranging) signal for characterizing particle distribution relies on a key parameter, χp(π), which relates the particulate volume scattering function (VSF) at 180° (ßp(π)) that a lidar measures to the particulate backscattering coefficient (bbp). However, χp(π) has been seldom studied due to challenges in accurately measuring ßp(π) and bbp concurrently in the field. In this study, χp(π), as well as its spectral dependence, was re-examined using the VSFs measured in situ at high angular resolution in a wide range of waters. ßp(π), while not measured directly, was inferred using a physically sound, well-validated VSF-inversion method. The effects of particle shape and internal structure on the inversion were tested using three inversion kernels consisting of phase functions computed for particles that are assumed as homogenous sphere, homogenous asymmetric hexahedra, or coated sphere. The reconstructed VSFs using any of the three kernels agreed well with the measured VSFs with a mean percentage difference <5% at scattering angles <170∘. At angles immediately near or equal to 180°, the reconstructed ßp(π) depends strongly on the inversion kernel. χp(π) derived with the sphere kernels was smaller than those derived with the hexahedra kernel but consistent with χp(π) estimated directly from high-spectral-resolution lidar and in situ backscattering sensor. The possible explanation was that the sphere kernels are able to capture the backscattering enhancement feature near 180° that has been observed for marine particles. χp(π) derived using the coated sphere kernel was generally lower than those derived with the homogenous sphere kernel. Our result suggests that χp(π) is sensitive to the shape and internal structure of particles and significant error could be induced if a fixed value of χp(π) is to be used to interpret lidar signal collected in different waters. On the other hand, χp(π) showed little spectral dependence.

7.
Biophys J ; 117(3): 533-541, 2019 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-31326108

RESUMO

Protein aggregation is believed to be a significant biological mechanism related to neurodegenerative disease, which makes the early-stage detection of aggregates a major concern. We demonstrated the use of terahertz (THz) time-domain spectroscopy to study protein-water interaction of monomeric and dimeric bovine insulin in aqueous samples. Regulated by changing pH and verified by size-exclusion chromatography and dynamic light scattering, we then measured their concentration-dependent changes in THz absorption between 0.5 and 3.0 THz and quantitatively deduced the extended hydration shell thickness by cubic distribution model and random distribution model. Under a random distribution assumption, the extended hydration thickness is 15.4 ± 0.4 Å for monomeric insulin and 17.5 ± 0.5 Å for dimeric insulin, with the hydration number of 6700 and 11,000, respectively. The hydration number of dimeric insulin is not twice but 1.64 times that of monomeric insulin, further supported by the ratio of solvent-accessible surface area. This "1.64-times" relation probably originates from the structural and conformational changes accompanied with dimerization. Combined with the investigations on insulin samples with different single amino acid mutations, residue B24 is believed to play an important role in the dimerization process. It is demonstrated that THz time-domain spectroscopy is a useful tool and has the sensitivity to provide the hydration information of different protein aggregates at an early stage.


Assuntos
Insulina/química , Espectroscopia Terahertz , Água/química , Animais , Bovinos , Cromatografia em Gel , Difusão Dinâmica da Luz , Simulação de Dinâmica Molecular
8.
Opt Express ; 27(16): A1188-A1206, 2019 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-31510499

RESUMO

The recently commercialized LISST-VSF instrument measures the volume scattering function (VSF) from 0.1° to 15° with a traditional laser diffraction unit (LISST) and from 15° to 155° with an eyeball component. Between these two optical components, only the LISST unit is calibrated. The eyeball measurements are scaled using the VSFs at 15° that are measured by both components. As this relative calibration relies on a valid measurement at 15° by the LISST, it might fail in clear oceanic waters, where the forward scattering is relative weak either due to a lack of large particles or an overall low concentration of all particles. In this study, we calibrated the LISST-VSF eyeball component through a series of lab experiments using standard polystyrene beads. Validation with the beads of two different sizes showed a median difference of 11.1% between theoretical and calibrated values. Further evaluations with in situ data collected by the LISST-VSF and an ECO-BB3 meter indicated that the new calibration worked well in both turbid and clear waters, while the relative calibration method tended to overestimate VSFs in clear waters.

9.
Opt Express ; 27(18): 25595-25602, 2019 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-31510429

RESUMO

The absorption region of a water-based absorber was expanded by introducing tetramethylurea (TMU) into the inclusion, whose dielectric properties are tunable through the concentration of TMU. The dielectric spectroscopy of a TMU/water mixture was deconstructed using a Debye model. We designed a four-layer ultra-broadband microwave absorber with a supernatant micro-structure. Simulation and experiment results indicate that the absorber can achieve 90% perfect absorption, covering a broad frequency range of 4-40 GHz. The concentration dependence of the absorber was also studied experimentally and numerically. The concentration control provides a more practical and large frequency-region modulation of perfect absorption.

10.
Mar Drugs ; 17(1)2019 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-30634667

RESUMO

The marine thraustochytrids are a promising source of docosahexaenoic acid (DHA) and the ketocarotenoid astaxanthin. In this study, the biosynthetic pathways of these two important metabolites in Aurantiochytrium sp. SK4 was illustrated by the analyses of the genome, transcriptome, key enzymes, and pathway products. Two sets of genes were involved in two pathways for the biosynthesis of fatty acids. The absence of Δ-15 desaturase genes and the presence of docosapentaenoic acid (DPA), up to 12% of total fatty acids suggest that Aurantiochytrium sp. SK4 may synthesize DHA mainly via a polyketide synthase (PKS) pathway. Three enzymes, namely geranyl diphosphate synthase (GPPS), farnysyl diphosphate synthase (FPPS), and geranylgeranyle diphosphate synthase (GGPPS) were found to be involved in the formation of GGPP that was subsequently catalyzed to ß-carotene by a trifunctional CrtIBY enzyme. ß-Carotene might be ketolated and then hydroxylated into astaxanthin based on the carotenoid profiles. The formation of GGPP was proposed to be the limiting steps for carotenoid production. Overexpression of the Archaeoglobus GPS together with the Escherichia coli isopentenyl pyrophosphate isomerase, and Vitreoscilla hemoglobin resulted in not only 1.85- and 5.02-fold increases of total carotenoids and astaxanthin, but also 2.40- and 2.74-fold increases of total fatty acids and DHA. This study provides insights into the biosynthesis of carotenoids and fatty acids in Aurantiochytrium.


Assuntos
Ácidos Docosa-Hexaenoicos/biossíntese , Eucariotos/metabolismo , Genoma , Engenharia Metabólica , Transcriptoma , Xantofilas/biossíntese
11.
Guang Pu Xue Yu Guang Pu Fen Xi ; 37(1): 42-7, 2017 01.
Artigo em Zh | MEDLINE | ID: mdl-30192465

RESUMO

Caulis spatholobi and caulis sargentodoxae are two different kinds of traditional Chinese medicine, which are similar to each other in appearance, but they are from differ sources with different functions.. This paper presents their spectrum using terahertz time-domain spectroscopy technology combines spectral matching algorithm to identify five different kinds of these samples. Due to the complex chemical composition of traditional Chinese medicine, different components of the characteristic absorption peak occurred easily mutually overlapping, therefore, it's very difficult to find obvious characteristic absorption peak in terahertz range, caulis spatholobi and caulis like this. Every sample was measured 10 times in some position. These standard spectral data have been calculated in different frequency, data show good stability in range of 0.2~1.3 THz. The second order differential method is used to process the THz spectrum data from 0.2~1.3 THz. These tiny differences of absorption coefficient have been hemerged between caulis sargentodoxae and caulis spatholobi and compare with these data using the method of correlation coefficient block coding method, spectral angle method and information divergence method, respectively. The analysis results, the spectral angle method is the best algorithm, the discriminate accuracy of a total of 100 sets of data is 95%. It is a new way to distinguish difference of traditional Chinese medicine.

12.
Mycologia ; 107(1): 12-20, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25344264

RESUMO

Phlebopus portentosus is a popular edible wild mushroom found in the tropical Yunnan, China, and northern Thailand. In its natural habitats, a gall often has been found on some plant roots, around which fungal fruiting bodies are produced. The galls are different from common insect galls in that their cavity walls are not made from plant tissue but rather from the hyphae of P. portentosus. Therefore we have termed this phenomenon "fungus-insect gall". Thus far six root mealy bug species in the family Pseudococcidae that form fungus-insect galls with P. portentosus have been identified: Formicococcus polysperes, Geococcus satellitum, Planococcus minor, Pseudococcus cryptus, Paraputo banzigeri and Rastrococcus invadens. Fungus-insect galls were found on the roots of more than 21 plant species, including Delonix regia, Citrus maxima, Coffea arabica and Artocarpus heterophyllus. Greenhouse inoculation trials showed that fungus-insect galls were found on the roots of A. heterophyllus 1 mo after inoculation. The galls were subglobose to globose, fulvous when young and became dark brown at maturation. Each gall harbored one or more mealy bugs and had a chimney-like vent for ventilation and access to the gall. The cavity wall had three layers. Various shaped mealy bug wax deposits were found inside the wall. Fungal hyphae invaded the epidermis of plant roots and sometimes even the cortical cells during the late stage of gall development. The identity of the fungus inside the cavity was confirmed by molecular methods.


Assuntos
Agaricales/crescimento & desenvolvimento , Agaricales/isolamento & purificação , Tumores de Planta/microbiologia , Plantas/microbiologia , Agaricales/classificação , Agaricales/genética , China , Dados de Sequência Molecular , Filogenia , Raízes de Plantas/microbiologia
13.
Biosensors (Basel) ; 14(4)2024 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-38667171

RESUMO

Transition metal doping is an ideal strategy to construct multifunctional and efficient nanozymes for biosensing. In this work, a metal-doped CoMnOx nanozyme was designed and synthesized by hydrothermal reaction and high-temperature calcination. Based on its oxidase activity, an "on-off-on" smartphone sensing platform was established to detect ziram and Cu2+. The obtained flower-shaped CoMnOx could exhibit oxidase-, catalase-, and laccase-like activities. The oxidase activity mechanism of CoMnOx was deeply explored. O2 molecules adsorbed on the surface of CoMnOx were activated to produce a large amount of O2·-, and then, O2·- could extract acidic hydrogen from TMB to produce blue oxTMB. Meanwhile, TMB was oxidized directly to the blue product oxTMB via the high redox ability of Co species. According to the excellent oxidase-like activity of CoMnOx, a versatile colorimetric detection platform for ziram and Cu2+ was successfully constructed. The linear detection ranges for ziram and Cu2+ were 5~280 µM and 80~360 µM, and the detection limits were 1.475 µM and 3.906 µM, respectively. In addition, a portable smartphone platform for ziram and Cu2+ sensing was established for instant analysis, showing great application promise in the detection of real samples including environmental soil and water.


Assuntos
Técnicas Biossensoriais , Colorimetria , Cobre , Smartphone , Cobre/análise , Limite de Detecção , Lacase , Nanoestruturas
14.
Front Med (Lausanne) ; 11: 1358161, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38523911

RESUMO

Early T-cell precursor acute lymphoblastic leukemia (ETP-ALL) is a highly aggressive subtype of T-ALL. No standard chemotherapy regimen exists for patients with recurrent/refractory (R/R) ETP-ALL; in these patients, the primary goal of salvage therapy is to achieve remission as a foundation for consolidation and intensification treatments. This study reports cases of two patients with R/R ETP-ALL who underwent salvage therapy of venetoclax combined with the CAG regimen and achieved complete remission in the bone marrow. Flow cytometry results were negative for minimal residual disease. Both patients were bridged to allogeneic hematopoietic stem cell transplantation (HSCT) and in complete remission over a 3-year follow-up period. These cases show that the use of venetoclax combined with the CAG regimen may offer patients with R/R ETP-ALL an opportunity for allogeneic HSCT.

15.
Talanta ; 278: 126489, 2024 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-38959667

RESUMO

Pyrazinamide (PZA) is a widely-used anti-tuberculosis pharmaceutical, but its poor solubility prompts us to optimize pharmaceutical performance. Cocrystallization is a promising technique to improve physiochemical properties of active pharmaceutical ingredient (API) by connecting it with cocrystal former (CCF) via intermolecular interactions. Even though a series of alkyl dicarboxylic acids are employed to form cocrystal structures, systematic understanding on the role of intermolecular interactions is still missing. Therefore, terahertz (THz) spectroscopy and quantum chemical calculation are combined to elucidate the behavior of ubiquitous supramolecular synthons, such as hetero-synthons of acid-pyrazine, acid-amide and homo-synthon of amide-amide, from energy's view. Potential energy is calculated to differentiate the stability within polymorphs of PZA-MA cocrystal and free energy is evaluated to compare the solubility of PZA-CCF cocrystals respectively. With regard to vibrational energy, THz spectral fingerprints are theoretically assigned to specific vibrations and attributed to the flexibility deformation of supramolecular synthons based on oscillation theory, where stretching and twisting modes dominate the collective vibrational behavior. It provides a promising tool to evaluate cocrystal performance from its driving force and insightful guidance to discover new pharmaceutical cocrystals.

16.
Appl Opt ; 52(3): 359-74, 2013 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-23338181

RESUMO

A radiative transfer model was applied to examine the effects of vertically stratified inherent optical properties of the water column associated with near-surface plumes of suspended particulate matter on spectral remote-sensing reflectance, R(rs)(λ), of coastal marine environments. The simulations for nonuniform ocean consisting of two layers with different concentrations of suspended particulate matter (SPM) are compared with simulations for a reference homogeneous ocean whose SPM is identical to the surface SPM of the two-layer cases. The near-surface plumes of particles are shown to exert significant influence on R(rs)(λ). The sensitivity of R(rs)(λ) to vertical profile of SPM is dependent on the optical beam attenuation coefficient within the top layer, c(1)(λ), thickness of the top layer, z(1), and the ratio of SPM in the underlying layer to that in the top layer, SPM(2)/SPM(1), as well as the wavelength of light, λ. We defined a dimensionless spectral parameter, P(λ)=c(1)(λ)×z(1)×(SPM(2)/SPM(1)), to quantify and examine the effects of these characteristics of the two-layer profile of SPM on the magnitude and spectral shape of R(rs)(λ). In general, the difference of R(rs)(λ) between the two-layer and uniform ocean decreases to zero with an increase in P(λ). For the interpretation of ocean color measurements of water column influenced by near-surface plumes of particles, another dimensionless parameter P'(λ) was introduced, which is a product of terms representing homogenous ocean and a change caused by the two-layer structure of SPM. Based on the analysis of this parameter, we found that for the two-layer ocean there is a good relationship between R(rs)(λ) in the red and near-infrared spectral regions and the parameters describing the SPM(z) profile, i.e., SPM(1), SPM(2), and z(1).

17.
Appl Opt ; 52(23): 5695-700, 2013 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-23938420

RESUMO

Gasolines of two different octane numbers are experimentally distinguished using a thin metal sheet perforated with a periodic hole array terahertz surface plasmon (SP) sensor. This sensor is proved to be very sensitive to the change in permittivities of analytes. The differences between the gasolines 93# and 97# in composition lead to various refractive indices, permittivities, and absorption coefficients, thus varying their interactions with surface waves on the sensor, which enables a distinction of 6 GHz between the two octane numbers in the transmission peaks. The freestanding SP sensor is effective and reliable and can be simply employed in analyte distinction, which has potential applications in the petroleum industry.

18.
Appl Opt ; 52(4): 824-8, 2013 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-23385924

RESUMO

The effect of a dielectric overlayer on terahertz transmission through a freestanding metallic array of subwavelength holes is experimentally presented. There is a remarkable resonance redshift from 0.600 to 0.498 THz at the surface plasmon (SP) metal-dielectric resonance mode with increasing film thickness. When the overlayer film is thicker than a critical thickness, the resonance frequency becomes steady at the final resonance frequency ω(f). On the basis of the dispersion relation of SPs, two kinds of glutamic acid enantiomers are distinguished by use of SP-enhanced terahertz spectra of metallic array of subwavelength holes according to the result of ω(f). The terahertz plasmonic hole array with the sensitive nature provides an approach to distinguish trace amount of powder substances, which has a promising application prospect in the fields of public security and biomedical science, such as distinguishing between isomers and identifying expensive medicines and drugs.

19.
Appl Opt ; 52(25): 6364-8, 2013 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-24085099

RESUMO

Experimental tests are presented to investigate the stress effect on terahertz (THz) waves with a THz time-domain spectroscopy system. Through the Jones matrix method, an experimental principle is derived according to the experimental system. Experimental results indicate the linear relationship between a polytetrafluoroethylene refractive index and applied stress. The result can be applied to the active modulation of a refractive index or phase of a THz wave.

20.
Spectrochim Acta A Mol Biomol Spectrosc ; 292: 122404, 2023 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-36746041

RESUMO

Cardiovascular pharmaceuticals have drawn huge attention in drug development. Nifedipine (NFD) is an important member of calcium channel blockers (CCB) with the structural characteristic of dihydropyridine (DHP), but the binding mechanism to its target remains an open question. Even though several analytical techniques have been used for structural characterizations, the information of collective vibrational behavior is still lacking. In this work, we use terahertz (THz) spectroscopy to investigate the spectral fingerprints of NFD, and quantitatively evaluate the temperature-induced frequency shifts. Combined with quantum chemical calculations, each THz fingerprint is attributed to specific collective vibrational modes. The collective vibrations of DHP are mainly distributed below 2.5 THz, which provides complementary information to understand the behavior of rigid DHP ring. The rotation of methyl group and the wagging of nitrophenyl group are widely distributed in the range of 1.0-4.0 THz, which is helpful for the conformational recognition between NFD and target molecule. THz spectroscopy is demonstrated to be suitable for characterizing the collective vibrational modes of DHP and elucidating the drug-target binding behavior from the perspective of noncovalent interactions. It has the potential to become a non-invasive technology for conformational analysis and pharmaceutical development.


Assuntos
Espectroscopia Terahertz , Espectroscopia Terahertz/métodos , Nifedipino , Vibração , Conformação Molecular
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