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Bigeng Chen, Xingshi Yu, Xia Chen, Milan M Milosevic, David J Thomson, Ali Z Khokhar, Shinichi Saito, Otto L Muskens, Graham T Reed
Fabrication errors pose significant challenges on silicon photonics, promoting post-fabrication trimming technologies to ensure device performance. Conventional approaches involve multiple trimming and characterization steps, impacting overall fabrication complexity. Here we demonstrate a highly accurate trimming method combining laser annealing of germanium implanted silicon waveguide and real-time monitoring of device performance. Direct feedback of the trimming process is facilitated by a differential spectroscopic technique based on photomodulation...
September 17, 2018: Optics Express
Kanchan Aggarwal, Mandira Banik, Brenda Medellin, Emily L Que
We report two small molecule azobenzenesulfonamide probes, CAP1 and CAP2, capable of photomodulating the activity of carbonic anhydrase (CA) on demand. In the trans form, CAP azobenzene probes adopt a linear shape, making them suitable for occupying the CA active site and interacting with Zn2+ , thereby inhibiting enzyme activity. Following irradiation with either 365 or 410 nm light, the CAP probes isomerize to their cis form. Because of the change in steric profile, the probe exits the active site, and the activity of the enzyme is restored...
November 1, 2018: Biochemistry
Haisi Hu, Yuan Qiu, Jing Wang, Dongxu Zhao, Hong Wang, Qin Wang, Yonggui Liao, Haiyan Peng, Xiaolin Xie
Photoresponsive supramolecular gels with various applications are being constantly pursued; however, achieving well-defined morphology changes of gels via light irradiation remains a formidable challenge. In this study, a gel is prepared through halogen bond between azopyridine-containing Azopy-C10 and 1,4-tetrafluorodiiodobenzene. The gel exhibits gel-sol transition due to trans-cis isomerization of the azopyridine moiety upon UV irradiation. During this transition, the morphologies vary from flake to fluffy bobble-like and finally to peony-like with increasing exposure time, which is difficult to achieve in traditional assembly systems...
October 22, 2018: Macromolecular Rapid Communications
Dan Zhang, Qinqin Wang, Xia Fan, Mingliang Zhang, Jin Zhai, Lei Jiang
Many natural photomodulated nanochannels are investigated and are crucial for biological activity. Biomimetic nanochannels with a bistable conductance state under light stimulus are demonstrated. In this system, two molecules, cis-bis-(4,4'-dicarboxy-2,2'-bipyridine) dithiocyanato ruthenium(II) (N3) and spiropyran 1'-(3-carboxypropyl)-3',3'-dimethyl-6-nitro-spiro[2H-1]benzopyran-2,2'-indoline (SP-COOH), each with unique photoresponsive properties, are modified in alumina nanochannels. The two segments of the hourglass-shaped alumina nanochannels are designated to graft a certain molecule...
November 2018: Advanced Materials
Lijia Yu, Nannan Jing, Zhenjun Yang, Lihe Zhang, Xinjing Tang
Manually controlling siRNA activity is an essentially important way to spatiotemporally investigate gene expression and function. Owing to ease of operation and precise manipulation, light can be used for controlled regulation of siRNA-induced gene silencing. Here, we developed a series of caged siRNAs with folic acid modification at the 5' terminus of the antisense strand of the siRNA through a photolabile linker. The attachment of the folic acid moiety temporarily masked the corresponding siRNA activity. Upon illumination, these caged siRNAs were activated, and their gene silencing activities were restored...
October 3, 2018: Organic & Biomolecular Chemistry
Ronghua Liu, Yu Yang, Qianling Cui, Wenqiang Xu, Rui Peng, Lidong Li
Photochromic diarylethene derivatives, which can reversibly switch the fluorescence of adjacent fluorophores between the ON and OFF states under light irradiation, have been widely used to construct photoswitchable materials. Herein, we integrate eight dithienylethene (DTE) groups onto one polyhedral oligomeric silsesquioxanes (POSS) core, obtaining a novel super molecular photoswitch. After being doped into conjugated polymer nanoparticles, the POSS-DTE8 molecules shows a higher contrast on/off photoswitching performance and a quicker responsive speed than free DTE molecules at same molar concentration of photochromic units...
September 19, 2018: Chemistry: a European Journal
A Dubois, Chih-Chieh Chiang, F Smekens, S Jan, V Cuplov, S Palfi, Keh-Shih Chuang, S Senova, F Pain
The use of optogenetics or photobiomodulation in non-human primate (NHP) requires the ability to noninvasively stimulate large and deep cortical brain tissues volumes. In this context, the optical and geometrical parameters of optodes are critical. Methods and general guidelines to optimize these parameters have to be defined. OBJECTIVE: We propose the design of an optode for safe and efficient optical stimulation of a large volume of NHP cortex, down to 3-5 mm depths without inserting fibers into the cortex...
September 7, 2018: Journal of Neural Engineering
Scott Kevin Cushing, Chih-Jung Chen, Chung Li Dong, Xiang-Tian Kong, Alexander O Govorov, Ru-Shi Liu, Nianqiang Wu
For semiconductors photosensitized with organic dyes or quantum dots, transferred electrons are usually considered thermalized at the conduction band edge. This study suggests that the electrons injected from a plasmonic metal into a thin semiconductor shell can be nonthermal with energy up to the plasmon frequency. In other words, the electrons injected into the semiconductor are still hot carriers. Photomodulated X-ray absorption measurements of the Ti L2,3 edge are compared before and after excitation of the plasmon in Au@TiO2 core-shell nanoparticles...
July 24, 2018: ACS Nano
Hong Zhao, Eleonora Garoni, Thierry Roisnel, Alessia Colombo, Claudia Dragonetti, Daniele Marinotto, Stefania Righetto, Dominique Roberto, Denis Jacquemin, Julien Boixel, Véronique Guerchais
We disclose a new family of photochromic cyclometalated platinum(II) complexes (PtDTE1 and PtDTE2), where a dithienylethene (DTE) unit is connected at the para-position of the central phenyl ring of (N^C^N) cyclometalated ligand, through two different linkages. Their syntheses are presented along with the X-ray characterizations of both the open and closed isomers of PtDTE1. The investigation of their photophysical properties is made, including absorption, photochromism, emission, and second-order nonlinear properties...
June 18, 2018: Inorganic Chemistry
Cristian Statkievicz, Luan Felipe Toro, João Martins de Mello-Neto, Daniela Pereira de Sá, Cláudio Aparecido Casatti, João Paulo Mardegan Issa, Luciano Tavares Angelo Cintra, Juliano Milanezi de Almeida, Maria José Hitomi Nagata, Valdir Gouveia Garcia, Leticia Helena Theodoro, Edilson Ervolino
The aim of this study was to evaluate the effects of photobiomodulation (PBM) with multiple sessions of low-level laser on the alveolar repair process of rats with major risk factors for medication-related osteonecrosis of the jaws (MRONJ). Senile rats received 0.45 mL of vehicle (VEH and VEH-PBM) or 0.45 mL of 100 μg/kg zoledronate (ZOL and ZOL-PBM) administrated intraperitoneally every two days during seven weeks. After three weeks of initiation of drug treatment the first lower left molar was extracted...
July 2018: Journal of Photochemistry and Photobiology. B, Biology
Ana Paula Taboada Sobral, Camila Leal H de Godoy, Kristianne P Santos Fernandes, Sandra Kalil Bussadori, Raquel Agnelli Mesquita Ferrari, Anna Carolina Ratto Tempestini Horliana, Sonia F Monken, Lara J Motta
INTRODUCTION: Epidemiological data show that the signs and symptoms of temporomandibular disorder (TMD) start becoming apparent from 6 years of age, and during adolescence these signs and symptoms are similar to those of adults. The present study aims to estimate the direct costs for treatment of chronic muscle pain with photobiomodulation therapy, occlusal splint and placebo in patients with TMD; to evaluate the effectiveness of photobiomodulation therapy and occlusal splint for treatment of muscle pain in patients with TMD; to analyse the cost-effectiveness of the two proposed treatments for pain; and to describe and compare the results of the analyses of these treatments...
May 5, 2018: BMJ Open
Lijia Yu, Duanwei Liang, Changmai Chen, Xinjing Tang
RNA interference (RNAi) mediated gene silencing holds significant promise in gene therapy. It is very important to manually regulate the activity of small interference RNAs (siRNAs) in the controllable mode. Here, we designed and synthesized a series of caged siRNAs through bioconjugation of cyclo(Arg-Gly-Asp-d-Phe-Lys) (cRGD) peptide to the 5' end of siRNA through a photolabile linker. These cRGD modified caged siRNAs allowed for precise light-regulation of gene expression of two exogenous reporter genes (firefly luciferase and green fluorescent protein, GFP) and an endogenous gene (the mitosis motor protein, Eg5) in the integrin αv β3 positive cells...
July 9, 2018: Biomacromolecules
Liangliang Zhang, Duanwei Liang, Yuan Wang, Dong Li, Jinhao Zhang, Li Wu, Mengke Feng, Fan Yi, Luzheng Xu, Liandi Lei, Quan Du, XinJing Tang
By means of RNA interference (RNAi), small interfering RNAs (siRNAs) play important roles in gene function study and drug development. Recently, photolabile siRNAs were developed to elucidate the process of gene silencing in terms of space, time and degree through chemical modification of siRNAs. We report herein a novel type of photolabile siRNA that was synthesized through cyclizing two ends of a single stranded RNA with a photocleavable linker. These circular siRNAs became more resistant to serum degradation...
January 7, 2018: Chemical Science
J Bogdanowicz, A Kumar, C Fleischmann, M Gilbert, J Houard, A Vella, W Vandervorst
This paper demonstrates the increased light absorption efficiency of semiconducting atom probe tips resulting from focused-ion-beam (FIB) preparation. We use transmission electron microscopy to show that semiconducting tips prepared with FIB are surrounded with an amorphized shell. Photomodulated optical reflectance measurements then provide evidence that FIB-induced damage leads to an increase in both sub- and supra-bandgap light absorption efficiency. Using laser-assisted atom probe tomography (La-APT) measurements, we finally show that, for a nanoscale tip geometry, the laser-induced heating of a tip during La-APT is enhanced by the FIB preparation...
May 2018: Ultramicroscopy
Liangliang Zhang, Changmai Chen, Xinli Fan, Xinjing Tang
Caged siRNAs incorporating terminal modification were rationally designed for photochemical regulation of gene silencing induced by RNA interference (RNAi). Through the conjugation of a single oligonucleotide aptamer at the 5' terminus of the antisense RNA strand, enhancement of the blocking effect for RNA-induced silencing complex (RISC) formation/processing was expected, due both/either to the aptamers themselves and/or to their interaction with large binding proteins. Two oligonucleotide aptamers (AS1411 and MUC-1) were chosen for aptamer-siRNA conjugation through a photolabile linker...
June 18, 2018: Chembiochem: a European Journal of Chemical Biology
Niels J Hauwert, Tamara A M Mocking, Daniel Da Costa Pereira, Albert J Kooistra, Lisa M Wijnen, Gerda C M Vreeker, Eléonore W E Verweij, Albertus H De Boer, Martine J Smit, Chris De Graaf, Henry F Vischer, Iwan J P de Esch, Maikel Wijtmans, Rob Leurs
Noninvasive methods to modulate G protein-coupled receptors (GPCRs) with temporal and spatial precision are in great demand. Photopharmacology uses photons to control in situ the biological properties of photoswitchable small-molecule ligands, which bodes well for chemical biological precision approaches. Integrating the light-switchable configurational properties of an azobenzene into the ligand core, we developed a bidirectional antagonist toolbox for an archetypical family A GPCR, the histamine H3 receptor (H3 R)...
March 28, 2018: Journal of the American Chemical Society
Xianbao Li, Jinbo Fei, Youqian Xu, Dongxiang Li, Tingting Yuan, Guangle Li, Chenlei Wang, Junbai Li
Tunable supramolecular assembly has found various applications in biomedicine, molecular catalysis, optoelectronics, and nanofabrication. Unlike traditional covalent conjugation, non-covalent introduction of a photoswitchable moiety enables reversible photomodulation of non-photosensitive dipeptide supramolecular assembly. Under light illumination, a long-lived photoacid generator releases a proton and mediates the dissociation of dipeptide-based organogel, thereby resulting in sol formation. Under darkness, the photoswitchable moiety entraps a proton, resulting in gel regeneration...
February 12, 2018: Angewandte Chemie
Wei-Qiu Kan, Shi-Zheng Wen, Yuan-Chun He, Chao-Yue Xu
Four coordination polymers, namely, [Zn(HL1)(L2)0.5 ]·H2 O (1), [Cd(HL1)(L2)0.5 ]·H2 O (2), [Zn(L1)(L3)0.5 ]·H2 O (3), and [Cd(L1)(L3)0.5 ] (4) (H3 L1 = (3,5-dicarboxyl-phenyl)-(4-(2'-carboxyl-phenyl)-benzyl)ether, H2 L2Cl2 = 1,1'-bis(4-carboxy-benzyl)-4,4'-bipyridinium dichloride, and L3Cl2 = 1,1'-dimethyl-4,4'-bipyridylium dichloride), have been synthesized hydrothermally. The structures of compounds 1-4 have been determined by single-crystal X-ray diffraction analyses, and further characterized by elemental analyses, infrared (IR) spectra, powder X-ray diffraction (PXRD) analyses, and thermogravimetric analyses...
December 18, 2017: Inorganic Chemistry
K Zelazna, M Gladysiewicz, M P Polak, S Almosni, A Létoublon, C Cornet, O Durand, W Walukiewicz, R Kudrawiec
The electronic band structure of phosphorus-rich GaNx Py As1-x-y alloys (x ~ 0.025 and y ≥ 0.6) is studied experimentally using optical absorption, photomodulated transmission, contactless electroreflectance, and photoluminescence. It is shown that incorporation of a few percent of N atoms has a drastic effect on the electronic structure of the alloys. The change of the electronic band structure is very well described by the band anticrossing (BAC) model in which localized nitrogen states interact with the extended states of the conduction band of GaAsP host...
November 16, 2017: Scientific Reports
Jenifer Rubio-Magnieto, Tuan-Anh Phan, Mathieu Fossépré, Valérie Matot, Jérémie Knoops, Thibaut Jarrosson, Pascal Dumy, Francoise Serein-Spirau, Claude Niebel, Sébastien Ulrich, Mathieu Surin
A new type of DNA ligand that contains a phosphate-binding group and a photoresponsive azobenzene moiety is reported. When the azobenzene is in trans configuration, the ligand binds to the minor groove of a double-stranded DNA, whereas it partially desorbs upon trans-cis isomerization with light. The ability to photoswitch the ligand upon interaction with DNA is evidenced by (chir)optical signatures, and deciphered by the differences of binding geometry, stability, and dynamics of the DNA/ligand complexes for the two isomers...
November 3, 2017: Chemistry: a European Journal
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