Experimental investigation of electrostatic particle-particle interactions in optoelectronic tweezers

This paper reports experimental and theoretical investigation of electrostatic attraction and repulsion of microparticles in an optoelectronic tweezers (OET). When we manipulate dielectric particles suspended in a fluid using OET, the electrostatic interactions of the polarized particles occur, limiting the effective manipulation of microparticles using a light-induced dielectrophoresis. In this study, we first demonstrate the electrostatic particle-particle interactions in the OET device using a liquid crystal display. At the same time, the experimental investigation of the dipole interactions between two spherical particles has been performed using the OET device. On the basis of the point-dipole model, simulation studies on the dipole forces acting on the particles and their trajectories by the forces are also performed. The experimental results show good agreement with the previously reported numerical studies as well as the results of our simulation studies.     

Dielectrophoretic tweezers as a platform for molecular force spectroscopy in a highly parallel format

We demonstrated the application of a simple electrode geometry for dielectrophoresis (DEP) on colloidal probes as a form of molecular force spectroscopy in a highly parallel format. The electric field between parallel plates is perturbed with dielectric microstructures, generating uniform DEP forces on colloidal probes in the range of several hundred piconewtons across a macroscopic sample area. We determined the approximate crossover frequency between negative and positive DEP using electrodes without dielectric microstructures-a simplification over standard experimental methods involving quadrupoles or optical trapping. 2D and 3D simulations of the electric field distributions validated the experimental behavior of several of our DEP tweezers geometries and provided insight into potential improvements. We applied the DEP tweezers to the stretching of a short DNA oligomer and detected its extension using total-internal reflection fluorescence microscopy. The combination of a simple cell fabrication, a uniform distribution of high axial forces, and a facile optical detection of our DEP tweezers makes this form of molecular force spectroscopy ideal for highly parallel detection of stretching or unbinding kinetics of biomolecules.     

Interactive manipulation of blood cells using a lens-integrated liquid crystal display based optoelectronic tweezers system

This paper reports a lens-integrated liquid crystal display (LCD)-based optoelectronic tweezers (OET) system for interactive manipulation of polystyrene microspheres and blood cells by optically induced dielectrophoretic force. When a dynamic image pattern is projected into a specific area of a photoconductive layer in an OET, virtual electrodes are generated by spatially resolved illumination of the photoconductive layer, resulting in dielectrophoresis of microparticles suspended in the liquid layer under nonuniform electric field. In this study, the simple-structured OET system has been easily constructed with an OET device, an LCD and a condenser lens integrated in a conventional microscope. By using a condenser lens, both stronger dielectrophoretic forces and higher virtual electrode resolution than previously reported lens-less LCD-based OET platform are obtained. The effects of blurred LCD image and liquid chamber height on the performances of optoelectronic particle manipulation are investigated by measuring the bead velocities according to their sizes. An interactive control program for OET-based microparticle manipulation is also developed by Flash language. The integrated system is successfully applied to the parallel and interactive manipulation of red and white blood cells. Due to its simple structures, cheap manufacturing costs, and high performances, this new LCD-based OET platform may be a widely usable integrated system for optoelectronic manipulation of microparticles including living cells.     

A conformationally reliable spacer for molecular tweezers

[figure: see text] A reliable and rigid spacer, trans,trans,trans-perhydronaphthacene, for molecular tweezers was designed. A synthesis and molecular recognition study of its 1,14-disubstituted derivatives was carried out.     

Soluble alkyl substituted poly(3,4‐propylenedioxyselenophene)s: A new platform for optoelectronic materials

Optical and electrochemical properties of regiosymmetric and soluble alkylenedioxyselenophene‐based electrochromic polymers, namely poly(3,3‐dibutyl‐3,4‐dihydro‐2H‐selenopheno[3,4‐b][1,4]dioxephine) (PProDOS‐C₄), poly(3,3‐dihexyl‐3,4‐dihydro‐2H‐selenopheno[3,4‐b][1,4]dioxephine) (PProDOS‐C₆), and poly(3,3‐didecyl‐3,4‐dihydro‐2H‐selenopheno[3,4‐b][1,4]dioxephine) (PProDOS‐C₁₀), are highlighted. It is noted that these unique polymers have low bandgaps (1.57–1.65 eV), and they are exceptionally stable under ambient atmospheric conditions. Polymer films retained 82–97% of their electroactivity after 5000 cycles. The percent transmittance of PProDOS‐C_n (n = 4, 6, 10) films found to be between 55 and 59%. Furthermore, these novel soluble PProDOS‐C_n polymers showed electrochromic behavior: a color change form pure blue to highly transparent state in a low switching time (1.0 s) during oxidation with high coloration efficiencies (328–864 cm² C^?1) when compared to their thiophene analogues. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Optical tweezers for medical diagnostics

Laser trapping by optical tweezers makes possible the spectroscopic analysis of single cells. Use of optical tweezers in conjunction with Raman spectroscopy has allowed cells to be identified as either healthy or cancerous. This combined technique is known as laser tweezers Raman spectroscopy (LTRS), or Raman tweezers. The Raman spectra of cells are complex, since the technique probes nucleic acids, proteins, and lipids; but statistical analysis of these spectra makes possible differentiation of different classes of cells. In this article the recent development of LTRS is described along with two illustrative examples for potential application in cancer diagnostics. Techniques to expand the uses of LTRS and to improve the speed of LTRS are also suggested.     

DNA-encoded antibody libraries: a unified platform for multiplexed cell sorting and detection of genes and proteins

Whether for pathological examination or for fundamental biology studies, different classes of biomaterials and biomolecules are each measured from a different region of a typically heterogeneous tissue sample, thus introducing unavoidable sources of noise that are hard to quantitate. We describe the method of DNA-encoded antibody libraries (DEAL) for spatially multiplexed detection of ssDNAs and proteins as well as for cell sorting, all on the same diagnostic platform. DEAL is based upon the coupling of ssDNA oligomers onto antibodies which are then combined with the biological sample of interest. Spotted DNA arrays, which are found to inhibit biofouling, are utilized to spatially stratify the biomolecules or cells of interest. We demonstrate the DEAL technique for (1) the rapid detection of multiple proteins within a single microfluidic channel, and, with the additional step of electroless amplification of gold-nanoparticle labeled secondary antibodies, we establish a detection limit of 10 fM for the protein IL-2, 150 times more sensitive than the analogue ELISA; (2) the multiplexed, on-chip sorting of both immortalized cell lines and primary immune cells with an efficiency that exceeds surface-confined panning approaches; and (3) the co-detection of ssDNAs, proteins, and cell populations on the same platform.     

Use of optical tweezers for colloid science

A space-borne optical tweezer apparatus for use with colloidal crystallization experiments has been characterized. The trapping force has been measured as a function of index mismatch between colloidal microspheres and the surrounding fluid and as a function of particle size. This work also presents a method to determine the refractive index of a colloidal microsphere, which is then used to calculate the applied trapping force for the case of an arbitrary background fluid. This is useful for work with dense colloidal suspensions when the usual (e.g., Stokes flow) trap force measurement methods do not apply, as well as microrheological studies of complex soft matter.     

Perylene polyphenylmethylsiloxanes for optoelectronic applications

The incorporation of fluorescent organic dyes in an encapsulating matrix represents a route to generate stable and processable materials for optoelectronic devices. Here, we present a method to embed perylene dyes into a high refractive index (HRI) polysiloxane matrix applying an allyl functionalized perylene dye and hydrosilylation chemistry. In a first approach, the dye molecules were covalently integrated into the backbone of linear polyphenylmethylsiloxane chains. The fluorescent and liquid polymers were synthesized with molecular weights from 5660 up to 8400 g mol^?1. In a second approach, the dye itself was used as a cross‐linking agent between linear polyphenylmethylsiloxane chains. These preformed fluorescent batch polymers are liquids with dye concentrations between 0.025 and 8 wt %. The applied synthetic methods incorporated the dye covalently into the polymer structure and avoided the crystallization of the dye molecules and thus the formation of excimers, which would reduce the optical emission. The resulting products can be easily incorporated into curable commercially available HRI polyphenylmethylsiloxane resins. The formed materials are ideal LED encapsulants with a solid and flexible consistency, a uniform dispersion of the dyes, and adjustable mechanical properties, realized by changing the amount of perylene polymers. Further properties of the obtained materials are thermal stabilities up to 478 °C, quantum yields larger than 0.97, and high photostabilities. Thus, the covalent integration of dyes into polyphenylsiloxane structures represents a possible route for the stabilization of the organic dyes against the extreme irradiance and thermal conditions in LED applications. © 2019 The Authors. Journal of Polymer Science Part B: Polymer Physics published by Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1062–1073     

BN-embedded aromatics for optoelectronic applications

The knowledge of azaborine chemistry is growing as an important branch in organic semiconductor materials. Specifically, BN-embedded aromatic compounds have attracted great attention due to their fascinating properties resulted from the replacement of CC unit with isoelectronic BN unit in aromatics. Though great insights have been provided into the synthetic chemistry and photophysical properties of BN-embedded aromatics, their applications in optoelectronic areas are still at a young stage. This short review summarizes the recent progress of BN-embedded aromatics with optoelectronic applications in organic field-effect transistors, organic light-emitting diodes, organic photovoltaics, stimuli-responsive luminescent devices, and chemical sensors.     

A unified scale for the Auger parameter: Methodology and benefits

The Auger parameter (AP) is a value extracted from the X-ray photoelectron spectrum (XPS) by addition of the binding energy of a photoelectron, for a given element in the spectrum, to the kinetic energy of the Auger electron emitted as the resulting hole in the electronic structure is filled by an electron from one of the outer orbitals. The value of the AP is sensitive to the polarization of electrons in the orbitals of neighbouring ions towards the photo-ionized atom and is thus related to other opto-electronic properties of the material. A correlation had been shown between the refractive index and the AP of aluminosilicates and thus the ability to compare, on a single chart, the AP's of the Al and Si ions gave important structural information. This comparison was made possible by normalising the individual APs to a common zero-point. In this contribution, the methodology employed is extended to a wider range of elements. The resulting ability, to compare and contrast the normalised AP, thus generated, greatly enhances the information available from XPS and thus relates it directly to the polarizability of the material's structure.     

芳酰胺分子钳对阴离子的识别研究

利用差紫外光谱法考察了新的分子钳1～4对阴离子的识别性能,测定了25 ℃下,在CHCl3中主客体间的结合常数(Ka)和自由能变化(ΔG°). 结果表明,所有分子钳主体对所考察的客体分子显示良好的识别作用,主客体间形成1∶ 1型超分子配合物.识别作用的主要推动力为多重氢键作用.并利用核磁共振氢谱与计算机模拟作为辅助手段对实验结果进行了解释.     

A unified theory for charge-carrier transport in organic crystals

To characterize the crossover from bandlike transport to hopping transport in molecular crystals, we study a microscopic model that treats electron-phonon interactions explicitly. A finite-temperature variational method combining Merrifield's transformation with Bogoliubov's theorem is developed to obtain the optimal basis for an interacting electron-phonon system, which is then used to calculate the bandlike and hopping mobilities for charge carriers. Our calculations on the one dimensional (1D) Holstein model at T=0 K and finite temperatures show that the variational basis gives results that compared favorably to other analytical methods. We also study the structures of polaron states at a broad range of parameters including different temperatures. Furthermore, we calculate the bandlike and hopping mobilities of the 1D Holstein model in different parameters and show that our theory predicts universal power-law decay at low temperatures and an almost temperature independent behavior at higher temperatures, in agreement with experimental observations. In addition, we show that as the temperature increases, hopping transport can become dominant even before the polaron state changes its character. Thus, our result indicates that the self-trapping transition studied in conventional polaron theories does not necessarily correspond to the bandlike to hopping transition in the transport properties in organic molecular crystals. Finally, a comparison of our 1D results with experiments on ultrapure naphthalene crystals suggests that the theory can describe the charge-carrier mobilities quantitatively across the whole experimental temperature range.     

A unified equation for matter transport: its derivation and application

The patterns formed by the limit to the range of (1) rill spacings on a given soil type, and (2) impact spacings of any two sets of waterdrops which differ minimally in pressure, obey the same boundary rules as any two consecutive natural numbers (CNN). The coefficients and exponents of the boundary rules can be multiplied so as to produce a unified equation for matter transport (UEMT). Subsequently, the UEMT can be used to determine the equivalents of environmental lapse rate, vertical wind velocities and temperatures above and below the earth for each of the seven independent co-ordinate systems of the earth. The rill field values agree closely with those measured from matching standard regions.     

Macromolecule complex for advanced optoelectronic devices

This paper describes reviews about characterizations of optical and electronic (opto-electronic) organic materials including macromolecule complex, and their applications for advanced key devices used for computers and communications technologies. On the basis of the author's recent investigations, discussions are made on organic electroluminescent thin film materials for emissive display devices, polymer dispersed liquid-crystal materials for passive display devices, organic photoconductive materials for electrophotographic printer devices, and highly electroconductive polymers for solid tantalum capacitors. Finally, the technical issues and development prospects for the opto-electronic organic materials in the 21st century are suggested.     

Borazine materials for organic optoelectronic applications

Borazine materials have been demonstrated to be a new class of multifunctional and thermally stable materials with high electron (10(-3) cm2 V(-1) s(-1)) and moderate hole (10(-4) cm2 V(-1) s(-1)) mobilities for applications in electroluminescent devices.     

Metal-containing triarylboron compounds for optoelectronic applications

Triarylboranes have recently emerged as a powerful new class of electron acceptors with great potential as optoelectronic materials. The empty p(z) orbital on the boron centre promotes strong charge-transfer transitions, leading to highly luminescent compounds with colors spanning the entire visible spectrum. Due to intense research efforts over the past decade, many examples now exist of organic molecules based on this structural motif. Only recently, however, have transition metal-containing triarylboranes been closely investigated. These compounds are capable of bright luminescence from a triplet excited state, and have been developed as efficient emissive materials for organic light-emitting diodes (OLEDs) as a result. In addition, their long-lived phosphorescence gives these materials potential as highly selective chemical sensors for small anions using time-gated detection, eliminating interference from background fluorescence. The research of the past several years has now led to a better understanding of the impact of the triarylboron group on the photophysical properties of metal complexes, which we expect will provide many opportunities for research into this class of functional phosphorescent materials.     

A unified electrostatic and cavitation model for first-principles molecular dynamics in solution

The electrostatic continuum solvent model developed by [Fattebert and Gygi J. Comput. Chem. 23, 662 (2002); Int. J. Quantum Chem. 93, 139 (2003)] is combined with a first-principles formulation of the cavitation energy based on a natural quantum-mechanical definition for the surface of a solute. Despite its simplicity, the cavitation contribution calculated by this approach is found to be in remarkable agreement with that obtained by more complex algorithms relying on a large set of parameters. Our model allows for very efficient Car-Parrinello simulations of finite or extended systems in solution and demonstrates a level of accuracy as good as that of established quantum-chemistry continuum solvent methods. We apply this approach to the study of tetracyanoethylene dimers in dichloromethane, providing valuable structural and dynamical insights on the dimerization phenomenon.