Synthesis, Structure, and Photophysical Properties of Platinum Compounds with Thiophene-Derived Cyclohexyl Diimine Ligands.

Platinum(II) and platinum(IV) compounds were prepared by the stereoselective and regioselective reactions of thiophene-derived cyclohexyl diimine C^N^N-ligands with [PtMe(μ-SMe)]. Newly synthesized ligands were characterized by NMR spectroscopy and elemental analysis, and Pt(II)/Pt(IV) compounds were characterized by NMR spectroscopy, elemental analysis, high-resolution mass spectrometry, and single-crystal X-ray diffraction. UV-vis absorbance and photoluminescence measurements were performed on newly synthesized complexes, as well as structurally related Pt(II)/Pt(IV) compounds with benzene-derived cyclohexyl diimine ligands, in dichloromethane solution, as solids, and as 5% by weight PMMA-doped films.

Photophysical Properties of Cyclometalated Platinum(II) Diphosphine Compounds in the Solid State and in PMMA Films.

Platinum(II) compounds were synthesized with both chelate cyclometalated ligands and chelate diphosphine ligands. The cyclometalated ligands include phenylpyridine and a benzothiophene-containing ligand. The three new benzothiophene compounds were characterized by nuclear magnetic resonance (NMR) spectroscopy, high-resolution mass spectrometry (HR-MS), and photophysical measurements.

Augmenting mask-based lithography with direct laser writing to increase resolution and speed.

A new method of hybrid photolithography, Laser Augmented Microlithographic Patterning (LAMP), is described in which direct laser writing is used to define additional features to those made with an inexpensive transparency mask. LAMP was demonstrated with both positive- and negative-tone photoresists, S1813 and SU-8, respectively. The laser written features, which can have sub-micron linewidths, can be registered to within 2.

Measuring atomic emission from beacons for long-distance chemical signaling.

In an effort to exploit chemistry for information science, we have constructed a system to send a message powered by a combustion reaction. Our system uses the thermal excitation of alkali metals to transmit an encoded signal over long distances. A message is transmitted by burning a methanol-soaked cotton string embedded with combinations of high, low, or zero levels of potassium, rubidium, and/or cesium ions.

Dynamic microbead arrays for biosensing applications.

In this paper we present the development of an optical tweezers platform capable of creating on-demand dynamic microbead arrays for the multiplexed detection of biomolecules. We demonstrate the use of time-shared optical tweezers to dynamically assemble arrays of sensing microspheres, while simultaneously recording fluorescence signals in real time. The detection system is able to achieve multiplexing by using quantum dot nanocrystals as both signaling probes and encoding labels on the surface of the trapped microbeads.

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.

InfoBiology by printed arrays of microorganism colonies for timed and on-demand release of messages.

This paper presents a proof-of-principle method, called InfoBiology, to write and encode data using arrays of genetically engineered strains of Escherichia coli with fluorescent proteins (FPs) as phenotypic markers. In InfoBiology, we encode, send, and release information using living organisms as carriers of data. Genetically engineered systems offer exquisite control of both genotype and phenotype.

Visualizing Fluorescence: Using a Homemade Fluorescence "Microscope" to View Latent Fingerprints on Paper.

We describe an inexpensive handheld fluorescence imager (low-magnification microscope), constructed from poly(vinyl chloride) pipe and other inexpensive components for use as a teaching tool to understand the principles of fluorescence detection. Optical filters are used to select the excitation and emission wavelengths and can be easily interchanged to accommodate different fluorescent samples. As a demonstration, we used the fluorescence imager to view lawsone-dyed fingerprints on paper, which fluoresce red when illuminated with green light.

Chromatically resolved optical microscope (CROMoscope): a grating-based instrument for spectral imaging.

The chromatically resolved optical microscope (CROMoscope) is capable of spectral imaging with tunable spectral and spatial resolutions. Because of its remarkably simple design, the CROMoscope can be easily assembled and aligned. Spectral resolution as low as 2.

Infochemistry and infofuses for the chemical storage and transmission of coded information.

This article describes a self-powered system that uses chemical reactions--the thermal excitation of alkali metals--to transmit coded alphanumeric information. The transmitter (an "infofuse") is a strip of the flammable polymer nitrocellulose patterned with alkali metal ions; this pattern encodes the information. The wavelengths of 2 consecutive pulses of light represent each alphanumeric character.

Multiplexed sandwich immunoassays using electrochemiluminescence imaging resolved at the single bead level.

A new class of bead-based microarray that uses electrogenerated chemiluminescence (ECL) as a readout mechanism to detect multiple antigens simultaneously is presented. This platform demonstrates the possibility of performing highly multiplexed assays using ECL because all the individual sensing beads in the array are simultaneously imaged and individually resolved by ECL. Duplex and triplex assay results are demonstrated as well as a cross reactivity study.

Multiphoton fabrication.

Chemical and physical processes driven by multiphoton absorption make possible the fabrication of complex, 3D structures with feature sizes as small as 100 nm. Since its inception less than a decade ago, the field of multiphoton fabrication has progressed rapidly, and multiphoton techniques are now being used to create functional microdevices. In this Review we discuss the techniques and materials used for multiphoton fabrication, the applications that have been demonstrated, as well as those being pursued.

Rapid, in-line, non-interferometric auto- and cross-correlator for microscopy.

We demonstrate a simple, in-line scheme for determining the duration of ultrafast pulses in the focal region of a high-numerical-aperture microscope objective. Photocurrent generated in a GaAsP photodiode by two-photon absorption of orthogonally-polarized laser beams that meet at a slight angle is used to autocorrelate lasers non-interferometrically. Cross-correlation between two lasers is also demonstrated.

Soft-lithographic replication of 3D microstructures with closed loops.

There is growing interest in lithographic technologies for creating 3D microstructures. Such techniques are generally serial in nature, prohibiting the mass production of devices. Soft-lithographic techniques show great promise for simple and rapid replication of arrays of microstructures but have heretofore not been capable of direct replication of structures with closed loops.

Selective functionalization of 3-D polymer microstructures.

We demonstrate the selective functionalization of 3-D polymer microstructures that were created using multiphoton absorption polymerization. By fabricating different portions of the structures with acrylic and methacrylic polymers, we are able to take advantage of the differential reactivities of these materials to perform functionalization chemistry on a single polymeric component. We demonstrate the selective deposition of metal to create structures, such as a functional microinductor.