Dear Colleagues

http://www.chem.fsu.edu/multilayers/ will show up, the search algorithm will be refined.

Of course, nobody is perfect, so I would like to apologize to all of you if work from your group should be included, but for some reason has been over­looked. In this case I would appreciate to receive the missing reference, preferably as Acrobat document (PDF file) via [e-mail] . Please also let me know if there are references that should not be in this list.

In the meantime we are looking forward to the publication of a reference book on “Thin Films – Polyelectrolyte Multilayers and Related Multicomposites” by VCH – Wiley and to the next symposium “Multi-Layered Polyelectrolyte-Based Materials: Synthesis, Characterization and Applications”, organized by Merlin Bruening, Frank Caruso and Nicholas Kotov. The symposium will be held on April 7-11, 2002 in Orlando under the auspices of the 223rd American Chemical Society National Meeting.
Gero Decher

[1] Surface Modification of Microporous Polypropylene Membranes by Polyelectrolyte Multilayers

T. Rieser, K. Lunkwitz, S. Berwald, J. Meierhaack, M. Muller, F. Cassel, Z. Dioszeghy and F. Simon

ACS SYMP SER 744 (2000), 189-204

Plasma-induced grafting of ionic monomers onto hydrophobic polypropylene membranes led to permanently charged surfaces. In addition, polyelectrolyte multilayers were built up by alternating adsorption of oppositely charged polyelectrolytes onto the grafted membrane surface. The modified membranes were characterized by FTIR-ATR and XPS. Streaming potential measurements were used to determine the electrokinetic properties of the charged surfaces. Filtration experiments were performed with human serum albumin (HSA) solutions to study the fouling behavior of the membranes. Membrane surfaces and the protein were both negatively charged under the applied conditions. The irreversible adsorption of HSA decreased remarkably for membranes that were modified by polyelectrolyte multilayers, as compared to untreated and plasma-treated samples.

[2] Controlled Precipitation of Dyes into Hollow Polyelectrolyte Capsules Based on Colloids and Biocolloids

G. Sukhorukov, L. Dähne, J. Hartmann, E. Donath and H. Möhwald

Adv. Mater. 12(2) (2000), 112-115

[3] Nanoengineering and Microengineering - 3-Dimensional Colloidal Photonic Crystals Prepared from Submicrometer-Sized Polystyrene Latex Spheres Pre-Coated with Luminescent Polyelectrolyte/ Nanocrystal Shells

A. Rogach, A. Susha, F. Caruso, G. Sukhorukov, A. Kornowski, S. Kershaw, H. Möhwald, A. Eychmuller and H. Weller

Adv. Mater. 12(5) (2000), 333
Colloidal photonic crystals doped with luminescent semiconductor nanocrystals are prepared here by a layer-by- layer deposition technique. This method, which involves the consecutive electrostatic adsorption of polyelectrolyte and nanocrystals such as CdTe onto submicrometer-sized polystyrene latex globules (see Figure), is described as being very Versatile and can be extended to the fabrication of either optically active or passive shells of different thickness.

[4] Core-Shell Microspheres of a Catalytically Active Rhodium Complex Bound to a Polyelectrolyte-Coated Latex

S. Mecking and R. Thomann

Adv. Mater. 12(13) (2000), 953

A strategy for the immobilization of catalytically active transition metal complexes is described in which the rhodium hydride complex [(H)Rh(CO)(NaTPPTS)(3)] is electrostatically bound to highly charged polystyrene microspheres coated with cationic polyelectrolyte (see Figure). The catalytic activity of this latex-bound catalyst in the hydroformylation of methyl acrylate is reported and compared with its unbound equivalent.

[5] Large Photoinduced Birefringence in Azo Dye/Polyion Films Assembled by Electrostatic Sequential Adsorption

S. P. Bian, J. A. He, L. Li, J. Kumar and S. K. Tripathy

Adv. Mater. 12(16) (2000), 1202-1205

[6] Self-Assembled Diode Junctions Prepared from a Ruthenium Tris(Bipyridyl) Polymer, N-Type TiO2 Nanoparticles, and Graphite Oxide Sheets

T. Cassagneau, J. H. Fendler, S. A. Johnson and T. E. Mallouk

Adv. Mater. 12(18) (2000), 1363-1366

[7] Fast Magic-Angle-Spinning and Double-Quantum H-1 Solid-State NMR-Spectroscopy of Polyelectrolyte Multilayers

L. N. J. Rodriguez, S. M. Depaul, C. J. Barrett, L. Reven and H. W. Spiess

Adv. Mater. 12(24) (2000), 1934

Polyelectrolyte multilayers on silica colloids are investigated here using a combination of fast magic-angle spinning (MAS) and double-quantum (DQ) solid-state H-1 NMR techniques. 2D DQ H-1 NMR spectra of the bulk complex and the multilayer films (see Figure) are found to be similar, revealing complexation between the alternating layers of poly(sodium 4-styrenesulfonate) (PSS) and poly(diallyldimethylammonium chloride) (PDADMAC).

[8] Multilayered Polymer Nanocapsules Derived from Gold Nanoparticle Templates

D. I. Gittins and F. Caruso

Adv. Mater. 12(24) (2000), 1947

Multilayered polymer nanocapsules have been fabricated via the sequential adsorption of oppositely charged polyelectrolytes onto gold nanoparticles followed by dissolution of the gold core in cyanide solution. The Figure shows a gold nanoparticle coated with eight polyelectrolyte layers.

[9] Multilayered Assembly of Dendrimers with Enzymes on Gold - Thickness-Controlled Biosensing Interface

H. C. Yoon and H. S. Kim

Anal. Chem. 72(5) (2000), 922-926

A new approach to construct a multilayered enzyme film on the Au surface for use as a biosensing interface is described, The film was prepared by alternate layer-by-layer depositions of G4 poly(amidoamine) dendrimers and periodate-oxidized glucose oxidase (GOx), The cyclic voltammograms obtained from the Au electrodes modified with the GOx/dendrimer multilayers revealed that bioelectrocatalytic response is directly correlated to the number of deposited bilayers, that is, to the amount of active enzyme immobilized on the Au electrode surface. From the analysis of voltammetric signals, the coverage of active enzyme per GOx/dendrimer bilayer during the multilayer-forming steps was estimated, which demonstrates that the multilayer is constructed in a spatially ordered manner. Also, with the ellipsometric measurements, a linear increment of the film thickness was registered, supporting the formation of the proposed multilayered structure. The E5D5 electrode showed the sensitivity of 14.7 mu A.mM(-1) glucose.cm(-2) and remained stable over 20 days under day-by-day calibrations. The proposed method is simple and would be applicable to the constructions of thickness- and sensitivity-controllable biosensing interfaces composed of multienzymes as well as a single enzyme.

[10] Glucose and Lactate Biosensors Based on Redox Polymer/ Oxidoreductase Nanocomposite Thin-Films

K. Sirkar, A. Revzin and M. V. Pishko

Anal. Chem. 72(13) (2000), 2930-2936

Glucose and lactate enzyme electrodes have been fabricated through the deposition of an anionic self-assembled monolayer and subsequent redox polymer/enzyme electrostatic complexation on gold substrates. These surfaces were functionalized with a negative charge using 11-mercaptoundecanoic acid (MUA), followed by alternating immersions in cationic redox polymer solutions and anionic glucose oxidase (GOX) or lactate oxidase (LAX) solutions to build the nanocomposite structure. The presence of the multilayer structure was verified by ellipsometry and sensor function characterized electrochemically. Reproducible analyte response curves from 2 to 20 mM (GOX) and 2-10 mM (LAX) were generated with the standard deviation between multiple sensors between 12 and 17%, a direct result of the reproducibility of the fabrication technique. In the case of glucose enzyme electrodes, the multilayer structure was further stabilized through the introduction of covalent bonds within and between the layers. Chemical cross-linking was accomplished by exposing the thin film to glutaraldehyde vapors, inducing linkage formation between lysine and arginine residues present on the enzyme periphery with amine groups present on a novel redox polymer, poly[vinyl-pyridine Os(bisbipyridine)(2)Cl]-co-allylamine. Finally, an initial demonstration of thin-film patterning was per formed as a precursor to the development of redundant sensor arrays. Microcontact printing was used to functionalize portions of a gold surface with a blocking agent, typically 1- hexadecanethiol. This was followed by immersion in MUA to functionalize the remaining portions of gold with negative charges. The multilayer deposition process was then followed, resulting in growth only on the regions containing MUA, resulting in a ''positive''-type pattern. This technique may be used for fabrication of thin-film redundant sensor arrays, with thickness under 100 Angstrom and lateral dimensions on a micrometer scale.

[11] In-Situ Assembled Mass-Transport Controlling Micromembranes and Their Application in Implanted Amperometric Glucose Sensors

T. Chen, K. A. Friedman, I. Lei and A. Heller

Anal. Chem. 72(16) (2000), 3757-3763

Micromembranes were assembled by sequentially chemisorbing polyanions and polycations on miniature (5 x 10(-4) cm(2)) enzyme electrodes. The sequential chemisorption process allowed the simultaneous tailoring of their sensitivity, dynamic range, drift, and selectivity. When assembled on tips of 250-mu m- diameter gold wires coated with redox polymer-''wired'' glucose oxidase, they allowed tailoring of the glucose electrodes for >2 nA/mM sensitivity; 0-30 mM dynamic range; drift of less than or equal to 5% per 24 h at 37 degrees C at 15 mM glucose concentration; and 15% current increment by the combination of 0.1 mM ascorbate, 0.2 mM acetaminophen, and 0.5 mM urate, The membranes also retained transition metal ions that bound to and damaged the redox polymer ''wiring'' the enzyme. The electrodes were tested in the jugular veins and in the intrascapular subcutaneous region of anaesthetized and heparinized nondiabetic Sprague-Dawley rats, in which rapid changes of glycemia were forced by intravenous injections of glucose and insulin. After one-point in vivo calibration of the electrodes, all of the 152 data points were clinically accurate when it was assumed that after insulin injection the glycemia in the subcutaneous fluid lags by 9 min behind that of blood withdrawn from the insulin-injected vein.

[12] Plastic Microfluidic Devices Modified with Polyelectrolyte Multilayers

S. L. R. Barker, M. J. Tarlov, H. Canavan, J. J. Hickman and L. E. Locascio

Anal. Chem. 72(20) (2000), 4899-4903

Control of the polymer surface chemistry is a crucial aspect of development of plastic microfluidic devices. When commercially available plastic substrates are used to fabricate microchannels, differences in the EOF mobility from plastic to plastic can be very high. Therefore, we have used polyelectrolyte multilayers (PEMs) to alter the surface of microchannels fabricated in plastics. Optimal modification of the microchannel surfaces was obtained by coating the channels with alternating layers of poly(allylamine hydrochloride) and poly(styrene sulfonate). Polystyrene (PS) and poly(ethylene terephthalate) glycol (PETG) were chosen las substrate materials because of the significant differences in the polymer chemistries and in the EOF of channels fabricated in these two plastic materials. The efficacy of the surface modification has been evaluated using XPS and by measuring the EOF mobility. When microchannels prepared in both PS and PETG are modified with PEMs, they demonstrate very similar electroosmotic mobilities. The PEMs are easily fabricated and provide a means for controlling the now direction and the electroosmotic mobility in the channels. The PEM-coated microchannels have excellent wettability, allowing facile filling of the channels. In addition, the PEMs produce reproducible results and are robust enough to withstand long-term storage.

[13] Electrochemical-Behavior of Polyphenol Oxidase Immobilized in Self-Assembled Structures Layer-by-Layer with Cationic Polyallylamine

E. S. Forzani, V. M. Solis and E. J. Calvo

Anal. Chem. 72(21) (2000), 5300-5307

We report here a novel bioelectrode based on self-assembled multilayers of polyphenol oxidase intercalated with cationic polyallylamine built up on a thiol-modified field surface. We use an immobilization strategy previously described by Hodak J, et al. (Langmuir 1997, 13, 2708-2716) Quartz crystal microbalance with electro-acustic impedance experiments were carried out to follow quantitatively the multilayer film formation. The response of the self-assembly polyphenol oxidase- polyallylamine electrodes toward different metabolically related cate-cholamines was studied, to evaluate enzyme kinetics. For the analyzed compounds, only dopamine and its metabolite Dopac gave catalytic currents at applied potential close to 0V. These responses were proportional to the number of polyphenol oxidase-immobilized layers and were also controlled by the enzymatic reaction. The combination of microgravimetric and electrochemical techniques allowed us to determine the kinetic enzymatic constants, showing that the decomposition rate for the enzyme-substrate complex is slower than the enzymatic reoxidation step.

[14] Control of Flow Direction in Microfluidic Devices with Polyelectrolyte Multilayers

S. L. R. Barker, D. Ross, M. J. Tarlov, M. Gaitan and L. E. Locascio

Anal. Chem. 72(24) (2000), 5925-5929

Electroosmotic flow (EOF) is commonly utilized in microfluidics. Because the direction of the EOF can be determined by the substrate surface charge, control of the surface chemical state offers the potential, in addition to voltage control, to direct the flow in microfluidic devices. We report the use of polyelectrolyte multilayers (PEMs) to alter the surface charge and control the direction of how in polystyrene and acrylic microfluidic devices. Relatively complex now patterns with simple arrangements of applied voltages are realized by derivatization of different arms of a single device with oppositely charged polyelectrolytes. In addition, flow in opposite directions in the same channel is possible. A positively derivatized plastic substrate with a negatively charged lid was used to achieve top-bottom opposite flows. Derivatization of the two sides of a plastic microchannel with oppositely charged polyelectrolytes was used to achieve side-by-side opposite flows. The flow is characterized using fluorescence imaging and particle velocimetry.

[15] A Novel-Approach of Antibody Immobilization Based on N-Butyl Amine Plasma-Polymerized Films for Immunosensors

Z. Y. Wu, Y. H. Yan, G. L. Shen and R. Q. Yu

Anal. Chim. Acta.