Dear Colleagues

Dear Colleagues,
here is, late as always, but hopefully still of interest, a list of references for the field of “Polyelectrolyte Multilayers”.

It covers the year 2000 and January to June of 2001. It is based on a Science Citation Search using the (in my opinion) 50 most important references of the field. Subsequently, I have manually taken out all references that do not clearly belong to the field or that are too borderline.

The result is a list with 257 references, I hope that it will help us all to see what has recently been done and where the field is going. I will try to update this list on a (hopefully) regular base and I will try to complete it for the years 1998 and 1999. If major differences with lists such as found on the poly­electrolyte multilayer homepage 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. 412(1-2) (2000), 29-35

A novel method based on plasma-polymerized films (PPFs) is proposed for immobilizing antibodies (antigens) through a polyelectrolyte-mediated layer. The immobilization of goat-anti- IgG antibody, as an example, is investigated. The n-butyl amine PPFs are deposited on the surfaces of quartz crystal microbalance (QCM) with a radio frequency plasma method using n- butyl amine as the precursor, the IR spectrum indicating the existence of amino-groups in the film. After self-assembling a polystyrenesulfonate (PSS) layer on the PPF, the goat-anti-IgG antibody is immobilized in a 0.2 mg ml(-1) of antibody immobilizing solution at pH 5.0. The QCM immunosensor can quantitatively determine NH IgG in the range of 0.7-126 mu g ml(-1). Moreover, the PSS and protein layers can easily be removed simply by shifting the pH, making the immunosensor regenerable. (C) 2000 Elsevier Science B.V. All rights reserved.

[16] Layer-by-Layer Assembly of Multilayer Films Consisting of Silicotungstate and a Cationic Redox Polymer on 4-Aminobenzoic Acid Modified Glassy-Carbon Electrode and Their Electrocatalytic Effects

L. Cheng, J. Y. Liu and S. J. Dong

Anal. Chim. Acta. 417(2) (2000), 133-142

A novel 4-aminobenzoic acid (4-ABA) monolayer film is formed on glassy carbon electrode (GCE) by amino cation radical method. Silicotungstic heteropolyanion (SiW12O404-, denoted as SiW12)- containing multilayer films have been fabricated on the 4-ABA modified GCE surface by alternate deposition with a quaternized poly(4-vinylpyridine) partially complexed with [Os(bpy)(2)Cl](2+/+) (denoted as QPVP-Os). Cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS) and X-ray reflectivity (XR) have been used to characterise the as- prepared multilayer films. It is proved that the multilayer films are uniform and stable. The average thickness for a bilayer of QPVP-Os/SiW12 in the multilayer film is 30.2 Angstrom. The electrocatalytic activities of the multilayer films have been investigated on the reduction of three substrates of important analytical interests, HNO2, BrO3- and H2O2. Especially, the influence of layer number of the multilayer films on the electrocatalytic reduction of HNO2 has been investigated in detail. (C) 2000 Elsevier Science B.V. All rights reserved.

[17] Fabrication of Multilayer Films Containing Horseradish- Peroxidase and Polycation-Bearing Os Complex by Means of Electrostatic Layer-by-Layer Adsorption and Its Application as a Hydrogen-Peroxide Sensor

W. J. Li, Z. Wang, C. Q. Sun, M. Xian and M. Y. Zhao

Anal. Chim. Acta. 418(2) (2000), 225-232

Layer-by-layer (LBL) assembled multilayer films were obtained on the surface of quartz slides and gold electrode by alternating deposition of negatively charged horseradish peroxidase (HRP) and quaternized poly(4-vinylpyridine) complexed of (Os(bpy)(2)Cl)(+/2+) (PVP-Os). The assembly process was monitored by UV-VIS spectroscopy. The electrochemical behavior of the enzyme electrode showed that multilayer films containing the enzyme and the redox polymer were highly stable. Mediator PVP-Os in the multilayer films as electron shuttle was able to transfer electrons successfully between the active center of the immobilized HRP and the electrode surface. The enzyme electrode of multilayer films was sensitive for the electrocatalytic reduction of hydrogen peroxide and can be used as amperometric sensors for hydrogen peroxide. (C) 2000 Elsevier Science B.V. All rights reserved.

[18] Polyelectrolyte Multilayer Film-Coated Electrodes for Amperometric Determination of Hydrogen-Peroxide in the Presence of Ascorbic-Acid, Uric-Acid and Acetaminophen

T. Hoshi, H. Saiki, S. Kuwazawa, Y. Kobayashi and J. Anzai

Anal. Sci. 16(10) (2000), 1009-1010

[19] Probing Protein-Peptide-Protein Molecular Architecture by Atomic-Force Microscopy and Surface-Plasmon Resonance

M. M. Stevens, S. Allen, W. C. Chan, M. C. Davies, C. J. Roberts, S. J. B. Tendler and P. M. Williams

Analyst 125(2) (2000), 245-250
We demonstrate the creation of a protein multilayer which utilises the high affinity interaction between streptavidin and biotin and incorporates a peptidic spacer. Surface plasmon resonance measurements enabled us to monitor the construction of the multilayer in real time. Atomic force microscopy was utilised to determine surface functionality at each stage of the multilayer construction, allowing us to investigate the associated mechanical properties. In this context we observed an increase in biomolecular stretching on the formation of the multilayer. We demonstrate, utilising circular dichroism, that variations in the solvent can affect the secondary structure of the peptide linker and hence its mechanical properties. Trifluoroethanol titrations on the assembled system indicate that the multilayer properties are also stimuli responsive with regard to solvent conditions. These results indicate that the multilayer stretch before cleavage is increased in the presence of trifluoroethanol. This was not expected from the study of the individual linker alone, indicating the need to study the system as a whole as opposed to the isolated components.

[20] Synthesis of Geometrically Well-Defined, Molecularly Thin Polymer-Films

W. T. S. Huck, A. D. Stroock and G. M. Whitesides

Angew. Chem., Int. Ed. Engl. 39(6) (2000), 1058

[21] Stepwise Assembled Photoactive Films Containing Donor-Linked Fullerenes

C. P. Luo, D. M. Guldi, M. Maggini, E. Menna, S. Mondini, N. A. Kotov and M. Prato

Angew. Chem., Int. Ed. Engl. 39(21) (2000), 3905

[22] Photovoltaic Heterostructure Devices Made of Sequentially Adsorbed Poly(Phenylene Vinylene) and Functionalized C-60

H. Mattoussi, M. F. Rubner, F. Zhou, J. Kumar, S. K. Tripathy and L. Y. Chiang

Appl. Phys. Lett. 77(10) (2000), 1540-1542

We report on the preparation and characterization of rectifying photovoltaic heterostructure devices made of poly(phenylene vinylene), PPV, and C-60. The heterojunctions were built from solution using the technique of layer-by-layer sequential adsorption. This technique permits one to control the heterostructure at the molecular scale. Upon illumination with a laser beam, the devices showed large photoresponses (current and voltage) that resulted from a photoinduced electron transfer between the PPV (donor layer) and the C-60 (acceptor layer). The photocurrent was found to increase with the laser power and with the photon energy of the incident radiation. Also, a constant high photovoltage response of similar to 700- 800 mV was measured. Analysis of the time dependence of the photocurrent rise and decay, when the device was illuminated with a modulated square wave signal (chopped laser beam), permitted us to draw an analogy between the present heterojunction and a circuit made of a capacitor and a resistance in series. (C) 2000 American Institute of Physics. [S0003-6951(00)03236-8].

[23] Optical-Properties of Self-Assembled Thin-Film of Poly(P- Phenylene Vinylene)S and Its Application to Light-Emitting Devices with Microring Geometry

T. Sonoda, T. Fujisawa, A. Fujii and K. Yoshino

Appl. Phys. Lett. 76(22) (2000), 3227-3229

Periodic multilayer structures of poly(p-phenylene vinylene)s have been fabricated by a self-assembly method on flat surfaces and round surfaces of optical fibers. Alternating multilayers consisting of poly{1,4-[2-(5-carboxypentyloxy)-5- methoxyphenylene]vinylene} (CPMOPPV) and poly(p-phenylene vinylene) (PPV) were adsorbed onto the positively charged substrates. The optical properties of the periodic multilayer structures of CPMOPPV/PPV have been studied. Periodic multilayers with microring geometry have also been fabricated around the quartz fibers. Their optical properties have been studied, and yellow electroluminescence from a light-emitting device with microring geometry has been observed. (C) 2000 American Institute of Physics. [S0003-6951(00)03822-5].

[24] Surface-Relief Gratings from Electrostatically Layered Azo-Dye Films

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

Appl. Phys. Lett. 76(22) (2000), 3233-3235

Surface relief gratings (SRGs) were fabricated on composite films assembled by alternate electrostatic deposition of a polyelectrolyte, poly(dimethyldiallylammonium chloride), and an organic azo dye, congo red. The modulation of SRGs was found to increase with the thickness of the matrix films. Significant photochemical bleaching of the azo dye in the polymeric microenvironment as well as gradient-force-induced migration of the small azo dye contributes to the formation of the SRG structure. This finding demonstrates a facile method to fabricate SRGs for optical and information storage applications using commercially available azo dyes and polyelectrolytes. (C) 2000 American Institute of Physics. [S0003-6951(00)04922-6].

[25] Conformational State and Molecular Ionic Transformations of Polycytidyl Acid Immobilized in Multilayer Langmuir and Polyelectrolyte Films

B. I. Sukhorukov, G. B. Sukhorukov, L. I. Shabarchina and M. M. Montrel

Biofizika