A surface plasmon resonance (SPR) setup in Kretschmann configuration is being utilized as a refractometer for both liquids as well as ultrathin films. The SPR signal detection technology used is based on a goniometer approach providing a wide angular scan range which facilitates highly accurate liquid and gas phase measurements.

Attention was paid to improve sample handling and preparation. In order to avoid cross-contamination between measurements an easily removable and exchangeable molded PDMS flow cell was used during the measurements. By careful choice of components for liquid handling the dead volume of the system could be reduced down to some microliters.

The angular change and thus the refractive index for sucrose, ethylene glycol (EG) and ethanol solutions with different concentrations, the thickness and refractive index of deposited Langmuir-Blodgett (LB) films, and the interaction kinetics between a biotin containing self-assembled monolayer (SAM) and streptavidin were determined. The measured refractive indices of sucrose, EG and ethanol solutions corresponded well with literature values. LB films were characterized by measuring the complete SPR curve in an angular scan range from 40 to 78[degree sign]. A two-color SPR approach combined with two-media measurements was successfully employed for simultaneous and unambiguous determination of both refractive index and thickness of stearic acid monolayers. The thickness obtained for the stearic acid monolayer was 2.66 nm, and the refractive indices at 635 and 670 nm were 1.5800 and 1.4138, respectively. The developed sensor-plate holder enabled functionalization of the SPR gold chip outside the instrument, therefore making the sample handling more flexible. The affinity constant obtained for the streptavidin-biotin interaction was 1.01 x 10-8 M. The total angle SPR method used in this study clearly shows its potential to be used as a refractometer for both liquids and ultrathin films, as well as for traditional liquid phase biomolecular kinetic studies.

This study investigates the adsorption of a symmetric triblock nonionic polymer comprising ethylene oxide (EO) and propylene oxide (PO) blocks (Pluronic P-105, EO37PO56EO37) on a range of substrates including hydrophobic, i.e., polypropylene (PP), poly(ethylene terephthalate) (PET), nylon, and graphite, and hydrophilic, i.e., cellulose and silica. The adsorption process and the structure of the hydrated adsorbed layers are followed by quartz crystal microgravimetry (QCM), surface plasmon resonance (SPR), and atomic force microscopy. The unhydrated surfaces are characterized by ellipsometry and contact angle techniques. The adsorption kinetics and the extent of adsorption are determined by monitoring the changes in resonance frequency and refractive index of sensors coated with ultrathin films of the various substrates. Langmuirian-type adsorption kinetics is observed in all cases studied. The amount of adsorbed Pluronic on hydrophobic polymer surfaces (PP, PET, and nylon) exceeds that on the hydrophilic cellulose. The hydrophobic (graphite) mineral surface adsorbs relatively low polymer mass, typical of a monolayer, while micellar structures are observed on the hydrophilic silica surface. The amount of water coupled to the adsorbed polymer layers is quantified by combining data from QCM, and SPR are found to increase with increasing polarity of the substrate. On the basis of contact angle data, the nonhydrated adsorbed structures produce modest increases in hydrophilicity of all the substrates investigated. Overall, insights are provided into the structure and stability of both hydrated and nonhydrated adsorbed triblock copolymer.

The aim of the study is to develop diagnostic tests for the detection of pharmaceutical compounds in saliva. Oral fluid is increasingly being considered as an ideal sample matrix. It can be collected non-invasively and causes less stress to the person being tested. The detection of pharmaceutical compounds and drugs in saliva can give valuable information on individual bases on dose response, usage, characterization and clinical diagnostics. Surface plasmon resonance (SPR) is a highly sensitive, fast and label free analytical technique for the detection of molecular interactions. The specific binding of measured analyte onto the active gold sensing surface of the SPR device induces a refractive index change that can be monitored. To monitor these pharmaceutical compounds in saliva the immunoassays were developed using a SPR instrument. The instrument is equipped with a 670nm laser diode and has two sensing channels. Monoclonal
antibodies against the pharmaceutical compounds were used to specifically recognise and capture the compounds which intern will have an effect of the refractive index monitored. Preliminary results show that the immunoassays for cocaine and MDMA (3,4-methylenedioxymethamphetamine) are very sensitive and have linear ranges of 0.01 pg/ml – 1 ng/ml and 0.1 pg/ml – 100 ng/ml, respectively.

In this paper we report on the development of a diagnostic test for the detection of illegal drugs in saliva using a disposable micro-fluidic sample preparation cartridge which was fabricated using CO2 and excimer laser ablation of a PMMA substrate assembly. The detection method is by immunoassay sensing on a surface plasmon resonance (SPR) platform. Experimental results shows that the immunoassay detection of the two illegal drugs tested are very sensitive and have a linear range for cocaine and MDMA of 0,01 pg/ml – 1 ng/ml and 0,1 pg/ml – 100 ng/ml respectively.

We study the adsorption of a symmetric triblockcopolymer of ethylene oxide, EO, and propylene oxide, PO,end-capped with quarternized poly(2-dimethylaminoethylmethacrylate), DMAEMA (DMAEMA24
EO132PO50EO132
DMAEMA24). Light scattering and tensiometry are used tomeasure the relative size of the associated structures and surfaceexcess at the air
liquid interface. The adsorbed amount, theamount of coupled water, and the viscoelasticity of the adsorbedpolymer layer are measured on hydrophobic and hydrophilicsurfaces (polypropylene, cellulose, and silica) by using quartz crystal microgravimetry (QCM) and surface plasmon resonance(SPR) at different ionic strengths and temperatures. The results of the experiments are compared with those obtained afteradsorption of the uncharged precursor copolymer, without the cationic end-caps (EO132PO50EO132). DMAEMA24
EO132PO50-EO132
DMAEMA24 possesses higher affinity with the negatively charged silica and cellulose surfaces while the unchargedcopolymer adsorbs to a larger extent on polypropylene surfaces. In this latter case, adsorption increases with increasing solutionionic strength and temperature. Adsorption of EO132PO50EO132 on silica surfaces has little effect on the water contact angle (WCA),while adsorption ofDMAEMA24
EO132PO50EO132
DMAEMA24 increases theWCA of silica to 32
, indicating a large density ofexposed PPO blocks upon adsorption. After adsorption of EO132PO50EO132 and DMAEMA24
EO132PO50EO132
DMAEMA24on PP, the WCA is reduced by ≈14
and ≈28
, respectively, due to the exposed hydrophilic EO and highly water-solubleDMAEMA segments on the surfaces. The extent of surface coverage at saturation at the polypropylene/liquid interfaces (≈31 and40 nm2/molecule obtained byQCMand SPR, respectively) is much lower, as expected, when compared with results obtained at theair/liquid interface, where a tighter packing is observed. The percentage of water coupled to the adsorbed cationic polymer decreaseswith solution ionic strength. Overall, these observations are ascribed to the effects of electrostatic screening, polymer hydrodynamicsize, and solvency.

This study investigates the adsorption of a symmetric triblock nonionic polymer comprising ethylene oxide (EO) andpropylene oxide (PO) blocks (Pluronic P-105, EO37PO56EO37) on a range of substrates including hydrophobic, i.e.,polypropylene (PP), poly(ethylene terephthalate) (PET), nylon, and graphite, and hydrophilic, i.e., cellulose and silica.The adsorption process and the structure of the hydrated adsorbed layers are followed by quartz crystal microgravimetry (QCM), surface plasmon resonance (SPR), and atomic force microscopy. The unhydrated surfaces arecharacterized by ellipsometry and contact angle techniques. The adsorption kinetics and the extent of adsorption aredetermined by monitoring the changes in resonance frequency and refractive index of sensors coated with ultrathin filmsof the various substrates. Langmuirian-type adsorption kinetics is observed in all cases studied. The amount of adsorbedPluronic on hydrophobic polymer surfaces (PP, PET, and nylon) exceeds that on the hydrophilic cellulose. Thehydrophobic (graphite) mineral surface adsorbs relatively low polymer mass, typical of a monolayer, while micellarstructures are observed on the hydrophilic silica surface. The amount of water coupled to the adsorbed polymer layers isquantified by combining data from QCM, and SPR are found to increase with increasing polarity of the substrate. Onthe basis of contact angle data, the nonhydrated adsorbed structures produce modest increases in hydrophilicity of allthe substrates investigated. Overall, insights are provided into the structure and stability of both hydrated andnonhydrated adsorbed triblock copolymer.

Designing a surface recognition layer with high anti-fouling ability, high affinity, and high specificity is an important issue to produce high sensitivity biosensing transducers. In this study, a self-assembled monolayer (SAM) consisting of a homogeneous mixture of oligo(ethylene glycol) (OEG)-terminated alkanethiolate and mercaptohexadecanoic acid (MHDA) on Au was employed for immobilizingtroponin T antibody and applied in detecting cardiac troponin T by using surface plasmon resonance (SPR). The mixed SAM showed no phase segregation and exhibited human serum albumin resistance, particularly with an antibody-immobilized surface. X-ray photoemission spectra revealed that the chemical composition ratio of OEG to the mixed SAM was 69 % and the OEG packing density was 82 %. The specific binding of troponin T on the designed surface indicated a good linearcorrelation (R=0.991, P<0.0009) at concentrations lower than 50 ?g mL-1 with thelimit of detection of 100 ng mL-1 using a SPR measuring instrument. It is concluded that the mixed SAM functions as designed since it has high detection capability, high accuracy and reproducibility, as well as shows strong potential to be applied in rapid clinical diagnosis for label-free detection within 2 min.

The adsorption of human immunoglobulin G (hIgG) and bovine serum albumin (BSA) on cellulose supports were investigated. The dynamics and extent of related adsorption processes were monitored by surface plasmon resonance (SPR) and quartz crystal microbalance with dissipation monitoring (QCM-D). Amine groups were installed on the cellulose substrate by adsorption of chitosan from aqueous solution, which allowed for hIgG to physisorb from acid media and produced a functionalized substrate with high surface density (10 mg/m2). hIgG adsorption from neutral and alkaline conditions was found to yield lower adsorbed amounts. The installation of the carboxyl groups on cellulose substrate via carboxymethylated cellulose (CMC) adsorption from aqueous solution enhanced the physisorption of hIgG at acidic (adsorbed amount of 5.6 mg/m2) and neutral conditions. hIgG adsorption from alkaline conditions reduced the surface density. BSA was used to examine protein attachment on cellulose after modification with chitosan or carboxymethyl cellulose. At the isoelectric point of BSA (pI 5) both of the surface modifications enhanced the adsorption of this protein, when compared to that on unmodified cellulose (a two-fold increase from 1.7 to 3.5 mg/m2). At pH 4 the electrostatic interactions favored the adsorption of BSA on the CMC-modified cellulose, revealing the affinity of the system and the possibility of tailoring biomolecule binding and regeneration by choice of the surface modifier and pH of the medium.

Phthalocyanine molecules are potential candidates for the structural elements of optoelectronic devices such as organic solar cells and chemical sensors. The binding self-assembling monolayers of phthalocyanine molecules to a gold surface was studied using surface plasmon resonance (SPR) method. Reference experiments were carried out with phthalocyanines holding bromine in place of the thioacetate, therefore having no ability of covalent bonding to the gold surface. Differences in binding were evaluated and compared with simulations. Measurement results show a significant difference in dissociation speed. While molecules with triacetates decay 2 percent per hour in a stabilized dissociation state, the molecule with bromine decayed 6.5 to 10 percent per hour. Measured results were verified with simulations. These results suggest that there are at least two different binding mechanisms present. 

Project was focused on testing photo-electroactive molecules for solar and sensor technologies. Phthatalyanines, porphyrins and other organic molecules where characterized with Surface Plasmon Resonance (SPR), Atomic Force Microscope (AFM), and X-ray crystallography. Several synthesis and self-assembling of functional molecules on glass, quartz, sapphire, ITO, ZnO and gold where made. ZnO and AZO ( ZnO doped with Al) electrodes where used to increase the durability of the organic solar cells. A away developed for ZnO layers that it can be deposited safely on top of organic monomolecular layers. Gaseous ammonia where detected by SPR, SAW and by conductivity measurements. Detective layer in all three options was Copper Porphyrin.

Poster

Dysregulation of PKCe is involved in several serious diseases such as cancer, type II diabetes and Alzheimer’s disease.Therefore, specific activators and inhibitors of PKCe hold promise as future therapeutics, in addition to being useful inresearch into PKCe regulated pathways. We have previously described llama single chain antibodies (VHHs) that specificallyactivate (A10, C1 and D1) or inhibit (E6 and G8) human recombinant PKCe. Here we report a thorough kinetic analysis ofthese VHHs. The inhibiting VHHs act as non-competitive inhibitors of PKCe activity, whereas the activating VHHs haveseveral different modes of action, either increasing V max and/or decreasing K m values. We also show that the binding of theVHHs to PKCe is conformation-dependent, rendering the determination of affinities difficult. Apparent affinities are in themicromolar range based on surface plasmon resonance studies. Furthermore, the VHHs have no effect on the activity of ratPKCe nor can they bind the rat form of the protein in immunoprecipitation studies despite the 98% identity between thehuman and rat PKCe proteins. Finally, we show for the first time that the VHHs can influence PKCe function also in cells,since an activating VHH increases the rate of PKCe translocation in response to PMA in HeLa cells, whereas an inhibiting VHHslows down the translocation. These results give insight into the mechanisms of PKCe activity modulation and highlight theimportance of protein conformation on VHH binding.