DNA immobilization/hybridization on plasma-polymerized pyrrole

The present work describes the fabrication and characterization of the conducting polymer coatings prepared by the continuous wave plasma polymerization and the applications as adhesion layers for studying DNA immobilization/hybridization. The stability of plasma polymerized pyrrole (ppPY) in the aqueous solution was characterized by ellipsometry. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were used to investigate polymer matrix properties and oligonucleotide/DNA binding interaction. The successful DNA immobilization on ppPY surfaces was found to depend on the macromolecular architecture of plasma polymerized films. The plasma polymers with similar thickness deposited at different input powers showed various comparable immobilization properties. The plasma-polymerized films prepared at the low input power showed a lower sensitivity toward DNA binding than those films deposited at the high input power. This result will be important to study plasma polymerized films as potential DNA biosensors in the future.     

Thermodynamic studies on the adsorption of fibronectin adhesion-promoting peptide on nanothin films of poly(2-vinylpyridine) by SPR

This paper describes a methodology for preparing uniform, nanothin polymer films for the study of biomolecule adsorption by surface plasmon resonance spectroscopy (SPR). The methodology combines molecular self-assembly of alkanethiols on gold with surface-confined atom transfer radical polymerization (ATRP). Poly(2-vinylpyridine) was chosen to demonstrate the methodology, and growth kinetics were studied by ex situ ellipsometry. Atomic force microscopy (AFM) indicated that the polymer films were uniform with RMS roughness of approximately 0.5 nm. Subsequent SPR measurements were done to determine thermodynamic adsorption properties (deltaG, deltaH, and deltaS) between fibronectin adhesion-promoting peptide and the surface-confined poly(2-vinylpyridine) at 15, 20, and 25 degrees C. The flexibility in synthesis conditions and the opportunities for manipulating film thicknesses and graft densities that ATRP provides to grow polymer films from gold surfaces holds advantages over conventional spin-coating and grafting to approaches in the design of model polymer films for biomolecule adsorption studies. These advantages are described.     

Liquid phase SPR imaging experiments for biosensors applications

Surface plasmon resonance (SPR) has recently gained attention as a label-free method for the detection of biological molecules binding onto functionalised surfaces. It is one of the most sensitive detection method for monitor variations in the thickness and refractive index in ultra-thin films. Here, the adsorption processes of oligonucleotides onto gold substrates have been investigated in aqueous buffer solution using SPR imaging measurements. The hybridization of a thiol-modified, single stranded oligonucleotide anchored to a gold surface via thiol group, with its complementary sequence has been observed and characterised monitoring the hybridization process by SPR equipment. In situ investigation of smallest changes in SPR imaging measurements dynamically performed in liquid phase in the presence of DNA complementary probes was performed. Infrared spectroscopy and scanning electron microscopy characterisation of the functionalised gold surfaces of the biosensor were compared with the images obtained by SPR experimental apparatus.     

Adsorption of dansylated amino acids on molecularly imprinted surfaces: a surface plasmon resonance study

Surface plasmon resonance spectroscopy (SPR) was used to measure the adsorption kinetics and isotherms of dansylated amino acids onto surface-confined molecularly imprinted polymer films (MIP-Fs) and the corresponding non-imprinted polymer control films (NIP-Fs). The surface-confined polymer films were grafted from flat gold surfaces using atom transfer radical polymerization (ATRP). This approach allowed uniform nanothin films to be grown, thereby ensuring that the amino acids see a uniform surface during adsorption. N,N'-Didansyl-l-cystine (DDC) and didansyl-l-lysine (DDK) were used as the template molecules to form the MIP-Fs. Adsorption kinetics data were analyzed using single- and dual-site Langmuir adsorption models. It was found that, within the experimental measurement range, adsorption isotherm data were well described by any of four isotherm models: Langmuir, dual-site Langmuir, Freundlich, or Langmuir-Freundlich (LF). The relatively high heterogeneity index values regressed using the Freundlich and LF isotherms suggest the formation of fairly homogeneous MIP-Fs; although Scatchard analysis reveals binding site heterogeneity does exist. Selectivity studies showed that the MIP-Fs display cross-reactivity between DDC and DDK; nevertheless, MIP-Fs prepared against one template showed selectivity for that template. Solution pH and polymer layer thickness were studied as independent parameters to determine their impacts on amino acid adsorption, as monitored by SPR.     

Zein adsorption to hydrophilic and hydrophobic surfaces investigated by surface plasmon resonance

Zein, the prolamine of corn, has been investigated for its potential as an industrial biopolymer. In previous research, zein was plasticized with oleic acid and formed into sheets/films. Physical properties of films were affected by film structure and controlled in turn by zein-oleic acid interactions. The nature of such interactions is not well understood. Thus, protein-fatty acid interactions were investigated in this work by the use of surface plasmon resonance (SPR). Zein adsorption from 75% aqueous 2-propanol solutions, 0.05% to 0.5% w/v, onto hydrophilic and hydrophobic self-assembled monolayers (SAMs) formed by 11-mercaptoundecanoic acid and 1-octanethiol, respectively, was monitored by high time resolution SPR. Initial adsorption rate and ultimate surface coverage increased with bulk protein concentration for both surfaces. The initial slope of plotted adsorption isotherms was higher on 11-mercaptoundecanoic acid than on 1-octanethiol, indicating higher zein affinity for hydrophilic SAMs. Also, maximum adsorption values were higher for zein on hydrophilic than on hydrophobic SAMs. Flushing off loosely bound zein in the SPR cell allowed estimation of apparent monolayer values. Differences in monolayer values for hydrophobic and hydrophilic surfaces were explained in terms of zein adsorption footprint.     

Synthesis, patterning and applications of star-shaped poly(ethylene glycol) biofunctionalized surfaces

Poly(ethylene) glycol (PEG) is an excellent material to modify surfaces to resist non-specific protein adsorption. Linear PEG has been extensively studied both theoretically and experimentally and it has been found that resistance of PEG-coated surfaces to protein adsorption depends mainly on the molecular weight of the polymer and the surface grafting density. End-functionalized star-shaped PEGs allow for interpolymer crosslinking to form a dense layer. An excellent example of such a system consists of a 6-arm PEG/PPG (4 : 1) star polymer functionalized with isocyanate using IPDI. The end functionalization may be further biofunctionalized to recognize specific biomolecules such as streptavidin, His-tagged proteins, amino-terminated oligonucleotides and cell receptors. This functionalization may be patterned into specific geometries using stamping techniques or randomly distributed by statistical reaction of the end group with the biofunctional molecule in solution. The surface preparation uses simple spin-, dip- or spray-coating and produces smooth layers with low background fluorescence. These properties, together with the advantageous chemical properties of PEG, render the surfaces ideal for immobilizing proteins on surfaces with detection limits down to the single molecule level. Proteins immobilized on such surfaces are able to maintain their folded, functional form and are able to completely refold if temporarily exposed to denaturing conditions. Immobilized enzyme molecules were able to perform their function with the same activity as the enzyme in solution. Future directions of using surfaces coated with such crosslinked star polymers in highly sensitive and robust biotechnology applications will be discussed.     

Protein adsorption at polymer-grafted surfaces: comparison between a mixture of saliva proteins and some well-defined model proteins

Grafting a dense layer of soluble polymers onto a surface is a well-established method for controlling protein adsorption. In the present study, polyethylene oxide (PEO) layers of three different grafting densities were prepared, i.e. 10-15 nm2, 5.5 nm2 and 4 nm2 per polymer chain, respectively. The adsorption of different proteins on the PEO grafted surfaces was measured in real time by reflectometry. Furthermore, the change of the zeta-potential of such surfaces resulting from adsorption of the proteins was determined using the streaming potential method. Both the protein adsorption and the zeta-potential were monitored for 1 h after exposure of the protein solution to the surface. The adsorption pattern for a mixture of saliva proteins was compared to those observed for a number of well-defined model-proteins (lysozyme, human serum albumin, beta-lactoglobulin and ovalbumin). The results of the adsorption kinetics and streaming potential measurements indicate that the effect of the PEO layer on protein adsorption primarily depends on the size and the charge of the protein molecules. The saliva proteins are strongly blocked for adsorption, whereas the change in the zeta-potential is larger than for the other proteins (except lysozyme). It is concluded that positively charged protein molecules, having dimensions larger than those of lysozyme, are involved in the initial stage of adsorption from saliva onto a negatively charged surface.     

Surface modification of chitosan films. Effects of hydrophobicity on protein adsorption

The surface of chitosan films was modified using acid chloride and acid anhydrides. Chemical composition at the film surface was analyzed by attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). ATR-FTIR data verified that the substitution took place at the amino groups of chitosan, thus forming amide linkages, and the modification proceeded to the depth at least 1 microm. Choices of molecules substituted at the amino groups of the glucosamine units did affect the hydrophobicity of the film surface, as indicated by air-water contact angle analysis. The surface became more hydrophobic than that of non-modified film when a stearoyl group (C(17)H(35)CO-) was attached to the films. The reaction of chitosan films with succinic anhydride or phthalic anhydride, however, produced more hydrophilic films. Selected modified films were subjected to protein adsorption study. The amount of protein adsorbed, determined by bicinchoninic acid (BCA) assay, related to the types of attached molecules. The improved surface hydrophobicity affected by the stearoyl groups promoted protein adsorption. In contrast, selective adsorption behavior was observed in the case of the chitosan films modified with anhydride derivatives. Lysozyme adsorption was enhanced by H-bonding and charge attraction with the hydrophilic surface. While the amount of albumin adsorbed was decreased possibly due to negative charges that gave rise to repulsion between the modified surface and albumin. This study has demonstrated that it is conceivable to fine-tune surface properties which influence its response to bio-macromolecules by heterogeneous chemical modification.     

Fab fragments imprinted SPR biosensor for real-time human immunoglobulin G detection

F(ab) fragments imprinted surface plasmon resonance (SPR) chip was prepared for the real-time detection of human immunoglobulin G (IgG). In order to attach polymerization precursor on SPR chip, the SPR chip surface was modified with allyl mercaptan. F(ab) fragments of the IgG molecules were prepared by papain digestion procedure and collected by fast protein liquid chromatography (FPLC) system using Hi-Trap_r Protein A FF column. The collected F(ab) fragments were complexed with histidine containing specific monomer, N-methacryloyl-l-histidine methyl ester (MAH). Molecular imprinted polymeric nanofilm was prepared on SPR chip in the presence of ethylene glycol dimethacrylate and 2-hydroxyethylmethacrylate. The template molecules, F(ab) fragments, were removed from the polymeric nanofilm using 1M NaCl solution (pH: 7.4, phosphate buffer system). The molecular imprinted SPR chip was characterized by contact angle, atomic force microscopy and Fourier transform infrared spectroscopy. By the real-time IgG detection studies carried out using aqueous IgG solutions in different concentrations, the kinetics and isotherm parameters of the molecular imprinted SPR chip-IgG system were calculated. To show selectivity and specificity of the molecular imprinted SPR chip, competitive kinetic analyses were performed using bovine serum albumin (BSA), IgG, F(ab) and F(c) fragments in singular and competitive manner. As last step, IgG detection studies from human plasma were performed and the measured IgG concentrations were well matched with the results determined by enzyme-linked immunosorbent assay (ELISA). The results obtained with the molecular imprinted SPR chip were well fitted to Langmuir isotherm and the detection limit was found as 56 ng/mL. In the light of the results, we can conclude that the proposed molecular imprinted SPR chip can detect IgG molecules from both aqueous solutions and complex natural samples.     

Stable self-assembly of a protein engineering scaffold on gold surfaces

The outer membrane protein OmpF from Escherichia coli is a member of a large family of beta-barrel membrane proteins. Some, like OmpF, are pore-forming proteins whilse others are active transporters or enzymes. We have previously shown that the receptor-binding domain (R-domain) of the toxin colicin N binds with high affinity to OmpF reconstituted into tethered lipid bilayers on gold electrodes. The binding can be measured by surface plasmon resonance (SPR) and ion channel blockage (impedance spectroscopy, IS). In this paper we report the use of a mutant OmpF-E183C in which a single cysteine had been introduced on a short periplasmic turn. OmpF-E183C binds directly to gold surfaces and creates high-density protein layers by self-assembly from detergent solution. When the gold surface is pretreated with beta-mercaptoethanol and thiolipids are added after the protein immobilisation step, the protein is shown, by Fourier transform infrared spectroscopy (FTIR), to retain its beta-rich structure. Furthermore, we could also measure R-domain binding by SPR and IS, confirming the functional reconstitution of a self-assembled membrane protein monolayer at the gold surface. Because these beta-barrel proteins are recognized protein engineering scaffolds, the method provides a generic method for the simple self-assembly of protein interfaces from aqueous solution.     

Hydrophilic monolayer formation of adsorbed cationic starch and cationic hydroxyethyl cellulose derivatives on polyester surfaces

Cationic starch, cationic cellulose derivatives, and hydrophobically modified cationic cellulose were physically adsorbed from aqueous solution onto oppositely charged hydrophobic polyester (poly(ethylene terephthalate)) fabric and nonwoven, and this resulted in hydrophilic surface properties. Surface coverage of the polysaccharides occurred primarily by strong electrostatic interactions, and the surface characteristics were evaluated by measuring the time required for a water droplet to be absorbed into the polyester material as well as by electron spectroscopy for chemical analysis (ESCA). From a comparison of the adsorption characteristics we assess the polysaccharide-dependent and substrate-dependent adsorption behavior and discuss the similarities and differences in the hydrophilic properties and wettability observed. In particular, the temperature of the cationic polysaccharide solutions in which the substrate was immersed, the configuration of the polymer in solution, and the presence of hydrophobic substituents on the cationic moiety have a considerable effect on the polysaccharide affinity and its adsorption on the surface, irrespective of the substrate type (fabric or nonwoven). We also evaluate the relative contribution of the polyelectrolyte molecular weight, concentration in solution, and degree of charge density along the polymer chain which determine the range of interactions and alter surface hydroplilicity dependent on the type of substrate.     

Protein Adsorption at Polymer-grafted Surfaces: Comparison between a Mixture of Saliva Proteins and some Well-defined Model Proteins

Grafting a dense layer of soluble polymers onto a surface is a well-established method for controlling protein adsorption. In the present study, polyethylene oxide (PEO) layers of three different grafting densities were prepared, i.e. 10?–?15 nm², 5.5 nm² and 4 nm² per polymer chain, respectively. The adsorption of different proteins on the PEO grafted surfaces was measured in real time by reflectometry. Furthermore, the change of the zeta-potential of such surfaces resulting from adsorption of the proteins was determined using the streaming potential method. Both the protein adsorption and the zeta-potential were monitored for 1?h after exposure of the protein solution to the surface. The adsorption pattern for a mixture of saliva proteins was compared to those observed for a number of well-defined model-proteins (lysozyme, human serum albumin, β-lactoglobulin and ovalbumin). The results of the adsorption kinetics and streaming potential measurements indicate that the effect of the PEO layer on protein adsorption primarily depends on the size and the charge of the protein molecules. The saliva proteins are strongly blocked for adsorption, whereas the change in the zeta-potential is larger than for the other proteins (except lysozyme). It is concluded that positively charged protein molecules, having dimensions larger than those of lysozyme, are involved in the initial stage of adsorption from saliva onto a negatively charged surface.     

Chemisorptions of bacterial receptors for hydrophobic amino acids and sugars on gold for biosensor applications: a surface plasmon resonance study of genetically engineered proteins

This paper demonstrates potential applications of two periplasmic receptor proteins from E. coli as sensing elements for biosensors using the surface plasmon resonance (SPR) technique. These molecules, namely the aspartate to cysteine mutant of the leucine-specific receptor (LS-D1C) and the glutamine to cysteine mutant of the D-glucose/D-galactose receptor (GGR-Q26C) proteins, are chemisorbed on a thin (approximately 40 nm) Au film in neutral K2HPO4 buffers. Using angle and time resolved SPR measurements; we show that adsorption behaviors of both proteins are dominated by diffusion-free second order Langmuir kinetics. We also show that the protein-modified Au films exhibit measurable SPR shifts upon binding to their respective target ligands. According to these SPR data, the kinetics of ligand binding for both LS-D1C and GGR-Q26C are governed by irreversible first order diffusion limited Langmuir model. The utility of the SPR technique for studying reactions of biological molecules is further illustrated in this work.     

Nanoneedle Surface Modification with 2-Methacryloyloxyethyl Phosphorylcholine Polymer to Reduce Nonspecific Protein Adsorption in a Living Cell

Previously, we developed a new molecular delivery system to target single living cells by using atomic force microscope and ultrathin needle referred to as nanoneedle. This system delivers molecules into the cell by attaching them to the surface of nanoneedle. However, nonspecific protein adsorption on the nanoneedle surface inside the living cells limits the range of application of this system. In the present study, we focused on nonspecific protein adsorption onto the nanoneedle surface inside the cells and examined whether this protein adsorption was reduced by modifying the nanoneedle surface with a biocompatible phospholipid polymer containing 2-methacryloyloxyethyl phosphorylcholine (MPC) unit. MPC polymer coating of the surface of silicon wafer reduced nonspecific adsorption of proteins from liver extracts and prevented the formation of clot-like protein aggregates. MPC polymer also decreased nonspecific adsorption of cytosolic protein onto the nanoneedle surface inside the living cell. On the other hand, MPC polymer showed no effect on nonspecific mechanical interaction between nanoneedle and the cell components. Surface modification with MPC polymer is a useful technique to modify the surface properties of nanoneedle.     

Synthesis of beta-cyclodextrin and starch based polymers for sorption of azo dyes from aqueous solutions

Three beta-cyclodextrin (polymers 1-3) and a starch-based (polymer 4) polymers were synthesized using hexamethylene diisocyanate (HMDI) as a cross-linking agent in dry dimethylformamide and used as a sorbent for the removal of some selected azo dyes from aqueous solutions. The cross-linked polymers were characterized by Fourier transform infrared spectroscopy, thermogravimetric and differential scanning calorimetric analysis. Results of sorption showed that cyclodextrin and starch based polymers can be effectively used as a sorbent for the removal of anionic azo dyes. The Influence of the amide groups and the chemical structure of azo dyes are also studied. Results of sorption experiments showed that these adsorbent exhibited high sorption capacities toward Direct Violent 51 (80% for polymer 1, 69% for polymer 2, 70% for polymer 3 and 78% for polymer 4). The sorption capacity of dyes on the polymers was dependent on the presence of sulfonate groups of the anionic dyes. In order to explain the results an adsorption mechanism mainly physical adsorption and interactions such as hydrogen bonding, ion-exchange due to the nature of the polymer network and the formation of an inclusion complex due to the beta-CD molecules through host-guest interaction is proposed.     

Measuring adsorption of a hydrophobic probe with a surface plasmon resonance sensor to monitor conformational changes in immobilized proteins

Conformational changes of proteins immobilized on solid matrices were observed by measuring the adsorption of Triton X-100 (TX), a nonionic detergent, as a hydrophobic probe with BIACORE, a biosensor that utilizes the phenomenon of surface plasmon resonance (SPR). Two kinds of proteins, alpha-glucosidase and lysozyme, were covalently attached to dextran matrices on the sensor surface in the flow cell and then exposed to various concentrations of TX solution. We measured SPR signal changes derived from adsorption of TX to the immobilized proteins and calculated the monolayer adsorption capacity using the Brunauer-Emmett-Teller (BET) equation. The results demonstrated that monolayer adsorption capacity is proportional to the amount of immobilized proteins. Further, the unfolding process of immobilized proteins on the sensor surface induced by guanidine hydrochloride was investigated by monitoring SPR signal increases due to the adsorption of TX to the exposed hydrophobic region of the protein. Results strongly suggested that the increase in the SPR signal reflected the formation of the agglutinative unfolded state. We expect our measuring method using the SPR sensor and TX adsorption will be a novel tool to provide conformational information regarding various proteins on solid matrices.     

Engineering surfaces for bioconjugation: developing strategies and quantifying the extent of the reactions

This study presents two-step and multistep reactions for modifying the surface of plasma-functionalized poly(tetrafluoroethylene) (PTFE) surfaces for subsequent conjugation of biologically relevant molecules. First, PTFE films were treated by a radiofrequency glow discharge (RFGD) ammonia plasma to introduce amino groups on the fluoropolymer surface. This plasma treatment is well optimized and allows the incorporation of a relative surface concentration of approximately 2-3.5% of amino groups, as assessed by chemical derivatization followed by X-ray photoelectron spectroscopy (XPS). In a second step, these amino groups were further reacted with various chemical reagents to provide the surface with chemical functionalities such as maleimides, carboxylic acids, acetals, aldehydes, and thiols, that could be used later on to conjugate a wide variety of biologically relevant molecules such as proteins, DNA, drugs, etc. In the present study, glutaric and cis-aconitic anhydrides were evaluated for their capability to provide carboxylic functions to the PTFE plasma-treated surface. Bromoacetaldehyde diethylacetal was reacted with the aminated PTFE surface, providing a diethylacetal function, which is a latent form of aldehyde functionality. Reactions with cross-linkers such as sulfo-succinimidyl derivatives (sulfo-SMCC, sulfo-SMPB) were evaluated to provide a highly reactive maleimide function suitable for further chemical reactions with thiolated molecules. Traut reagent (2-iminothiolane) was also conjugated to introduce a thiol group onto the fluoropolymer surface. PTFE-modified surfaces were analyzed by XPS with a particular attention to quantify the extent of the reactions that occurred on the polymer. Finally, surface immobilization of fibronectin performed using either glutaric anhydride or sulfo-SMPB activators demonstrated the importance of selecting the appropriate conjugation strategy to retain the protein biological activity.     

The Terpolymer Produced by Azotobacter Chroococcum 7B: Effect of Surface Properties on Cell Attachment

The copolymerization of poly(3-hydroxybutyrate) (PHB) is a promising trend in bioengineering to improve biomedical properties, e.g. biocompatibility, of this biodegradable polymer. We used strain Azotobacter chroococcum 7B, an effective producer of PHB, for biosynthesis of not only homopolymer and its main copolymer, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB-HV), but also novel terpolymer, poly(3-hydroxybutyrate-co-3-hydroxyvalerate)-poly(ethylene glycol) (PHB-HV-PEG), using sucrose as the primary carbon source and valeric acid and poly(ethylene glycol) 300 (PEG 300) as additional carbon sources. The chemical structure of PHB-HV-PEG was confirmed by ¹H nuclear-magnetic resonance analysis. The physico-chemical properties (molecular weight, crystallinity, hydrophilicity, surface energy) of produced biopolymer, the protein adsorption to the terpolymer, and cell growth on biopolymer films were studied. Despite of low EG-monomers content in bacterial-origin PHB-HV-PEG polymer, the terpolymer demonstrated significant improvement in biocompatibility in vitro in contrast to PHB and PHB-HV polymers, which may be coupled with increased protein adsorption, hydrophilicity and surface roughness of PEG-containing copolymer.     

Antifouling poly(β-peptoid)s

A new type of polymer highly resistant to nonspecific protein adsorption is reported. Poly(N-methyl-β-alanine) (PMeA) and poly(N-ethyl-β-alanine) (PEtA) synthesized via cobalt-catalyzed carbonylative polymerization of N-methylaziridine and N-ethylaziridine were end-functionalized with thiol groups and grafted onto Au surfaces. Protein adsorption was studied by the surface plasmon resonance (SPR) method. The amounts of representative single proteins adsorbed onto the PMeA- and PEtA-grafted surfaces were below the detection limit of SPR at the pg/mm(2) level. After exposure to full blood plasma and serum for 10 min, protein adsorption was at the level of ～ 100 pg/mm(2), similar to the level of protein adsorption on poly(ethylene glycol) surfaces subjected to identical conditions. These poly(β-peptoid)s therefore provide excellent protein resistance comparable to the best antifouling materials known to date. The strong proton-accepting ability when forming hydrogen bonds is suggested to be an important attribute for these poly(β-peptoid)s as well as other poly(tertiary amide)s as antifouling materials.     

Protein microarrays on hybrid polymeric thin films prepared by self-assembly of polyelectrolytes for multiple-protein immunoassays

We report here the development and characterization of protein microarrays fabricated on nanoengineered 3-D polyelectrolyte thin films (PET) deposited on glass slide by consecutive adsorption of polyelectrolytes via self-assembly technique. Antibodies or antigens were immobilized in the PET-coated glass slides by electrostatic adsorption and entrapment of porous structure of the 3-D polymer film and thus establishing a platform for parallel analysis. Both antigen and antibody microarrays were fabricated on the PET-coated slides, and direct and indirect immunoassays on protein microarrays for multiple-analyte detection were demonstrated. Microarrays produced on these PET-coated slides have consistent spot morphology and provide performance features needed for proteomic analysis. The protein microarrays on the PET films provide LOD as low as 6 pg/mL and dynamic ranges up to three orders of magnitude, which are wider than the protein microarrays fabricated on aldehyde and poly-L-lysine functionalized slides. The PET films constructed by self-assembly technique in aqueous solution is green chemistry based, cost-effective method to generate 3-D thin film coatings on glass surface, and the coated slide is well suited for immobilizing many types of biological molecules so that a wide variety of microarray formats can be developed on this type of slide.