Total Reflectance Fourier Transform Infrared Spectroscopy Research Articles

Minimally invasive identification of degraded polyester-urethane magnetic tape using attenuated total reflection Fourier transform infrared spectroscopy and multivariate statistics.

Audio recordings are a significant component of the world's modern cultural history and are retained for future generations in libraries, archives, and museums. The vast majority of tapes contain polyester-urethane as the magnetic particle binder, the degradation of which threatens the playability and integrity of these often unique recordings. Magnetic tapes with stored historical data are degrading and need to be identified prior to digitization and/or preservation. We demonstrate the successful differentiation of playable and nonplayable quarter-inch audio tapes, allowing the minimally invasive triage of tape collections. Without such a method, recordings are put at risk during playback, which is the current method for identifying degraded tapes. A total of 133 quarter-inch audio tapes were analyzed by attenuated total reflectance Fourier transform-infrared spectroscopy (ATR FT-IR). Classification of IR spectra in regards to tape playability was accomplished using principal component analysis (PCA) followed by quadratic discriminant analysis (QDA) and K-means cluster analysis. The first principal component suggests intensities at the following wavenumbers to be representative of nonplayable tapes: 1730 cm(-1), 1700 cm(-1), 1255 cm(-1), and 1140 cm(-1). QDA and cluster analysis both successfully identified 93.78% of nonplayable tapes in the calibration set and 92.31% of nonplayable tapes in the test set. This application of IR spectra assessed with multivariate statistical analysis offers a path to greatly improve efficiency of audio tape preservation. This rapid, minimally invasive technique shows potential to replace the manual playback test, a potentially destructive technique, ultimately allowing the safe preservation of culturally valuable content.

Alkali resistance of poly(ethylene terephthalate) (PET) and poly(ethylene glycol-co-1,4-cyclohexanedimethanol terephthalate) (PETG) copolyesters: The role of composition

The alkali resistance of poly(ethylene terephthalate) (PET) and a series of poly(ethylene glycol-co-1,4-cyclohexanedimethanol terephthalate) (PETG) copolyesters with different molar ratios of ethylene glycol (EG) to 1,4-cyclohexanedimethanol (CHDM) was systematically investigated. Differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) were used to probe the effect of the alkali treatment on the crystallization behavior and crystalline structure of the PET and PETG copolyesters. The surface groups and morphology changes were characterized by attenuated total reflectance Fourier transform-infrared spectroscopy (ATR-FTIR) and reflective polarized optical microscopy. The effects of temperature, duration, crystallinity and composition on the alkali resistance were examined. The incorporation of 1,4-cyclohexanedimethanol terephthalate (CT) in the PET chain, did not compromise the alkali resistance of the PETG copolyesters. On the contrary, the alkali resistance of the PETG copolyesters was enhanced when the CT content was increasing. The composition played an important role in the alkali resistance of the PET and PETG copolyesters, rather than the crystallinity. The ET component was more easily attacked by alkaline hydrolysis than the CT component, and the remaining polymer was enriched in the CT component. In addition, the amorphous regions on the surface of the PET and PETG copolyesters were more likely to be attacked by the hydroxyl anions compared to the crystalline regions. Moreover, the alkali treatment did not change the crystalline structure of the PET and PETG copolyesters, but the alkali treatment did result in corrosion to the crystals.

Distinguishing nuclei-specific benzo[a]pyrene-induced effects from whole-cell alterations in MCF-7 cells using Fourier-transform infrared spectroscopy.

Exposure to chemicals such as benzo[a]pyrene (B[a]P) can generate intracellular toxic mechanisms. Fourier-transform infrared (FTIR) spectroscopy is a novel approach that allows the non-destructive analysis of underlying chemical bond alterations in patho-physiological processes. This study set out to examine whether B[a]P-induced whole cell alterations could be distinguished from effects on nuclei of exposed cells. Using attenuated total reflection FTIR (ATR-FTIR) spectroscopy, alterations in nuclei isolated from B[a]P-treated MCF-7 cells concentrated either in G0/G1- or S-phase were observed. B[a]P-induced effects in whole-cells included alterations to lipids, DNA and protein spectral regions. Absorbance areas for protein and DNA/RNA regions in B[a]P-treated whole cells differed significantly (P<0.0001) from vehicle controls and these observations correlated with alterations noted in isolated nuclei. Our findings provide evidence that FTIR spectroscopy has the ability to identify specific chemical-induced alterations.

Enhancement of flame retardancy of cotton fabrics by grafting a novel organic phosphorous-based flame retardant

In this study, a novel, halogen-free, formaldehyde-free, organic phosphorus-based flame retardant, ammonium salt of hexamethylenediamine-N,N,N′,N′-tetra(methylphosphonic acid) (AHDTMPA), was synthesized using urea and hexamethylenediamine-N,N,N′,N′-tetra(methylphosphonic acid) (HDTMPA). AHDTMPA reacted with the O-6 hydroxyls of glucose residues in the cellulose of cotton fabric to form P–O–C covalent bonds. This ability was confirmed by Fourier-transform infrared (FTIR) spectroscopy, attenuated total reflection FTIR spectroscopy, and X-ray diffraction. Cotton fabric treated with 70 g/L AHDTMPA had a limiting oxygen index (LOI) value of 36.0 %, which remained relatively stable after 50 laundering cycles with a 28.0 % LOI value. The surface morphology and thermal stability of treated cotton fabrics were investigated using scanning electron microscopy and thermogravimetric analysis (TGA), respectively. TGA showed that AHDTMPA could exhibit flame retardancy at temperatures lower than the pyrolysis temperature of cotton fabrics. Additionally, the cotton fabric was treated with AHDTMPA through a pad-cure process, as its ease of operation, high efficiency, and excellent application made it an attractive treatment.

Adsorption of water and butanol in silicalite-1 film studied with in situ attenuated total reflectance-Fourier transform infrared spectroscopy.

Biobutanol produced by, e.g., acetone-butanol-ethanol (ABE) fermentation is a promising alternative to petroleum-based chemicals as, e.g., solvent and fuel. Recovery of butanol from dilute fermentation broths by hydrophobic membranes and adsorbents has been identified as a promising route. In this work, the adsorption of water and butanol vapor in a silicalite-1 film was studied using in situ attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy to better understand the adsorption properties of silicalite-1 membranes and adsorbents. Single-component adsorption isotherms were determined in the temperature range of 35-120 °C, and the Langmuir model was successfully fitted to the experimental data. The adsorption of butanol is very favorable compared to that of water. When the silicalite-1 film was exposed to a butanol/water vapor mixture with 15 mol % butanol (which is the vapor composition of an aqueous solution containing 2 wt % butanol, a typical concentration in an ABE fermentation broth, i.e., the composition of the gas obtained from gas stripping of an ABE broth) at 35 °C, the adsorption selectivity toward butanol was as high as 107. These results confirm that silicalite-1 quite selectively adsorbs hydrocarbons from vapor mixtures. To the best of our knowledge, this is the first comprehensive study on the adsorption of water and butanol in silicalite-1 from vapor phase.

FT-IR Examination of the Development of Secondary Cell Wall in Cotton Fibers

The secondary cell wall development of cotton fibers harvested at 18, 20, 24, 28, 32, 36 and 40 days after flowering was examined using attenuated total reflection Fourier transform-infrared (ATR FT-IR) spectroscopy. Spectra of deuterated cotton fibers did not demonstrate significant changes in their O–H stretching band shapes or positions during development. Only a progressive increase in O–H band intensity was observed. Results indicate that the highly crystalline cellulose component produced during secondary cell wall formation maintains the hydrogen bonding network observed for the primary cell wall. Other general changes were observed for the regular ATR spectra. A progressive intensity increase for bands assigned to cellulose Iβ was observed during fiber development, including a marked intensity increase for vibrations at 1002 and 985 cm−1. In contrast, C–O vibrational bands from dominant conformations observed at 1104, 1052, 1028 cm−1 undergo a modest intensity increase during secondary cell wall development.

Analysis of ‘legal high’ substances and common adulterants using handheld spectroscopic techniques

Three handheld spectrometers, near-infrared (NIR), Raman and attenuated total reflectance Fourier transform-infrared (ATR-FT-IR) spectroscopy, were used for the identification of ‘legal high’ model mixtures and Internet products.

Fourier Transform Infrared Spectroscopy and Imaging in Cancer Diagnosis and Characterization

Fourier Transform Infrared (FTIR) spectroscopy and imaging techniques are formidable, novel, rapid and non-destructive tools for characterization of different biological systems from molecules to membranes, cells and tissues. These techniques with multivariate analysis tools can be used in the diagnosis/follow-up of diseases including cancer, and in monitoring drug or chemical induced alterations in tissues and cells. In the current study, Attenuated Total Reflectance FTIR spectroscopy together with chemometric (cluster and principal component) analysis were utilized as a diagnostic tool for urinary bladder cancer while FTIR imaging technique was used in the clarification of sodium butyrate (NaB) induced-differentiation in colon cancer cells since butyrate has an anti-proliferative effect in colon cancer. For bladder cancer studies, bladder wash samples of bladder cancer and control groups were used directly for spectra collection. ATR-FTIR studies revealed significant alterations in lipid, protein, and nucleic acid content of bladder wash samples of cancer groups as compared to the control ones. Based on these spectral variations, bladder cancer group can be successfully differentiated from control via chemometric analysis with a higher sensitivity and specificity than many other methods used currently in bladder cancer diagnosis. In colon cancer study, aggressive CaCo2 cell lines were treated with 3mM NaB and cultured for 48h for complete differentiation. Specific band ratio analysis such as lipid/protein, glycogen/phosphate and RNA/DNA were calculated from the chemical maps of control and NaB-treated cells. Imaging results indicated the reconstruction of cancer induced changes in response to NaB treatment by modulating the saturated, unsaturated, triglyceride, protein and nucleic acid content in the treated cells. The findings of this study supported that FTIR spectroscopic and imaging techniques are valuable, label-free and sensitive bio-analytical tools for cancer diagnostics and investigating the global roles of drugs on cancer treatment.

UV-light assisted single step route to functional PEEK surfaces

Polyether ether ketone (PEEK) is a thermoplastic polymer of high technological relevance and is composed of repeating phenyl ether and benzophenone units. In the present work we will demonstrate the potential of UV irradiation assisted generation of free radicals on the surface benzophenone units to graft a variety of polymer chains on the PEEK surface. Both “grafting-to” and “grafting-from” approaches were explored by using different monomers and polymers. Styrene, butyl acrylate (BA), vinyl phosphonic acid (VPA), acrylic acid (AA), polyacrylic acid (PAA) and monomethoxy terminated oligo (ethylene glycol) methacrylate (MeOEGMA) were successfully utilized for this purpose. The functionalized membranes were characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier-transformed Infrared (ATR-FTIR) spectroscopy, atomic force microscopy (AFM), and contact angle (CA) goniometry. PAA and PVPA functionalized PEEK surfaces exhibited pH responsive wettability behavior. PAA functionalized PEEK surfaces were further modified with lysine, which led to the controlled surface wettability over a broader pH range as compared to the simple PAA functionalized surface. The grafting with polyMeOEGMA rendered PEEK surface with nonfouling properties against bacterial growth. Employing this highly economical and simple method, the surface properties of PEEK can be modulated and tuned according to a specific application.

Polymeric Nanohydrogels of Poly(N-Isopropylacrylamide) Combined with Others Functionalized Monomers: Synthesis and Characterization

Nanohydrogels from inverse microemulsion (w/o) polymerization, at 25°C, of N-isopropylacrylamide (NIPA) and functionalized monomers are described. The functionalized monomers were: N-(pyridine-4-ylmethyl) acrylamide (NP4MAM) and tert-butyl 2-acrylamidoethyl carbamate (2AAECM). The polymeric nanohydrogel obtained was characterized by attenuated total reflectance Fourier-transformed infrared spectroscopy (ATR-FTIR) and proton nuclear magnetic resonance spectrometry (1HNMR), while their morphology and particle size was assessed by scanning electron microscopy (SEM) and dynamic light scattering. Their thermal properties were studied by Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). As a preliminary measure of biocompatibility, in vitro evaluations of the nanohydrogels were carried out by cellular toxicity (colon carcinoma cells, CT-26) and hemocompatibility tests. These evaluations showed that these nanohydrogels were not toxic in the examined concentration range and exhibited preliminary blood compatibility; therefore they could be used in biomedical applications.

Degradation of polyurethane ester foam artifacts: Chemical properties, mechanical properties and comparison between accelerated and natural degradation

Polyurethane foams deteriorate rapidly; the effects of degradation can appear after 20–30 years. Conservation issues mainly related to the loss of polyurethane foam mechanical properties frequently affect museum artifacts. Many studies dealt with degradation of polyurethane, but no one correlated the polyurethane chemical changes with the mechanical properties loss of the foam structure. In order to find a degradation indicator permitting to obtain simultaneously information on the chemical and mechanical condition of the foam with a non-invasive method, we performed accelerated degradation at different relative humidity conditions. Chemical modifications have been observed by Attenuated Total Reflection–Fourier Transform Infrared Spectroscopy (ATR–FTIR). Differential Scanning Calorimetry (DSC) has been used to follow polyurethane glass transition temperature variations. Mechanical properties of degraded and undegraded samples have been studied by Compression Force Deflection Test (CFDT) and Scanning Electron Microscopy (SEM) allowed visualizing foam surface modifications during the entire degradation period. ATR–FTIR spectra analysis of artificially degraded samples allowed identifying the ester/hydroxyl band ratio as a good indicator of polyurethane ester foam degradation. A correspondence was found between the decrease of the ester/hydroxyl ratio value and the loss of elasticity of the foam structure. The reliability of this indicator (ester/hydroxyl band ratio) has been validated by ATR–FTIR analysis performed on naturally degraded TDI based polyurethane ester foams.

Polymerization kinetic calculations in dental composites: a method comparison analysis

This study aimed to describe the polymerization process and to quantify the parameters of influence in two bulk-fill resin-based composites by comparing two real-time methods: the Fourier transform infrared (FTIR) spectroscopy and the visible light transmission spectrometry. The degree of conversion (DC) was recorded in real time for 5 min using the attenuated total reflectance FTIR spectroscopy (n = 6) on the lower surface of 2, 4, and 6 mm thick samples irradiated for 20 s. The variation in irradiance was recorded during material irradiation at the bottom of the samples (n = 5). Results were statistically analyzed using one-way and multiple-way ANOVAs with Tukey HSD post hoc test (α = 0.05), partial eta-squared statistics, and Pearson correlation. No significant difference was found in DC in any materials as a function of incremental thickness, whereas the irradiance passing the specimens differed consistently within both analyzed increments and materials. These data could be described by the superposition of two exponential functions, the first being attributed to the gel phase and the second to the glass phase, resulting in an exponential sum function. DC data were able to calculate the end of the gel phase and the beginning of the glass phase, whereas irradiance measurements were able to detect only the last phase. The polymerization kinetics in the glass phase was less material-dependent as in the gel phase. The irradiance measurements were more sensitive to variation in thickness, meaning that translucency is continuing to change as a function of thickness at a higher extent than DC. Knowing the impact of the modulation factors describing the calculated sum exponential function allows the manipulation of the polymerization process at different stages to tailor material properties.

Discrimination of E. coli B E BL21(DE3) porin mutants by attenuated total reflectance Fourier-transformed infrared (ATR-FTIR) spectroscopy

Attenuated total reflectance Fourier-transformed infrared (ATR-FTIR) spectroscopy measures the changes that occur in a totally internally reflected infrared beam when the evanescent wave it produces penetrates only a few micrometers (0.5-5μm) into the sample, deposited on top of an optically dense crystal (Figure 1) [1]. Both conventional FTIR and ATR-FTIR have been successfully used for bacteria discrimination and classification, as each species presents an unique spectral “fingerprint”, making it a promising, fast and reliable screening method for pathogen identification in a clinic setting [2-3]. In this study, ATR-FTIR is used in an attempt to discriminate between Escherichia (E.) coli BE BL21(DE3) and a derived mutant lacking the major E. coli porins OmpF and OmpC (Table 1). Porins are transmembrane proteins located in the outer membrane of Gram-negative bacteria such as E. coli that allow the passage of various solutes, including antibiotics, playing therefore an important role in the development of antibiotic resistance. The ability to effectively distinguish between strains differing only in the porin profile would mean more than just information on structural differences, but also an initial indication on resistance mechanisms [4]. Strain Relevant genotype

Structural and functional characterization of simvastatin-induced myotoxicity in different skeletal muscles

BackgroundStatins are the most commonly used drugs for the treatment of hypercholesterolemia. Their most frequent side effect is myotoxicity. To date, it remains unclear whether statins preferentially induce myotoxicity in fast- or in slow-twitch muscles. Therefore, we investigated these effects on fast- (extensor digitorum longus; EDL), slow- (soleus; SOL), and mixed-twitch muscles (diaphragm; DIA) in rats by comparing their contractile and molecular structural properties. MethodsSimvastatin-induced functional changes were determined by muscle contraction measurements, and drug-induced molecular changes were investigated using Fourier transform infrared (FTIR) and attenuated total reflectance (ATR) FTIR spectroscopy. ResultsWith simvastatin administration (30days, 50mg/kg), a depression in the force–frequency curves in all muscles was observed, indicating the impairment of muscle contractility; however, the EDL and DIA muscles were affected more severely than the SOL muscle. Spectroscopic findings also showed a decrease in protein, glycogen, nucleic acid, lipid content and an increase in lipid order and lipid dynamics in the simvastatin-treated muscles. The lipid order and dynamics directly affect membrane thickness. Therefore, the kinetics and functions of membrane ion channels were also affected, contributing to the statin-induced impairment of muscle contractility. Furthermore, a reduction in α-helix and β-sheet and an increase in random coil, aggregated and antiparallel β-sheet were observed, indicating the protein denaturation. Spectral studies showed that the extent of molecular structural alterations in the muscles following simvastatin administration was in the order EDL>DIA>SOL. ConclusionsSimvastatin-induced structural and functional alterations are more profound in the fast-twitch than in the slow-twitch muscles. General significanceMyotoxic effects of simvastatin are primarily observed in the fast-twitch muscles.

Gallate derivatives as antioxidant additives for polypropylene

ABSTRACTOctyl gallate (OG), dodecyl gallate (DG), and hexadecyl gallate (HG) were synthesized and characterized by Fourier transform infrared (FTIR) and NMR, and their thermal stability was measured by thermogravimetric analysis (TGA). The antioxidant effect of these derivatives in polypropylene (PP) was measured by oxidation induction temperature measurement on DSC, and by measurement of carbonyl groups in the polymer on attenuated total reflectance FTIR spectroscopy after they were aged at 120°C. The results indicated that the gallate derivatives could provide long‐term stabilization to PP under conditions of oxidative degradation. The antioxidant performance of HG with longer alkyl chain was superior to the OG and DG, making the former a good candidate to be used as antioxidant additive in PP. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39850.

One‐pot synthesized poly(vinyl pyrrolidone‐co‐methyl methacrylate‐co‐acrylic acid) blended with poly(ether sulfone) to prepare blood‐compatible membranes

ABSTRACTIn this study, a random copolymer of poly(vinyl pyrrolidone‐co‐methyl methacrylate‐co‐acrylic acid) was synthesized via a one‐pot reaction with the reversible addition–fragmentation chain‐transfer method and was then blended with poly(ether sulfone) (PES) to prepare flat‐sheet membranes that were expected to have anticoagulant and antifouling properties. The synthesized copolymer was characterized by Fourier transform infrared (FTIR) and NMR spectroscopy. The molecular weights and molecular weight distributions were determined by gel permeation chromatography. Elemental analysis was used to calculate the molar ratios of vinyl pyrrolidone (VP), methyl methacrylate (MMA), and acrylic acid (AA) in the copolymer. A liquid–liquid phase‐inversion technique was used to prepare the copolymer‐blended PES membranes. X‐ray photoelectron spectroscopy and attenuated total reflectance–FTIR spectroscopy were used to investigate the copolymer on the membrane surfaces. Compared with the pristine PES membrane, the modified PES membranes showed improved hydrophilicity, low hemolysis ratios, decreased protein adsorption, and suppressed platelet adhesion. Furthermore, the thrombin time and activated partial thromboplastin time indicated that the blood compatibility of the modified PES membranes were improved. The results of the 3‐(4,5‐Dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay and the cell morphology suggested that the cytocompatibility increased. In addition, the modified membranes showed good protein antifouling properties. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4284–4298, 2013

High-resolution, high-throughput, positive-tone patterning of poly(ethylene glycol) by helium beam exposure through stencil masks.

In this work, a collimated helium beam was used to activate a thiol-poly(ethylene glycol) (SH-PEG) monolayer on gold to selectively capture proteins in the exposed regions. Protein patterns were formed at high throughput by exposing a stencil mask placed in proximity to the PEG-coated surface to a broad beam of helium particles, followed by incubation in a protein solution. Attenuated Total Reflectance–Fourier Transform Infrared Spectroscopy (ATR–FTIR) spectra showed that SH-PEG molecules remain attached to gold after exposure to beam doses of 1.5–60 µC/cm2 and incubation in PBS buffer for one hour, as evidenced by the presence of characteristic ether and methoxy peaks at 1120 cm−1 and 2870 cm−1, respectively. X-ray Photoelectron Spectroscopy (XPS) spectra showed that increasing beam doses destroy ether (C–O) bonds in PEG molecules as evidenced by the decrease in carbon C1s peak at 286.6 eV and increased alkyl (C–C) signal at 284.6 eV. XPS spectra also demonstrated protein capture on beam-exposed PEG regions through the appearance of a nitrogen N1s peak at 400 eV and carbon C1s peak at 288 eV binding energies, while the unexposed PEG areas remained protein-free. The characteristic activities of avidin and horseradish peroxidase were preserved after attachment on beam-exposed regions. Protein patterns created using a 35 µm mesh mask were visualized by localized formation of insoluble diformazan precipitates by alkaline phosphatase conversion of its substrate bromochloroindoyl phosphate-nitroblue tetrazolium (BCIP-NBT) and by avidin binding of biotinylated antibodies conjugated on 100 nm gold nanoparticles (AuNP). Patterns created using a mask with smaller 300 nm openings were detected by specific binding of 40 nm AuNP probes and by localized HRP-mediated deposition of silver nanoparticles. Corresponding BSA-passivated negative controls showed very few bound AuNP probes and little to no enzymatic formation of diformazan precipitates or silver nanoparticles.

Amaranth Milling Strategies and Fraction Characterization by FT-IR

Amaranth nutritional value has been widely recognized, but the required conditions for its processing cannot be adapted to traditional technologies. For the proposal of alternative strategies, the changes of several components should be understood. Enriched starch and lipid–protein fractions of amaranth flour upon different milling treatments were obtained and characterized by attenuated total reflectance–Fourier transform-infrared spectroscopy. Starch- and lipid–protein-enriched amaranth fractions were obtained by abrasive milling; amaranth starch was isolated by wet-milling procedure, and flour samples were obtained from planetary ball milling. Changes on starch, protein, and lipids relative contents, on starch crystallinity and on lipids and protein stability after milling and 6-month storage, were evaluated. The Fourier transform-infrared (FT-IR) spectroscopy peaks of the main grain components were identified in the middle-infrared range. By calculating the ratios between height intensities of selected specific peaks, several characteristics of the samples could be explained: increased protein content and lipid proportion of the enriched fraction; decrease of the starch crystallinity degree by abrasive milling and especially by ball milling due to starch amorphization during these processes; and lipids modification in milled and in 6-month aged samples. FT-IR analysis can be considered a rapid, nondestructive, solvent-free, sensitive, and useful tool to investigate starch, lipid, and protein modifications provoked by processing and storage as well as to determine, based on intensity ratio, the relative proportion of grain components within amaranth milling fractions. The abrasive milling associated to planetary ball milling to obtain modified different fractions is presented as an interesting strategy for the processing of amaranth grain.

Improved immobilization of biomolecules to quinone-rich polydopamine for efficient surface functionalization

Polydopamine (PDA), a bio-inspired polymer, has been very attractive for diverse functional applications by immobilizing biomolecules. In this work, a novel approach of using PDA for improved biomolecule immobilization was developed. A thin PDA layer was strategically coated onto 316L stainless steel and thermally treated at 150°C (PDA-Th150). Subsequently, amino-terminated polyethylene glycol (mPEG-NH2) or vascular endothelial growth factor (VEGF) was immobilized onto PDA and PDA-Th150 surface. The results of attenuated total reflection-Fourier transform-infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) showed higher coverage of quinine on PDA-Th150 surface. The functionalized PDA-Th150 significantly improved its ability of immobilizing mPEG-NH2 or VEGF, as shown by platelet adhesion test and endothelial cell proliferation experiments. This novel approach may also be used for efficient immobilization of biomolecules on different metal devices.

Method for Fabrication of Paper-Based Microfluidic Devices by Alkylsilane Self-Assembling and UV/O3-Patterning

This work presents a novel and facile method for fabricating paper-based microfluidic devices by means of coupling of hydrophobic silane to paper fibers followed by deep UV-lithography. After filter paper being simply immersed in an octadecyltrichlorosilane (OTS) solution in n-hexane for 5 min, the hydrophilic paper became highly hydrophobic (water contact angle of about 125°) due to the hydrophobic OTS molecules were coupled to paper's cellulose fibers. The hydrophobized paper was then exposed to deep UV-lights through a quartz mask that had the pattern of the to-be-prepared channel network. Thus, the UV-exposed regions turned highly hydrophilic whereas the masked regions remained highly hydrophobic, generating hydrophilic channels, reservoirs and reaction zones that were well-defined by the hydrophobic regions. The resolution for hydrophilic channels was 233 ± 30 μm and that for between-channel hydrophobic barrier was 137 ± 21 μm. Contact angle measurement, X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance Fourier transform-infrared (ATR-FT-IR) spectroscopy were employed to characterize the surface chemistry of the OTS-coated and UV/O(3)-treated paper, and the related mechanism was discussed. Colorimetric assays of nitrite are demonstrated with the developed paper-based microfluidic devices.