Fourier Transform Infrared Spectroscopy Data Research Articles

A Hybrid Sensing Approach for Pure and Adulterated Honey Classification

This paper presents a comparison between data from single modality and fusion methods to classify Tualang honey as pure or adulterated using Linear Discriminant Analysis (LDA) and Principal Component Analysis (PCA) statistical classification approaches. Ten different brands of certified pure Tualang honey were obtained throughout peninsular Malaysia and Sumatera, Indonesia. Various concentrations of two types of sugar solution (beet and cane sugar) were used in this investigation to create honey samples of 20%, 40%, 60% and 80% adulteration concentrations. Honey data extracted from an electronic nose (e-nose) and Fourier Transform Infrared Spectroscopy (FTIR) were gathered, analyzed and compared based on fusion methods. Visual observation of classification plots revealed that the PCA approach able to distinct pure and adulterated honey samples better than the LDA technique. Overall, the validated classification results based on FTIR data (88.0%) gave higher classification accuracy than e-nose data (76.5%) using the LDA technique. Honey classification based on normalized low-level and intermediate-level FTIR and e-nose fusion data scored classification accuracies of 92.2% and 88.7%, respectively using the Stepwise LDA method. The results suggested that pure and adulterated honey samples were better classified using FTIR and e-nose fusion data than single modality data.

Melamine formaldehyde: curing studies and reaction mechanism

Melamine formaldehyde (MF) resin was synthesized by the reaction between melamine and formaldehyde under alkaline condition in tetrohydrofuran medium with 1:3 melamine to formaldehyde molar ratio. The synthesized resins were characterized by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and thermal gravimetric analysis (TGA). Curing and reaction mechanism was studied by thermal and spectroscopic analysis. Two exothermic peaks were observed in the DSC analysis indicating a two-step crosslinking reaction process was correlated to TGA analysis. FTIR studies at different temperatures explained the two-stage curing mechanism which is concurring with the DSC data. At a temperature range of 140–160 °C, reversible demethylolation is dominating to the crosslinking reaction. At temperature >160 °C, the crosslinking reaction dominates. On the basis of DSC and FTIR data, a possible crosslinking reaction route was derived and explained. The first stage of curing is the conversion of methylol groups to primary amine and the second stage is the crosslinking of methylol groups to the final product, methylene bridges. The thermal stability of the methylol groups, methylene bridges and the triazine ring, as well as the evaporation of effluents at different stages of curing, are also discussed based on combined TGA and DSC results. Curing studies and reaction mechanism of MF resin was studied by thermal and spectroscopic tools comparing DSC and FTIR studies explains the two-stage thermal curing mechanism. The first step of thermal curing at temperature range of 140–160 °C is the reverse reaction of methylol groups to melamine and second step occurring at temperature >160 °C is the crosslinking of methylol groups to the final product, methylene bridge. Hence, by the mutual agreement of DSC and FTIR studies, a possible reaction route was derived for the thermal curing process. The DSC–TGA thermogram supports the two-step process of the cure reaction by exhibiting two peaks in the same temperature region.

Host-guest complexes of phenoxy alkyl acid herbicides and cyclodextrins. MCPA and β-cyclodextrin

The chlorophenoxy herbicide MCPA (4-chloro-2-methylphenoxyacetic acid), widely used for the control of broad-leaf weeds primarily in cereal and grass seed crops, still remains one of the most often used herbicides in Portugal. As the formation of inclusion complexes with cyclodextrins can improve its solubility properties, the interaction between the herbicide MCPA and β-cyclodextrin was investigated. The stability constants describing the extent of formation of the complexes have been determined by phase-solubility studies. Different analytical techniques [ultraviolet-visible spectroscopy (UV-Vis), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (1H NMR)] were employed for a thorough investigation of the structural characteristics of the obtained complexes, which exhibited distinct features and properties from both “guest” and “host” molecules. FTIR and 1H NMR data obtained for the MCPA/β-CD complexes gave information about the interaction between MCPA and the nonpolar cyclodextrin cavity. The dramatic change observed in band frequency and proton displacements of OCH2 group and H6 aromatic proton confirmed the inclusion of MCPA in β-CD. The formation of an inclusion complex between MCPA and β-CD increased the aqueous solubility of this herbicide which could be a particularly advantageous property for some specific applications, namely to improve commercial formulation and for environmental protection.

Protein based tablets as reversible gelling systems for delayed release applications

Succinylated β-lactoglobulin (S-β-lg) was previously shown to be efficient as new excipient for the formation of enteric tablets, suitable for several applications including probiotics delivery. This work investigates the mechanisms leading to S-β-lg tablets delayed release. Release kinetics were evaluated in vitro. Fourier transformed infra red spectroscopy (FTIR) was used to visualize the effect of dissolution medium on matrix tablet surface. Results demonstrated that tablets release in simulated gastric fluids (SGF) might be due to water/drug diffusion through an in situ formed gel layer, as revealed by FTIR data. As SGF penetrated the tablet, regardless of protein succinylation rate (50% or 100%), molecular rearrangements occurred, allowing the development of an important band located in the 1621-1623 cm(-1) region. This band was characteristic of the formation of protein intermolecular β-sheets. The gel was showed to be reversible in intestinal conditions, allowing delayed release. While the molecular structure of the gel layer was not depending on protein succinylation rate, it appeared that 100% S-β-lg tablets showed slower release. This low release was probably related to 100% S-β-lg lower solubility, lower charge density, and their ability to form stronger intermolecular hydrogen bonds. This work highlights proteins potential for the conception of controlled drug delivery systems.

Solid State Self-Assembly Mechanism of RADA16-I Designer Peptide

We report that synthetic RADA16-I peptide transforms to β-strand secondary structure and develops intermolecular organization into β-sheets when stored in the solid state at room temperature. Secondary structural changes were probed using solid state nuclear magnetic resonance spectroscopy (ssNMR) and Fourier transform infrared spectroscopy (FTIR). Intermolecular organization was analyzed via wide-angle X-ray diffraction (WAXD). Observed changes in molecular structure and organization occurred on the time scale of weeks during sample storage at room temperature. We observed structural changes on faster time scales by heating samples above room temperature or by addition of water. Analysis of hydration effects indicates that water can enhance the ability of the peptide to convert to β-strand secondary structure and assemble into β-sheets. However, temperature dependent FTIR and time dependent WAXD data indicate that bound water may hinder the assembly of β-strands into β-sheets. We suggest that secondary structural transformation and intermolecular organization together produce a water-insoluble state. These results reveal insights into the role of water in self-assembly of polypeptides with hydrophilic side chains, and have implications on future optimization of RADA16-I nanofiber production.

Evolution of silicon nanoclusters and hydrogen in SiNx:H films: Influence of high hydrostatic pressure under annealing

Hydrogenated silicon-rich nitride (SRN) films of various stoichiometry (SiNx:H, 0.7<x≤1.3) were deposited on single-crystalline Si substrates with the use of plasma enhanced chemical vapor deposition at a temperature of 100°С. Furnace annealing for 5h in ambient Ar at 1130°С under atmospheric and enhanced hydrostatic pressure (HP — 11kbar, 1.1GPa) was applied to modify the structure of the films. The properties of as-deposited and annealed films were studied using ellipsometry, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, photoluminescence (PL), as well as high-resolution transmittance electron microscopy (HRTEM). According to the Raman data, the as-deposited film, in which the stoichiometry parameter x is below 1.0, contains amorphous silicon nanoclusters. Furnace annealing leads to crystallization of the nanoclusters. From the HRTEM and Raman data, the average size of the Si nanocrystals in the annealed films was 6–7nm. No silicon nanoclusters were observed in the as-deposited films with relatively low concentration of excessive silicon atoms (the case of SiNx:H, x>1); furnace annealing leads to segregation of the Si and Si3N4 phases, so, the amorphous Si clusters were observed in annealed films according to Raman data. Surprisingly, after annealing with such high thermal budget, according to the FTIR data, the SRN film with parameter x close to that of the stoichiometric silicon nitride contains hydrogen in the form of SiH bonds. From analysis of the FTIR data of the SiN bond vibrations one can conclude that silicon nitride is partly crystallized in the films with x>1 after annealing for 5h. No influence of HP on the structure of Si nanoclusters was observed in the case of SRN films with x≤1.1. Dramatic changes in the PL spectra of the SRN films with the x parameter close to that of the stoichiometric silicon nitride (x≈1.3), annealed under atmospheric pressure and HP, were observed. HP stimulates the formation of very small hydrogenated amorphous nanoclusters. The size of amorphous Si nanoclusters determined from the quantum size effect model describing the PL spectra, should be 2–4nm in this case.

Application of second derivative spectroscopy for increasing molecular specificity of fourier transform infrared spectroscopic imaging of articular cartilage

Fourier transform infrared (FT-IR) spectroscopic imaging is a promising method that enables the analysis of spatial distribution of biochemical components within histological sections. However, analysis of FT-IR spectroscopic data is complicated since absorption peaks often overlap with each other. Second derivative spectroscopy is a technique which enhances the separation of overlapping peaks. The objective of this study was to evaluate the specificity of the second derivative peaks for the main tissue components of articular cartilage (AC), i.e., collagen and proteoglycans (PGs). Histological bovine AC sections were measured before and after enzymatic removal of PGs. Both formalin-fixed sections (n = 10) and cryosections (n = 6) were investigated. Relative changes in the second derivative peak heights caused by the removal of PGs were calculated for both sample groups. The results showed that numerous peaks, e.g., peaks located at 1202 cm(-1) and 1336 cm(-1), altered less than 5% in the experiment. These peaks were assumed to be specific for collagen. In contrast, two peaks located at 1064 cm(-1) and 1376 cm(-1) were seen to alter notably, approximately 50% or more. These peaks were regarded to be specific for PGs. The changes were greater in cryosections than formalin-fixed sections. The results of this study suggest that the second derivative spectroscopy offers a practical and more specific method than routinely used absorption spectrum analysis methods to obtain compositional information on AC with FT-IR spectroscopic imaging.

Biomimetic chitosan–calcium phosphate composites with potential applications as bone substitutes: Preparation and characterization

A novel biomimetic technique for obtaining chitosan-calcium phosphates (Cs-CP) scaffolds are presented: calcium phosphates are precipitated from its precursors, CaCl(2) and NaH(2) PO(4) on the Cs matrix, under physiological conditions (human body temperature and body fluid pH; 37°C and pH = 7.2, respectively). Materials composition and structure have been confirmed by various techniques: elemental analysis, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM). FTIR and SEM data have shown the arrangement of the calcium phosphates-hydroxyapatite (CP-Hap) onto Cs matrix. In this case the polymer is acting as glue, bonding the calcium phosphates crystals. Behavior in biological simulated fluids (phosphate buffer solution-PBS and PBS-albumin) revealed an important contribution of the chelation between -NH3(+) and Ca(2+) on the scaffold interaction with aqueous mediums; increased quantities of chitosan in composites permit the interaction with human albumin and improve the retention of fluid. The composites are slightly degraded by the lysozyme which facilitates an in vivo degradation control of bone substitutes. Modulus of elasticity is strongly dependent of the ratio chitosan/calcium phosphates and recommends the obtained biomimetic composites as promising materials for a prospective bone application.

Spectroscopic, morphological and chemical characterization of historic pigments based on carbon. Paths for the identification of an artistic pigment

Analytical characterization of reference carbon-based black pigments has been performed using Fourier transform infrared spectroscopy (FTIR) with attenuated total reflectance (ATR) and scanning electron microscopy (SEM) coupled to an energy-dispersive X-ray spectrometer (EDS). The unambiguous identification of these pigments, which are found in paintings, rock art and archeological artifacts, still remains a big challenge due to the variety of sources and manufacturing processes used in their preparation. The analytical results achieved in this study allowed us to discriminate between carbon-based pigments from different sources and detect adulterations. The methodological approach was successfully applied to the identification of vegetable charcoal and bone black in two colonial paintings dated from the eighteenth century. Conclusions regarding the pictorial techniques were drawn from FTIR data.

FTIR and DSC studies on gamma irradiated P(VdF-HFP) fluoropolymers applied to dosimetry

Radiation effects on semicrystalline poly(fluorovinylidene- co-hexafluoropropylene) copolymer [P(VdF-HFP)] induced by high-energy irradiation were investigated. Films with 150 μm thickness were irradiated with gamma doses ranging from 1.0 kGy to 3.0 MGy. Fourier transform infrared (FTIR) spectroscopy was used to follow the radio-induction of new molecular bonds. Differential scanning calorimetry (DSC) was employed to study the crystalline degradation of the irradiated samples. P(VdF-HFP) copolymers have fluorinated monomers [–CF 2–CF–CF 3–] randomly added to the [–CH 2–CF 2–] main chain of PVdF homopolymer. In this case, the [–CF 3–] molecular bonds are branched to the main chain. There is an increasing interest about the effect of high gamma radiation dose on the P(VdF-HFP) radiolysis, once it could enhance some of their already known interesting properties such as biomedical applications and electrostrictive transducers/actuators. FTIR spectroscopic data revealed two optical absorption bands at 1730 and 1754 cm −1 whose intensities are unambiguously related to gamma delivered dose ranging from 0.0 to 1000 kGy. Fading analysis has demonstrated no loss of signal until 11 months after irradiation. DSC and XRD data revealed a continuous decrease in both the melting latent heat and crystalline dimensions for doses ranging from 250 to 3000 kGy. Because of the low fading and the linear behavior with respect to delivered gamma doses of the absorption band at 1754 cm −1, P(VdF-HFP) copolymers are good candidates for being explored for high gamma dose dosimetry application.

Data fusion of Fourier transform infrared spectra and powder X-ray diffraction patterns for pharmaceutical mixtures

Fusing complex data from two disparate sources has been demonstrated to improve the accuracy in quantifying active ingredients in mixtures of pharmaceutical powders. A four-component simplex-centroid design was used to prepare blended powder mixtures of acetaminophen, caffeine, aspirin and ibuprofen. The blends were analyzed by Fourier transform infra-red spectroscopy (FTIR) and powder X-ray diffraction (PXRD). The FTIR and PXRD data were preprocessed and combined using two different data fusion methods: fusion of preprocessed data (FPD) and fusion of principal component scores (FPCS). A partial least square (PLS) model built on the FPD did not improve the root mean square error of prediction. However, a PLS model built on the FPCS yielded better accuracy prediction than PLS models built on individual FTIR and PXRD data sets. The improvement in prediction accuracy of the FPCS may be attributed to the removal of noise and data reduction associated with using PCA as a preprocessing tool. The present approach demonstrates the usefulness of data fusion for the information management of large data sets from disparate sources.

Alterations in the metabolic fingerprint of Cladonia portentosa in response to atmospheric nitrogen deposition

Nitrogen availability has profound ecological consequences in nutrient-limited systems. In terrestrial settings these would include the upland heaths, sand dunes and blanket bogs of temperate latitudes. Understanding the physiological consequences of nitrogen enrichment is a first critical step in predicting possible consequences. Results are presented from a metabolic fingerprinting study using Fourier transform-infrared spectroscopy (FTIR) to detect biochemical differences in the lichen Cladonia portentosa collected from 25 sites across mainland Britain varying in their nitrogen input. Partial least-squares regression analysis of the FTIR data demonstrated that changes in broad biochemical classes were consistently correlated with mean annual wet inorganic nitrogen deposition loads. These results demonstrated a direct coupling of a broad range of metabolic processes in C. portentosa to nitrogen deposition.

Effect of Co substitution on the structural and optical properties of ZnO nanoparticles synthesized by sol–gel route

Co doped ZnO nanoparticles were synthesized by sol–gel method and characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), Energy dispersive X-ray analysis (EDAX), UV–Visible absorption spectroscopy and Fourier transform infrared spectroscopy (FTIR). XRD analysis revealed the formation of single phase structure of all samples which was further supported by FTIR data. With the increase in Co concentration from 0% to 5%, crystallite size was observed to vary from 27.1 to 21.3 nm. It suggests the prevention of crystal growth as a result of Co doping in ZnO. It was also evident from the absorption spectra that the absorbance tends to increase with the increase in dopant concentration. Optical band gap was found to increase slightly with the increase in Co content, confirming the size reduction as a result of Co doping.

He plasma pretreatment effects on oxygen plasma-induced carbon loss and surface roughening in an ultralow-k organosilicate glass film

Ex situ Fourier transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) have been used to characterize the effects of He plasma pretreatment on O2 plasma-induced modification of the surface composition and structure of nanoporous ultralow dielectric constant (k) organosilicate glass (OSG) films. Oxygen plasma induces Si–C bond scission and carbon abstraction, and increased k values. Carbon abstraction exhibits diffusion-dominated kinetics. FTIR data, however, indicate that He plasma pretreatment prior to O2 plasma exposure induces pore sealing in the OSG film interior, inhibiting carbon abstraction, but only at longer O2 plasma exposure times (exposure time >5 min). The data are consistent with XPS data showing that OSG exposure to He plasma results in a more SiO2-like surface layer, but that atomic O will diffuse through a continuous SiO2 film. AFM data also indicate that He plasma pretreatment inhibits subsequent OSG surface roughening upon exposure to oxygen plasma.

Capping-Ligand Effect on the Stability of CdSe Quantum Dot Langmuir Monolayers

The stability of Langmuir monolayers of CdSe Qdots capped with dodecan-ethiol (DDT), with dithiocarbamates having one, two, or three long alkyl chains (DTC-1, DTC-2 and DTC-3) or with tri-n-octylphosphine oxide (TOPO), was investigated and linked to the transport of Qdots into the subphase via a dissolution and diffusion mechanism. Langmuir films of Qdots were created by depositing droplets of purified Qdots in chloroform at the air-water interface. While holding the Qdot films at 13 mN/m for 1 h in a Langmuir trough, the average monolayer areas decreased by roughly 9% for TOPO-capped Qdots, ∼15-18% for the three DTC-capped Qdot preparations, and ∼21% for DDT-capped Qdots. Using the model of Ter Minassian-Saraga, the relative stabilities of the Qdot films studied were related to differences in equilibrium partitioning into the subphase and to apparent Qdot diffusivities within the subphase. An analysis of the Qdot preparations by Fourier-transform infrared spectroscopy (FTIR) revealed that the aliphatic tails of capping ligands were assembled on Qdot surfaces with similar packing densities for all ligand chemistries. A combined analysis of the film-area contraction and FTIR data suggested that, for the chemistries examined in this study, both the capping-ligand headgroup and the aliphatic tail groups impact Qdot Langmuir film stability through their joint influence on nanoparticle wettability and the tendency to aggregate upon partitioning into the subphase.

Targeted killing of Leishmania donovani in vivo and in vitro with amphotericin B attached to functionalized carbon nanotubes

This study describes the antileishmanial efficacy of the novel drug formulation of amphotericin B (AmB) attached to functionalized carbon nanotubes (f-CNTs) and compares it with AmB. f-CNTs were prepared in a two-step chemical carboxylation and amidation process. The AmB was then attached to make f-CNT-AmB and its construction was confirmed by Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM). The cytotoxicity of the constructed compound, f-CNT-AmB, was assessed in vitro using the J774A.1 macrophage cell line and in vivo using healthy BALB/c mice. Antileishmanial activity of AmB and f-CNT-AmB was assessed in vitro using a macrophage (J774A.1 cell line) model of Leishmania donovani infection. Antileishmanial activity was assessed in vivo by comparing the parasite load of hamsters treated with a 5 day course of AmB, f-CNTs or f-CNT-AmB initiated at 30 days after infection with L. donovani parasites. The FTIR spectroscopy and TEM data demonstrate the successful attachment of AmB to f-CNTs. The in vitro cytotoxicity of AmB, f-CNTs and f-CNT-AmB was measured by the cytotoxic concentration required to kill 50% of the cells: 0.48±0.06 μg/mL; 7.31±1.16 μg/mL; 0.66±0.17 μg/mL, respectively, in the J774A.1 cell line. The in vivo toxicity assessment of the compounds in BALB/c mice revealed no hepatic or renal toxicity. Against intracellular amastigotes the in vitro antileishmanial efficacy of f-CNT-AmB was significantly higher than that of AmB (IC50 0.00234±0.00075 μg/mL versus 0.03263±0.00123 μg/mL; P≤0.0001). The percentage inhibition of amastigote replication in hamsters treated with f-CNT-AmB was significantly more than that with AmB (89.85%±2.93% versus 68.97%±1.84%; P=0.0004). The results of these experiments clearly demonstrate that f-CNT-AmB has significantly greater antileishmanial efficacy than AmB and had no significant cytotoxic effects.

Temperature dependence of graphene oxide reduced by hydrazine hydrate

Graphene oxide (GO) was successfully prepared by a modified Hummer’smethod. The reduction effect and mechanism of the as-prepared GO reducedwith hydrazine hydrate at different temperatures and time were characterized byx-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy(FTIR), elemental analysis (EA), x-ray diffractions (XRD), Raman spectroscopy andthermo-gravimetric analysis (TGA). The results showed that the reduction effect of GOmainly depended on treatment temperature instead of treatment time. Desirablereduction of GO can only be obtained at high treatment temperature. Reduced at95 °C for 3 h, theC/O atomicratio of GO increased from 3.1 to 15.1, which was impossible to obtain at low temperatures, such as 80,60 or 15 °C, even for longer reduction time. XPS, 13C NMR and FTIR results show that most of theepoxide groups bonded to graphite during the oxidation were removed from GO and form thesp2 structure after being reduced by hydrazine hydrate at high temperature (>60 °C), leading to the electric conductivity of GO increasing from1.5 × 10 − 6 to5 S cm − 1, while the hydroxyls on the surface of GO were not removed by hydrazine hydrate even athigh temperature. Additionally, the FTIR, XRD and Raman spectrum indicate that theGO reduced by hydrazine hydrate can not be entirely restored to the pristine graphitestructures. XPS and FTIR data also suggest that carbonyl and carboxyl groups can bereduced by hydrazine hydrate and possibly form hydrazone, but not a C = C structure.

Gel time prediction of multifunctional acrylates using a kinetics model

A kinetics model for prediction of double-bond conversion and gel time in the photopolymerization of multifunctional acrylates is presented. The system consisting of a trifunctional acrylate, trimethylolpropane triacrylate (TMPTA), and a photoinitiator, 2,2-dimethoxy-1,2-diphenylethan-1-one (DMPA), was studied using Fourier-transform infrared spectroscopy (FTIR) measurements to monitor double-bond conversion and microrheology techniques to quantify the gel time for this system. Rate constants for the kinetics model were first estimated by fitting the model only to the FTIR double-bond conversion data, and later to both the FTIR and microrheology data. The measured gel time correlated with both the calculated initial rate of radical generation and a constant value of the predicted double-bond conversion, over a broad range of conditions. The model allows for materials formulation and exposure source intensity variables to be included in stereolithography inverse problem solutions, and could be applied to other cross-linking based photopolymerization systems.

Determination of the Influence of Primary Drying Rates on the Microscale Structural Attributes and Physicochemical Properties of Protein Containing Lyophilized Products

This work investigated the impact of primary drying conditions on the microstructure and protein stability of bovine serum albumin (BSA) containing lyophilized cakes. Two primary drying conditions were employed (termed 'conservative', slower drying rate and 'aggressive', higher drying rate) at two protein loadings (5 and 50 mg mL(-1)). The cake attributes were characterized using micro-X-ray computed tomography (micro-CT), scanning electron microscopy, manometric temperature measurements, Fourier transform infrared spectroscopy (FTIR) and size exclusion chromatography (SEC). The combination of analytical techniques revealed that although the aggressive drying conditions produced intact cakes which retained their macrostructure, they had undergone various degrees of microcollapse. The study demonstrates the applicability of micro-CT for resolving microstructural attributes of the freeze-dried cakes such as residual porosity, pore size distribution and connectivity. Micro-CT data showed significant differences in residual porosity and matrix connectivity between aggressively and conservatively dried cakes. The FTIR data show that at each protein loading, there is no observable difference in the secondary structure of the protein and the SEC data show comparable stability in the cakes produced under different primary drying conditions. Good content uniformity was observed with respect to BSA and sucrose distribution in the cakes.

Electrochemical deposition of composite biopolymer films

Composite films of alginic acid–hyaluronic acid and alginic acid–heparin were deposited by electrochemical method for the surface modification of conductive substrates. Obtained films were studied by SEM, thermogravimetric analysis (TGA), differential thermal analysis (DTA) and Fourier transform infrared spectroscopy (FTIR). The deposition yield increased with increasing concentration of hyaluronate and heparin in the alginate solutions. The results of deposition yield measurements coupled with the results of TGA and DTA studies showed the possibility of the formation of deposits of different composition. These results are in a good agreement with the FTIR data, which revealed characteristic adsorption peaks of hyaluronic acid and heparin for the composite films. Film thickness was varied in the range of 0–10 μm by the variation of the deposition time at a constant deposition voltage. Obtained films can be used for the surface modification of biomedical implants with improved biocompatibility.