Unloaded Films Research Articles

The Role of WO3 Nanoparticles on the Properties of Gelatin Films.

Gelatin films are very versatile materials whose properties can be tuned through functionalization with different systems. This work investigates the influence of WO3 nanoparticles on the swelling, barrier, mechanical, and photochromic properties of gelatin films. To this purpose, polyvinylpirrolidone (PVP)-stabilized WO3 nanoparticles were loaded on gelatin films at two different pH values, namely, 4 and 7. The values of swelling and solubility of functionalized films displayed a reduction of around 50% in comparison to those of pristine, unloaded films. In agreement, WO3 nanoparticles provoked a significant decrease in water vapor permeability, whereas the decrease in the values of elastic modulus (from about 2.0 to 0.7 MPa) and stress at break (from about 2.5 to 1.4 MPa) can be ascribed to the discontinuity created by the nanoparticles inside the films. The results of differential scanning calorimetry and X-ray diffraction analysis suggest that interaction of PVP with gelatin reduce gelatin renaturation. No significant differences were found between the samples prepared at pH 4 and 7, whereas crosslinking with glutaraldehyde greatly influenced the properties of gelatin films. Moreover, the incorporation of WO3 nanoparticles in gelatin films, especially in the absence of glutaraldehyde, conferred excellent photochromic properties, inducing the appearance of an intense blue color after a few seconds of light irradiation and providing good resistance to several irradiation cycles.

Demonstration and kinetics of hydrogen loading in titanium thin films

Experimental hydrogen loadings in titanium thin films were compared to the Mintz-Bloch model. 500 nm titanium thin films were deposited with an electron-beam evaporator onto sapphire substrates and were capped with a 10 nm palladium thin film. The titanium films were loaded with hydrogen in a custom Sievert apparatus where the pressure drop showed full hydriding at a hydrogen pressure of 2 bar and loading temperatures of 100 °C, 150 °C, 200 °C and 250 °C. Comparisons of X-ray diffractions of loaded and unloaded films showed the presence of titanium hydride in loaded films. The experimental loadings were compared to the Mintz-Bloch model where the Mintz-Bloch model overpredicted experimental loadings. This was due to the Mintz-Bloch assuming that hydride forms immediately upon hydrogen exposure in the metal. However, the difference between the experimental loading kinetics and Mintz-Bloch model was reduced as loading temperatures increased until the temperature reached 250 °C where some titanium hydride outgassing occurred.

Epoxy/Silicone Blend Loaded with N-Doped CNT Composites: Study on the Optoelectronic Properties

Thin films of epoxy/silicone loaded with N-CNT were prepared by a method of sol-gel and deposited on ITO glass substrates at room temperature. The properties of the loaded monolayer samples (0.00, 0.07, 0.1, and 0.2 wt% N-CNTs) were analyzed by UV-visible spectroscopy. The transmittance for the unloaded thin films is 88%, and an average transmittance for the loaded thin film is about 42 to 67% in the visible range. The optical properties were studied from UV-visible spectroscopy to examine the transmission spectrum, optical gap, Tauc verified optical gap, and Urbach energy, based on the envelope method proposed by Swanepoel (1983). The results indicate that the adjusted optical gap of the film has a direct optical transition with an optical gap of 3.61 eV for unloaded thin films and 3.55 to 3.19 eV for loaded thin films depending on the loading rate. The optical gap is appropriately adapted to the direct transition model proposed by Tauc et al. (1966); its value was 3.6 eV for unloaded thin films and from 3.38 to 3.1 eV for loaded thin films; then, we determined the Urbach energy which is inversely variable with the optical gap, where Urbach’s energy is 0.19 eV for the unloaded thin films and varies from 0.43 to 1.33 eV for the loaded thin films with increasing rate of N-CNTs. Finally, nanocomposite epoxy/silicone N-CNT films can be developed as electrically conductive materials with specific optical characteristics, giving the possibility to be used in electrooptical applications.

Nanostructural Arrangements and Surface Morphology on Ureasil-Polyether Films Loaded with Dexamethasone Acetate.

Ureasil-Poly(ethylene oxide) (u-PEO500) and ureasil-Poly(propylene oxide) (u-PPO400) films, unloaded and loaded with dexamethasone acetate (DMA), have been investigated by carrying out atomic force microscopy (AFM), ultrasonic force microscopy (UFM), contact-angle, and drug release experiments. In addition, X-ray diffraction, small angle X-ray scattering, and infrared spectroscopy have provided essential information to understand the films’ structural organization. Our results reveal that while in u-PEO500 DMA occupies sites near the ether oxygen and remains absent from the film surface, in u-PPO400 new crystalline phases are formed when DMA is loaded, which show up as ~30–100 nm in diameter rounded clusters aligned along a well-defined direction, presumably related to the one defined by the characteristic polymer ropes distinguished on the surface of the unloaded u-PPO film; occasionally, larger needle-shaped DMA crystals are also observed. UFM reveals that in the unloaded u-PPO matrix the polymer ropes are made up of strands, which in turn consist of aligned ~180 nm in diameter stiffer rounded clusters possibly formed by siloxane-node aggregates; the new crystalline phases may grow in-between the strands when the drug is loaded. The results illustrate the potential of AFM-based procedures, in combination with additional physico-chemical techniques, to picture the nanostructural arrangements in polymer matrices intended for drug delivery.

Chitosan derivatives-based films as pH-sensitive drug delivery systems with enhanced antioxidant and antibacterial properties

The purpose of this study was to develop and characterize chitosan (Ch)-based films incorporated with varying molecular weight (Mw) and acetylation degree (AD) chitosan-depolymerization-products (CDP), to be applied as drug delivery materials. As compared to Ch-film, optical and antioxidant potentials of Ch/CDP-based films were improved, particularly using low Mw and AD-CDP. Whereas, films water resistance, mechanical and antibacterial properties increased as CDP-Mw increased and AD decreased. For the thermal and swelling behaviors, better values were obtained using higher Mw and AD-CDP. Further, to assess their in vitro ciprofloxacin (CFX)-release behavior, loaded-CFX Ch/CDP-based films, crosslinked using glutaraldehyde, were prepared. Expect of elongation at break, crosslinked CFX-loaded films showed increased optical, water resistance, tensile strength and thermal properties, as compared to unloaded films. The CFX-release profiles indicated that a slower and sustained release was observed, particularly when using lower Mw and AD-CDP, and mainly for the crosslinked films during 48 h. These films can release CFX for up to 54% in 6 and 24 h, at pH 1.2 and 7.4, respectively. Through this study, novel biodegradable, swellable and pH-sensitive crosslinked Ch/CDP-based films may be considered as suitable and promising drug delivery systems.

PEG-crosslinked-chitosan hydrogel films for in situ delivery of Opuntia ficus-indica extract

In the present study, chitosan-based wound dressings loaded with the extract of Opuntia ficus-indica (OPU) were prepared. OPU is known for its capability to accelerate skin injury repair. Chitosan (Ch) was crosslinked with a low molecular weight diepoxy-poly(ethylene glycol) (diePEG), and hydrogel films with different Ch/PEG composition and OPU content were prepared by casting. The occurrence of crosslinking reaction was confirmed by FTIR spectroscopy. FTIR and DSC analysis suggested that ionic interactions occur between chitosan and OPU. Tensile tests evidenced that the crosslinking caused a decrease of Young’s modulus, which approaches the value of the human skin modulus. Swelling characteristics, water vapor transmission rate, and release kinetics demonstrated that these films are adequate for the proposed application. Finally, a scratch test on a keratinocytes monolayer showed that the rate of cell migration in the presence of OPU-loaded samples is about 3-fold higher compared to unloaded films, confirming the repairing activity of OPU.

Eugenol-Containing Essential Oils Loaded onto Chitosan/Polyvinyl Alcohol Blended Films and Their Ability to Eradicate Staphylococcus aureus or Pseudomonas aeruginosa from Infected Microenvironments.

Chronic wounds (CW) create numerous entryways for pathogen invasion and prosperity, further damaging host tissue and hindering its remodeling and repair. Essential oils (EOs) exert quick and efficient antimicrobial (AM) action, unlikely to induce bacterial resistance. Cinnamon leaf and clove oils (CLO and CO) display strong AM activity, namely against Staphylococcus aureus and Pseudomonas aeruginosa. Chitosan (CS) is a natural and biodegradable cationic polysaccharide, also widely known for its AM features. CS and poly (vinyl alcohol) (PVA) films were prepared (ratio 30/70 w/w; 9 wt%) by the solvent casting and phase inversion method. The film’s thermal stability and chemical composition data reinforced polymer blending and EO entrapment. Films were supplemented with 1 and 10 wt% of EO in relation to total polymeric mass. The film thickness and degree of swelling (DS) tended to increase with EO content, particularly with 10 wt % CLO (* p < 0.05). UV-visible absorbance scans in the 250–320 cm−1 region confirmed the successful uptake of CLO and CO into CS/PVA films, particularly with films loaded with 10 wt% EO that contained 5.30/5.32 times more CLO/CO than films supplemented with 1 wt% EO. AM testing revealed that CS films alone were effective against both bacteria and capable of eradicating all P. aeruginosa within the hour (*** p < 0.001). Still, loaded CS/PVA films showed significantly improved AM traits in relation to unloaded films within 2 h of contact. This study is a first proof of concept that CLO and CO can be dispersed into CS/PVA films and show bactericidal effects, particularly against S. aureus, this way paving the way for efficient CW therapeutics.

Biopolymeric films as delivery vehicles for controlled release of hydrocortisone: Promising devices to treat chronic skin diseases.

Atopic dermatitis (AD) is the most common chronic inflammatory skin disease with nasty effects on the psychosocial wellbeing of patients. Overall, glucocorticoids, such as hydrocortisone (HC), are the primary pharmacologic drugs used to treat AD and its symptoms. However, the long-term treatment with HC is often accompanied by severe adverse effects. So, this study reports the encapsulation of HC in polymeric films based on gelatin (Gel) and gelatin/starch (Gel/St) and investigates their potential to treat and attenuate 2,4-Dinitrochlorobenzene (DNCB)-induced AD-like symptoms in BALB/c mice model. The prepared films were characterized by different techniques, which indicated that HC was physically entrapped into the polymer matrices. In vitro experiments indicate that the HC release process occurs in a controlled manner (up to 48h) for both films. Regarding the in vivo experiments, HC-loaded films (Gel@HC and Gel/St@HC), unloaded films (Gel and Gel/St) and HC cream (1%) (as reference) were applied topically on the back of the DNCB-sensitized animals and skin severity scores and scratching behavior were determined. Ex-vivo experiments were done to quantify inflammatory and/or biochemical parameters. As assessed, the topical application of the biopolymeric films (loaded or not with HC) improved the inflammatory parameters, while a lower corticosterone level was observed for the animals treated with Gel and Gel@HC films. In summary, the HC-loaded films showed superior efficiency to treat/attenuate the analyzed parameter than the HC cream (1%). Further, no death or sign of toxicity was observed in animals exposed to HC-loaded films. Thus, the encapsulation of HC in biopolymeric films seems to be a promising alternative for the treatment of injuries caused by chronic skin diseases that require prolonged use of glucocorticoids.

Characterization of photochemically grown Pd loaded WO3 thin films and its evaluation as ammonia gas sensor

Pd-loaded tungsten oxide thin films have been successfully fabricated by direct UV irradiation of bis(β-diketonate)dioxotungsten(VI) and Pd(II) precursor complexes spin-coated on Si(100) substrates. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to analyze the crystal structure and the chemical composition of the films before and after annealing at 500 °C. The results of XRD and AFM analysis showed that the as-photodeposited films are amorphous whereas thermally treated films present a rougher morphology. Post-annealing of the films in air at 500 °C transforms the oxides to a monoclinic WO3 phase. Annealed 10% Pd/WO3 films exhibited an excellent response towards 50 ppm ammonia gas at an operating temperature of 300 °C. The Pd-loaded sensors presented higher sensitivity and quicker response-recovery rates than unloaded WO3 films.

Gamma irradiation of polyethylene nanocomposites for food packaging applications against stored‐product insect pests

Films of high‐density polyethylene (HDPE) incorporated with different nanoparticles, ZnO or Ag, were prepared to protect food products from the stored‐product insect pests. The developed composites were irradiated at different radiation doses and the associated properties were investigated in terms of gel content percent, tensile mechanical properties, thermal properties, and morphology. The possible application of the irradiated products in food industry via the insect pest test was investigated. The gel content percentage of the irradiated HDPE films loaded with ZnO and Ag nanoparticles demonstrated higher values than those of unirradiated unloaded films and unirradiated loaded HDPE. The mechanical measurements indicated significant increments by loading with nanoparticles as well as by irradiation. The tensile strength raised up to about 177 and 158% by adding 2% ZnO and Ag, respectively. Conversely, the elongation percentage was decreased by increasing nanoparticle concentration and by radiation dose. Thermogravimetric analysis elaborated that the thermal stability of the nanocomposites was lesser than that of HDPE unloaded films, yet improved by irradiation. The insect pest test revealed that the adults of Sitophilus granarius could not penetrate the loaded and irradiated HDPE film. The most efficient formulation was reported for the HDPE films incorporated with 2% Ag irradiated with a dose of 75 kGy. J. VINYL ADDIT. TECHNOL., 25:E120–E129, 2019. © 2018 Society of Plastics Engineers

Considering the effect of graphene loading in water-based epoxy coatings

Recently, graphene has gained increasing interest in numerous fields of application and, in particular, it has been used as a nanofiller in the preparation of polymeric composites to improve their mechanical and transport properties. However, the effect of graphene as a potential additive for anticorrosive organic coatings is not widely studied. In this work, low levels of graphene nanosheets, 0.5 and 1 wt%, were added to an additive-free waterborne epoxy resin applied to Al2024-T3 aluminum alloy samples. The presence of graphene did not affect the polymerization process of the resin and the adhesion at coating/substrate interface, as demonstrated by experimental results, while showing a slight effect on coatings wettability. Electrochemical analysis revealed an improvement of the protective properties of the coating that could be assigned to a slow absorption rate of the electrolytes in the polymeric matrix and a lesser amount of absorbed water than the unloaded film.

Osteogenic effects of simvastatin-loaded mesoporous titania thin films

The use of statins in the field of bone regeneration is under current investigation due to the existing demand for non-toxic anabolic agents capable of enhancing bone formation in cases of substantial loss. Simvastatin, a coenzyme currently prescribed in clinics to inhibit cholesterol biosynthesis, has been proven to promote osteogenic differentiation by stimulating bone formation and inhibiting osteoclasts activity. We present the loading of simvastatin in mesoporous TiO2 thin films toward combining the pro-osteogenic properties of this molecule with the demonstrated bioactivity of titania. TiO2 thin films processing and characterization were carried out, as well as evaluation of MC3T3-E1 pre-osteoblasts viability when directly incubated with different concentrations of simvastatin, followed by the analysis of osteogenic activity promoted by simvastatin upon loading in the thin films. The accessible porosity of 36% quantified on the 95 ± 5 nm thick mesoporous thin films, together with pore diameters of 5.5 nm, necks between pores of 2.8 nm and interpore distances of 12 ± 2 nm allow the loading of the simvastatin molecule, as confirmed by FTIR spectroscopy. Simvastatin was found to promote MC3T3-E1 pre-osteoblasts viability at concentrations ≤0.01 g l−1, with a cytotoxicity threshold of 0.05 g l−1. We additionally found that film loadings with 0.001 g l−1 simvastatin promotes statistically higher MC3T3-E1 pre-osteoblast proliferation whereas a higher concentration of 0.01 g l−1 leads to statistically higher osteogenic activity (ALP synthesis), after 21 days of incubation, as compared to unloaded films. These results demonstrate the potential of simvastatin local administration based on bioactive mesoporous thin films to promote pro-osteogenic properties. By focusing this strategy on the coating of metallic prostheses, the supply of simvastatin to the target tissue can be favored and risks of systemic side effects will be reduced while enhancing the osteointegration of the implants.

Preparation and characterization of chitosan–poly(vinyl alcohol)–neomycin sulfate films

The aim of our study was obtaining chitosan–poly(vinyl alcohol)–neomycin sulfate films (Cs–PVA–Ne) by using solvent casting technique and the characterization of the products. The films were analyzed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, thermogravimetry (TG and DTG), differential scanning calorimetry (DSC), contact angle (CA) measurements, mechanical, and antibacterial activity tests. FTIR and DSC analysis demonstrated that interaction between Cs, PVA, and Ne took place. Static water CA measurements showed an improvement in the hydrophilicity of the Cs–PVA–Ne films. Also, the drug-loaded films proved to have fairly good mechanical strength and significant effects against Staphylococcus aureus and Escherichia coli. The unloaded films show minimum bacterial inhibition (~ 10.00 mm) compared to drug-loaded films (~ 30.00 mm). The bacterial inhibition was higher in all the cases of S. aureus than E. coli. Furthermore, PVA was found to improve the films properties. Due to their physical–chemical and mechanical features and the excellent antibacterial properties, the obtained Cs–PVA–Ne films are suitable for their use as wound-dressing materials.

Modelling of measured optical properties of Pd–Au alloy ultrathin film for room temperature hydrogen sensing

A theoretical framework is presented to describe optical properties of palladium gold alloy ultra‐thin film of thickness about 5 nm. Density functional theory is employed to calculate complex dielectric function of hydrogen loaded Pd3Au alloy. Using Bruggeman's effective medium theory, the effective dielectric function of hydrogenated alloy is calculated in case of non‐uniform diffusion of hydrogen starting from very low concentration. Reflectance of deposited film on silica substrate is calculated using transfer matrix method and results are compared with the measured reflectance of sputter deposited thin film of alloy on identical substrate. The change of reflectance with hydrogen concentration is also calculated and verified experimentally. In both the cases, hydrogen loaded films show low reflectance due to reduction of the available electronic states near Fermi level compared to unloaded films. From TEM images and Grazing Incidence X‐ray diffraction analyses, crystal structure of the deposited alloy film is predicted. Using this alloy a four‐layered plasmonic waveguide is designed for room temperature hydrogen sensing. Analytical calculations show that absorption loss of fundamental TM mode of the waveguide at 633 nm changes almost linearly with hydrogen concentration variation. The loss will decrease about 5 dB/100% atomic concentration of hydrogen for 10 µm device length.

Drug loading and release behaviors of freestanding polysaccharide composite films

We developed freestanding, water-insoluble thin films made of polyion complexes (PICs) that consist of glycosaminoglycans such as chondroitin sulfate C (CS) and chitosan (CHI) by utilizing hot press techniques. In this study, material loading and release abilities of CS/CHI composite films were spectroscopically examined using small dye molecules; cationic methylene blue (MB) and anionic carboxyfluorescein (CF) were used as model drugs. The dye-loading films were prepared using pre- and post-loading methods. Microscopic film morphologies were not affected by the dye loadings. The mechanical strengths of the dye-loaded CS/CHI films were almost identical to those of the unloaded films. The dye release behaviors of the films in various aqueous solutions were examined, and the results demonstrated that the CS/CHI films exhibited media-responsive dye release abilities. The experimental results obtained under different conditions were compared and discussed based on the chemical structures of the polysaccharides used to generate the film components and the dye molecules. The present results demonstrate that these polysaccharide composite films are promising materials for use in applications that require sustained drug release under physiological conditions. Drug loading and release abilities of freestanding films made of polyion complexes of chondroitin sulfate C and chitosan were examined using dye molecules such as methylene blue and carboxyfluorescein. The dye-loading films were prepared using pre- and post-loading methods. Microscopic film morphologies were not affected by the dye loadings. The mechanical strengths of the dye-loaded films were almost identical to those of the unloaded films. The dye release behaviors of the films in various aqueous solutions were examined, and the results demonstrated that the films exhibited media-responsive dye release abilities.

Activity of Chlorhexidine Gluconate Loaded at Varying Polyelectrolyte Multilayers against Aggregatibacter Actinomycetemcomitans

Chlorhexidine gluconate (CHX) has a bactericidal effect to Aggregatibacter actinomycetemcomitans (Aa) which causes periodontal disease. Therefore the controlled loading and release of CHX from multilayer thin film is beneficial for the local treatment of periodontitis. This study used ten bilayers of PDADMAC/PSSMA and PDADMAC/AL and loaded CHX into each film. Both un-loaded and loaded thin films were analysed using UV-Vis spectroscopy and AFM. The loaded film was thicker and rougher than the un-loaded film for both PDADMAC/PSSMA and PDADMAC/AL film. The loaded films were released in H2O2 for 24 h, and UV-Vis spectroscopy was measured and compared with the standard calibration curve of CHX. Results indicated that PDADMAC/PSSMA released 0.00052 M and PDADMAC/AL released 0.00071 M respectively. Both the loaded films were tested for toxicity to Aa. Neither film killed all colonies of Aa, however they reduced colony growth by 99% compared to the blank condition.

Aspirin-loaded P(3HO)/P(3HB) blend films: potential materials for biodegradable drug-eluting stents

Poly(3-hydroxyoctanoate)/poly(3-hydroxybutyrate), P(3HO)/P(3HB), blend films loaded with aspirin were prepared, and the influence of aspirin loading on the surface properties, mechanical, thermal and degradation properties were investigated. Scanning electron microscopy images revealed that the addition of aspirin introduced a new topography on the surface of the blend films. Aspirin contributed to the increase in the hydrophilic nature of the blend films compared with the unloaded blend films. This was complemented by a considerable increase in the total protein adsorption in the aspirin-loaded blend films. The percentage cell viability was higher in the aspirin-loaded blend films compared with the unloaded blend films. There was a decrease in the tensile strength and the Young’s modulus with the addition of the aspirin. However, the percentage elongation at break, a measure of elasticity, was higher in the aspirin-loaded films, indicating an increase in their flexibility compared with the unloaded blend films. There was a decrease in the melting temperature (Tm), glass transition temperature (Tg) and the crystallization temperature (Tc) due to the decrease in the crystallinity of the aspirin-loaded blend films in comparison with the unloaded blend films. Finally, controlled release of aspirin was observed without any burst release, and 96·6% release was achieved within 25 d, ideal for the development of biodegradable drug-eluting stents.

Flame‐Made Pt‐Loaded TiO2 Thin Films and Their Application as H2 Gas Sensors

The hydrogen gas sensors were developed successfully using flame‐made platinum‐loaded titanium dioxide (Pt‐loaded TiO2) nanoparticles as the sensing materials. Pt‐loaded TiO2 thin films were prepared by spin‐coating technique onto Al2O3 substrates interdigitated with Au electrodes. Structural and gas‐sensing characteristics were examined by using scanning electron microscopy (SEM) and showed surface morphology of the deposited film. X‐ray diffraction (XRD) patterns can be confirmed to be the anatase and rutile phases of TiO2. High‐resolution transmission electron microscopy (HRTEM) showed that Pt nanoparticles deposited on larger TiO2 nanoparticles. TiO2 films loaded with Pt nanoparticles were used as conductometric sensors for the detection of H2. The gas sensing of H2 was studied at the operating temperatures of 300, 350, and 400°C in dry air. It was found that 2.00 mol% Pt‐loaded TiO2 sensing films showed higher response towards H2 gas than the unloaded film. In addition, the responses of Pt‐loaded TiO2 films at all operating temperatures were higher than that of unloaded TiO2 film. The response increased and the response time decreased with increasing of H2 concentrations.

Effect of incorporation of graphene oxide and graphene nanoplatelets on mechanical and gas permeability properties of poly(lactic acid) films

AbstractNanocomposite thin films of poly(lactic acid) (PLA) were produced incorporating small amounts (0.2 to 1 wt%) of graphene oxide (GO) and graphene nanoplatelets (GNP). The films were prepared by solvent‐casting. Mechanical properties were evaluated for plasticized (by residual solvent) and unplasticized films. Plasticized nanocomposite films presented yield strength and Young's modulus about 100% higher than those of pristine PLA. For unplasticized films improvements in tensile strength and Young's modulus were about 15 and 85%, respectively. For both film types, a maximum in mechanical performance was identified for about 0.4 wt% loadings of the two filler materials tested. Permeabilities towards oxygen and nitrogen decreased, respectively, three‐ and fourfold in films loaded with both GO or GNP. The glass transition temperature showed maximum increases, in relation to unloaded PLA films, of 5 °C for 0.4 wt% GO and 7 °C for 0.4 wt% GNP, coinciding with the observed maxima in mechanical properties. Copyright © 2012 Society of Chemical Industry

Pt/WO3 thin films prepared by photochemical metal–organic deposition (PMOD) and its evaluation as carbon monoxide sensor

Pure and 10% Pt-loaded tungsten oxide thin films have been successfully prepared by direct UV irradiation of bis(β-diketonate)dioxotungsten(VI) and Pt(II) precursor complexes spin-coated on Si(100) substrates. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) techniques were used to analyze the crystal structure and chemical composition of the films before and after heat treatment at 500°C. The results of XRD and AFM analysis showed that the as-photodeposited films are amorphous and have a rougher surface than thermally treated films. Post-annealing of the films in air at 500°C transforms the oxides to a monoclinic WO3 phase. Gas sensing tests reveal that annealed 10% Pt/WO3 films exhibit a better response than unloaded WO3 films towards 20ppm carbon monoxide at an operating temperature of 350°C. The sensors also posses fast response and recovery characteristics.