Use Of Polymeric Films Research Articles

Проблеми використання мікробіологічних систем у процесі ремісії вуглекислого газу із атмосферного повітря

The initiatives of the Kyoto Protocol, the Paris Convention on Climate Change 2015, the X Prize Prize Fund for Revolutionary Innovation and the announcement by Grand Elon Musk of the invention of the best carbon capture technology with a total budget of $ 100 million suggest that air absorption from carbon. In our opinion, the use of biological photosynthetic crops and technological solutions based on them, which will ensure the absorption of carbon dioxide, is a great prospect, as this process has already changed the Earth's atmosphere in the distant past. In addition, the use of plants will not only absorb carbon dioxide from the atmosphere, but also obtain additional raw materials rich in hydrocarbons and lipids, as well as generate oxygen. This technological solution to the problem of the presence of greenhouse gases establishes the feasibility of using the process of growing unicellular microalgae in photoreactor systems. Energy and technical and economic indicators of functioning of carbon dioxide utilization systems on the basis of standard approaches are determined. The need to create a system of automatic analysis of the state of culture based on the use of artificial intelligence and systems of automatic pattern recognition has been identified. The necessity of integration of the heat accumulator into the structure of the photoreactor for smoothing of daily temperature differences (which in turn minimized energy consumption) and systems of additional lighting and mixing is proved. A number of own designs of photoreactors and further ways of their modernization on use of polymeric films for isolation of working space of photoreactors for the purpose of avoidance of infection of culture are offered.

Prevention and Treatment of Fungal Skin Infections Using Cationic Polymeric Films.

Dermatophytosis is a fungal infection of skin, nails and hair. Treatments can be long and infections are often recurrent, and novel treatments are desirable. Here we tested the use of polymeric films that can be sprayed on the skin for the prevention and treatment of dermatophytosis. The two polymers selected were ABIL T Quat 60 and Eudragit E100, which were tested ex vivo using a porcine skin model, and in vitro using microbiological and microscopy techniques. Acceptability of the polymeric films was tested on the skin of healthy volunteers. The results showed that ABIL and Eudragit films prevented and treated fungal skin infections. Whilst polymer films may provide a physical barrier that prevents fungal colonization, it was shown that both polymers are active antifungals ex vivo and in vitro and have intrinsic antifungal activity. For ABIL, we also established that this polymer binds essential nutrients such as metal ions and sugars, thereby restricting the growth of fungi. When applied to healthy subjects’ skin, the polymeric films neither modified the skin color nor increased trans-epidermal water loss, suggesting a low potential for skin irritation, and the approach was generally found to be acceptable for use by the volunteers. In conclusion, we developed a novel strategy for the potential prevention and treatment of dermatophytosis.

Increased Dapivirine Tissue Accumulation through Vaginal Film Codelivery of Dapivirine and Tenofovir

The HIV-1 replication inhibitor dapivirine (DPV) is one of the most promising drug candidates being used in topical microbicide products for prevention of HIV-1 sexual transmission. To be able to block HIV-1 replication, DPV must have access to the viral reverse transcriptase enzyme. The window for DPV to access the enzyme happens during the HIV-1 cellular infection cycle. Thus, in order for DPV to exert its anti-HIV activity, it must be present in the mucosal tissue or cells where HIV-1 infection occurs. A dosage form containing DPV must be able to deliver the drug to the tissue site of action. Polymeric films are solid dosage forms that dissolve and release their payload upon contact with fluids. Films have been used as vaginal delivery systems of topical microbicide drug candidates including DPV. For use in topical microbicide products containing DPV, polymeric films must prove their ability to deliver DPV to the target tissue site of action. Ex vivo exposure studies of human ectocervical tissue to DPV film revealed that DPV was released from the film and did diffuse into the tissue in a concentration dependent manner indicating a process of passive diffusion. Analysis of drug distribution in the tissue revealed that DPV accumulated mostly at the basal layer of the epithelium infiltrating the upper part of the stroma. Furthermore, as a combination microbicide product, codelivery of DPV and TFV from a polymeric film resulted in a significant increase in DPV tissue concentration [14.21 (single entity film) and 31.03 μg/g (combination film)], whereas no impact on TFV tissue concentration was found. In vitro release experiments showed that this observation was due to a more rapid DPV release from the combination film as compared to the single entity film. In conclusion, the findings of this study confirm the ability of polymeric films to deliver DPV and TFV to human ectocervical tissue and show that codelivery of the two agents has a significant impact on DPV tissue accumulation. These findings support the use of polymeric films for topical microbicide products containing DPV and/or TFV.

Loss of AM additives from antimicrobial films during storage

Films based on linear low-density polyethylene (LLDPE) and low-density polyethylene (LDPE) containing linalool or methylchavicol were prepared by extrusion film blowing. Film rolls of LLDPE containing linalool or methylchavicol were stored at ambient temperature for 1 year. Samples of these films were then evaluated for the amount of linalool or methylchavicol retained and for their antimicrobial (AM) activity by the agar disc diffusion assay. In addition, film rolls of LDPE-EVA (LDPE-ethylene vinyl acetate) containing linalool or methylchavicol were stored at 25 and 35 °C. Samples of these films were periodically collected to quantify the amount of linalool or methylchavicol retained as a function of time. For the AM LLDPE films, a decrease in additive retention was observed but there was no statistically significant difference in their AM activity against Escherichia coli at the beginning and after 1 year of storage. For the AM LDPE-EVA films, the amount of additive in the film decreased with time and the additive retention in all films tended to deviate from the theoretical first-order decay. These findings suggest that an amount of linalool or methylchavicol that is sufficient to maintain AM activity remained in the polymeric matrix after the storage period. This study confirms the potential use of polymeric films containing basil constituents as AM films for enhancing quality and safety as well as the extension of the shelf life of foods.

Efficacy of polyethylene-based antimicrobial films containing principal constituents of basil

The feasibility of low-density polyethylene (LDPE)-based films containing linalool or methylchavicol as antimicrobial (AM) packages to retard microbial growth on food surfaces was investigated. The AM LDPE-based films were tested for inhibition against selected microorganisms. Both compounds retained their AM activity, after an extrusion film-blowing process, against Escherichia coli in solid medium. Cheddar cheese was wrapped with the AM films and the packaged cheese samples were stored at 4 °C. The changes in the mesophilic aerobic bacteria and coliform, as well as yeast and mould counts were monitored. In addition, cheese samples inoculated with E. coli or Listeria innocua were wrapped with the AM films, stored at refrigerated (4 °C) or at abuse (12 °C) temperatures and the count of these microorganisms was monitored as a function of time. The results showed an inhibitory effect of these AM films against microbial growth in naturally contaminated cheese and in inoculated samples. The effect on suppression of E. coli and L. innocua growth was more pronounced at the abuse temperature. Methylchavicol-LDPE-based film exhibited a higher efficacy of inhibition than that of linalool-LDPE-based film. In addition, a sensory evaluation was performed with regards to possible taint in the flavour of the cheese. Taint in flavour as affected by linalool or methylchavicol was not significantly detectable by the panelists at the end of the storage period of 6 weeks. This study shows the potential use of polymeric films containing the principal constituents of basil as the AM components for enhancing quality and safety of cheeses.

Spectroscopic and optical characterization of porphyrin chromophores incorporated into ultrathin polyimide films

Polyamic acid (PAA) containing free-base porphyrin and zinc(II) porphyrin chromophores was synthesized by copolymerization of diphenylether-type tetracarboxylic dianhydride and diamines. The monolayer of the alkylamine salts of PAA (PAASs) at the air/water interface was deposited on solid substrates by the Langmuir–Blodgett (LB) technique. The PAAS LB films thus obtained were converted to polyimide (PI) LB films by chemical treatment. The fluorescence of porphyrin moieties in the PI LB film was observed, because of the weak electron-accepting properties of the diphenylether unit. Therefore, the photophysically important processes, such as photoinduced electron transfer, excitation energy transfer, and excitation energy migration could be investigated in relation to the layered nanostructures of the ultrathin PI films. The fluorescence spectrum suggested that the aggregation of porphyrin moieties in the PI LB films was effectively prevented by the use of polymeric films. The surface plasmon (SP) measurement showed that the thickness of the monolayers was 0.9–1.0 nm for PAAS films and 0.32–0.40 nm on average for PI LB films. The absorption dichroism of the Soret band of porphyrin indicated that porphyrin moieties in the PAAS and PI LB films are oriented in parallel with the substrate. These results showed that the orientation and the spatial distribution of porphyrin units can be efficiently regulated in the PI LB films in a nanometer dimension.

Shelf life extension of almond paste pastries

Almond paste products have a brief shelf life due to both lipid oxidation and hardening. Since oxidation and hardening are respectively induced by headspace oxygen and moisture migration, the use of polymeric films having high barrier properties to low molecular weight compounds in combination with a low oxygen concentration in the package headspace is expected to extend almond paste shelf life. During this research, two flexible films, having a nylon or an ethylene–vinyl alcohol copolymer layer as a barrier to low molecular weight compounds, were tested. Products were packed alternatively under nitrogen or in presence of oxygen scavengers. A part of them was kept as controls and packed under air. Samples were stored at 37 °C and regularly analysed. Results showed that the loss of moisture, and the consequent hardening of samples, is the main phenomenon affecting quality and shelf life of almond paste.

IN-VITRO ANTIMICROBIAL ACTIVITY OF CHLORHEXIDINE POLYMERIC FILMS

The minimum inhibitory concentration (MIC) of chlorhexidine for Staphylococcus aureus, Bacillus subtilus, Escherichia Coli and Candida albicans was studied. Chlorhexidine polymeric films composed of ethylcellulose (EC) and hydroxypropyl methyl- cellulose (HPMC) in a ratio of 8:2 were prepared. The inhibition zone diameters of chlorhexidine polymeric film were compared with that of chlorhexidine gauze dressing. Also, the inhibition zone sizes of different concentrations of chlorhexidine (0.5, 1 and 5%) in films plasticized with 20% propylene glycol, in presence of 10% Tween 80 as enhancer, or plasticized with 20% polyethylene glycol 400 were evaluated. Results indicated that the MIC of chlorhexidine was ranged from 1 to 1.8 ug/ml. Also the inhibition zone diameters of the selected polymeric film was higher than that of gauze dressing. There were correlation between drug concentrations and inhibition zone sizes. Also polymeric film containing 20% propylene glycol and 10% Tween 80 showed relatively higher response than polymeric film containing 20% ployethylene glycol 400. It can be concluded that the tested microorganisms were susceptible to chlorhexidine and the use of polymeric films as drug delivery system enhanced chlorhexidine in-vitro antimicrobial activity. Accordingly, it was recommended to use chlorhexidine polymeric films for topical antisepsis.

Use of polymer films in amperometric biosensors

AbstractDifferent types of polymeric films implemented in various capacities in amperometric biosensor design are reviewed. Conducting and nonconductinzg polymer films and composite films are considered. Methods of film fabrication such as solvent casting, electropolymerization, and adsorption are presented. Film function, including prevention of interference and fouling problems, immobilization of the enzyme or active biocomponent, extension of linear range, or to address biocompatibility problems are described. The use of polymeric films as a medium to incorporate mediators, while an important function, is too vast for review here. The applications of polymer film‐modified biosensors for selected analytical determinations are also presented. This review focuses upon the use of polymer films in amperometric biosensors and emphasizes innovative biosensor designs and unique applications, and omits traditional free‐standing films unless they are coupled with new types of polymer films or used innovatively.

Membrane-supported rhodium hydroformylation catalysts

Films prepared from THF solutions containing cellulose acetate, [HRh(CO)(PPh 3) 3] and PPh 3 were tested for catalytic activity in the vapor phase hydroformylation of ethylene and propylene: RCH=CH 2+CO+H 2→RCH 2CH 2CHO. The reaction proceeded smoothly at 800 ton- and 80 °C. Turnover rates were about 25 mol propanai per mol Rh per h. No loss of PPh 3 or Rh from the film was observed even after long periods of reaction. The excess PPh 3 seemed to stabilize the catalytic activity of the film but concentrations beyond 10 molar produced no further improvement. The turnover rate with the films was equal to or even slightly higher than that obtained under similar conditions using a homogeneous solution of [HRh(CO)PPh 3] in 2-methylmaphthalene solvent. The turnover rate for propylene to C-4 aldehydes was about an order of magnitude smaller than that for ethylene to propanal. Films prepared from poly(phenylsulfone) were also active catalysts. The ratio of n/iso C-4 aldehydes with this support was about 20. In the absence of oxygen the catalyst system retained its activity for more than 13 days but no attempt was made to test for longer lifetimes. The use of polymeric films or membranes as a support for the rhodium catalysis of the hydroformylation reaction thus appears to hold considerable promise.

Chemistry of polymer molecules for ultrathin films

Because of their versatility, their unique properties and their ease of processing and fabrication, polymeric materials have found applications as plastics, elastomers, fibres, protective coatings and adhesives. In parallel with these well-established applications, new needs have emerged from technologies which are still in their infancy, such as microelectronics, optoelectronics and biotechnology. Some of these high technologies require the use of polymeric films with a thickness of less than 2 microm (integrated circuits, non-linear optics etc.). Progress in organic and polymer chemistry has made possible the synthetic modification of polymer structure and the improvement in polymer properties to fit the needs. For example, progress in polymeric resist materials for microlithography has partly allowed the advent of very-large-scale integrated circuits. Use of conveniently oriented ultrathin films of liquid crystal polymers for non-linear optics seems very attractive since the films can be produced much faster than crystals can and at greatly reduced cost. They can be applied over very large areas relative to the crystal size and on various substrates. This paper is a review of the main families of polymers for making resists useful in microlithography and of polymers exhibiting liquid crystal properties. Other polymers giving rise to ultrathin film systems, such as conductive polymers, will be discussed elsewhere during this workshop.