Thin-film Techniques Research Articles

In situ measurement of an emerging persistent, mobile and toxic (PMT) substance - Melamine and related triazines in waters by diffusive gradient in thin-films

Melamine has received increasing public attention as a persistent, mobile and toxic (PMT) substance. To better assess environmental exposure and risks of melamine and related triazines (cyromazine, ammeline, and atrazine), a new passive sampling method based on the diffusive gradients in thin films (DGT) technique has been developed and validated in this study. The studied triazines were adsorbed quickly and strongly by the selected mixed cation exchange (MCX) binding gels. This MCX-DGT can linearly accumulate these chemicals over at least 5 days, with neither significant individual influence from pH (6–8), ionic strength (0.01–0.5 M) or dissolved organic matter (0–10 M), or interaction effects. Field applications in Southern China showed that DGT performed well in both sewage treatment plant (STP) and river samples. Melamine was found to be the dominant triazine with the concentrations at μg·L−1 in the STP and receiving river. Surprisingly, much higher concentration of melanine was found in the STP effluent than influent, and appeared to be some of the highest concentrations reported in STPs worldwide to date. Comparable melamine and atrazine concentraions in the STP effluent and receiving river suggested other sources to the river. The MCX-DGT sampler developed here was demonstrated to be reliable and robust for measuring the triazines in waters, and is promising as an in situ tool in understanding the occurrence, sources, and fate of the emerging PMT substances in aquatic environment.

Evaluation of mercury bioavailability and phytoaccumulation by means of a DGT technique and of submerged aquatic plants in an aquatic ecosystem situated in the vicinity of a cinnabar mine

The ability of submerged aquatic plants (Elodea canadensis, Myriophyllum spicatum, Ceratophyllum demersum) and a natant plant (Eichhornia crassipes) to bioaccumulate mercury was evaluated in a laboratory experiment as well as in a real aquatic ecosystem situated in the vicinity of a cinnabar mine. Moreover, the ability of the diffusive gradients in the thin films technique (DGT) to predict mercury bioavailability for selected aquatic plants was tested. The submerged plants had sufficient bioaccumulation capacity for long-term phytoaccumulation of mercury in a real aquatic ecosystem. The determined bioaccumulation factor was greater than 1000. On average, the submerged plant leaves accumulated 13 times more mercury than the leaves of the natant aquatic plants. Chlorides at concentrations up to 200 mg/L had no statistically significant effect on mercury accumulation, nevertheless, the presence of humic acid in the water environment resulted in its significant (p < 0.002) decrease. A strong positive correlation (r > 0.66) was determined between mercury concentration in the input parts (leaves and/or roots) of the aquatic plants and the flow of mercury into DGT units.

Sampling of Ammonium Ion in High Salinity Waters Using Diffusive Gradients in Thin Films Technique

Sampling of Ammonium Ion in High Salinity Waters Using Diffusive Gradients in Thin Films Technique

The Tragedy of Alzheimer's Disease: Towards Better Management via Resveratrol-Loaded Oral Bilosomes.

Alzheimer’s disease (AD) is a neurodegenerative disease where oxidative stress plays a major role as a key pathologic factor. The study aims to develop resveratrol (RES)-loaded bilosomes for oral use, aiming to enhance RES bioavailability. RES-loaded bilosomes were prepared using the thin-film hydration technique. The effect of different formulation variables viz. the number of extrusion cycles, drug concentration and the effect of pH of the medium and cholesterol addition on the physicochemical properties of the prepared bilosomes was investigated. Results revealed the successful entrapment of RES into bilosomes. An optimized formula was selected, showing the lowest particle size (189 ± 2.14), acceptable PDI (0.116) and entrapment efficiency (76.2 ± 1.36). In vivo studies on a streptozotocin-induced animal model of AD showed the preeminence of bilosomes over traditional drug suspension to enhance mice memory via Y-maze and Morris water maze tests. Moreover, mice treated with the optimized formula exhibited decreased COX2, IL-6, amyloid-beta peptide and Tau protein levels compared to the drug suspension. Immuno-histochemical analysis revealed a significant decrease of glial fibrillary acidic protein values and microglial cell count in mice treated with bilosomes. Finally, it could be advocated that RES-loaded bilosomes could be a promising drug delivery system to control AD.

Combining Multiple High-Resolution In Situ Techniques to Understand Phosphorous Availability Around Rice Roots.

Resolving chemical/biological drivers of P behavior around lowland/flooded rice roots remains a challenge because of the heterogeneity of the plant-soil interactions, compounded by sampling and analytical constraints. High-spatial-resolution (sub-mm) visualization enables these processes to be isolated, characterized, and deciphered. Here, three advanced soil imaging systems, diffusive gradients in thin-film technique coupled with laser ablation-ICPMS (DGT-LA-ICPMS), O2 planar optode, and soil zymography, were integrated. This trio of approaches was then applied to a rice life cycle study to quantify solute-P supply, through two dimensions, in situ, and low-disturbance high-resolution (HR) chemical imaging. This allowed mechanisms of P release to be delineated by O2, Fe, and phosphatase activity mapping at the same scale. HR-DGT revealed P depletion around both living and dead rice roots but with highly spatially variable Fe/P ratios (∼0.2-12.0) which aligned with changing redox conditions and root activities. Partnering of HR-DGT and soil zymography revealed concurrent P depletion and phosphatase hotspots in the rhizosphere and detritusphere zones (Mantel: 0.610-0.810, p < 0.01). This close affinity between these responses (Pearson correlation: -0.265 to -0.660, p < 0.01) cross-validates the measurements and reaffirms that P depletion stimulates phosphatase activity and Porg mineralization. The μ-scale biogeochemical landscape of rice rhizospheres and detritusphere, as documented here, needs greater consideration when implementing interventions to improve sustainable P nutrition.

Tenoxicam-loaded polymeric micelles material: Formulation, optimization, and evaluation

The objective of the current study was to encapsulate Tenoxicam a poorly soluble drug within self-assembled polymeric micelles created from amphiphilic block copolymer poloxamer 407 to enhance its solubility and thus increasing oral bioavailability. Thin-film hydration technique was adapted in preparation of Tenoxicam loaded polymeric micelles based on different ratios of copolymer poloxamer 407 (ranging from 1:5 up to 1:90), selection of the best micellar formula was based on the values of entrapment efficiency (EE%), particle size (PS), polydispersity index (PDI), and rate of in vitro drug release, then lyophilization was done for selected formula. Prepared micellar solutions (PM1-PM10) were characterized and the best formula PM6 was chosen according to good EE% (84.05%), smaller particle size (33.07 ± 2.23 nm), lower PDI value (0.155), and higher in vitro drug release (81.43% ± 0.048), which further lyophilized and subjected for powder characterization. Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) indicated that TNX was encapsulated in polymeric micelle core, due to the disappearance of a characteristic peak of TNX. Saturated solubility of PM6 lyophilized powder showed an increase in aqueous solubility (122 times) compared with pure drug, while transmission electron microscopy (TEM) showed the polymeric micelles in images with a spherical structure, smooth surface, uniform particle size, and homogeneous distribution in an aqueous medium. It was concluded that the prepared amphiphilic copolymer micelles loaded with TNX exhibited significant improvement in drug solubility and consequently may enhance oral bioavailability and suggested to be used to prepare solid oral dosage form as an alternative to the marketed one with lower dose size and reduce drug side effects.

Niosomal Encapsulation of Curcumin: Formulation and Characterization

Aim: Because of its many actions, curcumin, a plant-derived polyphenolic substance found naturally in turmeric (Curcuma longa), has been the focus of a significant investigation. The utilization of safe, useful, and highly functional chemicals obtained from natural sources in human nutrition/prevention/therapy needs some modifications to achieve multifunctionality, enhance the bioavailability, and delivery methods, all to enhance their efficacy. Curcumin's limited water solubility, fast metabolism and removal from the body, and hence low bioavailability, are significant obstacles to its use. To address these issues, a variety of new drug delivery systems with multiple routes of administration have evolved. Encapsulating the medication in vesicular structures is one such technique that, if successful in enabling selective absorption, can be predicted to extend the drug's life in systemic circulation and reduce toxicity. As a result, several vesicular drug delivery methods, including liposomes, niosomes, transfersomes, and pharmacosomes, have been developed. Since then, developments in vesicular drug delivery have resulted in the creation of systems that enable drug targeting as well as the prolonged or controlled release of traditional medications. The present study aimed to develop and characterize curcumin-loaded niosomes.&#x0D; Design of Study: In present study 32 factorial method was used to formulate different formulations of niosomes containing curcumin.&#x0D; Place and Duration of Study: Department of Pharmacy, IFTM University Moradabad, From December to May 2021.&#x0D; Methodology: Various niosomal formulations of curcumin were developed by using surfactant and cholesterol by thin-film hydration technique. Total 9 formulations were developed and characterized (32 factorial designs).&#x0D; Results: Formulation N7 was considered as an optimized formulation since formulation F7 has maximum drug entrapment and a prolonged drug release rate. The present study suggests that the concentration of surfactant and cholesterol affects % drug loading efficiency of niosomes. The percentage entrapment efficiency of niosomes increases on the increasing concentration of surfactant (Span 60) and cholesterol but above a certain concentration of cholesterol further increment in cholesterol concentration reduces drug entrapment efficiency of niosomes.

TOPICAL DELIVERY OF QUERCETIN LOADED TRANSFERSOMES FOR WOUND TREATMENT: IN VITRO AND IN VIVO EVALUATION

Objective: To design topical Quercetin (Qc)-loaded transfersomes (TFs) for wound treatment. Methods: Qc-loaded TFs were prepared by thin-film hydration technique using 2241full factorial design and the optimum formula was selected. In vivo skin, deposition and cutaneous wound induction studies were performed for four groups of male wistar rats. At the end of the experiment, biochemical parameters were measured in the healed tissues (total proteins (TP), total antioxidant capacity (TAC), glutathione reductase (GSH), nitric oxide (NO), and malonaldehyde (MDA). Two in vivo histopathological experiments using male wistar rats were performed; the first study was done for the healed tissues of the above experiment and the second was to confirm the safety of formulations. Results: Qc optimum TFs (F6) showed EE% of 91.1%, PS of 695.35 nm, PDI of 0.592, and ZP of-11.1 mV, and spherical shape. In vivo skin deposition study showed that drug percentage retained in the skin from Qc optimum TFs was significantly higher than that from Qc suspension and Qc liposomes (p&lt;0.05). There was no significant difference in the values of TP, TAC and MDA between the treated groups (p&gt;0.05). GSH in TFs treated groups was significantly higher than the other groups (p&lt;0.05) while NO in TFs treated groups was significantly lower than the other treated groups (p&lt;0.05). Histopathological experiments showed that wounds treated by TFs healed better than those treated by both liposomes and Qc suspension. Conclusion: Qc-loaded TFs can be used as successful drug-delivery system for wound healing.

DEVELOPMENT OF RIVASTIGMINE LOADED SELF ASSEMBLED NANOSTRUCTURES OF NONIONIC SURFACTANTS FOR BRAIN DELIVERY

Objective: Aim of the study is to develop rivastigmine-loaded niosomal in situ gel via the intranasal route to the brain by crossing the Blood-Brain Barrier. For the treatment of Alzheimer’s disease, it provides a speedy onset of action, a faster therapeutic effect, avoidance of the first-pass metabolism, and enhanced bioavailability. Methods: Rivastigmine niosomal in situ nasal gel was developed, refined and tested with the goal of delivering the medicine to the brain via the intranasal route Rivastigmine niosomes were formulated by thin-film hydration technique, optimized using (32) factorial design and characterized for its physicochemical parameters. Rivastigmine-loaded niosomes were further incorporated into Carbopal-934P and HPMC-K4M liquid gelling system to form in situ nasal gel. The resulting solution was evaluated for several parameters including, viscosity at pH 5 and pH 6, gelling capacity and gelling time. Results: Optimized best formulation containing span 60 (A) and cholesterol (B) with (1:0.5) ratio identified from the model developed from Design-Expert®12 software, exhibited Entrapment efficiency (76.5±0.23%), particle size (933.4±0.14 nm), in vitro drug release maximum (68.94±0.26%) at 8th hour and further studied for its characteristics by SEM and TEM showed stable vesicles. Polynomial equations of Y1, Y2, and Y3 were conducted and ANOVA results showed a significant impact (p&lt;0.05) on three levels. In vivo perfusion studies using rat model showed, the niosomes developed has good perfusion compared to pure drug with 27.2% of drug absorption in the brain at the end of 3 h. In vitro permeation of Rivastigmine through the dialysis membrane showed that 60.74% w/w drug permeated after 8 h. The formation of stable vesicles was proved by Zeta potential measurements and SEM analysis. Conclusion: Optimized formulation had greater perfusion and was expected to have a good bioavailability compared to conventional other drug delivery systems.

In situ arsenic speciation at the soil/water interface of saline-alkaline lakes of the Pantanal, Brazil: A DGT-based approach

Arsenic (As) is a naturally occurring element in the Earth's crust, exhibiting toxicity towards a wide range of living organisms. Its properties and environmental dynamics are strongly regulated by its speciation, and the species As(III) and As(V) are the most commonly found in environmental systems. Recently, high concentrations of As were found in saline-alkaline lakes of the Pantanal (Brazil), which is the largest wetland area in the world. Therefore, we evaluated As contamination and its redox speciation (As(III) and As(V)) at the soil/water interface of biogeochemically distinct saline-alkaline lakes of Pantanal wetlands (Brazil). Both conventional sampling and in situ diffusive gradients in thin films (DGT) technique were employed. Zirconium oxide and 3-mercaptopropyl were used as ligand phases in DGT to selectively bind As species. High concentrations of total dissolved As in a shallow water table were found (<2337.5 μg L−1), whereas levels in soils were up to 2.4 μg g−1. Distinct scenarios were observed when comparing speciation analysis through spot sampling and DGT. Considering spot sampling, As(V) was the main species detected, whereas As(III) was only detected in only a few samples (<4.2 μg L−1). Conversely, results obtained by DGT showed that labile As(III) dominated arsenic speciation at the soil/water interface with levels up to 203.0 μg L−1. Coupling DGT data and DGT induced fluxes in sediments and soils model allowed obtaining kinetic data, showing that the soil barely participated in the arsenic dynamics on the shore of the lakes, and that this participation depends on the evapoconcentration process occurring in the region. Therefore, soil acts like a nonreactive matrix depending on the natural concentration process. In addition, our results reinforced the different geochemical characteristics of the studied saline-alkaline lakes and highlights the importance of robust passive sampling techniques in the context of metal/metalloid speciation in environmental analysis.

TPGS-Modified Long-Circulating Liposomes Loading Ziyuglycoside I for Enhanced Therapy of Myelosuppression.

BackgroundZiyuglycoside I (ZgI), an active ingredient isolated from traditional Chinese medicine Sanguisorba officinalis L, has been demonstrated to increase the leucocytes and protect hematopoietic stem cells. However, the poor solubility and a short half-life of ZgI limit its bioavailability and efficacy. The D-α-tocopherol polyethylene glycol 1000 succinate (TPGS) has been widely used to increase the solubility, improve the encapsulation rate, and extend the half-life of drugs.MethodsHere, we formulated the TPGS-modified long-circulating liposomes loading ZgI with a sustained drug release and enhanced therapy for myelosuppression. ZgI-TPGS-liposomes were manufactured using a thin-film hydration technique, followed by characterizations of physicochemical properties, including the particle size, zeta potential, TEM, SEM, FTIR, XRD, stability, drug loading (DL), encapsulation efficiency (EE). The in vitro and in vivo delivery efficiency were further evaluated by cellular uptake, in vitro drug release and in vivo pharmacokinetics. Finally, therapeutic effect on myelosuppression was investigated.ResultsThe ZgI-TPGS-liposomes had an particle size of 97.89 ± 1.42 nm and ZP of −28.65 ± 0.16 mV. It exhibited DL of 9.06 ± 0.76% and EE of 92.34 ± 3.83%, along with excellent storage stability, cellular uptake and sustained drug release to free ZgI and liposomes without TPGS. Additionally, the TPGS modified liposomes significantly enhanced the therapeutic effect of ZgI on CTX induced myelosuppression, which can be confirmed in the apoptosis inhibition and cell viability promotion of CTX injured HSPC-1 cells. Also, the mice in vivo pharmacodynamics demonstrated that TPGS liposomes promoted ZgI increasing the numbers of leucocytes and neutrophils in myelosuppression mice induced by CTX.ConclusionOur research suggest that TPGS-modified long-circulating liposomes loading ziyuglycoside I has potential application in myelosuppression therapy.

Microbial induced carbonate precipitation contributes to the fates of Cd and Se in Cd-contaminated seleniferous soils

Bioremediation based on microbial induced carbonate precipitation (MICP) was conducted in Cd-contaminated seleniferous soils with objective to investigate effects of MICP on the fates of Cd and Se in soils. Results showed that soil indigenous microorganisms could induce MICP process to stabilize Cd and mobilize Se without inputting exogenous urease-producing strain. After remediation, soluble Cd (SOL-Cd) and exchangeable Cd (EXC-Cd) concentrations were decreased respectively by 59.8% and 9.4%, the labile Cd measured by the diffusive gradients in thin-films technique (DGT) was decreased by 14.2%. The MICP stabilized Cd mainly by increasing soil pH and co-precipitating Cd during the formation of calcium carbonate. Compared with chemical extraction method, DGT technique performs better in reflecting Cd bioavailability in soils remediated with MICP since this technique could eliminate the interference of Ca2+. The increase in pH resulted in Se conversion from nonlabile fraction to soluble and exchangeable fractions, thus improving Se bioavailability. And Se in soil solution could adsorb to or co-precipitate with the insoluble calcium carbonate during MICP, which would partly weaken Se bioavailability. Taken together, MICP had positive effects on the migration of Se. In conclusion, MICP could stabilize Cd and improve Se availability simultaneously in Cd-contaminated seleniferous soils.

Geochemical distribution and speciation of Tl and other trace metals in upper Beijiang River in South China: Approach of in-situ DGT monitoring

Mining activities frequently result in severe contamination of river water. This study aimed to better understand the spatial distribution characteristics of Tl and other metals (e.g., Al, Cd, Co, Mn, Ni, Zn, Pb, V, As, Mo, and Sb), and to assess their risks to human health. Surface water samples were collected from the upper Beijiang River (South China) via grab sampling and the diffusive gradients in thin-films (DGT) technique. The concentrations of Tl measured by grab sampling and δ-MnO2-DGT ranged from 0.045 μg L−1 to 0.231 μg L−1 and from 0.056 μg L−1 to 0.131 μg L−1, respectively. Most of the metals monitored were below the threshold levels allowed by the drinking water standard in China, except for As, Sb, and Mn at specific sampling sites. The concentrations of other metals measured by grab sampling were higher than those measured using the DGT technique because of the differences in speciation during these measurements. The hazard quotient (5.43 × 10−4–8.0 × 10−1 for grab sampling and 2.23 × 10−4–2.8 × 10−1 for DGT technique) for the monitored trace metals demonstrated minimal health risk to human beings. The pollution status of these toxic metals in the study area was generally acceptable. As was found to be potentially the most harmful metal in the studied area, with hazard quotients at some sampling sites calculated by grab sampling of >1. It has previously been suggested that As is the most important non-carcinogenic contaminant. The combination of grab sampling and the DGT technique provides a comprehensive understanding of trace metals, especially Tl, in terms of potential bioavailability and ecological assessment.

Synthesis, characterization and chemical sensor properties of a novel Zn(II) phthalocyanine containing 15-membered dioxa-dithia macrocycle moiety

The issue of utilizing organic materials in chemical sensing devices has recently received considerable critical attention. Phthalocyanines (Pcs) and metal phthalocyanines (MPcs) have been identified as promising materials thanks to their outstanding properties reported in this study. A novel zinc(II) phthalocyanine containing four 15-membered dioxa-dithia macrocyclic moieties was synthesized via the reaction of anhydrous Zn(II) acetate and 13,14-dihydro-6H,12H,20H-tribenzo[f,j,n][1,5]dioxa[9,12] dithiacyclopenta-decine-2,3-dicarbonitrile which was prepared from 1,3-di(2-thio-methylphenoxy) propane and 4,5-dichloropthalonitrile. In order to synthesize and characterize this novel compound, elemental analysis, MS, FT-IR, 1H, 13C NMR, and UV–vis spectral techniques were utilized. To create a Quartz Crystal Microbalance (QCM) sensor, zinc(II) phthalocyanine-based macrocyclic molecules were deposited onto a quartz crystal using the Langmuir-Blodgett (LB) thin film technique. The sensing ability of this chemical sensor was examined by recording the interaction between this novel material as a QCM-sensor and selected chemical vapors such as carbon tetrachloride, chloroform, benzene and toluene. The interaction results for this zinc(II) phthalocyanine based macrocyclic material indicated that this material can be used as a QCM chemical sensor element for chloroform sensing devices with a low detection limit, fast response and recovery times, selectivity, and high sensitivity.

Selective Growth and Micropatterning Technique for Oxide Thin Films by Sacrificial a-CaO Layer

Selective growth and micropatterning through a water lift-off (WLO) process utilizing a sacrificial amorphous CaO (a-CaO) layer were demonstrated to fabricate hetero-epitaxial all-oxides film capacitors. Patterned Pb(Zr,Ti)O3 (PZT) and SrRuO3 (SRO) films were grown on (100) SrTiO3 (STO) substrate by pulsed laser deposition, and the subsequent lift-off process for target oxides was carried out using pure water. The results showed that selective growth and micropatterning of an all-oxides capacitor structure could be realized through WLO process using a-CaO as the sacrificial layer. Electron backscattered diffraction results revealed that SRO/PZT/SRO capacitor structures were grown hetero-epitaxially on the STO substrate. Furthermore, the electrical properties of patterned SRO/PZT/SRO film capacitors could be improved by suppressing the height of overgrown parts of the SRO bottom electrodes with a thick a-CaO sacrificial layer.

Predictive model for cadmium uptake by maize and rice grains on the basis of bioconcentration factor and the diffusive gradients in thin-films technique

It is possible for heavy metals in soils to be adsorbed by crop roots and then accumulated in crops, which eventually causes great health risk when the crops are ingested by humans. Thus, it is valuable to understand the enrichment model of heavy metals in crops. Diffusive gradients in thin-films (DGT) technique, as an in-situ passive sampling method, can be used to evaluate the bioavailable heavy metals contents in soils. In this study, data of the bioavailable cadmium (Cd) in soils determined by DGT and Cd contents uptake in rice and maize grains in Tianjin, Zhejiang and Guangxi provinces of China were collected from previous references in Web of Science. By comparing bioconcentration factors, it was found that the heavy metal concentrations accumulated in rice and maize followed a general order roots > stems or leaves > grains. An accurate and robust model for the prediction of Cd content in maize and rice grains was established based on bioconcentration factor (BCF) and the bioavailable Cd content determined by DGT method, with R2 0.986 and root mean square error (RMSE) 0.128. This result suggests that the DGT method can be good tool for predicting heavy metals uptake in crops.

Correlating surface stoichiometry and termination in SrTiO3 films grown by hybrid molecular beam epitaxy

Hybrid oxide molecular beam epitaxy (hMBE), a thin-film deposition technique in which transition metal cations are delivered using a metal-organic precursor, has emerged as the state-of-the-art approach to the synthesis of electronic-grade complex oxide films with a stoichiometric growth window. However, numerous questions remain regarding the chemical mechanisms of the growth process and the surface properties of the resulting films. To examine these properties, thin film SrTiO3 (STO) was prepared by hMBE using a titanium tetraisopropoxide (TTIP) precursor for Ti delivery and an elemental Sr source on annealed STO and Nb-doped STO substrates with varying TTIP:Sr flux ratios to examine the conditions for the reported stoichiometric growth window. The films were transferred in vacuo to an x-ray photoelectron spectroscopy system to study the surface elemental composition. Samples were examined using x-ray diffraction to compare our surface sensitive results with previously reported measurements of the bulk of the films in the literature. Ex situ studies by atomic force microscopy, scanning tunneling microscopy, and low-energy electron microscopy confirmed the presence of surface reconstructions and an Ehrlich–Schwoebel barrier consistent with A-site SrO termination. We find that a surface exhibiting a mixture of SrO and TiO2 termination or a full SrO termination is necessary to obtain stoichiometric adsorption-controlled growth. These results indicate that surface Sr is necessary to maintain the chemical equilibrium for stoichiometric growth during the hMBE process, which is important for the design of future interfacial systems using this technique.

Green CVD—Toward a sustainable philosophy for thin film deposition by chemical vapor deposition

Thin films of materials are critical components for most areas of sustainable technologies, making thin film techniques, such as chemical vapor deposition (CVD), instrumental for a sustainable future. It is, therefore, of great importance to critically consider the sustainability aspects of CVD processes themselves used to make thin films for sustainable technologies. Here, we point to several common practices in CVD that are not sustainable. From these, we offer a perspective on several principles for a sustainable, “Green CVD” philosophy, which we hope will spur research on how to make CVD more sustainable without affecting the properties of the deposited film. We hope that these principles can be developed by the research community over time and be used to establish research on how to make CVD more sustainable and that a Green CVD philosophy can develop new research directions for both precursor and reactor design to reduce the precursor and energy consumption in CVD processes.

Effect of the deposition method and ageing in atmosphere on the optical properties of tetraphenylporphyrins (TPPs) films

In this work thin films of 5,10,15,20-tetraphenylporphyrin (H2TPP) and 5,10,15,20-tetrakis(4-methoxyphenyl)porpyhrin (H2TMPP)) were prepared by organic molecular beam deposition (OMBD). In addition, spin coating was applied as an alternative preparation technique for thin films of H2TPP to investigate the influence of the deposition method on the optical properties.The preservation of the molecular structure was proven by comparative Raman spectroscopy studies between films and powder. Modelling of the spectroscopic ellipsometry data yields a uniaxial anisotropy of the optical constants for the films of both molecules deposited by OMBD, which was used to determine the relative orientation of the molecules with respect to the substrate. The effect of the storage in air on the optical properties of the OMBD films was investigated using the example of H2TMPP. The molecular order in the films was found to decrease while the film roughness increased compared to samples stored in nitrogen.

ORMULATION, CHARACTERIZATION AND EVALUATION OF LIPOSOMAL HYDROGEL FOR THE TREATMENT OF ANTIBIOTIC RESISTANT PROPIONIBACTERIUM ACNE

This work aimed to prepare and evaluate the topical liposomal hydrogel to treat antibiotic-resistant propionic bacterium acne. Nadifloxacin-loaded liposomes were prepared by thin-film hydration technique. Nadifloxacin, soya lecithin, cholesterol were dissolved in a mixture of chloroform and taken in different levels, and liposomes were prepared. The prepared liposomes were evaluated for in-vitro drug release. Formulation F2 was the highest percentage entrapment of 71±1.50% and released 58.12±1.2% of the drug in 6hrs. Minocycline hydrochloride-based hydrogel was prepared using the methylcellulose gelling agent, and the drug concentration was kept constant at 0.25%. The concentration of propylene glycol and methylparaben was kept constant at 15% and 0.3%. The hydrogel formulation was evaluated for various physicochemical parameters like percentage drug content, spreadability, and drug release. Formulation H9 was the highest drug content, 98.23 ± 0.031%, and the drug released 90.96±2.6% of the drug in 6hr. Out of these formulations, F2 from liposomes and H9 from hydrogel formula was selected to prepare the final liposomal hydrogel formulation. Developed liposomal hydrogel(F2H9) were evaluated like size, drug content and drug entrapment spreadability, homogeneity, washability, pH, etc. In-vitro drug release from liposomal hydrogel in Nadifloxacin release 54.86±3.1% and Minocycline hydrochloride 91.24±1.82% in 6hr. Developed liposomal hydrogel formulation can better treat acne due to high drug retention and permeation in skin layers. KEYWORDS: Acne, antibiotics, liposomes, hydrogel, Nadifloxacin, Minocycline hydrochloride