Propylene Glycol Gel Research Articles

Structural Characterization and Optical Properties of BiFeO3 Nanoparticles Synthesized by Propylene Glycol-Gel Route

This work focuses on the synthesis of phase-pure rhombohedral (R3c) nanocrystalline BiFeO3. The BiFeO3 nanoparticles were synthesized using the sol-gel method with propylene glycol as the complexing agent. The formation mechanism was investigated through thermal analysis and IR spectroscopy. The phase purity, crystal structure and nanocrystalline properties were studied using X-ray diffraction (XRD), Raman spectroscopy and transmission electron microscopy (TEM). The elemental composition and bonding states were analyzed with X-ray photoelectron spectroscopy (XPS). The XRD and Raman spectra confirmed the formation of pure and well-crystallized BiFeO3 nanoparticles at 400 ºC. The optical band gap, determined by UV-visible spectroscopy, was found to be 2.08 eV, indicating that the synthesized BiFeO3 nanoparticles could be an effective photocatalyst in the visible light region.

Wound healing of experimental equine skin wounds and concurrent microbiota in wound dressings following topical propylene glycol gel treatment.

Topical wound treatments rely on carrier formulations with little to no biological impact. The potential for a common vehicle, a propylene glycol (PG) gel, to affect wound healing measures including microbiota is not known. Microbiome characterization, based on next generation sequencing methods is typically performed on tissue or directly obtained wound fluid samples. The utility for primary wound dressings to characterize equine wound microbiota in the context of topical treatments is currently unknown. This investigation reports the topical effect of an 80% PG based gel on wound healing and microbiota in wound dressings. Experiments were performed in six mature horses utilizing a surgical, distal limb wound model, histology of sequential wound biopsies, photographic wound measurements and microbiota profiling via 16s rRNA sequencing of wound dressing samples. Experimental wounds were surveyed for 42 days and either treated (Day 7, 14, 21 and 28; at 0.03 ml/cm2) or unexposed to the PG gel. Wound surface area, relative and absolute microbial abundances, diversity indices and histologic parameters were analyzed in the context of the experimental group (treatment; control) using qualitative or quantitative methods depending on data characteristics. Compared to controls, treatment slowed the wound healing rate (17.17 ± 4.27 vs. 18.56 ± 6.3 mm2/day), delayed the temporal decline of polymorphonucleated cells in wound beds and operational taxonomic units (OTU) in wound dressings and lowered alpha-diversity indices for microbiota in primary wound dressing. Relative abundances of OTUs were in line with those previously reported for equine wounds. Clinical outcomes 42 days post wounding were considered similar irrespective of PG gel exposure. Results highlight the potential for vehicle exposure to alter relevant wound outcome measures, imposing the need for stringent experimental control measures. Primary wound dressings may represent an alternate sample source for characterization of the wound microbiome alleviating the need for additional interventions. Further studies are warranted to contrast the microbiome in wound dressings against that present on wound surfaces to conclude on the validity of this approach.

Evidence of two dimensional dilute antiferromagnet mediated exchange bias field and vertical shift in LaFeO3-NiO nanocomposite

Low dimensional antiferromagnetic systems, such as nanoparticles, are known to exhibit weak ferromagnetic behavior due to the uncompensated surface spins. In this report, we present a detailed magnetic study of LaFeO3/NiO nanocomposite, synthesized by propylene glycol gel method. The X-ray diffraction (XRD) based analyses, in combination with transmission electron microscopy (TEM), confirms 50:50 ratio composite with ~35–40 nm size particles. Owing to the high Néel temperatures (TN) of LaFeO3 and NiO, significant exchange bias (EB) and vertical magnetization shift (VMS) have been observed in the nanocomposite at room temperature. These features are attributed to the exchange interaction at the interface between the core and shell of the nanoparticles that are homogeneously dispersed in the nanocomposite. In our studies, the EB field and the VMS attains a value as high as 2050 Oe & 1.8 × 10-1 emu/g at 5 K and 75 Oe & 1.7 × 10-2 emu/g at 300 K, respectively. The thermoremanent magnetization (TRM) and isothermoremanent magnetization (IRM) analyses are done to identify the two-dimensional (2D) diluted antiferromagnet (DAFF) behavior of the surface shell of nanoparticles. We propose a phenomenological antiferromagnetic-(2D-DAFF)-antiferromagnetic magnetic structure model, to explain all the rich features and the observed magnetic properties of this nanocomposite.

The effect of additives on release and in vitro skin retention of flavonoids from emulsion and gel semisolid formulations.

To assess the effect of two different additives (propylene glycol (PG) and polyethylene glycol 400 (PEG 400)) on release and in vitro skin retention of quercetin and chrysin from semisolid bases (amphiphilic creams and acidic carbomer gels). For obtaining semisolid formulations, flavonoids were pre-dissolved in the liquid (PG or PEG 400) or directly suspended in the semisolid base. Three chrysin formulations ('cream 0', 'PG-cream' and 'PEG 400-cream') and five quercetin formulations ('cream 0', 'PG cream', 'PEG 400 cream', 'gel 0' and 'PG gel') were prepared. The release studies were carried out in Franz diffusion cells by means of a cellulose membrane. The porcine ear skin was used in in vitro skin retention studies. The dissolution was a prerequisite to increase the release rates of tested flavonoids from obtained semisolid formulations. The cumulative amount of chrysin released after 6 h from 'PEG 400 cream' containing partly dissolved form of that flavonoid was higher than that from 'cream 0' or 'PG cream' containing its suspended form. The formulations containing quercetin dissolved in PG ('PG cream', 'PG gel') or PEG 400 ('PEG 400 cream') exhibited higher release rates of that flavonoid than corresponding semisolid suspensions ('cream 0' or 'gel 0'). The effects of both liquid additives (PG and PEG 400) on the cumulative amount of quercetin released after 6 h were comparable. However, there was no correlation between the release rate and the skin retention. The amounts of the flavonoids found in the skin were strongly affected by the type of the used solvent. While PG increased the skin retention of both flavonoids, PEG 400 had no effect on chrysin skin retention and delayed quercetin skin absorption. The proper choice of the solvent added to the semisolid base is crucial for enhanced skin delivery of the tested flavonoids. PG is more efficient absorption promoter than PEG 400 of both chrysin and quercetin.

Structural transformation and enhancement in magnetic properties of single-phase Bi1−xPrxFeO3 nanoparticles

Single-phase Bi1−xPrxFeO3 (x = 0.0, 0.05, and 0.10) nanoparticles have been synthesized by propylene glycol-gel route at a temperature of 400 °C. Rietveld refinement of X-ray diffraction data and Raman spectra reflect a structural phase transition from rhombohedral for x = 0 to triclinic for x = 0.10. Magnetic measurements reveal that Pr-doped BiFeO3 nanoparticles for x = 0.10 have enhanced remnant magnetization about 10 times as compared to pure BiFeO3 nanoparticles. It has been shown by 57Fe Mössbauer spectroscopy that the observed enhancement in magnetic properties of BiFeO3 with Pr doping is mainly due to suppression of modulated spiral spin structure near x = 0.10 and not due to Fe multiple valence, i.e., oxygen deficiency.

Microengineering of Supramolecular Soft Materials by Design of the Crystalline Fiber Networks

Crystalline spherulitic fiber networks are commonly observed in polymeric and supramolecular functional materials. The elasticity of materials with this type of network is low if interactions between the individual spherulites are weak (mutually exclusive). Improving the elasticity of these materials is necessary because of their important applications in many fields. In this work, the engineering of the microstructures and rheological properties of this type of material is carried out. A small molecule organogel formed by the gelation of N-lauroyl-L-glutamic acid di-n-butylamide (GP-1) in propylene glycol (PG) is used as an example. The elasticity of this material is improved by controlling the thermodynamic driving force, the supersaturation of the gelator, and by using a selected copolymer additive to manipulate the primary nucleation of GP-1. Because of the weak interactions between the GP-1 spherulites, with the same fiber mass, the elasticity of GP-1/PG gel is less than half of those of the other two gels formed by GP-1 and 2-hydroxystearlic acid in solvent benzyl benzoate (BB), which are supported by interconnecting spherulitic fiber networks. This work develops a robust approach to the engineering of supramolecular functional materials especially those with mutually exclusive spherulite fiber networks.

Influence of formulation factors on PpIX production and photodynamic action of novel ALA‐loaded microparticles

A novel 5-aminolevulinic acid (ALA)-containing microparticulate system was produced recently, based on incorporation of ALA into particles prepared from a suppository base that maintains drug stability during storage and melts at skin temperature to release its drug payload. The novel particulate system was applied to the skin of living animals, followed by study of protoporphyrin IX (PpIX) production. The effect of formulating the microparticles in different vehicles was investigated and also the phototoxicity of the PpIX produced using a model tumour.Particles formulated in propylene glycol gels (10% w/w ALA loading) generated the highest peak PpIX fluorescence levels in normal mouse skin. Peak PpIX levels induced in skin overlying subcutaneously implanted WiDr tumours were significantly lower than in normal skin for both the 10% w/w ALA microparticles alone and the 10% w/w ALA microparticles in propylene glycol gels during continuous 12 h applications. Tumours not treated with photodynamic therapy continued to grow over the 17 days of the anti-tumour study. However, those treated with 12 h applications of either the 10% w/w ALA microparticles alone or the 10% w/w ALA microparticles in propylene glycol gel followed by a single laser irradiation showed no growth. The gel formulation performed slightly better once again, reducing the tumour growth rate by approximately 105%, compared with the 89% reduction achieved using particles alone. Following the promising results obtained in this study, work is now going on to prepare particle-loaded gels under GMP conditions with the aim of initiating an exploratory clinical trial.

Enhanced anti-tumor activity and alleviated hepatotoxicity of clotrimazole-loaded suppository using poloxamer–propylene glycol gel

To develop a novel clotrimazole-loaded poloxamer-based suppository with enhanced anti-tumor activity and alleviated hepatotoxicity, the melting point of various formulations composed of P 188 and propylene glycol were investigated. The dissolution and anti-tumor activity of clotrimazole delivered by the poloxamer-based suppository was performed. Furthermore, the hepatotoxicity of clotrimazole was carried out after its rectal administration compared to oral administration in mice. The poloxamer mixtures composed of P 188 and propylene glycol were homogeneous phases. P 188 greatly affected the melting point of poloxamer mixtures. In particular, the poloxamer mixture [P 188/propylene glycol (70%/30%)] with the melting point of about 32 °C was a solid form at room temperature and instantly melted at physiological temperature. The ratio of P 188/propylene glycol greatly affected the dissolution rates of clotrimazole from poloxamer-based suppository. Dissolution mechanism analysis showed the dissolution rate of clotrimazole from poloxamer-based suppositories was independent of the time. The clotrimazole-loaded suppository with P 188 and propylene glycol could not irritate or damage the rectal tissues of rats and gave the improved anti-tumor activity in a dose-dependent manner at mouse. Furthermore, its rectal administration decreased the hepatotoxicity compared to oral administration. Thus, the poloxamer-based solid suppository system with clotrimazole/P 188/propylene glycol was an effective rectal dosage form for the treatment of tumors with alleviated adverse effects.

Buccal absorption through golden hamster cheek pouch in vitro and in vivo of 17 β-estradiol from hydrogels containing three types of absorption enhancers

The combined effects of hydrogels and absorption enhancers on the permeability of 17 β-estradiol (E 2) through buccal membrane were investigated by measuring the rate of permeation of E 2 through hamster cheek pouch buccal mucosa in vitro and in vivo. Glycerylmonolaurate (LAU), l-menthol (MEN) and sodium caprate (CAP) were selected as absorption enhancers in hydrogels containing ethanol and propylene glycol (PG). Based on the rate of penetration through the buccal mucosa of E 2 in the PG and ethanol gels containing the enhancers, the permeability of E 2 was observed to be greater in the hydrogel containing ethanol than in that containing PG. CAP increased the permeability of E 2 compared with that of the control in both the PG and ethanol gels. MEN increased the permeability of E 2 in a 40% (w/w) ethanol gel, and LAU was more effective in the ethanol gel than in the PG gel without decreasing the gel strength. Regarding the mechanisms of these absorption enhancers in the ethanol gel, CAP and MEN mainly contributed to the diffusion of E 2 in the mucosa, but LAU increased the solubility of E 2 in the hydrogel. The buccal administration of E 2 in the 40% (w/w) ethanol hydrogels containing 2% (w/w) LAU allowed the maintenance of the plasma level at above 300 ng/ml cm 2 for 7 h after application in hamster. No primary morphological change of buccal membrane was detected using scanning electron microscopy 7 h after application. These findings suggest that the combination of LAU and ethanol is useful and safe in hydrogels containing E 2 for application to the buccal mucosa.

Topical chemotherapy for experimental African trypanosomiasis with cerebral involvement: the use of melarsoprol combined with the 5‐nitroimidazole, megazol

Megazol, one of a number of related 5-nitroimidazoles, can be dissolved in dimethylsulphoxide and the solution can be converted into a gel by the addition of hydroxypropylcellulose which facilitates the ease and accuracy of administration. This megazol gel, when used in combination with melarsoprol (3.6%) in propylene glycol gel, will cure experimental CNS-trypanosomiasis in mice. A single application of 0.1 ml of melarsoprol (3.6%) gel plus 0.1 ml of either 8 or 16 mg/ml megazol gel successfully treated experimental CNS-trypanosomiasis while two consecutive days' treatment with 0.05 ml melarsoprol and 0.1 ml of 16 or 32 mg/ml megazol gels also produced satisfactory cures.

Liposome encapsulation improves efficacy of betamethasone dipropionate in atopic eczema but not in psoriasis vulgaris

The effect of a liposomal preparation of beta-methasone dipropionate (0.039%, BDP) has been compared to that of a commercial propylene glycol-gel containing 0.064% BDP in a double-blind, randomized, paired trial lasting 14 d in 10 patients with atopic eczema and 10 patients with psoriasis vulgaris. In eczema, the liposome preparation tended to reduce erythema and scaling more than the conventional gel, the difference in the latter parameter being significant on Day 7. There was greater improvement of psoriasis on the side treated with the reference gel. Hence, liposome encapsulation of BDP may increase the antiinflammatory action but not the antiproliferative effect. Since inhibition of mitotic activity is linked to the atrophogenicity of topical corticosteroids, the results suggest that liposome encapsulation may improve the benefit-risk ratio in eczema.