Facile methodology of nanoemulsion preparation using oily polymer for the delivery of poorly soluble drugs

Aqueous solubility of an active pharmaceutical ingredient (API) is a determining factor that has a direct impact on formulation strategies and overall bioavailability. Fabrication of nanoemulsions of poorly soluble drugs is one of the widely utilized approaches to overcome this problem. However, thermodynamic instability and tedious manufacturing processes of nanoemulsions limit their clinical translation. Therefore, this study was focused on circumventing the abovementioned hurdles by utilizing the polymer as an oil phase, instead of conventional oils. The nanoemulsion was prepared via a facile low-energy nanoprecipitation method using renewable poly(δ-decalactone) (PDL), as an oil phase and Pluronic F-68 as surfactant. The prepared nanoemulsions were characterized in terms of size, drug encapsulation efficiency, stability, and toxicity. Five different hydrophobic drugs were utilized to evaluate the drug delivery capability of the PDL nanoemulsion. The prepared nanoemulsions with sizes less than 200 nm were capable to enhance the aqueous solubility of the drugs by 3 to 10 times compared with the well-established Pluronic F-68 micelles. No phase separation or significant changes in size and drug content was observed with PDL nanoemulsions after high-speed centrifugation and 3 months of storage at two different temperatures (20 °C and 50 °C). PDL nanoemulsions were found to be non-heamolytic up to concentrations of 1 mg/mL, and the cell cytotoxicity studies on MDA-MB-231 and MEF cells suggest a concentration and time-dependent toxicity, where the PDL polymer itself induced no cytotoxicity. The results from this study clearly indicate that the PDL polymer has a tremendous potential to be utilized as an oil phase to prepare stable nanoemulsions via a facile methodology, ultimately favouring clinical translations.

Graphical abstract

EFFECT OF ENVIRONMENT ON BROMOBUTYL RUBBER–STEEL ADHESION

Optimizing the maintenance cycles of rubber-lined components is of great importance. Especially for the industry sectors operating under demanding conditions, challenges in the lifetime evaluation of rubber linings may cause apparent premature failures. Thus, understanding the effect of environmental factors on the performance and durability of rubber linings, as well as on the weakest links of the structure in certain environments, is essential. The performances of bromobutyl rubber and rubber–steel interfaces after exposure to different environments, namely, high temperature (95 °C), moisture (95% relative humidity and immersion), and sulfuric acid (solution with 75 g/L of acid) were investigated. The weakest link of the rubber–metal structure and, consequently, the location of the fracture were mostly within the adhesive layer or at the primer–metal interface. However, the most degraded component of the adhesive system depends on the aging environments.

Role of Polymers in 3D Printing Technology for Drug Delivery - An Overview

Background:

3D printing (3DP) is an emerging technique for fabrication of a variety of structures and complex geometries using 3D model data. In 1986, Charles Hull introduced stereolithography technique that took advances to beget new methods of 3D printing such as powder bed fusion, fused deposition modeling (FDM), inkjet printing, and contour crafting (CC). Being advantageous in terms of less waste, freedom of design and automation, 3DP has been evolved to minimize incurred cost for bulk production of customized products at the industrial outset. Due to these reasons, 3DP technology has acquired a significant position in pharmaceutical industries. Numerous polymers have been explored for manufacturing of 3DP based drug delivery systems for patient-customized medication with miniaturized dosage forms.

Method:

Published research articles on 3D printed based drug delivery have been thoroughly studied and the polymers used in those studies are summarized in this article.

Results:

We have discussed the polymers utilized to fabricate 3DP systems including their processing considerations, and challenges in fabrication of high throughput 3DP based drug delivery systems.

Conclusion:

Despite several advantages of 3DP in drug delivery, there are still a few issues that need to be addressed such as lower mechanical properties and anisotropic behavior, which are obstacles to scale up the technology. Polymers as a building material certainly plays crucial role in the final property of the dosage form. It is an effort to bring an assemblage of critical aspects for scientists engaged in 3DP technology to create flexible, complex and personalized dosage forms.

Renewable poly(δ-decalactone) based block copolymer micelles as drug delivery vehicle: in vitro and in vivo evaluation

Polymers from natural resources are attracting much attention in various fields including drug delivery as green alternatives to fossil fuel based polymers. In this quest, novel block copolymers based on renewable poly(δ-decalactone) (PDL) were evaluated for their drug delivery capabilities and compared with a fossil fuel based polymer i.e. methoxy-poly(ethylene glycol)-b-poly(ε-caprolactone) (mPEG-b-PCL). Using curcumin as a hydrophobic drug model, micelles of PDL block copolymers with different orientation i.e. AB (mPEG-b-PDL), ABA (PDL-b-PEG-b-PDL), ABC (mPEG-b-PDL-b-poly(pentadecalactone) and (mPEG-b-PCL) were prepared by nanoprecipitation method. The size, drug loading and curcumin stability studies results indicated that mPEG-b-PDL micelles was comparable to its counterpart mPEG-b-PCL micelles towards improved delivery of curcumin. Therefore, mixed micelles using these two copolymers were also evaluated to see any change in size, loading and drug release. Drug release studies proposed that sustained release can be obtained using poly(pentadecalactone) as crystalline core whereas rapid release can be achieved using amorphous PDL core. Further, mPEG-b-PDL micelles were found to be non-haemolytic, up to the concentration of 40 mg/mL. In vivo toxicity studies on rats advised low-toxic behaviour of these micelles up to 400 mg/kg dose, as evident by histopathological and biochemical analysis. In summary, it is anticipated that mPEG-b-PDL block copolymer micelles could serve as a renewable alternative for mPEG-b-PCL copolymers in drug delivery applications.

Tailored Approaches in Drug Development and Diagnostics: From Molecular Design to Biological Model Systems

Approaches to increase the efficiency in developing drugs and diagnostics tools, including new drug delivery and diagnostic technologies, are needed for improved diagnosis and treatment of major diseases and health problems such as cancer, inflammatory diseases, chronic wounds, and antibiotic resistance. Development within several areas of research ranging from computational sciences, material sciences, bioengineering to biomedical sciences and bioimaging is needed to realize innovative drug development and diagnostic (DDD) approaches. Here, an overview of recent progresses within key areas that can provide customizable solutions to improve processes and the approaches taken within DDD is provided. Due to the broadness of the area, unfortunately all relevant aspects such as pharmacokinetics of bioactive molecules and delivery systems cannot be covered. Tailored approaches within (i) bioinformatics and computer-aided drug design, (ii) nanotechnology, (iii) novel materials and technologies for drug delivery and diagnostic systems, and (iv) disease models to predict safety and efficacy of medicines under development are focused on. Current developments and challenges ahead are discussed. The broad scope reflects the multidisciplinary nature of the field of DDD and aims to highlight the convergence of biological, pharmaceutical, and medical disciplines needed to meet the societal challenges of the 21st century.

Three-Dimensional Printed PCL-Based Implantable Prototypes of Medical Devices for Controlled Drug Delivery

The goal of the present study was to fabricate drug-containing T-shaped prototypes of intrauterine system (IUS) with the drug incorporated within the entire backbone of the medical device using 3-dimensional (3D) printing technique, based on fused deposition modeling (FDM™). Indomethacin was used as a model drug to prepare drug-loaded poly(ε-caprolactone)-based filaments with 3 different drug contents, namely 5%, 15%, and 30%, by hot-melt extrusion. The filaments were further used to 3D print IUS. The results showed that the morphology and drug solid-state properties of the filaments and 3D prototypes were dependent on the amount of drug loading. The drug release profiles from the printed devices were faster than from the corresponding filaments due to a lower degree of the drug crystallinity in IUS in addition to the differences in the external/internal structure and geometry between the products. Diffusion of the drug from the polymer was the predominant mechanism of drug release, whereas poly(ε-caprolactone) biodegradation had a minor effect. This study shows that 3D printing is an applicable method in the production of drug-containing IUS and can open new ways in the fabrication of controlled release implantable devices.

Improved dimensional stability with bioactive glass fibre skeleton in poly(lactide-co-glycolide) porous scaffolds for tissue engineering

Bone tissue engineering requires highly porous three-dimensional (3D) scaffolds with preferable osteoconductive properties, controlled degradation, and good dimensional stability. In this study, highly porous 3D poly(d,l-lactide-co-glycolide) (PLGA) - bioactive glass (BG) composites (PLGA/BG) were manufactured by combining highly porous 3D fibrous BG mesh skeleton with porous PLGA in a freeze-drying process. The 3D structure of the scaffolds was investigated as well as in vitro hydrolytic degradation for 10weeks. The effect of BG on the dimensional stability, scaffold composition, pore structure, and degradation behaviour of the scaffolds was evaluated. The composites showed superior pore structure as the BG fibres inhibited shrinkage of the scaffolds. The BG was also shown to buffer the acidic degradation products of PLGA. These results demonstrate the potential of these PLGA/BG composites for bone tissue engineering, but the ability of this kind of PLGA/BG composites to promote bone regeneration will be studied in forthcoming in vivo studies.

Towards fabrication of 3D printed medical devices to prevent biofilm formation

The use of three-dimensional (3D) printing technologies is transforming the way that materials are turned into functional devices. We demonstrate in the current study the incorporation of anti-microbial nitrofurantoin in a polymer carrier material and subsequent 3D printing of a model structure, which resulted in an inhibition of biofilm colonization. The approach taken is very promising and can open up new avenues to manufacture functional medical devices in the future.

Essential fatty acid status in teenage girls with eating disorders and weight loss

AIM

To explore the relationship between essential fatty acids (FA) and weight changes in adolescent girls with eating disorders (ED).

METHODS

Blood samples were obtained from 220 girls with ED and 39 healthy controls. The girls with ED were 15.3 ± 1.5 years of age and weighed 49.8 ± 8.7 kg (BMI 18.3 ± 2.8 kg/m(2)) after a weight loss of 6.8 ± 6.4 kg. FA were analysed in plasma phospholipids (PPL) and erythrocyte membranes (ERY).

RESULTS

The proportions of saturated and monounsaturated FA were increased during weight loss, while linoleic acid (18:2ω6) was decreased. The proportions of eicosapentanoic acid (EPA) (20:5ω3) and docosahexanoic acid (DHA) (22:6ω3) in PPL and ERY did not differ from controls. The activity of stearoyl-CoA-desaturase was increased as evidenced by an increased product/precursor ratio and correlated with the rate of weight loss. The activities of delta-6-desaturase and delta-5-desaturase did not differ from controls. The rate of weight loss was inversely correlated with delta-6-desaturase and directly correlated with delta-5-desaturase.

CONCLUSION

The FA profile indicates low-fat intake, fat mobilization from stores and an increased conversion of essential FA at the delta-5-desaturase step during weight loss in adolescent girls with ED. Normal levels of EPA and DHA were maintained.

Fate of bone marrow-derived stromal cells after intraperitoneal infusion or implantation into femoral bone defects in the host animal

The fate of intraperitoneally injected or implanted male rat bone marrow-derived stromal cells inside female sibling host animals was traced using Y-chromosome-sensitive PCR. When injected intraperitoneally, Y-chromosome-positive cells were found in all studied organs: heart muscle, lung, thymus, liver, spleen, kidney, skin, and femoral bone marrow with a few exceptions regardless of whether they had gone through osteogenic differentiation or not. In the implant experiments, expanded donor cells were seeded on poly(lactide-co-glycolide) scaffolds and grown under three different conditions (no additives, in osteogenic media for one or two weeks) prior to implantation into corticomedullar femoral defects. Although the impact of osteogenic in vitro cell differentiation on cell migration was more obvious in the implantation experiments than in the intraperitoneal experiments, the donor cells stay alive when injected intraperitoneally or grown in an implant and migrate inside the host. However, when the implants contained bioactive glass, no signs of Y-chromosomal DNA were observed in all studied organs including the implants indicating that the cells had been eliminated.

Localisation of phosphomonoesterase activity in ectomycorrhizal fungi grown on different phosphorus sources

Phosphorus (P) is a major limiting nutrient for plants in boreal forest ecosystems where a substantial part of the total P is sequestered in organic compounds. Some ectomycorrhizal (ECM) fungi are known to produce phosphomonoesterases, enzymes that degrade organic P sources. Here, we test 16 ECM species for this enzymatic activity by growing them on media containing orthophosphate, phytic acid or apatite. A method with an overlay gel that determined both phosphomonoesterase activity and its spatial distribution was developed. The phosphomonoesterase activity was not significantly higher when growing on organic P; conversely some isolates only produced measurable enzyme activity when grown on apatite. Species-specific variations with respect to phosphomonoesterase activity as well as growth responses to different substrates were found. The production of phosphomonoesterases was found to be widespread in ECM fungi and the enzyme activity did not need induction by organic P. The enzyme activity was highest in the central parts of the mycelia, potentially reflecting breakdown and recycling of phospholipids from old hyphae or potentially higher mycelial density.

Calcium phosphate formation and ion dissolution rates in silica gel-PDLLA composites

Sol-gel derived silicas are potential biomaterials both for tissue regeneration and drug delivery applications. In this study, both SiO(2) and calcium and phosphate-containing SiO(2) (CaPSiO(2)) are combined with poly-(DL-lactide) to form a composite. The main properties studied are the ion release rates of biologically important ions (soluble SiO(2) and Ca(2+)) and the formation of bone mineral-like calcium phosphate (CaP) on the composite surface. These properties are studied by varying the quality, content and granule size of silica gel in the composite, and porosity of the polymer. The results indicate that release rates of SiO(2) and Ca(2+) depend mostly on the formed CaP layer, but in some extent also on the granule size of silicas and polymer porosity. The formation of the bone mineral-like CaP is suggested to be induced by a thin SiO(-) layer on the composite surface. However, due to absence of active SiO(2) or CaPSiO(2) granules on the outermost surface, the suitable nanoscale dimensions do not contribute the nucleation and growth and an extra source for calcium is needed instead. The result show also that all composites with varying amount of CaPSiO(2) (10-60 wt%) formed bone mineral-like CaP on their surfaces, which provides possibilities to optimise the mechanical properties of composites.

Vertical distribution of ectomycorrhizal fungal taxa in a podzol soil profile

•   Studies of ectomycorrhizal fungal communities in forest soils are usually restricted to the uppermost organic horizons. Boreal forest podzols are highly stratified and little is known about the vertical distribution of ectomycorrhizal communities in the underlying mineral horizons. •   Ectomycorrhizal root tips were sampled from seven horizons in three continuous columns of a 52-cm deep podzol profile. Root tips were sorted into morphological groups and the colonising fungi identified by sequencing of the rDNA ITS region. The vertical distribution of mycorrhizal taxa was examined. •   A relationship between ectomycorrhizal species composition and soil horizon was found. Tomentellopsis submollis, three Piloderma species and Dermocybe spp. were found predominantly in the upper horizons while Suillus luteus, Lactarius utilis and three undescribed Piloderma species were associated with the mineral horizons. •   Two thirds of the root tips were found in the mineral soil and half of the taxa were restricted to the mineral horizons. The results highlight the need to include the mineral soil in order to gain a more accurate representation of the ectomycorrhizal community.