Semisolid Systems Research Articles

Space-Resolved Tissue Analysis by Solid-Phase Microextraction Coupled to High-Resolution Mass Spectrometry via Desorption Electrospray Ionization.

It is hard to overstate the tremendous utility of desorption electrospray ionization (DESI) and its various configurations for rapid and high-throughput analyses or spatially resolved imaging of heterogeneous systems. However, there have been few attempts to employ this technique in spatially resolved mode with solid substrates featuring extractive and analyte-enrichment properties. This study documents the development of a platform that combines solid-phase microextraction (SPME) with desorption electrospray ionization mass spectrometry (DESI-MS) for unidimensional investigation of the heterogeneous distribution of compounds in semisolid systems (i.e., depth profiling across the fiber axis), with the ultimate end of employing it for brain tissue analysis. To this end, a DESI interface and a custom holder accommodating SPME probes were built in house, with the latter contributing to reduction of mechanical sources of signal instability. The system was evaluated through the quantitative reconstruction of the laminar and radial concentration gradients of xenobiotics introduced in multilayer gel arrangements and surrogate brain tissue models. Good quantitative capability was achieved by employing a strategy that combined signal correction via preloading internal standard onto SPME fibers and signal integration in scan-by-scan mode. The proposed technique's suitability for characterizing more complex systems, such as rat brains ex vivo, was also evaluated. The proposed approach allows for fast and noninvasive probing of three-dimensional objects without the need for their slicing, and the space-resolved mode reduces the number of required probe insertions, allowing in vivo applications. We foresee suitability of this setup for examining the spatial patterns of local drug release in the brain and the extent of the resultant physiological responses.

Optimization of Oleogel Formulation for Curcumin Vehiculization and Lipid Oxidation Stability by Multi-response Surface Methodology

Curcumin is a natural polyphenolic compound with multiple properties such as anticancer, anti-inflammatory, antioxidant, antiviral, and cytoprotective action. It is expected that curcumin has the therapeutic potential to prevent diverse lifestyle-related diseases. However, curcumin is not readily soluble in water and presents low stability under light, heat and physiological pH conditions which, in addition, implies an extremely low level of bioavailability. On the other hand, oleogels are semisolid systems composed of a liquid phase that is physically entrapped by a structurant network, ultimately leading to the formation of a gel. The continuous phase consists of a hydrophobic liquid (e.g., an oil) where a self-assembled network (composed by the structurant) is responsible for the physical entrapment of the liquid. The structural conformation is always dependent on the type of structurant used, which will dictate the desired final application of the oleogels. In this work, the formulation of an oleogel specially designed to stabilize and transport curcumin and to protect the lipid phase –mainly composed of a fish oil concentrate– against oxidation processes has been optimized.To this end, a Box-Behnken Design was carried out to study the influence of the curcumin amount, the structurant concentration and the manufacturing temperature on the oxidation degree of the oleogelified lipid matrix and on the chemical stability of the curcumin transported by this system. The results were interpreted by using the multi-response surface methodology, obtaining the optimal oleogel formulation to minimize the lipid oxidation and maximize the content of vehiculized curcumin.The results show that the optimal oleogel formulation –for samples stored at 23 oC– was achieved for the following values of the variables studied: [Curc.] = 0.150 wt.%, [Struc.] = 4.461 wt.% and T = 64.63 oC. In contrast, for samples stored at 40 oC, the optimal formulation obtained changed slightly: [Curc.] = 0.150 wt.%, [Struc.] = 7.000 wt.% and T = 62.82 oC. Finally, results suggest that oleogels are interesting structured lipid systems to transport and protect bioactive compounds.

Effects of hydrocolloids on the rheological and microstructural properties of semisolid whey protein-rich systems

Effects of xanthan gum (XG), κ-carrageenan (KC) and gum Arabic (GA) on rheological properties and microstructural properties of semisolid whey protein-rich systems were studied. Results of oscillation frequency sweeps and temperature ramp experiments indicated that whey protein-rich systems containing XG and KC formed a viscoelastic structure that had different rheological properties compared to GA. XG or KC intensified the rheological properties of whey protein-rich systems, while forming an additional network separate from the whey protein isolate (WPI). The double-labelled (WPI and hydrocolloids) micrographs showed that a continuous network structure formed with 1% added XG or KC while the system maintained a relative homogeneous structure with GA. Small-angle X-ray scattering (SAXS) also confirmed that an ordered structure was formed when the XG or KC reached 1%. Furthermore, these ordered structures were not completely destroy with heat.

Thermally stabilised whey protein-pectin complexes modulate the thermodynamic incompatibility in hydrocolloid matrixes: A feasibility-study on sensory and rheological characteristics in dairy desserts

This study investigated thermally stabilised whey protein-pectin complexes (WPPC) regarding their potential as fat-replacer. Sensory and rheological characteristics of WPPC in dairy based desserts were studied using generic descriptive analysis and rotative and oscillatory rheometry. The aroma profile of WPPC was dominated by dairy associated attributes, whereas textural attributes similar to high-fat products were achieved. Attribute intensities increased proportionally with WPPC concentration, enabling a tailoring of sensory parameters. Addition in suspensions and vanilla sauces revealed that WPPC acted as non-interactive fat-replacers, reaching apparent viscosities similar to products rich in fat. In solid gelled puddings, a slight softening of the gel was found which was attributed to thermodynamic incompatibility between unbound pectin and the embedding starch matrix. Based on this, a model for the modes of action of WPPC depending on the matrix – requirements was postulated stressing the role of pectins as thickeners in liquid and semi-solid systems and of excluded volume effects in solid gels.

Green biocatalytic synthesis of biodiesel from microalgae in one-pot systems based on sponge-like ionic liquids

Abstract Binary mixtures of ionic liquids (ILs) have been used for developing one-pot systems suitable for the direct extraction and biocatalytic transformation of algal oil to biodiesel without prior isolation. These mixtures were based on the combination of sponge-like ionic liquids (e.g. 1-hexadecyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C16mim][NTf2]) with the IL 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]), taking into account the excellent suitability to carry out the biocatalytic synthesis of biodiesel of the first one, and the ability for dissolving cellulosic biomass of the second. The extraction of oils was carried out by incubating the dry microalgae (Chlorella vulgaris or Chlorella protothecoides) in the appropriated IL binary mixture at 110 °C, which after being cooled at 60 °C allowed to be transformed to biodiesel by an immobilized lipase. This resulted in a fast and efficient biodiesel synthesis, e.g. up to 100% yield in 2 h at 60 °C. The subsequent cooling until room temperature and the iterative centrifugation of the resulting semi-solid systems at 20 and 18 °C led to the separation of the liquid algae biodiesel from the solid IL mixture, which was recovered and reused for further operation cycles.

Improving micropropagation of Mentha × piperita L. using a liquid culture system

In the current study, in vitro shoot proliferation and plant regeneration of Mentha × piperita L. (peppermint) cultivar ‘Black Mitcham’ was compared in semi-solid and liquid culture systems. Shoot tips from field-grown plants were used as explants to study shoot proliferation response on either Murashige and Skoog (MS) or Chee and Pool (C2D) medium containing varying levels of 6-benzylaminopurine (BAP), kinetin, and 6-γ,γ-dimethylallyl aminopurine (2iP). Differences in leaf ultrastructure and antioxidant capacity of greenhouse-grown and micropropagation-derived plants were studied to identify potential changes occurring during in vitro culture. Among the various media treatments tested, the maximum number of shoots was produced on the C2D medium with 4.0 μM BAP (40.7) followed by the MS medium with 4.0 μM BAP (32.2). Among the rooting treatments, shoots on the MS medium with 1.0 μM indole-3-butyric acid (IBA) produced the maximum number of roots (14.4). The number of shoots produced in Liquid Lab Rocker® (LLR) vessels containing liquid C2D medium with BAP (103.4) was significantly higher than that produced on semi-solid medium (40.7). No differences were observed in the leaf ultrastructure and antioxidant capacity of leaf extracts obtained from greenhouse-grown and micropropagation-derived plants. The study indicates that the liquid culture system under the described conditions can enhance peppermint micropropagation, with plant material being potentially valuable for use in herbal supplements and essential oil production.

PLB Regeneration of Paphiopedilum rothschildianum using Callus and Liquid Culture System

This research was conducted to rapidly propagate Paphiopedilum rothschildianum using semi-solid and liquid culture systems. Calli were induced from seed, leaf segments (LS), seed-derived protocorms (SDP) and secondary protocorms (SP) cultured on half-strength semi-solid MS media supplemented with 0-22.6 µM 2,4-dichlorophenoacetic acid (2,4-D) and 4.54 µM 1-phenyl-3-(1,2,3-thiadiazol-5-yl)-urea (TDZ). Regeneration of PLB from callus was optimized on semisolid medium and were evaluated in various concentrations and types of PGRs. PLB regeneration was further optimized using callus originating from a different induction medium, and cultured on different concentrations (0, 15 and 58 mM) of sucrose. For PLB regeneration using liquid culture system, 0.5 g callus were inoculated in a temporary immersion bioreactor system (RITA®) containing 150 ml liquid medium with immersion time of 5 minutes in every 125 minutes. SE, SDP and SP explants produced calli as early as 30 days with the percentages of explant forming callus at 77.0% ± 4.5, 94.4% ± 11.0, and 66.7% ± 14.4 respectively after 90 days of culture. The calli regenerated on medium supplimented with 2.27 µM TDZ and 12.0 µM BAP, but with very low percentage (15.0% ± 13.7 callus produced the average of 3 PLBs). PLB regeneration capacity increased to 37.5% ± 13.7 with the average of 5.9 PLBs for callus originating from an induction medium containing 4.54 µM TDZ, when a lower sucrose concentration (15 mM) was used in the regeneration medium. Callus proliferation using RITA® system showed an almost 2-fold increased in fresh weight and 168 PLBs per gram calli were regenerated. In contrast to semi-solid culture, the regeneration capacity in liquid culture system increased to 190 PLBs per gram calli when sucrose concentration in the medium was elevated from 15 mM to 58 mM.

FABRICATION AND EVALUATION OF HERBAL OINTMENT FORMULATIONS OF MORINGA OLIFERA FOR TOPICAL DELIVERY

Traditional medicine is an important source of potentially useful new compounds for the development of chemotherapeutic agents. Moringa oleifera Lam. is a multipurpose and exceptionally nutritious vegetable tree with a variety of potential uses. It is distributed in many countries of the tropics and subtropics. Ointments are semisolid systems which behave as viscoelastic materials when shear stress is applied. They contain medicaments and are intended to be applied externally to the body or to the mucous membrane. In present study the Morenga oleifera leaves extract was used to formulate four different ointment formulations with different bases like cetostearyl alcohol, hard paraffin, and liquid paraffin. Formulations were evaluated for different parameters such as general appearance, spreadability, pH, extrudability, centrifugation, irritancy, loss on drying, stability study etc;

In vitro propagation of Epipactis flava Seidenf., an endangered rheophytic orchid: a first study on factors affecting asymbiotic seed germination, seedling development and greenhouse acclimatization

Epipactis flava Seidenf., is an endangered Thai rheophytic orchid that has decreased rapidly throughout its natural habitat and urgently requires conservation using in vitro techniques. Effect of pollination types (self- and cross-pollination) and seed from different capsule ages (2, 4, 6 and 8 weeks after pollination) on asymbiotic seed germination efficiency was performed on semi-solid VW medium supplemented with 150 mL/L coconut water and 50 g/L potato extract. Highest germination rate was 79.2% with definite rate of protocorm developmental stage 5 at 24.0% using seeds from 6 week old cross-pollination capsules. Anatomical investigation revealed young seed has been formed at 6 weeks old capsules. Identical seeds were then cultured on semi-solid and liquid systems of five different media including modified-VW, MS, BM, MM and KC for 2 months. Results showed that semi-solid and liquid VW medium promoted the highest seed germination rates at 70.2% and 70.4%, respectively, with the highest definite rate of protocorm developmental stage 5 at 54% found on semi-solid BM medium. In vitro seedlings were transferred to culture on both semi-solid and liquid VW and MS media for 2 months. Higher growth parameters, as indicated by shoot number and fresh weight, were obtained on liquid MS medium. Clumps of plantlets containing 5–8 shoots were acclimatized and transplanted into different potting media for 3 months. Survival percentages in all tested substrates were recorded at nearly 100% with no significant differences, while 63–68% of the living plantlets produced new shoots.

Semisolid self-microemulsifying drug delivery systems (SMEDDSs): Effects on pharmacokinetics of acyclovir in rats

Semisolid self-microemulsifying drug delivery system (SMEDDS) with optimized drug loading capacity, stability, dispersibility in aqueous media and in vitro drug release profile, was evaluated in vivo regarding effects on pharmacokinetics of acyclovir, an antiviral with low bioavailability (BA) and short half-life (t1/2). Additional goal of this study was evaluation of safety of this semisolid SMEDDS consisted of medium chain length triglycerides (oil) (10% w/w), macrogolglycerol hydroxystearate (surfactant) (56.25% w/w), polyglyceryl-3-dioleate (cosurfactant) (6.25% w/w), glycerol (cosolvent) (20% w/w), macrogol 8000 (viscosity modifier) (7.5% w/w), and acyclovir (2.5 mg/ml). The study was performed on fully mature white male Wistar rats. The pharmacokinetics of acyclovir was monitored in three groups (1–3) of animals after administration of drug solution (intravenously (IV)), drug suspension (orally) and semisolid SMEDDS (orally), respectively. The determined pharmacokinetic parameters were: maximum concentration of acyclovir in serum (Cmax), time taken to reach Cmax (Tmax), areas under time-concentration curves (AUC0–t and AUC0–∞), terminal elimination rate constant (kel), t1/2, volume of distribution (Vd), mean residence time (MRT), clearance (Cl), zero concentration (C0), steady state volume of distribution (Vss), and BA. Additionally, for safety evaluation, animals were treated orally with aqueous solution of acyclovir, drug-free semisolid SMEDDS and acyclovir-loaded semisolid SMEDDS, during 21 days (groups 4–7). Serum samples of sacrificed animals were used for biochemical analysis of enzymatic activity of alanine transaminase (ALT) and aspartate transaminase (AST), urea, creatinine, and uric acid. Acyclovir administered by semisolid SMEDDS reached twice higher Cmax (0.92 ± 0.21 μg/ml) and has significantly shorter Tmax (14 ± 10.84 min) compared to the suspension of acyclovir (Cmax 0.29 ± 0.09 μg/ml and Tmax 26.00 ± 5.48 min). BA of the drug was significantly increased by semisolid SMEDDS, while the analysis of biochemical parameters excluded damage on function of liver and kidneys caused by the investigated drug delivery system.

ORGANOGELS AS A POTENTIAL TOPICAL DRUG DELIVERY SYSTEM

Semisolid preparations for external application to skin have gained much demand, since it is easily absorbed through the skin layers. Many novel topical dosage forms have been discovered, among which organogels appears to play an important role. Interest in organogels has increased in a wide variety of fields including chemistry, biotechnology and pharmaceutics. Organogels are thermodynamically stable, biocompatible, isotropic gel, which not only give localized effect, but also systemic effect through percutaneous absorption. Organogels are semi-solid systems, in which an organic liquid phase is immobilized by a three-dimensional network composed of self assembled, intertwined gelator fibers. The apolar phase gets immobilized within spaces of the three-dimensional networked structure formed due to the physical interactions amongst the self assembled structures of compounds regarded as gelators. Organogels have been explored as matrices for the delivery of bioactive agents. Compared to conventional topical dosage forms, these novel formulations are found to be more advantageous and efficient. In future, organogels can give way to many promising discoveries in the field of topical dosage forms. The current review aims at giving an idea about organogels, its applications and importance in topical delivery.

Organogels: A Versatile Drug Delivery Tool in Pharmaceuticals

Organogels have been explored as a versatile tool in pharmaceuticals for topical as well as transdermal delivery of various drugs. These are semisolid systems consists of apolar phase and a solid phase. Gels are formed by the mechanism of entrapment of a polar phase into the three-dimensional networked structure of solid phase. Apolar phase is used as a solvent such as isopropyl palmitate, isopropyl myristate etc. Solid phase is an organogelator such as sorbiatan monostearte, lecithin etc. These systems are good carrier for both hydrophilic and lipophilic therapeutic agents. The present review describes some of the important properties of organogel, different types of organogel based on organogelator, method of preparation and various applications in pharmaceuticals.

Application of quality by design principles in the development and evaluation of semisolid drug carrier systems for the transdermal delivery of lidocaine

The aim of this work was the formulation and comparison of different drug carrier systems for the transdermal delivery of lidocaine. Quality target product profile and quality attributes were identified, and an initial risk assessment was made according to the Quality by Design methodology. The critical quality attributes influencing the quality and efficacy of the final drug formulation were then defined in order to select the control points. Four formulation types, each containing 5% lidocaine were compared: conventional hydrogel, oleogel, lyotropic liquid crystal and nanostructured lipid carrier. Microscopic analysis, particle size and zeta potential measurements, Fourier transform infrared spectroscopy and Raman spectroscopy were performed to characterize the critical parameters in case of the different vehicles. Membrane diffusion and penetration studies were completed as well for each formulation in vitro and ex vivo, followed by measurements on skin hydration and transepidermal water loss in vivo. Our results lead us to the conclusion that the nanostructured lipid carrier is the most promising vehicle for the topical delivery of lidocaine. It showed the best penetration properties through heat separated epidermis and the highest moisturizing effect which are the most critical parameters based on the Quality by Design initial risk assessment and evaluation.

Non-aerated liquid culture promotes shoot organogenesis in Eucalyptus globulus Labill

Eucalyptus is very recalcitrant to in vitro culture. In this research, an efficient shoot organogenesis system was developed using 60-day-old plants of Eucalyptus globulus grown in vitro and non-aerated liquid medium to improve shoot proliferation. Cultures were initiated with hypocotyls and leaf segments from plantlets cultivated on semisolid ½ MS modified medium supplemented with 4.44 µM 6-Benzyladenine (BA) and 16.1 µM 1-Naphthaleneacetic acid (NAA). Calli were transferred to shoot induction medium, with either 0.5 or 2.7 µM NAA. Shoot multiplication was carried out on 4.44 µM BA + 0.5 µM NAA medium, and semisolid and non-aerated liquid systems were compared for improving shoot proliferation. Rooting of adventitious shoots was evaluated on medium containing NAA or Indole-3-butyric acid -IBA (5 and 16 µM). Callogenesis was obtained from both types of explants, although shoot formation was only obtained from leaf-derived calli. Shoot proliferation on 4.44 µM BA + 0.5 µM NAA resulted in the most shoots/callus. Non-aerated liquid medium was more efficient in promoting shoot multiplication (53.5 shoots/callus) than was semisolid medium (28.5 shoots/callus). Levels of phenolic compounds were significantly reduced in the shoots cultivated in liquid medium. Efficient rooting (76%) was obtained using 16 µM IBA.

Novel microemulsion-based gels for topical delivery of indomethacin: Formulation, physicochemical properties and in vitro drug release studies

HypothesisMicroemulsion-based semisolid systems may be considered as an interesting alternative to the traditional dosage forms applied in topical drug delivery. Mechanical properties of topical products are important both in terms of application and dosage form effectiveness. In this study we designed and evaluated novel microemulsion-based gels with indomethacin and analyzed the factors affecting their mechanical characteristics and drug release. ExperimentsThe impact of the microemulsion composition on the extent of isotropic region was investigated with the use of pseudoternary phase diagrams. Selected microemulsions were analyzed in terms of electrical conductivity and surface tension in order to determine the microemulsion type. Microemulsions were transformed into polymer-based gels and subjected to rheological and textural studies. Finally, the indomethacin release from the analyzed gels was studied and compared to commercially available product. FindingsThe extent of isotropic domain in pseudoternary phase diagrams seems to be dependent on the polarity of the oil phase. The surface tension and conductivity monitored as a function of water content in microemulsion systems revealed possible structural transformations from w/o through bicontinuous systems into o/w. The mechanical properties of semisolid microemulsion-based systems depended on the composition of surface active agents and the drug presence. The drug release profiles observed in the case of the investigated gels differed from those recorded for the commercially available product which was most probably caused by the different structure of both systems.

Development of semisolid self-microemulsifying drug delivery systems (SMEDDSs) filled in hard capsules for oral delivery of aciclovir

The study aimed to develop semisolid self-microemulsifying drug delivery systems (SMEDDSs) as carriers for oral delivery of aciclovir in hard hydroxypropylmethyl cellulose (HPMC) capsules. Six self-dispersing systems (SD1-SD6) were prepared by loading aciclovir into the semisolid formulations consisting of medium chain length triglycerides (lipid), macrogolglycerol hydroxystearate (surfactant), polyglyceryl-3-dioleate (cosurfactant), glycerol (hydrophilic cosolvent), and macrogol 8000 (viscosity modifier). Their characterization was performed in order to identify the semisolid system with rheological behaviour suitable for filling in hard HPMC capsules and fast dispersibility in acidic and alkaline aqueous media with formation of oil-in-water microemulsions. The optimal SMEDDS was loaded with aciclovir at two levels (2% and 33.33%) and morphology and aqueous dispersibility of the obtained systems were examined by applying light microscopy and photon correlation spectroscopy (PCS), respectively. The assessment of diffusivity of aciclovir from the SMEDDSs by using an enhancer cell model, showed that it was increased at a higher drug loading. Differential scanning calorimetry (DSC) analysis indicated that the SMEDDSs were semisolids at temperatures up to 50°C and physically stable and compatible with HPMC capsules for 3 months storage at 25°C and 4°C. The results of in vitro release study revealed that the designed solid dosage form based on the semisolid SMEDDS loaded with the therapeutic dose of 200mg, may control partitioning of the solubilized drug from in situ formed oil-in-water microemulsion carrier into the sorrounding aqueous media, and hence decrease the risk for precipitation of the drug.

Birch Bark Dry Extract by Supercritical Fluid Technology: Extract Characterisation and Use for Stabilisation of Semisolid Systems

Triterpene compounds like betulin, betulinic acid, erythrodiol, oleanolic acid and lupeol are known for many pharmacological effects. All these substances are found in the outer bark of birch. Apart from its pharmacological effects, birch bark extract can be used to stabilise semisolid systems. Normally, birch bark extract is produced for this purpose by extraction with organic solvents. Employing supercritical fluid technology, our aim was to develop a birch bark dry extract suitable for stabilisation of lipophilic gels with improved properties while avoiding the use of toxic solvents. With supercritical carbon dioxide, three different particle formation methods from supercritical solutions have been tested. First, particle deposition was performed from a supercritical solution in an expansion chamber. Second, the Rapid Expansion of Supercritical Solutions (RESS) method was used for particle generation. Third, a modified RESS-procedure, forming the particles directly into the thereby gelated liquid, was developed. All three methods gave yields from 1% to 5.8%, depending on the techniques employed. The triterpene composition of the three extracts was comparable: all three gave more stable oleogels compared to the use of an extract obtained by organic solvent extraction. Characterizing the rheological behaviour of these gels, a faster gelling effect was seen together with a lower concentration of the extract required for the gel formation with the supercritical fluid (SCF)-extracts. This confirms the superiority of the supercritical fluid produced extracts with regard to the oleogel forming properties.

Hydrogel Containing an Extract of Tormentillae Rhizoma for the Treatment of Biofilm-Related Oral Diseases

In the present study, hydrogels containing the dried extract of tormentil (Potentilla erecta (L.) Raeusch., Rosaceae) were designed and qualitatively evaluated regarding their viscosity, thixotropy, and texture properties. As mucoadhesiveness is a crucial factor determining drug retention within the oral cavity, mucoadhesive properties expressed as the work of adhesion and maximum detachment force under the presence of porcine buccal mucosa and two different models of mucoadhesive layers: mucin and gelatin discs were evaluated. The fingerprints of the analyzed tormentil extract were established by using a LC- -ESI-MS method. The dominating compounds of the tested extract are oligomeric proanthocyanidins and agrimoniin. This study reveals that designed hydrogels are promising semi-solid delivery systems for the dry extract of tormentil with beneficial mucoadhesive, thixotropic, and texture characteristics and may be utilized as platforms for tormentil delivery to the oral cavity in periodontal diseases. In vitro evaluation of the efficacy of the tormentil hydrogel against cariogenic Streptococcus mutans biofilms was also performed. The hydrogel significantly reduced artificial biofilm formation. For all Streptococci, complete inhibition was revealed at a final concentration of the extract of 2 mg/mL. These beneficial characteristics, as well as the anti-biofilm activity, enable its use for dental care, but further clinical studies are required.

Characterization and biocompatibility evaluation of cutaneous formulations containing lipid nanoparticles

Nanostructured lipid carriers (NLC) are well-known systems that show effectiveness to improve skin hydration, being suggested for cosmetic and dermatological use. Nonetheless, NLC dispersions present low viscosity, which is non-attractive for cutaneous application. To circumvent this drawback, the dispersions can be gelled or incorporated in semisolid systems, increasing the final formulation consistency.In this study, we prepared a hydrogel based on NLC containing vitamin E (HG-NLCVE) and evaluated its suitability for cutaneous application. The experiments started with the HG-NLCVE characterization (organoleptic analysis, accelerated stability, particle size, morphology, pH, texture and rheology). Afterwards, in vitro experiments were carried out, evaluating the formulation biocompatibility (MTT and Neutral Red) and irritant potential (Hen’s egg test on the chorioallantoic membrane, HET-CAM) for cutaneous application. The results showed that the HG-NLCVE has adequate features for skin application, is biocompatible and non-irritant. From this study, it was predicted the in vivo irritant potential of the developed formulation, avoiding the need to perform a high number of tests on human volunteers. Regarding vitamin E and NLC potential to improve skin hydration, we suggest that the HG-NLCVE could be used in cosmetic (e.g. moisturizers and anti-aging) or dermatologic (e.g. xerosis and other skin disorders) products.

Application of 3D printing to prototype and develop novel plant tissue culture systems

BackgroundDue to the complex process of designing and manufacturing new plant tissue culture vessels through conventional means there have been limited efforts to innovate improved designs. Further, development and availability of low cost, energy efficient LEDs of various spectra has made it a promising light source for plant growth in controlled environments. However, direct replacement of conventional lighting sources with LEDs does not address problems with uniformity, spectral control, or the challenges in conducting statistically valid experiments to assess the effects of light. Prototyping using 3D printing and LED based light sources could help overcome these limitations and lead to improved culture systems.ResultsA modular culture vessel design in which the fluence rate and spectrum of light are independently controlled was designed, prototyped using 3D printing, and evaluated for plant growth. This design is compatible with semi-solid and liquid based culture systems. Observations on morphology, chlorophyll content, and chlorophyll fluorescence based stress parameters from in vitro plants cultured under different light spectra with similar overall fluence rate indicated different responses in Nicotiana tabacum and Artemisia annua plantlets. This experiment validates the utility of 3D printing to design and test functional vessels and demonstrated that optimal light spectra for in vitro plant growth is species-specific.Conclusions3D printing was successfully used to prototype novel culture vessels with independently controlled variable fluence rate/spectra LED lighting. This system addresses several limitations associated with current lighting systems, providing more uniform lighting and allowing proper replication/randomization for experimental plant biology while increasing energy efficiency. A complete procedure including the design and prototyping of a culture vessel using 3D printing, commercial scale injection molding of the prototype, and conducting a properly replicated experiment are discussed. This open source design has the scope for further improvement and adaptation and demonstrates the power of 3D printing to improve the design of culture systems.