The biological activity of natural plant-oil-based nanostructured lipid carriers (NPO-NLCs) can be enhanced by the encapsulation of bioactive compounds, and they in turn can improve topical delivery ...of the drugs. Quercetin (QR), a vital plant flavonoid, expresses antibacterial properties, and we recently showed that empty NPO-NLCs also have antimicrobial activity. The main objective of this study was to evaluate the synergetic effect of loading natural plant-oil-based nanostructured lipid carriers with quercetin (QR-NPO-NLCs) as a topical delivery system for the treatment of bacterial skin infections. Five nanostructured lipid carrier systems containing different oils (sunflower, olive, corn, coconut, and castor) were engineered. The particles’ stability, structural properties, bioavailability, and antimicrobial activity were studied. NLCs with an average size of <200 nm and Z-potential of −40 mV were developed. Stable QR-NPO-NLCs were obtained with high encapsulation efficiency (>99%). The encapsulation of QR decreased cytotoxicity and increased the antioxidant effect of nanocarriers. An increase in antibacterial activity of the systems containing QR was demonstrated against Staphylococcus aureus. QR-NPO-NLCs could transport QR to an intranuclear location within HaCaT cells, indicating that QR-NPO-NLCs are promising candidates for controlled topical drug delivery.
In recent years, gold nanoparticles (AuNPs) have aroused the interest of many researchers due to their unique physicochemical and optical properties. AuNPs are being explored in a variety of ...biomedical fields, either in diagnostics or therapy, particularly for localized thermal ablation of cancer cells after light irradiation. Besides the promising therapeutic potential of AuNPs, their safety constitutes a highly important issue for any medicine or medical device. For this reason, in the present work, the production and characterization of physicochemical properties and morphology of AuNPs coated with two different materials (hyaluronic and oleic acids (HAOA) and bovine serum albumin (BSA)) were firstly performed. Based on the above importantly referred issue, the in vitro safety of developed AuNPs was evaluated in healthy keratinocytes, human melanoma, breast, pancreatic and glioblastoma cancer cells, as well as in a three-dimensional human skin model. Ex vivo and in vivo biosafety assays using, respectively, human red blood cells and
were also carried out. HAOA-AuNPs were selected for in vivo acute toxicity and biodistribution studies in healthy Balb/c mice. Histopathological analysis showed no significant signs of toxicity for the tested formulations. Overall, several techniques were developed in order to characterize the AuNPs and evaluate their safety. All these results support their use for biomedical applications.
Biodegradable aliphatic polyester formulations as carriers for topical drug delivery show the potential to encapsulate structurally different therapeutic compounds. Poly(octamethylene suberate) (POS) ...nanoparticles (POS-NPs) were used as a matrix to encapsulate four therapeutic molecules used to treat skin disorders: caffeine (CF), quercetin (QR), hydrocortisone (HC), and adapalene (AD). Hydrophobicity and chemical structure of bioactive compounds (BCs) influenced the physicochemical stability of drug-loaded nanoparticles. The particle size of drug-loaded nanoparticles was between 254.9 nm for the CF-POS-NP and 1291.3 for QR-POS-NP. Particles had a negative charge from −27.6 mV (QR) to −49.2 mV (HC). Drug loading content for all BC-POS-NPs varies between 36.11 ± 1.48% (CF-POS-NP) and 66.66 ± 4.87% (AD-POS-NP), and their entrapment efficiency is relatively high (28.30 ± 1.81% and 99.95 ± 0.04%, respectively). Calorimetric analysis showed the appearance of polymorphism for AD- and HC-loaded systems and the drug’s complete solubilisation into all nanoparticle formulations. FTIR and NMR spectra showed apparent drug incorporation into the polymer matrix of NPs. The encapsulation of BCs enhanced the antioxidative effect. The prepared POS nanoparticles’ cytotoxicity was studied using two dermal cell lines, keratinocyte (HaCaT) cells and fibroblasts (HDFn). The nanoparticle cytotoxic effect was more substantial on HaCaT cell lines. A reconstructed human epidermis (RHE) was successfully used to investigate the penetration of polymeric NPs. Based on permeation and histology studies, HC-POS-NPs and CF-POS-NPs were shown not to be suitable for dermal applications with the explored drug concentrations. AD presents a high permeation rate and no toxic impact on RHE.
Nanostructured lipid carriers (NLCs) have gained significant attention as tools for the dermal delivery of therapeutics due to their stability, biocompatibility, and ability to improve drug ...bioavailability. The use of natural plant oils (NPO) in NLC formulations has numerous benefits for the skin due to their therapeutic potential. This work shows the effect of NLC composition on bioavailability in epidermal cells and antimicrobial activity against Staphylococcus aureus. Sixteen systems containing fixed (sunflower, olive, corn, peanut, coconut, castor, and sweet almond) and essential (eucalyptus) oils, with different solid lipid (SL): liquid lipid (LL) ratios, were engineered. The structural properties, bioavailability, and antimicrobial action of the particles was studied. The choice of NPO influenced the physicochemical stability by changing the diameter of NLC formulations (between 160 nm and 185 nm) and Z-potential (between −46 mV and −61 mV). All of the systems were characterized by concentration-dependent cytocompatibility with human epidermal keratinocytes (HaCaT) and human dermal fibroblasts (HDFn). The SL:LL ratio in some NLC systems impacted cell cytotoxicity differently. Antimicrobial properties were observed in all 16 systems; however, the type of oil and SL:LL ratio affected the activity of the formulations. Two NLC-NPO systems were found to be non-cytotoxic to human cells lines at concentrations that completely inhibited bacterial growth. These results present a strong argument that the use of natural oils in NLC formulations presents a promising tool for the treatment of skin infections.
•The partitioning behavior of proteins in aqueous two phase systems was examined.•A linear correlation between the proteins partition coefficients was observed.•A semi-empirical model was applied to ...predict proteins partition coefficients.•The electrostatic energy is influenced by the solvent electrostatic properties.•The model shows a good predicting ability on proteins partitioning.
The present work aims to achieve an additional insight into the protein partitioning behavior in aqueous two phase systems (ATPSs), together with a study on the viability of a semi-empirical model based on continuum electrostatics to predict the protein partition characteristics. The partitioning behaviors of 14 globular proteins, with different properties, were explored in three polymer/polymer ATPSs. By the Collander equation, a linear correlation between protein partitioning coefficients in all systems was observed. Using the semi-empirical model it was possible to predict the partitioning behavior of proteins. The electrostatic energy depends on the protein size and ATPSs characteristics and varies in agreement with the difference in phase dielectric constants. Linear correlation of nonpolar energy, and the solvent accessible surface area was observed. Polymer structure and concentration have a significant influence on model viability. A good qualitative prediction of preferred phase for studied proteins was observed.
•The partitioning of amino acids was studied in aqueous two phase systems (ATPS).•The Collander equation was successfully applied.•A semi-empirical model was developed to predict partition ...coefficients.•The model shows a good predicting capacity on amino acids partitioning.
A new model to obtain fast prediction of partition coefficients in polymer/polymer aqueous two phase systems (ATPSs) is presented, using amino acids as test systems. In particular, the partitioning behavior of eleven amino acids (glycine, alanine, leucine, phenylalanine, lysine, arginine, histidine, aspartic acid, glutamic acid, glutamine and serine) has been studied in 6 polymer/polymer ATPSs, formed by different pairs of nonionic polymers, including polyethylene glycol (PEG), Dextran, Ucon and Ficoll at 0.15M NaCl in 0.01M sodium phosphate buffer. The partition coefficients of the amino acids in the different ATPSs under study showed linear correlations as described by the Collander equation. Based on continuum electrostatics (CE), a semi-empirical model was developed to study the partitioning behavior in ATPSs. The approach employs a thermodynamic cycle where the electrostatic and nonpolar contributions to the free energy of partition are assumed to be additive. Three systems were chosen for the modeling studies: PEG-Dextran, PEG-Ficoll and Ficoll-Dextran. In general, the model was found to correctly predict the preferred phase for the studied amino acids, and, except for the charged ones, a good quantitative correlation of the calculated and experimental partition free energies was also obtained (e.g., with RMSE values of 150Jmol−1 for PEG-Ficoll). The model performance could be improved by grouping amino acids according to their electrostatic properties, resulting in very good quantitative partition coefficient predictions (e.g., RMSE values for nonpolar amino acids of 29, 16 and 0.4Jmol−1 for PEG-Dextran, PEG-Ficoll and Ficoll-Dextran system, respectively). The good performance of the proposed model in predicting partition coefficients of amino acids, the building blocks of proteins, offers a good prospect to its application to protein molecules and complexes.
•Stability of lipases in miniemulsions is a key issue to be evaluated.•Secondary structure might be a good parameter to correlate with the drop in activity.•Enzyme unfolding with no secondary ...structural changes may cause a drop in activity.
The exploitation of an efficient enzymatic system to perform biopolymers synthesis, namely polyesters from dicarboxylic acids and dialcohols, requires the evaluation of the enzyme operational stability. This becomes particularly relevant when non-conventional media, such as miniemulsions, are used due to the inhomogeneity of the reaction media and presence of surfactants and high concentrations of organic compounds which might be deleterious to the structure-function of the enzyme. The stability of three lipases, Candida sp., Candida rugosa and Burkholderia cepacia, in miniemulsions during polyester synthesis, was accessed through the secondary structure integrities and activities in order to establish any putative correlations between secondary structure and activity. The effect of the individual components that constitute the emulsion system was also evaluated to identify those which are more disruptive to the secondary structure-function of the enzyme. Depending on the lipase and the presence of different reaction components, three scenarios were observed: a close correlation between secondary structural changes and activity, a drop in activity with no secondary structure alterations but unfolding of tertiary structure and disruption of secondary structure that allows regain of activity in the presence of substrate.
Display omitted
•Effective lipid nanocarriers were formulated using vegetable oils.•Lipids ratio and type of surfactant determine the properties of lipid nanocarriers.•Nanostructured lipid carriers ...presented well controlled tocopherol release profile.•Sunflower oil nanocarriers present enhanced in vitro antioxidant activity.•Lipid nanocarriers loaded with tocopherol were stable during eight months.
Vegetable oils are commonly used as components in many cosmetic products intended for daily care due to their high beneficial and multifunctional effect on skin. The general objective of this study was to develop new nanostructured lipid carrier (NLC) formulations containing vegetable oils and enrich them with α-tocopherol (TOC) in order to explore their potential as effective and safe advanced biocosmetic prototypes. The influence of lipids composition and physical state on the production and physicochemical properties of vegetable oil NLCs and enriched nanoparticles with TOC (TOC-NLCs), as a model bioactive antioxidant compound, was studied. Sunflower, sweet almond, olive and coconut oils were successfully used in the development of free and loaded NLCs. The formulations of free lipid nanoparticles with each vegetable oil presented an appropriate nanoscale size from approximately 120–350 nm and good physical stability with zeta potential values ranging between −45.6 to −65.9 mV. Likewise, the TOC-NLCs demonstrated suitable particle sizes from approximately 240–315 nm and zeta potential values raging between −45.6 to −55.1 mV, being then verified that these parameters were affected by differences on the lipids core composition. TOC-NLCs presented a high entrapment efficiency with values above 79.4% and also assured a controlled release of TOC, independently of the percentage of incorporated active compound. Differential scanning calorimetry results showed that the incorporation of TOC and the increase of its concentration on NLCs lipids matrix caused a decrease on the onset and melting temperatures, indicating a reduced crystallinity of the obtained vegetable oil TOC-NLCs. These lipid nanoparticles and free NLCs presented good antioxidant activity with scavenging activity values above 56.7%, which was improved by the encapsulation of TOC (scavenging activity values above 64.3%) and demonstrated the ability to be incorporated in long-term stable cosmetic products based on stability studies performed during 8 months.
The aim of this study was to design and optimize a new formulation of lipid nanoparticles for the topical administration of retinoids. The standard procedure involves nanostructured lipid carriers ...(NLCs) synthesized by the miniemulsion methodology, using sunflower oil as a bioactive ingredient and retinyl palmitate (RP) as model retinoid.
A 5-factor, 3-level central composite design was used to predict responses and construct 3D-response contour plots. The independent variables were the concentration of total lipids, solid lipid, surfactant, encapsulated retinoid and number of carbons on the solid lipid fatty acid chain length, in function of the selected responses as the particle size, surface charge of the nanoparticles and the encapsulation efficiency (EE %) at 3 levels. Experimental trials were performed at all 31 possible combinations.
An optimized NLC composition of 2.5% total lipids, 2.0% myristic acid and 0.5% sunflower oil and 1.5% of surfactant Tween 80 was reached. The type of surfactant was adjusted from Tween 80 to Span 80 to improve the electrostatic stability of the lipid nanoparticles and the resultant optimized NLC formulation was evaluated to incorporate another two retinoids as tretinoin (TRT) and adapalene (ADP).
The resultant retinoid delivery systems were characterized in terms of particle size and electrostatic stability, morphology, crystallinity of the lipid matrix, EE (%) and drug loading capacity and release profile. Particle sizes of 134.5 ± 5.4 nm and zeta potential values of −57.0 ± 2.8 mV were obtained for optimized ADP-NLCs and high entrapment efficiency values were obtained for RP-NLC, TRT-NLC and ADP-NLC as 84.4 ± 3.0%, 84.1 ± 7.8% and 73.7 ± 3.3%, respectively. DSC analysis indicated that the melting temperatures of the three optimized NLCs loaded with the retinoids were above 40 °C, proving to be suitable for use in topical administration. The in vitro drug release studies were conducted for 48 h, using a dialysis regenerated cellulose membrane. The results demonstrated a very well-controlled release of RP and TRT, which improves the stability of these active compounds and confirms a high encapsulation efficiency.
Display omitted
•Bioactive NLCs were successfully optimized through the CCD statistic approach.•Three retinoids were effectively loaded in the lipid matrices of optimized NLCs.•Selected surfactants determined the electrostatic and steric stability of formulated NLCs.•A very well-controlled release of retinoids loaded NLCs indicated a reduction of their secondary effects.
The aim of this work is to devise an efficient enzymatic process for the production of linear alkyl esters in aqueous miniemulsion systems. The esterification reactions of linear alcohols and ...carboxylic acids were performed with three different enzymes, commercial Amano lipase PS from Pseudomonas cepacia, Lipase type VII from Candida rugosa, and lyophilized Fusarium solani pisi cutinase expressed in Saccharomyces cerevisiae SU50. The miniemulsion system shows a high potential for the synthesis of linear alkyl esters, for example, hexyl octanoate, which could be synthesized with an ester yield of 94% using Amano lipase PS. Even with hydrophilic alcohols as ethanol, ethyl decanoate could be obtained with a concentration of 0.45 M and a yield of 62% using F. s. pisi cutinase as catalyst. High esterification rates for ethyl- and hexyloleate in miniemulsion showed a significant shift in cutinase selectivity towards longer chain length carboxylic acids. The stepwise addition of the alcohol led to an increase of the esterification yield. Moreover, increasing the amount of dispersed organic phase, mainly consisting of the substrates, led to a significant increase of the final ester concentration (e.g., concentration of 1.4 M for ethyl decanoate for the esterification with Amano Lipase PS). Biotechnol. Bioeng. 2010;106: 507-515.
PDF
