Effect of electron beam irradiation pretreatment and different fatty acid types on the formation, structural characteristics and functional properties of starch-lipid complexes

The effects of different electron beam irradiation doses (2, 4, 8 KGy) and various types of fatty acids (lauric acid, stearic acid, and oleic acid) on the formation, structure, physicochemical properties, and digestibility of starch-lipid complex were investigated. The complexing index of the complexes was higher than 85 %, indicating that the three fatty acids could easily form complexes with starch. With the increase of electron beam irradiation dose, the complexing index increased first and then decreased. The highest complexing index was lauric acid (97.12 %), stearic acid (96.80 %), and oleic acid (97.51 %) at 2 KGy radiation dose, respectively. Moreover, the microstructure, crystal structure, thermal stability, rheological properties, and starch solubility were analyzed. In vitro digestibility tests showed that adding fatty acids could reduce the content of hydrolyzed starch, among which the resistant starch content of the starch-oleic acid complex was the highest (54.26 %). The lower dose of electron beam irradiation could decrease the digestibility of starch and increase the content of resistant starch.

Engineering lauric acid-based nanodrug delivery systems for restoring chemosensitivity and improving biocompatibility of 5-FU and OxPt against Fn-associated colorectal tumor

Colorectal cancer (CRC) occurs in the colorectum and ranks second in the global incidence of all cancers, accounting for one of the highest mortalities. Although the combination chemotherapy regimen of 5-fluorouracil (5-FU) and platinum(IV) oxaliplatin prodrug (OxPt) is an effective strategy for CRC treatment in clinical practice, chemotherapy resistance caused by tumor-resided Fusobacterium nucleatum (Fn) could result in treatment failure. To enhance the efficacy and improve the biocompatibility of combination chemotherapy, we developed an antibacterial-based nanodrug delivery system for Fn-associated CRC treatment. A tumor microenvironment-activated nanomedicine 5-FU-LA@PPL was constructed by the self-assembly of chemotherapeutic drug derivatives 5-FU-LA and polymeric drug carrier PPL. PPL is prepared by conjugating lauric acid (LA) and OxPt to hyperbranched polyglycidyl ether. In principle, LA is used to selectively combat Fn, inhibit autophagy in CRC cells, restore chemosensitivity of 5-FU as well as OxPt, and consequently enhance the combination chemotherapy effects for Fn-associated drug-resistant colorectal tumor. Both in vitro and in vivo studies exhibited that the tailored nanomedicine possessed efficient antibacterial and anti-tumor activities with improved biocompatibility and reduced non-specific toxicity. Hence, this novel anti-tumor strategy has great potential in the combination chemotherapy of CRC, which suggests a clinically relevant valuable option for bacteria-associated drug-resistant cancers.

Anticancer potential of thiocolchicoside and lauric acid loaded chitosan nanogel against oral cancer cell lines: a comprehensive study

The present study explored the anticancer activity of a Chitosan-based nanogel incorporating thiocolchicoside and lauric acid (CTL) against oral cancer cell lines (KB-1). Cell viability, AO/EtBr dual staining and Cell cycle analysis were done to evaluate the impact of CTL nanogel on oral cancer cells. Real-time PCR was performed to analyze proapoptotic and antiapoptotic gene expression in CTL-treated KB-1 cells. Further, molecular docking analysis was conducted to explore the interaction of our key ingredient, thiocolchicoside and its binding affinities. The CTL nanogel demonstrated potent anticancer activity by inhibiting oral cancer cell proliferation and inducing cell cycle arrest in cancer cells. Gene expression analysis indicated alterations in Bax and Bcl-2 genes; CTL nanogel treatment increased Bax mRNA expression and inhibited the Bcl-2 mRNA expression, which showed potential mechanisms of the CTL nanogel's anticancer action. It was found that thiocolchicoside can stabilize the protein's function or restore it as a tumour suppressor. The CTL nanogel exhibited excellent cytotoxicity and potent anticancer effects, making it a potential candidate for non-toxic chemotherapy in cancer nanomedicine. Furthermore, the nanogel's ability to modulate proapoptotic gene expression highlights its potential for targeted cancer therapy. This research contributes to the growing interest in Chitosan-based nanogels and their potential applications in cancer treatment.

The influence of short-range molecular order in gelatinized starch on the formation of starch-lauric acid complexes

A model system of gelatinized wheat starch (GWS) and lauric acid (LA) was used to examine the effect of residual short-range molecular order in GWS on the formation of starch-lipid complexes. The extent of residual short-range molecular order, as determined by Raman spectroscopy, decreased with increasing water content or heating duration of gelatinization. The enthalpy changes, crystallinity, short-range molecular order and the in vitro enzymic digestion of GWS-LA complexes increased initially to a maximum and then declined as the short-range molecular order in GWS decreased, showing that there was an optimal amount of residual short-range molecular order in GWS for maximizing GWS-LA complexes formation. Below this optimum amount, the limited disruption of short-range molecular order may constrain the mobility of amylose chains for complexation with LA, whereas with excessive disruption above this amount the amylose chains may be too disorganized or entangled to form complexes with LA. The susceptibility of GWS-LA complexes to enzymatic hydrolysis was influenced by both long- and short-range structural order, and to a lesser extent the amounts of complexes. This study showed clearly the role of short-range molecular order in gelatinized starch in influencing the formation of GWS-LA complexes.

Micelle Formation of Dodecanoic Acid with Alkali Metal Counterions

Alkali series with different atomic numbers affect the physicochemical properties of aqueous solutions. The micellar properties of aqueous solutions of dodecanoate as surfactants were measured by changing the counterions (C12-Na, C12-K, C12-Rb, and C12-Cs). A plot of Krafft temperature vs. alkali metal atomic number showed a downward convex curve, with its minimum temperature (20°C) in the C12-K system. By contrast, a plot of the critical micelle concentration (CMC) vs. alkali metal atomic number exhibited an upward convex curve with the maximum CMC (25.6 mmol L-1) at C12-K. Furthermore, the minimum surface tension (γ min ) of the solution at the CMC increased with increasing atomic number (C12-Na ≈ C12-K < C12-Rb < C12-Cs). The size of the dodecanoate micelles decreased with increasing atomic number. The ionization degree of the micelles also increased with increasing atomic number of the alkali metal. Small-angle X-ray scattering (SAXS) measurements revealed that alkali dodecanoate micelles formed spherical to ellipsoidal structures. In addition, micelles from the shell region showed large electrostatic repulsion, judging from the shape of the spectrum in the higher Q -1 region. From the measurement results of the solubilization of naphthalene into the micelles, the size of the micelles corresponded to the maximum solubilization quantity of naphthalene.

Can Photothermal Post-Operative Cancer Treatment Be Induced by a Thermal Trigger?

One of the current challenges in the post-operative treatment of breast cancer is to develop a local therapeutic vector for preventing recurrence and metastasis. Herein, we develop a core-shell fibrous scaffold comprising phase-change materials and photothermal/chemotherapy agents, as a thermal trigger for programmable-response drug release and synergistic treatment. The scaffold is obtained by in situ growth of a zeolitic imidazolate framework-8 (ZIF-8) shell on the surface of poly(butylene succinate)/lauric acid (PBS/LA) phase-change fibers (PCFs) to create PCF@ZIF-8. After optimizing the core-shell and phase transition behavior, gold nanorods (GNRs) and doxorubicin hydrochloride (DOX) co-loaded PCF@ZIF-8 scaffolds were shown to significantly enhance in vitro and in vivo anticancer efficacy. In a healthy tissue microenvironment at pH 7.4, the ZIF-8 shell ensures the sustained release of DOX. If the tumor recurs, the acidic microenvironment induces the decomposition of the ZIF-8 shell. Under the second near-infrared (NIR-II) laser treatment, GNR-induced thermal not only directly destroys the relapsed tumor cells but also accelerates DOX release by inducing the phase transition of LA. Our study sheds light on a well-designed programmable-response trigger, which provides a promising strategy for post-operative recurrence prevention of cancer.

Size- and Surface- Dual Engineered Small Polyplexes for Efficiently Targeting Delivery of siRNA

Though siRNA-based therapy has achieved great progress, efficient siRNA delivery remains a challenge. Here, we synthesized a copolymer PAsp(-N=C-PEG)-PCys-PAsp(DETA) consisting of a poly(aspartate) block grafted with comb-like PEG side chains via a pH-sensitive imine bond (PAsp(-N=C-PEG) block), a poly(l-cysteine) block with a thiol group (PCys block), and a cationic poly(aspartate) block grafted with diethylenetriamine (PAsp(DETA) block). The cationic polymers efficiently complexed siRNA into polyplexes, showing a sandwich-like structure with a PAsp(-N=C-PEG) out-layer, a crosslinked PCys interlayer, and a complexing core of siRNA and PAsp(DETA). Low pH-triggered breakage of pH-sensitive imine bonds caused PEG shedding. The disulfide bond-crosslinking and pH-triggered PEG shedding synergistically decreased the polyplexes' size from 75 nm to 26 nm. To neutralize excessive positive charges and introduce the targeting ligand, the polyplexes without a PEG layer were coated with an anionic copolymer modified with the targeting ligand lauric acid. The resulting polyplexes exhibited high transfection efficiency and lysosomal escape capacity. This study provides a promising strategy to engineer the size and surface of polyplexes, allowing long blood circulation and targeted delivery of siRNA.

Effects of proteins on the structure, physicochemical properties, and in vitro digestibility of wheat starch-lauric acid complexes under various cooking methods

Herein, we investigated the effects of gluten proteins (Pr) on the structure, physicochemical properties, and in vitro digestibility of wheat starch-lauric acid (WS-LA) complexes under various cooking methods (steaming, boiling, and baking). There was no ternary complex formation between WS, LA, and Pr in the samples after different cooking methods. Scanning electron microscopy (SEM) and fluorescence microscopy showed variation in size, structure and distribution of WS-LA of WS-LA-Pr samples after cooking. An increase in the intensity of V-type diffraction peak and thermal stability was observed in steamed and baked samples, however, opposite trend was noticed in boiled sample. Additionally, a higher 1022/995 cm^-1 absorbance ratio was noted in WS-LA-Pr sample treated with boiling than other cooking methods. Further, in vitro resistance to enzymatic hydrolysis was improved in samples treated with steaming and baking compared with boiled treated samples. In sum, this study may offer a thorough understanding on how these interactions take place during food processing, to optimize the production and development of new food products with desired microstructure and functionality features.

Biosynthesis of Chlorinated Lactylates in Sphaerospermopsis sp. LEGE 00249

Lactylates are an important group of molecules in the food and cosmetic industries. A series of natural halogenated 1-lactylates, chlorosphaerolactylates (1-4), were recently reported from Sphaerospermopsis sp. LEGE 00249. Here, we identify the cly biosynthetic gene cluster, containing all the necessary functionalities for the biosynthesis of the natural lactylates, based on in silico analyses. Using a combination of stable isotope incorporation experiments and bioinformatic analysis, we propose that dodecanoic acid and pyruvate are the key building blocks in the biosynthesis of 1-4. We additionally report minor analogues of these molecules with varying alkyl chains. This work paves the way to accessing industrially relevant lactylates through pathway engineering.

Effect of moist and dry-heat treatment processes on the structure, physicochemical properties, and in vitro digestibility of wheat starch-lauric acid complexes

Herein, we investigated the impact of moist (steaming and boiling) and dry (baking and microwaving)-heat treatment processes on the structure and physicochemical properties of wheat starch (WS) supplemented with lauric acid (LA). Elemental composition analysis revealed the interplay between WS and LA. Scanning electron microscopy (SEM) and iodine staining revealed that lamellar crystalline structure of WS-LA complexes was improved after moist-heat treatment (relative to samples without any heat treatments); the finding which is at variance to dry-heat treatment process. Additionally, high resistance to thermal decomposition and a lower 1022/995 cm^-1 absorbance ratio were observed in moist-heat treated WS-LA compared with dry-heat samples. Moreover, the V-type diffraction peak intensity and resistance to in vitro enzymatic hydrolysis of samples treated with moist-heat were increased to a greater extent than the dry-heat treated counterparts. In sum, this study would facilitate the application of functional starch-lipid complexes in food necessitated heat treatments.

Effects of cooling rate and complexing temperature on the formation of starch-lauric acid-β-lactoglobulin complexes

The aim of present study was to investigate the effects of cooling rate (3, 5, 10, 15 °C/min) and complexing temperature (50, 60, 70, 80 and 90 °C) on the formation of complexes between wheat starch (WS), lauric acid (LA) and β-lactoglobulin (βLG) in Rapid Visco Analyser (RVA). Higher cooling rate resulted in the higher viscosity peak and final viscosity of WS-LA or WS-LA-βLG complexes than the lower cooling rate during setback of RVA procedure. Results from differential scanning calorimetry (DSC) and Raman spectroscopy showed that larger amount of complexes with lower thermal transition temperatures were formed at higher cooling rate. Higher complexing temperature led to the formation of more complexes with higher thermal transition temperatures. XRD patterns of binary and ternary complexes presented no differences at different cooling rates or different complexing temperatures. We conclude that both higher cooling rate and complexing temperature facilitate the formation of WS-LA and WS-LA-βLG complexes.

Determining binding of polycyclic aromatic hydrocarbons to micelles formed by SDS and SOL using semi-equilibrium dialysis

Micellar enhanced ultra-filtration (MEUF) is a modified ultrafiltration (UF) method that can remove small molecules that are not effectively removed by UF alone. In this work we used a similar semi-equilibrium dialysis (SED) method to characterize two anionic surfactants, sodium dodecyl sulfate (SDS) and sodium laurate (SOL), as MEUF candidates to remove several polycyclic aromatic hydrocarbon (PAH) compounds. These anionic surfactants have low toxicity and are more biodegradable compared to the fairly toxic and persistent cetyltrimethylammonium bromide (CTABr) and similar cationic surfactants, which is important as MEUF surfactants may be present in the treated effluent. The log binding constants (Log K_B) of the PAHs naphthalene, phenanthrene, pyrene and fluorene to SDS ranged from 3.07 to 4.48, which compared well with the previous results for CTABr and indicated that SDS is an excellent candidate for MEUF. The log binding constants for the same PAHs with SOL micelles ranged from 2.11 to 3.53, which suggested that SOL might be adequate for stronger-binding PAH like pyrene and fluorene but less suitable for naphthalene and phenanthrene. The results demonstrated a strong correlation between the Log K_B with one micelle type and the Log K_B with the other, suggesting a common set of properties and interactions are responsible for the binding. Similar to the previous results for CTABr, a significant correlation between Log K_B and Log K_OW values indicates that hydrophobic character is the main driving force for PAH binding with these anionic micelles. This may also be useful for predicting MEUF performance for various compound/surfactant combinations where Log K_B is not known.

Physicochemical properties of pea starch-lauric acid complex modified by maltogenic amylase and pullulanase

An enzymatic method was investigated to initiate a strategy of increasing the branch density of pea starch, thus facilitating the formation of a starch-lipid complex after debranching. When the starch was modified by exposure to maltogenic amylase (MAL) and pullulanase (PUL), lower molecular weight values and higher amylose content resulted compared to the untreated sample. High-performance anion-exchange chromatography results suggested that the average chain length decreased and the branch density increased after the starch received MAL treatment. The diffraction intensities and the total melting enthalpies of the dual-enzyme treated complex were greater than those for other samples when the level of MAL between 4-12 U/g. Fourier transform infrared spectroscopy revealed that more ordered structure was formed in MAL (4/8/12)-PUL-starch-lauric acid (Lau) complexes. Digestive performance analysis indicated that the enzyme resistance of the starch-Lau complex was reinforced by applying the MAL-PUL modification to the starch.

Competing Interactions of Fatty Acids and Monoglycerides Trigger Synergistic Phospholipid Membrane Remodeling

Using quartz crystal microbalance-dissipation and time-lapse fluorescence microscopy, we demonstrate that adding mixtures of lauric acid (LA) and glycerol monolaurate (GML), two of the most biologically active antimicrobial fatty acids and monoglycerides, to a supported lipid bilayer triggers concurrent tubule and bud formation, which unexpectedly results in synergistic phospholipid membrane remodeling that far exceeds the effects of GML or LA alone. Together, GML and LA drive pearling instability, dynamic transformation of buds into tubules and vice versa, and extensive membrane lysis. The most pronounced effects occurred with equimolar concentrations of GML and LA, highlighting that synergistic membrane disruption arises from competition for the lipid supply to buds and tubules and an inability to relieve membrane strains. These findings offer a conceptually new model to explain how fatty acid and monoglyceride interactions can trigger phospholipid membrane remodeling events relevant to various biophysical and biological systems.

Resolving Binding Events on the Multifunctional Human Serum Albumin

Physiological processes rely on initial recognition events between cellular components and other molecules or modalities. Biomolecules can have multiple sites or mode of interaction with other molecular entities, so that a resolution of the individual binding events in terms of spatial localization as well as association and dissociation kinetics is required for a meaningful description. Here we describe a trichromatic fluorescent binding- and displacement assay for simultaneous monitoring of three individual binding sites in the important transporter and binding protein human serum albumin. Independent investigations of binding events by X-ray crystallography and time-resolved dynamics measurements (switchSENSE technology) confirm the validity of the assay, the localization of binding sites and furthermore reveal conformational changes associated with ligand binding. The described assay system allows for the detailed characterization of albumin-binding drugs and is therefore well-suited for prediction of drug-drug and drug-food interactions. Moreover, conformational changes, usually associated with binding events, can also be analyzed.

An open source and reduce expenditure ROS generation strategy for chemodynamic/photodynamic synergistic therapy

The therapeutic effect of reactive oxygen species (ROS)-involved cancer therapies is significantly limited by shortage of oxy-substrates, such as hypoxia in photodynamic therapy (PDT) and insufficient hydrogen peroxide (H2O2) in chemodynamic therapy (CDT). Here, we report a H2O2/O2 self-supplying nanoagent, (MSNs@CaO2-ICG)@LA, which consists of manganese silicate (MSN)-supported calcium peroxide (CaO2) and indocyanine green (ICG) with further surface modification of phase-change material lauric acid (LA). Under laser irradiation, ICG simultaneously generates singlet oxygen and emits heat to melt the LA. The exposed CaO2 reacts with water to produce O2 and H2O2 for hypoxia-relieved ICG-mediated PDT and H2O2-supplying MSN-based CDT, acting as an open source strategy for ROS production. Additionally, the MSNs-induced glutathione depletion protects ROS from scavenging, termed reduce expenditure. This open source and reduce expenditure strategy is effective in inhibiting tumor growth both in vitro and in vivo, and significantly improves ROS generation efficiency from multi-level for ROS-involved cancer therapies.

Lipophilized Epigallocatechin Gallate Derivative Exerts Anti-Proliferation Efficacy through Induction of Cell Cycle Arrest and Apoptosis on DU145 Human Prostate Cancer Cells

Epigallocatechin gallate (EGCG) is the predominant tea polyphenol and it exhibits a hydrophilic character. The lipophilized EGCG derivative (LEGCG) was synthesized by enzymatic esterification of EGCG with lauric acid to enhance its bioactivity. The tetralauroyl EGCG was confirmed by high-performance liquid chromatography-tandem mass spectrometry and further identified as 3', 5', 3″, 5″-4-O-lauroyl EGCG by 1H and 13C nuclear magnetic resonance. The anti-proliferation effect of LEGCG on DU145 human prostate carcinoma cells was evaluated by MTT assay. In addition, the underlying molecular mechanism by which LEGCG exerts anti-proliferation efficacy was elucidated by flow cytometry and immunoblot analysis. Results suggested that LEGCG exhibited a dose-dependent anti-proliferation effect on DU145 cells by G0/G1 phase arrest and induction of apoptosis. LEGCG induced cell cycle arrest via p53/p21 activation, which down-regulated the cyclin D1 and CDK4 expression. In addition, LEGCG induced apoptosis by increasing the Bax/Bcl-2 ratio, the cytochrome c release, and the caspases cleavage on DU145 cells. The results provide theoretical support to prevent prostate cancer with LEGCG.

Cytochrome P450 119 Compounds I Formed by Chemical Oxidation and Photooxidation Are the Same Species

Compound I from cytochrome P450 119 prepared by the photooxidation method involving peroxynitrite oxidation of the resting enzyme to Compound II followed by photooxidation to Compound I was compared to Compound I generated by m-chloroperoxybenzoic acid (MCPBA) oxidation of the resting enzyme. The two methods gave the same UV/Visible spectra, the same products from oxidations of lauric acid and palmitic acid and their (ω-2,ω-2,ω-3,ω-3)-tetradeuterated analogues, and the same kinetics for oxidations of lauric acid and caprylic acid. The experimental identities between the transients produced by the two methods leave no doubt that the same Compound I species is formed by the two methods.

Anti-leishmanial activity of Brevinin 2R and its Lauric acid conjugate type against L. major: In vitro mechanism of actions and in vivo treatment potentials

Leishmaniasis, as a major health problem in tropical and sub-tropical areas in the world, needs novel, safe, nontoxic and plausible therapeutic solutions for its control. As a part of innate immune system, natural antimicrobial peptides have a potential to be used as new generation of antibiotics especially after persistent resistance of conventional antimicrobial agents. Brevinin 2R, a member of Defensin families of host defense peptides, showed promising effects against bacterial and fungal infections as well as cancerous cell lines. In the current research, the anti-leishmanial effect of Brevinin 2R and its lauric acid conjugate was investigated against Leishmania major (L. major) parasite. The data revealed that, conjugation of fatty acid to Brevinin 2R, strengthen its effect on L. major promastigotes as well as toxicity and hemolytic effect. These peptides showed anitleishmanial activity through cell membrane disruption and changes in the electrical and mitochondrial membrane potential. No signs of apoptosis induction or caspase activation were detected. Despite its hemolytic and cytotoxic effect in in vitro conditions, lauric acid- Brevinin 2R (L- Brevinin 2R) did not show site specific adverse reactions in animal model. Treatment course with L- Brevinin 2R in the L. major infected mice exhibited decreased parasite load in the lymph nodes adjacent to the infected site despite cytokine production profile and footpad swelling data.

Seeking novel drugs against leishmaniasis is a necessity due to inefficiency of current medications. Brevinin 2R, as a non-hemolytic natural antimicrobial peptide, was effective against vast majority of bacterial and fungal infections as well as cancerous cell lines. In this regard in the current study, the efficacy of Brevinin 2R and its lauric acid conjugate version were studied against L. major parasite growth inhibition at in vitro and in animal model. The results exhibited that, conjugation of fatty acid to Brevinin 2R exacerbated anti-leishmanial effect. L- Brevinin 2R resolved the promastigotes through membrane disruption and changes in the membrane and mitochondrial potential. Also, L- Brevinin 2R was able to limit successfully the parasite load in the lymph nodes of L. major infected animals.

Structural basis of DSF recognition by its receptor RpfR and its regulatory interaction with the DSF synthase RpfF

The diffusible signal factors (DSFs) are a family of quorum-sensing autoinducers (AIs) produced and detected by numerous gram-negative bacteria. The DSF family AIs are fatty acids, differing in their acyl chain length, branching, and substitution but having in common a cis-2 double bond that is required for their activity. In both human and plant pathogens, DSFs regulate diverse phenotypes, including virulence factor expression, antibiotic resistance, and biofilm dispersal. Despite their widespread relevance to both human health and agriculture, the molecular basis of DSF recognition by their cellular receptors remained a mystery. Here, we report the first structure-function studies of the DSF receptor regulation of pathogenicity factor R (RpfR). We present the X-ray crystal structure of the RpfR DSF-binding domain in complex with the Burkholderia DSF (BDSF), which to our knowledge is the first structure of a DSF receptor in complex with its AI. To begin to understand the mechanistic role of the BDSF-RpfR contacts observed in the biologically important complex, we have also determined the X-ray crystal structure of the RpfR DSF-binding domain in complex with the inactive, saturated isomer of BDSF, dodecanoic acid (C12:0). In addition to these ligand-receptor complex structures, we report the discovery of a previously overlooked RpfR domain and show that it binds to and negatively regulates the DSF synthase regulation of pathogenicity factor F (RpfF). We have named this RpfR region the RpfF interaction (FI) domain, and we have determined its X-ray crystal structure alone and in complex with RpfF. These X-ray crystal structures, together with extensive complementary in vivo and in vitro functional studies, reveal the molecular basis of DSF recognition and the importance of the cis-2 double bond to DSF function. Finally, we show that throughout cellular growth, the production of BDSF by RpfF is post-translationally controlled by the RpfR N-terminal FI domain, affecting the cellular concentration of the bacterial second messenger bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP). Thus, in addition to describing the molecular basis for the binding and specificity of a DSF for its receptor, we describe a receptor-synthase interaction regulating bacterial quorum-sensing signaling and second messenger signal transduction.

Continuous processing of phase-change materials into uniform nanoparticles for near-infrared-triggered drug release

We report a method based on interfacial, anti-solvent-induced precipitation in a fluidic device for the continuous and scalable processing of phase-change materials (PCMs) into uniform nanoparticles with controlled diameters in the range of 10-100 nm. A eutectic mixture of lauric acid and stearic acid, with a well-defined melting point at 39 °C, serves as an example to demonstrate the concept. In the fluidic device, a coaxial flow is created by introducing a PCM solution in ethanol and a lipid solution in water (the anti-solvent) as the focused and focusing phases, respectively. The formation of lipid-capped PCM nanoparticles is governed by diffusion-controlled mixing of ethanol and water. During the production, both doxorubicin (DOX, an anticancer drug) and indocyanine green (ICG, a near-infrared dye) can be readily loaded into the PCM nanoparticles to give a smart drug release system. Upon irradiation with near-infrared light, the photothermal heating caused by ICG can melt the PCM and thereby trigger the release of DOX. This work not only provides a new technique for the continuous processing of PCMs and other soft materials into uniform nanoparticles with controlled sizes but also demonstrates a biocompatible system for controlled release and related applications.

The mechanism of lauric acid-modified protein nanocapsules escape from intercellular trafficking vesicles and its implication for drug delivery

Protein nanocapsules have exhibited promising potential applications in the field of protein drug delivery. A major issue with various promising nano-sized biotherapeutics including protein nanocapsules is that owing to their particle size they are subject to cellular uptake via endocytosis, and become entrapped and then degraded within endolysosomes, which can significantly impair their therapeutic efficacy. In addition, many nano-sized biotherapeutics could be also sequestered by autophagosomes and degraded through the autolysosomal pathway. Thus, a limiting step in achieving an effective protein therapy is to facilitate the endosomal escape and auto-lysosomal escape to ensure cytosolic delivery of the protein drugs. Here, we prepared a protein nanocapsule based on BSA (nBSA) and the BSA nanocapsules modified with a bilayer of lauric acid (LA-nBSA) to investigate the escape effects from the endosome and autophagosome. The size distribution of nBSA and LA-nBSA analyzed using DLS presents a uniform diameter centered at 10 nm and 16 nm. The data also showed that FITC-labeled nBSA and LA-nBSA were taken up by the cells mainly through Arf-6-dependent endocytosis and Rab34-mediated macropinocytosis. In addition, LA-nBSA could efficiently escape from endosomal before the degradation in endo-lysosomes. Autophagy could also sequester the LA-nBSA through p62 autophagosome vesicles. These two types of nanocapsules underwent different intracellular destinies and lauric acid (LA) coating played a vital role in intracellular particle retention. In conclusion, the protein nanocapsules modified with LA could enhance the protein nanocapsules escape from intercellular trafficking vesicles, and protect the protein from degradation by the lysosomes.

Development of Novel Microparticles for Effective Delivery of Thymol and Lauric Acid to Pig Intestinal Tract

Antibiotics have been widely supplemented in feeds at subtherapeutic concentrations to prevent postweaning diarrhea and increase the overall productivity of pigs. However, the emergence of antimicrobial-resistant bacteria worldwide has made it urgent to minimize the use of in-feed antibiotics. The development of promising alternatives to in-feed antibiotics is crucial for maintaining the sustainability of swine production. Both medium-chain fatty acids (MCFA) and essential oils exhibit great potential to postweaning diarrhea; however, their direct inclusion has compromised efficacy because of several factors including low stability, poor palatability, and low availability in the lower gut. Therefore, the objective of this study was to develop a formulation of microparticles to deliver a model of essential oil (thymol) and MCFA (lauric acid). The composite microparticles were produced by the incorporation of starch and alginate through a melt-granulation process. The release of thymol and lauric acid from the microparticles was in vitro determined using simulated salivary fluid (SSF), simulated gastric fluid (SGF), and simulated intestinal fluid (SIF), consecutively. The microparticles prepared with 2% alginate solution displayed a slow release of thymol and lauric acid in the SSF (21.2 ± 2.3%; 36 ± 1.1%), SGF (73.7 ± 6.9%; 54.8 ± 1.7%), and SIF (99.1 ± 1.2%; 99.1 ± 0.6%), respectively, whereas, the microparticles without alginate showed a rapid release of thymol and lauric acid from the SSF (79.9 ± 11.8%; 84.9 ± 9.4%), SGF (92.5 ± 3.5%; 75.8 ± 5.9%), and SIF (93.3 ± 9.4%; 93.3 ± 4.6%), respectively. The thymol and lauric acid in the developed microparticles with or without alginate both exhibited excellent stabilities (>90%) during being stored at 4 °C for 12 weeks and after being stored at room temperature for 2 weeks. These results evidenced that the approach developed in the present study could be potentially employed to deliver thymol and lauric acid to the lower gut of pigs, although further in vivo investigations are necessary to validate the efficacy of the microparticles.

A Fatty Acids Mixture Reduces Anxiety-Like Behaviors in Infant Rats Mediated by GABAA Receptors

Fatty acids (C6-C18) found in human amniotic fluid, colostrum, and maternal milk reduce behavioral indicators of experimental anxiety in adult Wistar rats. Unknown, however, is whether the anxiolytic-like effects of fatty acids provide a natural mechanism against anxiety in young offspring. The present study assessed the anxiolytic-like effect of a mixture of lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, elaidic acid, and linoleic acid in Wistar rats on postnatal day 28. Infant rats were subjected to the elevated plus maze, defensive burying test, and locomotor activity test. Diazepam was used as a reference anxiolytic drug. A group that was pretreated with picrotoxin was used to explore the participation of γ-aminobutyric acid-A (GABAA) receptors in the anxiolytic-like effects. Similar to diazepam, the fatty acid mixture significantly increased the frequency of entries into and time spent on the open arms of the elevated plus maze and decreased burying behavior in the defensive burying test, without producing significant changes in spontaneous locomotor activity. These anxiolytic-like effects were blocked by picrotoxin. Results suggest that these fatty acids that are contained in maternal fluid may reduce anxiety-like behavior by modulating GABAergic neurotransmission in infant 28-day-old rats.

Coconut phytocompounds inhibits polyol pathway enzymes: Implication in prevention of microvascular diabetic complications

Coconut oil (CO), the primary choice of cooking purposes in the south Asian countries, is rich in medium chain saturated fatty acids, especially lauric acid (50-52%). The oil has high medicinal use in Ayurvedic system and known to contain polyphenolic antioxidants. Studies have reported that CO improves insulin sensitivity and shows hypoglycemic effect. However, there is no information regarding its effect on chronic diabetic complications including retinopathy and nephropathy is available. The secondary diabetic complications are mediated by the activation of polyol pathway, where aldose reductase (AR) plays crucial role. In this study, in silico analysis has been used to screen the effect of CO as well as its constituents, MCFAs and phenolic compounds, for targeting the molecules in polyol pathway. The study revealed that lauric acid (LA) interacts with AR and DPP-IV of polyol pathway and inhibits the activity of these enzymes. Validation studies using animal models confirmed the inhibition of AR and SDH in wistar rats. Further, the LA dose dependently reduced the expression of AR in HCT-15 cells. Together, the study suggests the possible role of CO, particularly LA in reducing secondary diabetic complications.

Influence of Alkylammonium Acetate Buffers on Protein-Ligand Noncovalent Interactions Using Native Mass Spectrometry

We investigate the influence of three volatile alkylammonium acetate buffers on binding affinities for protein-ligand interactions determined by native electrospray ionization-mass spectrometry (ESI-MS). Four different types of proteins were chosen for this study. A charge-reduction effect was observed for all the cases studied, in comparison to the ions formed in ammonium acetate solution. When increasing the collision energy, the complexes of trypsin and the ligand were found to be more stable when sprayed from alkylammonium acetate buffers than from ammonium acetate. The determined dissociation constant (K_d) also exhibited a drop (up to 40%) when ammonium acetate was replaced by alkylammonium acetate buffers for the case of lysozyme and the ligand. The prospective uses of these ammonium acetate analogs in native ESI-MS are discussed in this paper as well. Graphical Abstract ᅟ.

Crystal structure of a putrescine aminotransferase from Pseudomonas sp. strain AAC

The putrescine aminotransferase KES24511 from Pseudomonas sp. strain AAC was previously identified as an industrially relevant enzyme based on the discovery that it is able to promiscuously catalyse the transamination of 12-aminododecanoic acid. Here, the cloning, heterologous expression, purification and successful crystallization of the KES24511 protein are reported, which ultimately generated crystals adopting space group I2. The crystals diffracted X-rays to 2.07 Å resolution and data were collected using the microfocus beamline of the Australian Synchrotron. The structure was solved using molecular replacement, with a monomer from PDB entry 4a6t as the search model.

Straightforward Protocol for Gel-Free Proteomic Analysis of Adipose Tissue

After conducting systematic and quantitative comparisons of different sample preparation techniques regarding their capability to efficiently and reproducibly recover proteins from biopsies, we present here our superior protocol for extracting proteins from low amounts of adipose tissue. Adipose tissue as a matrix in bottom-up proteomics is challenging due to the extremely high lipid content.The lysis buffer utilized contains the detergent sodium deoxycholate, which does not impair the activity of trypsin and therefore enables direct digestion without detergent removal steps. The resulting workflow is time saving, cost efficient, easy to perform, and it can also be applied to other hydrophobic samples.

Long-Chain Fatty Acids Elicit a Bitterness-Masking Effect on Quinine and Other Nitrogenous Bitter Substances by Formation of Insoluble Binary Complexes

We have previously found that fatty acids can mask the bitterness of certain nitrogenous substances through direct molecular interactions. Using isothermal titration calorimetry, we investigated the interactions between sodium oleate and 22 bitter substances. The hydrochloride salts of quinine, promethazine, and propranolol interacted strongly with fatty acids containing 12 or more carbon atoms. The (1)H NMR spectra of these substances, obtained in the presence of the sodium salts of the fatty acids in dimethyl sulfoxide, revealed the formation of hydrogen bonds between the nitrogen atoms of the bitter substances and the carboxyl groups of the fatty acids. When sodium laurate and the hydrochloride salt of quinine were mixed in water, an equimolar complex formed as insoluble heterogeneous needlelike crystals. These results suggested that fatty acids interact directly with bitter substances through hydrogen bonds and hydrophobic interactions to form insoluble binary complexes that mask bitterness.

Tangential Flow Ultrafiltration Allows Purification and Concentration of Lauric Acid-/Albumin-Coated Particles for Improved Magnetic Treatment

Superparamagnetic iron oxide nanoparticles (SPIONs) are frequently used for drug targeting, hyperthermia and other biomedical purposes. Recently, we have reported the synthesis of lauric acid-/albumin-coated iron oxide nanoparticles SEON(LA-BSA), which were synthesized using excess albumin. For optimization of magnetic treatment applications, SPION suspensions need to be purified of excess surfactant and concentrated. Conventional methods for the purification and concentration of such ferrofluids often involve high shear stress and low purification rates for macromolecules, like albumin. In this work, removal of albumin by low shear stress tangential ultrafiltration and its influence on SEON(LA-BSA) particles was studied. Hydrodynamic size, surface properties and, consequently, colloidal stability of the nanoparticles remained unchanged by filtration or concentration up to four-fold (v/v). Thereby, the saturation magnetization of the suspension can be increased from 446.5 A/m up to 1667.9 A/m. In vitro analysis revealed that cellular uptake of SEON(LA-BSA) changed only marginally. The specific absorption rate (SAR) was not greatly affected by concentration. In contrast, the maximum temperature Tmax in magnetic hyperthermia is greatly enhanced from 44.4 °C up to 64.9 °C by the concentration of the particles up to 16.9 mg/mL total iron. Taken together, tangential ultrafiltration is feasible for purifying and concentrating complex hybrid coated SPION suspensions without negatively influencing specific particle characteristics. This enhances their potential for magnetic treatment.

Acylation of Antioxidant of Bamboo Leaves with Fatty Acids by Lipase and the Acylated Derivatives' Efficiency in the Inhibition of Acrylamide Formation in Fried Potato Crisps

This study selectively acylated the primary hydroxyl groups on flavonoids in antioxidant of bamboo leaves (AOB) using lauric acid with Candida antarctica lipase B in tert-amyl-alcohol. The separation and isolation of acylated derivatives were performed using silica gel column chromatography with a mixture of dichloromethane/diethyl ether/methanol as eluents. Both thin layer chromatography and high-performance liquid chromatography analyses confirmed the high efficiency of the isolation process with the purified orientin-6″-laurate, isoorientin-6″-laurate, vitexin-6″-laurate, and isovitexin-6″-laurate that were obtained. The addition of AOB and acylated AOB reduced acrylamide formation in fried potato crisps. Results showed that 0.05% AOB and 0.05% and 0.1% acylated AOB groups significantly (p < 0.05) reduced the content of acrylamide in potato crisps by 30.7%, 44.5%, and 46.9%, respectively.

Composition and structural transitions of polyelectrolyte-surfactant complexes in the presence of fatty acid studied by NMR and cryo-SEM

Insoluble complexes formed when a cationic polyelectrolyte is neutralized by the oppositely charged surfactant sodium dodecylethersulfate (SDES) in the presence and absence of lauric acid (LA) have been examined directly using NMR spectroscopy and cryo-SEM. Below the SDES critical micelle concentration (CMC') the insoluble complex contains about 10 times more water than just above CMC'. This is related to a structural transition of the complex, where water is contained mainly in larger compartments below CMC' and then mainly in narrower compartments above CMC'. The structure of the complex's solid matrix was monitored by recording two-dimensional T2-diffusion correlation spectra of the water proton resonance, which reveal the presence of several different water environments which correspond to different complex structures. Structural features in the micrometer range were confirmed using cryo-SEM. When LA is present, the larger water compartments seen below CMC' are to some extent present in the entire SDES concentration range, which is not the case in the absence of LA. Furthermore, the inclusion of LA into the SDES aggregates above CMC' leads to a lamellar sheetlike organization of the polyelectrolyte-stabilized surfactant phase. In the absence of LA, a stringy network of fibers is seen in cryo-SEM images, indicating a spherical or rodlike SDES phase. Consequently, the complex without LA holds about 1.7-1.9 times more water than the complex with LA above the SDES CMC'. T1 relaxation, (13)C chemical shifts, and (1)H resonance line widths of SDES in the system support the above observations. The combination of MAS NMR, T2-diffusion correlation, and cryo-SEM proved to be an effective method for studying structural transitions in the surfactant-polyelectrolyte(-LA) insoluble complexes.

Solid Lipid Nanoparticles Loaded with Retinoic Acid and Lauric Acid as an Alternative for Topical Treatment of Acne Vulgaris

Topical therapy is the first choice for the treatment of mild to moderate acne and all-trans retinoic acid is one of the most used drugs. The combination of retinoids and antimicrobials is an innovative approach for acne therapy. Recently, lauric acid, a saturated fatty acid, has shown strong antimicrobial activity against Propionibacterium acnes. However, topical application of retinoic acid is followed by high incidence of side-effects, including erythema and irritation. Solid lipid nanoparticles represent an alternative to overcome these side-effects. This work aims to develop solid lipid nanoparticles loaded with retinoic acid and lauric acid and evaluate their antibacterial activity. The influence of lipophilic stearylamine on the characteristics of solid lipid nanoparticles was investigated. Solid lipid nanoparticles were characterized for size, zeta potential, encapsulation efficiency, differential scanning calorimetry and X-ray diffraction. The in vitro inhibitory activity of retinoic acid-lauric acid-loaded solid lipid nanoparticles was evaluated against Propionibacterium acnes, Staphylococcus aureus and Staphylococcus epidermidis. High encapsulation efficiency was obtained at initial time (94 ± 7% and 100 ± 4% for retinoic acid and lauric acid, respectively) and it was demonstrated that lauric acid-loaded-solid lipid nanoparticles provided the incorporation of retinoic acid. However, the presence of stearylamine is necessary to ensure stability of encapsulation. Moreover, retinoic acid-lauric acid-loaded solid lipid nanoparticles showed growth inhibitory activity against Staphylococcus epidermidis, Propionibacterium acnes and Staphylococcus aureus, representing an interesting alternative for the topical therapy of acne vulgaris.

Loading capacity and interaction of DNA binding on catanionic vesicles with different cationic surfactants

Cationic and anionic (catanionic) vesicles were constructed from the mixtures of sodium laurate (SL) and alkyltrimethylammonium bromide (CnTAB, n = 12, 14, and 16) and were used to control the loading capacity of DNA. The binding saturation point (BSP) of DNA to catanionic vesicles increases with the chain length of cationic surfactants, which is at 1.0, 1.3 and 1.5 for CnTAB with n = 12, 14, and 16, respectively. Our measurements showed that the loading capacity and affinity of DNA can be controlled by catanionic vesicles. It increases with the chain length of cationic surfactants. Because of a large reduction in surface charge density, catanionic vesicles are prone to undergo re-aggregation or fusion with the addition of DNA. DNA molecules can still maintain original coil state during the interaction with catanionic CnTAL vesicles. (1)H NMR data reveals that the obvious dissociation of anionic ions, L(-), from catanionic C14TAL vesicles is due to the interaction with DNA; however, this phenomenon cannot be observed in C12TAB-SL vesicles. Agarose gel electrophoresis (AGE) results demonstrate that the electrostatic interaction between the two oppositely charged cationic and anionic surfactants is stronger than that between DNA and cationic surfactant, CnTAB (n = 12, 14, and 16). Not only is the dissociation of L(-) simply determined by the charge competition, but it also depends largely on the variations in the surface charge density as well as the cationic and anionic surfactant competing ability in geometry configuration of catanionic vesicles. The complicated interaction between DNA and catanionic vesicles induces the deformation of cationic vesicles. Our results should provide clear guidance for choosing more proper vectors for DNA delivery and gene therapy in cell experiments.

Efficient synthesis and characterization of ergosterol laurate in a solvent-free system

Ergosterol and its derivatives have attracted much attention for a variety of health benefits, such as anti-inflammatory and antioxidant activities. However, ergosterol esters are advantageous because this compound has better solubility than the free ergosterol. In this work, ergosterol laurate was efficiently synthesized for the first time by direct esterification in a solvent-free system. The desired product was purified, characterized by Fourier transform infrared spectroscopy, mass spectrometry, and nuclear magnetic resonance, and finally confirmed to be ergosterol laurate. Meanwhile, the effect of various catalysts, catalyst dose, reaction temperature, substrate molar ratio, and reaction time were studied. Both the conversion of ergosterol and the selectivity of the desired product can reach above 89% under the selected conditions: sodium dodecyl sulfate + hydrochloric acid as the catalyst, 2:1 molar ratio of lauric acid/ergosterol, catalyst dose of 4% (w/w), 120 °C, and 2 h. The oil solubility of ergosterol and its laurate was also compared. The results showed that the solubility of ergosterol in oil was significantly improved by direct esterification with lauric acid, thus greatly facilitating the incorporation into a variety of oil-based systems.

Development of a lauric acid/albumin hybrid iron oxide nanoparticle system with improved biocompatibility

The promising potential of superparamagnetic iron oxide nanoparticles (SPIONs) in various nanomedical applications has been frequently reported. However, although many different synthesis methods, coatings, and functionalization techniques have been described, not many core-shell SPION drug delivery systems are available for clinicians at the moment. Here, bovine serum albumin was adsorbed onto lauric acid-stabilized SPIONs. The agglomeration behavior, zeta potential, and their dependence on the synthesis conditions were characterized with dynamic light scattering. The existence and composition of the core-shell-matrix structure was investigated by transmission electron microscopy, Fourier transform infrared spectroscopy, and zeta potential measurements. We showed that the iron oxide cores form agglomerates in the range of 80 nm. Moreover, despite their remarkably low tendency to aggregate even in a complex media like whole blood, the SPIONs still maintained their magnetic properties and were well attractable with a magnet. The magnetic properties were quantified by vibrating sample magnetometry and a superconducting quantum interference device. Using flow cytometry, we further investigated the effects of the different types of nanoparticle coating on morphology, viability, and DNA integrity of Jurkat cells. We showed that by addition of bovine serum albumin, the toxicity of nanoparticles is greatly reduced. We also investigated the effect of the particles on the growth of primary human endothelial cells to further demonstrate the biocompatibility of the particles. As proof of principle, we showed that the hybrid-coated particles are able to carry payloads of up to 800 μg/mL of the cytostatic drug mitoxantrone while still staying colloidally stable. The drug-loaded system exhibited excellent therapeutic potential in vitro, exceeding that of free mitoxantrone. In conclusion, we have synthesized a biocompatible ferrofluid that shows great potential for clinical application. The synthesis is straightforward and reproducible and thus easily translatable into a good manufacturing practice environment.

CYP77A19 and CYP77A20 characterized from Solanum tuberosum oxidize fatty acids in vitro and partially restore the wild phenotype in an Arabidopsis thaliana cutin mutant

Cutin and suberin represent lipophilic polymers forming plant/environment interfaces in leaves and roots. Despite recent progress in Arabidopsis, there is still a lack on information concerning cutin and suberin synthesis, especially in crops. Based on sequence homology, we isolated two cDNA clones of new cytochrome P450s, CYP77A19 and CYP77A20 from potato tubers (Solanum tuberosum). Both enzymes hydroxylated lauric acid (C12:0) on position ω-1 to ω-5. They oxidized fatty acids with chain length ranging from C12 to C18 and catalysed hydroxylation of 16-hydroxypalmitic acid leading to dihydroxypalmitic (DHP) acids, the major C16 cutin and suberin monomers. CYP77A19 also produced epoxides from linoleic acid (C18:2). Exploration of expression pattern in potato by RT-qPCR revealed the presence of transcripts in all tissues tested with the highest expression in the seed compared with leaves. Water stress enhanced their expression level in roots but not in leaves. Application of methyl jasmonate specifically induced CYP77A19 expression. Expression of either gene in the Arabidopsis null mutant cyp77a6-1 defective in flower cutin restored petal cuticular impermeability. Nanoridges were also observed in CYP77A20-expressing lines. However, only very low levels of the major flower cutin monomer 10,16-dihydroxypalmitate and no C18 epoxy monomers were found in the cutin of the complemented lines.

Controlled release properties of zein-fatty acid blend films for multiple bioactive compounds

To develop edible films having controlled release properties for multiple bioactive compounds, hydrophobicity and morphology of zein films were modified by blending zein with oleic (C18:1)Δ⁹, linoleic (C18:2)Δ(9,12), or lauric (C₁₂) acids in the presence of lecithin. The blend zein films showed 2-8.5- and 1.6-2.9-fold lower initial release rates for the model active compounds, lysozyme (LYS) and (+)-catechin (CAT), than the zein control films, respectively. The change of fatty acid chain length affected both CAT and LYS release rates while the change of fatty acid double bond number affected only the CAT release rate. The film morphologies suggested that the blend films owe their controlled release properties mainly to the microspheres formed within their matrix and encapsulation of active compounds. The blend films showed antilisterial activity and antioxidant activity up to 81 μmol Trolox/cm². The controlled release of multiple bioactive compounds from a single film showed the possibility of combining application of active and bioactive packaging technologies and improving not only safety and quality but also health benefits of packed food.

Effects of heat treatment and moisture contents on interactions between lauric acid and starch granules

This study aimed to understand the effects of the moisture content of granular normal cornstarch (NC), heat treatment at 80 °C, and order of adding lauric acid (LA) to starch before or after the heat treatment on the physicochemical properties and digestibility of the starch. LA was added to NC priority heated with different moisture contents (10, 20, 30, 40, and 50%) or added to dried NC and then heated with different moisture contents. The hydrothermal/LA treatments increased the pasting temperature but decreased the peak viscosity of the NC. Light and scanning electron microscopy revealed that the addition of LA retarded gelatinization. The hydrothermal/LA treatments changed the X-ray pattern of the NC to a mixture of A- and V-type patterns. The thermal property and digestibility analysis showed that 40% was the optimum moisture content for the formation of the amylose-LA complex and adding LA prior to heating the NC favored the formation of slowly digestible starch.

Formation of worm-like micelles in mixed N-hexadecyl-N-methylpyrrolidinium bromide-based cationic surfactant and anionic surfactant systems

Through the descriptive and rheological characterization of worm-like micelles formed by N-hexadecyl-N-methylpyrrolidinium bromide and sodium laurate, the formation and properties of the worm-like micelles were affected by the concentrations of sodium laurate and temperature. Additionally, cryogenic transmission electron microscopy images further validated the formation of worm-like micelles.

Role of water structure on the high pressure micellization and phase transformations of sodium dodecanoate aqueous solutions

The aim of this work is to study the micelle formation and possible subsequent transformations of sodium dodecanoate aggregates in aqueous solutions at pressures up to 700 MPa. This pressure range is much larger than in most available studies on surfactant solutions and allows for evaluating the possible effect of the low-density to high-density water transformation on the aggregative behavior of the surfactant. The speed-of-sound and attenuation coefficient were determined at 298.15 K as a function of pressure at concentrations up to 0.13 mol kg(-1) in water. The speed-of-sound behavior with concentration is maintained up to pressures around 350 MPa. The attenuation coefficient, initially insensitive to pressure, exhibits a sudden increase around 250 MPa, reaching a maximum around 350 MPa and a plateau above 500 MPa in the case of the highest studied surfactant concentrations. From the analysis of the changes observed in these properties, it was possible to extend the concentration-pressure phase diagram of sodium dodecanoate at constant temperature. Some peculiarities found were: (1) the critical micellar concentration reaches a maximum around 170 MPa, (2) the micellar phase disappears above 400 MPa, (3) a phase transformation starts around 250 MPa, setting the solubility limit of the surfactant at concentrations around 0.06 mol kg(-1) in this pressure region, and (4) further transformations occur between 350 and 500 MPa. We discuss in length the possibility that such transformations might be driven by structural changes linked to the so-called low-density-water to high-density-water transition.

Multiplexed analysis of cage and cage free chicken egg fatty acids using stable isotope labeling and mass spectrometry

Binary stable isotope labeling couple with LC-ESI-MS has been used as a powerful non-targeted approach for the relative quantification of lipids, amino acids, and many other important metabolite classes. A multiplexed approach using three or more isotopic labeling reagents greatly reduces analytical run-time while maintaining excellent sensitivity and reproducibility. Three isotopic cholamine labeling reagents have been developed to take advantage of the pre-ionized character of cholamine, for ESI, and the ease by which stable isotopes can be incorporated into the cholamine structure. These three cholamine labeling reagents have been used to relatively quantify three fatty acid samples simultaneously. The quantification resulted in the observation of 12 fatty acids that had an average absolute error of 0.9% and an average coefficient of variation of 6.1%. Caged versus cage-free isotope labeling experiments showed that cage-free eggs have an increased level of omega-3 fatty acids as compared to caged eggs. This multiplexed fatty acid analysis provides an inexpensive and expedited tool for broad-based lipid profiling that will further aid discoveries in the mechanisms of fatty acid action in cells.

Study of reaction parameters and kinetics of esterification of lauric acid with butanol by immobilized Candida antarctica lipase

Esterification of lauric acid with n-butanol, catalyzed by immobilized Candida antarctica lipase (CAL) in aqueous-organic biphasic solvent system was studied. Effects of various reaction parameters on esterification were investigated, such as type and amount of solvent, amount of buffer, pH, temperature, speed of agitation, amount of enzyme, butanol and lauric acid. The most suitable reaction conditions for esterification were observed at 50 degrees C and pH 7.0 using 5000 micromoles of lauric acid, 7000 pmoles of butanol, 0.25 ml phosphate buffer, 1 ml of isooctane as the solvent and 50 mg of immobilized enzyme in the reaction medium at agitation speed of 150 rpm. Maximum esterification of 96.36% was acheived in 600 min of reaction time at n-butanol to lauric acid molar ratio of 1: 0.7. Kinetic study for the esterification of lauric acid with n-butanol using immobilized CAL was carried out and the kinetic constants were estimated by using non-linear regression method. The estimated value of Michaelis kinetic constants for butanol (KmBt) and acid (KmAc) were 451.56 (M) and 4.7 x 10(-7)(M), respectively and the value of dissociation constant (KBt) of the butanol-lipase complex was 9.41 x 10(7)(M). The estimated constants agreed fairly well with literature data.

Coherent longitudinal acoustic phonons in three-dimensional supracrystals of cobalt nanocrystals

We use broadband picosecond acoustics to detect longitudinal acoustic phonons with few-gigahertz frequency in three-dimensional supracrystals (with face-centered cubic lattice) of 7 nm cobalt nanocrystal spheres. In full analogy with atomic crystals, where longitudinal acoustic phonons propagate with the speed of sound through coherent movements of atoms of the lattice out of their equilibrium positions, in these supracrystals atoms are replaced by (uncompressible) nanocrystals and atomic bonds by coating agents (carbon chains) that act like mechanical springs holding together the nanocrystals. By repeating the measurements at different laser angles of incidence it was possible to accurately determine both the index of refraction of the supracrystal (n = 1.26 ± 0.03) and the room-temperature longitudinal speed of sound (v(s)= 1235 ± 12 m/s), which is quite low due to the heavy weight of the spheres (with respect to atoms in a crystal) and the soft carbon chains (with respect to atomic bonds). Interestingly, the speed of sound inside the supracrystal was found to dramatically increase by decreasing the sample temperature due to a change in the stiffness of the dodecanoic acid chains which coat the Co nanocrystals.

Enzymatic hydrolysis preparation of mono-O-lauroylsucrose via a mono-O-lauroylraffinose intermediate

1'-O-Lauroylsucrose and 6'-O-lauroylsucrose were formed through hydrolysis of the C-6″ galactose group of 1'-O-lauroylraffinose and 6'-O-lauroylraffinose, respectively, in the presence of α-galactosidase. The enzymatic hydrolysis of 1'-O-lauroylraffinose and 6'-O-lauroylraffinose is discussed in detail. Acetic acid-sodium acetate was chosen as the buffer solution of the enzymatic hydrolysis reaction. The optimum conditions for the enzymatic hydrolysis reaction were as follows: buffer solution, pH 3.8; enzymatic time, 48 h; and enzymatic temperature, 37 °C. Under the optimal process conditions, the efficiency of α-galactosidase was ca. 82.6%. The isomers were fully compared in solubility, hydrophile-lipophile balance (HLB) values, critical micelle concentration (CMC), and thermal stability. The results showed that all lauroylsucrose isomers have similar solubilities in polar solvent, HLB values, CMC values, and thermal stabilities.

In vivo treatment of Propionibacterium acnes infection with liposomal lauric acids

Propionibacterium acnes (P. acnes) is a Gram-positive bacterium strongly associated with acne infection. While many antimicrobial agents have been used in clinic to treat acne infection by targeting P. acnes, these existing anti-acne agents usually produce considerable side effects. Herein, the development and evaluation of liposomal lauric acids (LipoLA) is reported as a new, effective and safe therapeutic agent for the treatment of acne infection. By incorporating lauric acids into the lipid bilayer of liposomes, it is observed that the resulting LipoLA readily fuse with bacterial membranes, causing effective killing of P. acnes by disrupting bacterial membrane structures. Using a mouse ear model, we demonstrated that the bactericidal property of LipoLA against P. acne is well preserved at physiological conditions. Topically applying LipoLA in a gel form onto the infectious sites leads to eradication of P. acnes bacteria in vivo. Further skin toxicity studies show that LipoLA does not induce acute toxicity to normal mouse skin, while benzoyl peroxide and salicylic acid, the two most popular over-the-counter acne medications, generate moderate to severe skin irritation within 24 h. These results suggest that LipoLA hold a high therapeutic potential for the treatment of acne infection and other P. acnes related diseases.

The effect of diesters and lauric acid on rheological properties of air/water interfaces stabilized by oligofructose lauric acid monoesters

In this study, the rheological properties of interfaces stabilized by oligofructose fatty acid esters were elucidated. First, the properties of interfaces stabilized by monoesters (ME), diesters (DE), lauric acid (LA), oligofructose (OF), and mixtures of ME with DE, LA, or OF were studied. Second, the properties of interfaces stabilized by the crude product (CP) containing ME, DE, LA, and OF were studied. The dependency of the dilatational modulus on frequency and deformation amplitude indicated the possible formation of a soft glass phase for ME, and a viscous interface for DE. When ME and DE were mixed at a ratio of 0.8/0.2, the experimental results suggest that the interfacial structure consists of islands of a glass phase formed by ME, dispersed in a 2D viscous phase of DE. CP stabilized interfaces, where the ratio ME/DE was higher, lead to a different rheological response. The ratio ME/DE plays an important role in the surface properties of the CP. This may have significant consequences for applications in macroscopic systems such as foams.

Total synthesis of fellutamide B and deoxy-fellutamides B, C, and D

The total syntheses of the marine-derived lipopeptide natural product fellutamide B and deoxy-fellutamides B, C, and D are reported. These compounds were accessed through a novel solid-phase synthetic strategy using Weinreb amide-derived resin. As part of the synthesis, a new enantioselective route to (3R)-hydroxy lauric acid was developed utilizing a Brown allylation reaction followed by an oxidative cleavage-oxidation sequence as the key steps. The activity of these natural products, and natural product analogues was also assessed against Mycobacterium tuberculosisin vitro.

Determination of thermodynamic and transport parameters of naphthenic acids and organic process chemicals in oil sand tailings pond water

Oil sand tailings pond water contains naphthenic acids and process chemicals (e.g., alkyl sulphates, quaternary ammonium compounds, and alkylphenol ethoxylates). These chemicals are toxic and can seep through the foundation of the tailings pond to the subsurface, potentially affecting the quality of groundwater. As a result, it is important to measure the thermodynamic and transport parameters of these chemicals in order to study the transport behavior of contaminants through the foundation as well as underground. In this study, batch adsorption studies and column experiments were performed. It was found that the transport parameters of these chemicals are related to their molecular structures and other properties. The computer program (CXTFIT) was used to further evaluate the transport process in the column experiments. The results from this study show that the transport of naphthenic acids in a glass column is an equilibrium process while the transport of process chemicals seems to be a non-equilibrium process. At the end of this paper we present a real-world case study in which the transport of the contaminants through the foundation of an external tailings pond is calculated using the lab-measured data. The results show that long-term groundwater monitoring of contaminant transport at the oil sand mining site may be necessary to avoid chemicals from reaching any nearby receptors.

Dynamic lipid lateral segregation driven by lauryl cyclodextrin interactions at the membrane surface

Amphiphilic cyclodextrins, with a cholesterol anchor (βChol) or an aspartic acid moiety esterified by two lauryl acyl chains (βDLC), were designed to combine the inclusion ability of the cyclodextrin cavity with the carrier properties of model membranes. Their insertion in phosphatidylcholine bilayers induces a marked lateral phase separation into a pure lipid phase and a cyclodextrin-rich phase (LCD), organized as a 2D cyclodextrin network stabilized by intermolecular hydrogen bonds between the saccharide headgroups at the membrane surface (Roux, M.; Perly, B.; Djedaïni-Pilard, F. Self-Assemblies of Amphiphilic Cyclodextrins. Eur. Biophys. J.2007, 36, 861-867). We have replaced the dilauryl anchor by a single lauryl chain grafted onto a leucine residue, giving monolauryl-β-cyclodextrin (βMLC), which readily inserts into bilayers of chain-deuterated DMPC-d27. The removal of one lauryl acyl chain leads to a dynamic membrane insertion of this new cyclodextrin derivative, with significant lipid exchange on the deuterium NMR time scale between a loosely packed cyclodextrin-enriched phase (L'CD) and free lipid regions, yielding broadened two-component NMR spectra. Like the LCD phases, the cyclodextrin-enriched L'CD regions remain (partially) fluid below the DMPC-d27 main fluid-to-gel transition but do not undergo a clear transition toward a gel state, as observed at 14.5 °C in the LCD phase induced by the dilauryl derivative. Partially fluid lipids of the βMLC-induced L'CD phase coexist with pure lipids in the Pβ' gel phase with possible exchange between them until all of the lipids undergo a transition toward an Lβ' gel state at around 7 °C. Trimethylated monolauryl-β-cyclodextrins induce only an ordering of the lipid acyl chains just above the main transition, without any lateral phase separation. Similar chain ordering is also observed within the βMLC-induced L'CD phase as a consequence of the deep membrane insertion of the monolauryl nonmethylated cyclodextrin derivative.