Photo-triggerable liposomes based on lipid-porphyrin conjugate and cholesterol combination: Formulation and mechanistic study on monolayers and bilayers.

Lipid-porphyrin conjugates are considered nowadays as promising building blocks for the conception of drug delivery systems with multifunctional properties such as photothermal therapy (PTT), photodynamic therapy (PDT), phototriggerable release, photoacoustic and fluorescence imaging. For this aim, we have recently synthesized a new lipid-porphyrin conjugate named PhLSM. This was obtained by coupling pheophorbide-a (Pheo-a), a photosensitizer derived from chlorophyll-a, to egg lyso-sphingomyelin. The pure PhLSMs were able to self-assemble into vesicle-like structures that were however not stable and formed aggregates with undefined structures due to the mismatch between the length of the alkyl chain in sn-1 position and the adjacent porphyrin. Herein, stable PhLSMs lipid bilayers were achieved by mixing PhLSMs with cholesterol which exhibits a complementary packing parameter. The interfacial behavior as well as the fine structures of their equimolar mixture was studied at the air/buffer interface by the mean of Langmuir balance and x-ray reflectomerty (XRR) respectively. Our XRR analysis unraveled the monolayer thickening and the increase in the lateral ordering of PhLSM molecules. Interestingly, we could prepare stable vesicles with this mixture that encapsulate hydrophilic fluorescent probe. The light-triggered release kinetics and the photothermal conversion were studied. Moreover, the obtained vesicles were photo-triggerable and allowed the release of an encapsulated cargo in an ON-OFF fashion.

First-Principles Simulations of Biological Molecules Subjected to Ionizing Radiation.

Ionizing rays cause damage to genomes, proteins, and signaling pathways that normally regulate cell activity, with harmful consequences such as accelerated aging, tumors, and cancers but also with beneficial effects in the context of radiotherapies. While the great pace of research in the twentieth century led to the identification of the molecular mechanisms for chemical lesions on the building blocks of biomacromolecules, the last two decades have brought renewed questions, for example, regarding the formation of clustered damage or the rich chemistry involving the secondary electrons produced by radiolysis. Radiation chemistry is now meeting attosecond science, providing extraordinary opportunities to unravel the very first stages of biological matter radiolysis. This review provides an overview of the recent progress made in this direction, focusing mainly on the atto- to femto- to picosecond timescales. We review promising applications of time-dependent density functional theory in this context.

Research progress in the effects of terahertz waves on biomacromolecules.

With the rapid development of terahertz technologies, basic research and applications of terahertz waves in biomedicine have attracted increasing attention. The rotation and vibrational energy levels of biomacromolecules fall in the energy range of terahertz waves; thus, terahertz waves might interact with biomacromolecules. Therefore, terahertz waves have been widely applied to explore features of the terahertz spectrum of biomacromolecules. However, the effects of terahertz waves on biomacromolecules are largely unexplored. Although some progress has been reported, there are still numerous technical barriers to clarifying the relation between terahertz waves and biomacromolecules and to realizing the accurate regulation of biological macromolecules by terahertz waves. Therefore, further investigations should be conducted in the future. In this paper, we reviewed terahertz waves and their biomedical research advantages, applications of terahertz waves on biomacromolecules and the effects of terahertz waves on biomacromolecules. These findings will provide novel ideas and methods for the research and application of terahertz waves in the biomedical field.

Isolation and characterization of Lipomyces starkeyi mutants with greatly increased lipid productivity following UV irradiation.

The oleaginous yeast Lipomyces starkeyi is an intriguing lipid producer that can produce triacylglycerol (TAG), a feedstock for biodiesel production. We previously reported that the L. starkeyi mutant E15 with high levels of TAG production compared with the wild-type was efficiently obtained using Percoll density gradient centrifugation. However, considering its use for biodiesel production, it is necessary to further improve the lipid productivity of the mutant. In this study, we aimed to obtain mutants with better lipid productivity than E15, evaluate its lipid productivity, and analyze lipid synthesis-related gene expression in the wild-type and mutant strains. The mutants E15-11, E15-15, and E15-25 exhibiting higher lipid productivity than E15 were efficiently isolated from cells exposed to ultraviolet light using Percoll density gradient centrifugation. They exhibited approximately 4.5-fold higher lipid productivity than the wild-type on day 3. The obtained mutants did not exhibit significantly different fatty acid profiles than the wild-type and E15 mutant strains. E15-11, E15-15, and E15-25 exhibited higher expression of acyl-CoA synthesis- and Kennedy pathway-related genes than the wild-type and E15 mutant strains. Activation of the pentose phosphate pathway, which supplies NADPH, was also observed. These results suggested that the increased expression of acyl-CoA synthesis- and Kennedy pathway-related genes plays a vital role in lipid productivity in the oleaginous yeast L. starkeyi.

Effect of Heavy Ion 12C6+ Radiation on Lipid Constitution in the Rat Brain.

Heavy ions refer to charged particles with a mass greater than four (i.e., alpha particles). The heavy ion irradiation used in radiotherapy or that astronauts suffer in space flight missions induces toxicity in normal tissue and leads to short-term and long-term damage in both the structure and function of the brain. However, the underlying molecular alterations caused by heavy ion radiation have yet to be completely elucidated. Herein, untargeted and targeted lipidomic profiling of the whole brain tissue and blood plasma 7 days after the administration of the 15 Gy (260 MeV, low linear energy (LET) = 13.9 KeV/µm) plateau irradiation of disposable 12C6+ heavy ions on the whole heads of rats was explored to study the lipid damage induced by heavy ion radiation in the rat brain using ultra performance liquid chromatography-mass spectrometry (UPLC-MS) technology. Combined with multivariate variables and univariate data analysis methods, our results indicated that an orthogonal partial least squares discriminant analysis (OPLS-DA) could clearly distinguish lipid metabolites between the irradiated and control groups. Through the combination of variable weight value (VIP), variation multiple (FC), and differential (p) analyses, the significant differential lipids diacylglycerols (DAGs) were screened out. Further quantitative targeted lipidomic analyses of these DAGs in the rat brain tissue and plasma supported the notion that DAG 47:1 could be used as a potential biomarker to study brain injury induced by heavy ion irradiation.

Pulling of Tethers from the Cell Plasma Membrane Using Optical Tweezers.

Here, we describe how to extract tethers or lipid membrane nanotubes from the plasma membrane of cells using optical tweezers. This technique allows measuring the force required to hold the membrane tether at a constant length, which is related to the cell membrane tension. Following the evolution of this force during mechanical or chemical perturbations of the cell gives insight about the regulation of cell membrane tension. By pulling very long membrane tethers, one can also probe the membrane reservoir of a cell and a sudden rise in the tether force is usually due to the depletion of excess membranes stored in membrane folds or invaginations.

Kinetics Study of Microwave-Assisted Brine Extraction of Lipid from the Microalgae Nannochloropsis sp.

The kinetics of lipid extraction utilizing microwave-assisted extraction (MAE) from Nannochloropsis sp. microalgae were studied using a low cost and green solvent, namely brine (NaCl) solution. The kinetic modelling of the lipid extraction was performed to evaluate the mechanism of the lipid mass transfer using different extraction models, including Fick's Law, First and Second-order Rate Law and the Patricelli mathematical model. The Patricelli mathematical model described the kinetics of lipid extraction well, with the highest average values of determination coefficient (R2 ≥ 0.952) and the lowest average values of mean relative percentage deviation (MRPD ≤ 8.666%). The lipid analysis indicated a positive influence of the microwave temperature and time on the quantity and quality of extracted lipids. SEM analysis of spent microalgae clearly shows an increase in the distorted cell with increase microwave temperature and time, which could be directly correlated to the mechanism of the MAE-brine technique.

Ultraviolet Photodissociation Mass Spectrometry for Analysis of Biological Molecules.

The development of new ion-activation/dissociation methods continues to be one of the most active areas of mass spectrometry owing to the broad applications of tandem mass spectrometry in the identification and structural characterization of molecules. This Review will showcase the impact of ultraviolet photodissociation (UVPD) as a frontier strategy for generating informative fragmentation patterns of ions, especially for biological molecules whose complicated structures, subtle modifications, and large sizes often impede molecular characterization. UVPD energizes ions via absorption of high-energy photons, which allows access to new dissociation pathways relative to more conventional ion-activation methods. Applications of UVPD for the analysis of peptides, proteins, lipids, and other classes of biologically relevant molecules are emphasized in this Review.

Effects of stearic acid and irradiation alone and in combination on properties of amylose-lipid nanomaterial from high amylose maize starch.

This study determines the effects of stearic acid and gamma irradiation, alone and in combination, on properties of amylose-lipid nanomaterials from pasted high amylose maize starch (HAMS) with and without alpha amylase hydrolysis. HAMS was incorporated with stearic acid (0, 1.5% and 5%, w/w), irradiated at 0, 30 and 60 kGy and pasted under pressure in a rheometer. Isolated materials after thermostable alpha amylase or hot water washing were freeze-dried and characterised using differential scanning calorimetry (DSC), X-ray diffraction (XRD), Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM). The isolated materials contain amylose-lipid complexes (ALCs) as determined by DSC and XRD. Pasting of gamma irradiated HAMS produced type I ALCs, whereas that for un-irradiated HAMS produced type II ALCs. The ALCs occurred at nanoscale with sizes ranging from 10 to 110 nm as observed with AFM and TEM. Tailor-made ALCs nanomaterials can be produced from HAMS (with and without added stearic acid).

A Serum Small Molecule Biosignature of Radiation Exposure from Total Body Irradiated Patients.

The potential for radiological accidents and nuclear terrorism has increased the need for the development of new rapid biodosimetry methods. In addition, in a clinical setting the issue of an individual's radiosensitivity should be taken into consideration during radiotherapy. We utilized metabolomics and lipidomics to investigate changes of metabolites in serum samples following exposure to total body ionizing radiation in humans. Serum was collected prior to irradiation, at 3-8 h after a single dose of 1.25-2 Gy, and at 24 h with a total delivered dose of 2-3.75 Gy. Metabolomics revealed perturbations in glycerophosphocholine, phenylalanine, ubiquinone Q2, and oxalic acid. Alterations were observed in circulating levels of lipids from monoacylglycerol, triacylglycerol, phosphatidylcholine, and phosphatidylglycerol lipid classes. Polyunsaturated fatty acids were some of the most dysregulated lipids, with increased levels linked to proinflammatory processes. A targeted metabolomics approach for eicosanoids was also employed. The results showed a rapid response for proinflammatory eicosanoids, with a dampening of the signal at the later time point. Sex differences were observed in the markers from the untargeted approach but not the targeted method. The ability to identify and quantify small molecules in blood can therefore be utilized to monitor radiation exposure in human populations.

Dual-function nanostructured lipid carriers to deliver IR780 for breast cancer treatment: Anti-metastatic and photothermal anti-tumor therapy.

Cancer treatments that use a combination of approaches with the ability to affect multiple disease pathways have proven highly effective. The present study reports on CXCR4-targeted nanostructured lipid carriers (NLCs) with a CXCR4 antagonist AMD3100 in the shell (AMD-NLCs). AMD-NLCs loaded with IR780 (IR780-AMD-NLCs) reduced the invasiveness of cancer cells, while simultaneously mediating efficient tumor targeting and photothermal therapeutic outcomes. We present the combined effect of encapsulated IR780 on photothermal therapy and of the AMD3100 coating on tumor targeting, CXCR4 antagonism and inhibition of cancer cell invasion and breast cancer lung metastasis in vitro and in vivo. IR780-AMD-NLCs exhibited excellent IR780 loading capacity and AMD3100 coating efficiency. The photothermal properties of IR780 were improved by encapsulation in NLCs. The encapsulated IR780 displayed better heat generating efficiency than free IR780 when exposed to repeated laser irradiation. CXCR4 antagonism and cell invasion assays confirmed that IR780-AMD-NLCs fully inhibited CXCR4 while IR780-NLCs did not function as CXCR4 antagonists. AMD3100-coated NLCs accumulated at high levels in tumors, as judged by in vivo imaging and biodistribution assays. Furthermore, CXCR4-targeted NLCs exhibited an encouraging photothermal anti-tumor effect as well as anti-metastatic efficacy in vivo. These findings suggest that this simple and stable CXCR4-targeted IR780 delivery system holds great promise for prevention of metastasis and for photothermal treatment of tumors. STATEMENT OF SIGNIFICANCE: Breast cancer is a major threat to human health, it is not the primary breast tumor that is ultimately responsible for the majority of deaths, but the tumor metastasis, which frequently follows a specific pattern of dissemination. We report development of a novel dual-function nanostructured lipid carrier (NLC) for breast cancer treatment. The carrier encapsulates NIR dye IR780 in its core and contains antagonist of the chemokine receptor CXCR4 in its shell. Our results show that by combining the CXCR4 antagonism with photothermal effect of the dye leads to remarkable antitumor and antimetastatic activity in syngeneic orthotopic model of metastatic breast cancer. Furthermore, the developed system also shows a theranostic potential due to NIR fluorescence of the encapsulated dye.

Phototoxic target lipid model of single polycyclic aromatic hydrocarbons.

A phototoxic target lipid model (PTLM) is developed to predict phototoxicity of individual polycyclic aromatic hydrocarbons (PAHs) measured either as median lethal concentration (LC50) or median lethal time (LT50) for a 50% toxic response. The model is able to account for the differences in the physical/chemical properties of PAHs, test species sensitivities, and variations in light source characteristics, intensity, and length of exposure. The PTLM is based on the narcotic target lipid model (NTLM) of PAHs. Both models rely on the assumption that mortality occurs when the toxicant concentration in the target lipid of the organism reaches a threshold concentration. The PTLM is applied to observed LC50s and LT50s for 20 individual PAHs, 15 test species-including arthropods, fishes, amphibians, annelids, mollusks, and algae-exposed to simulated solar and various UV light sources, for exposure times varying from less than 1 h to 100 h, a total of 333 observations. The LC50 concentrations range from less than 0.1 µg/L to greater that 104 µg/L. The model has 2 fitting parameters that are constant and apply to all PAHs and organisms. The root mean square errors of prediction for log(LC50) and log(LT50) are 0.473 and 0.382, respectively. The results indicate that the PTLM can predict the phototoxicity of single PAHs over a wide range of exposure conditions and to organisms with a wide range of sensitivities. Environ Toxicol Chem 2017;36:926-937. © 2016 SETAC.

In situ visualization of carbonylation and its co-localization with proteins, lipids, DNA and RNA in Caenorhabditis elegans.

All key biological macromolecules are susceptible to carbonylation - an irreparable oxidative damage with deleterious biological consequences. Carbonyls in proteins, lipids and DNA from cell extracts have been used as a biomarker of oxidative stress and aging, but formation of insoluble aggregates by carbonylated proteins precludes quantification. Since carbonylated proteins correlate with and become a suspected cause of morbidity and mortality in some organisms, there is a need for their accurate quantification and localization. Using appropriate fluorescent probes, we have developed an in situ detection of total proteins, DNA, RNA, lipids and carbonyl groups at the level of the whole organism. In C. elegans, we found that after UV irradiation carbonylation co-localizes mainly with proteins and, to a lesser degree, with DNA, RNA and lipids. The method efficiency was illustrated by carbonylation induction assessment over 5 different UV doses. The procedure enables the monitoring of carbonylation in the nematode C. elegans during stress, aging and disease along its life cycle including the egg stage.

Fluid Viscosity Affects the Fragmentation and Inertial Cavitation Threshold of Lipid-Encapsulated Microbubbles.

Ultrasound and microbubble optimization studies for therapeutic applications are often conducted in water/saline, with a fluid viscosity of 1 cP. In an in vivo context, microbubbles are situated in blood, a more viscous fluid (∼4 cP). In this study, ultrahigh-speed microscopy and passive cavitation approaches were employed to investigate the effect of fluid viscosity on microbubble behavior at 1 MHz subject to high pressures (0.25-2 MPa). The propensity for individual microbubble (n = 220) fragmentation was found to significantly decrease in 4-cP fluid compared with 1-cP fluid, despite achieving similar maximum radial excursions. Microbubble populations diluted in 4-cP fluid exhibited decreased wideband emissions (up to 10.2 times), and increasingly distinct harmonic emission peaks (e.g., ultraharmonic) with increasing pressure, compared with those in 1-cP fluid. These results suggest that in vitro studies should consider an evaluation using physiologic viscosity perfusate before transitioning to in vivo evaluations.

Light attenuates lipid accumulation while enhancing cell proliferation and starch synthesis in the glucose-fed oleaginous microalga Chlorella zofingiensis.

The objective of this study was to investigate the effect of light on lipid and starch accumulation in the oleaginous green algae Chlorella zofingiensis supplemented with glucose. C. zofingiensis, when fed with 30 g/L glucose, synthesized lipids up to 0.531 g/g dry weight; while in the presence of light, the lipid content dropped down to 0.352 g/g dry weight. Lipid yield on glucose was 0.184 g/g glucose, 14% higher than that cultured with light. The light-mediated lipid reduction was accompanied by the down-regulation of fatty acid biosynthetic genes at the transcriptional level. Furthermore, light promoted cell proliferation, starch accumulation, and the starch yield based on glucose. Taken together, light may attenuate lipid accumulation, possibly through the inhibition of lipid biosynthetic pathway, leading to more carbon flux from glucose to starch. This study reveals the dual effects of light on the sugar-fed C. zofingiensis and provides valuable insights into the possible optimization of algal biomass and lipid production by manipulation of culture conditions.

Lipid Liquid-Crystal Phase Change Induced through near-Infrared Irradiation of Entrained Graphene Particles.

Lipid packing is intimately related to the geometry of the lipids and the forces that drive self-assembly. Here, the photothermal response of a cubic liquid-crystalline phase formed using phytantriol in the presence of low concentrations of pristine graphene was evaluated. Small-angle X-ray scattering showed the reversible phase changes from cubic to hexagonal to micellar due to localized heating through irradiation with near-infrared (NIR) light and back to cubic after cooling.

Lipid extraction from microalgae cell using UV-Fenton-like reaction.

In this study, UV light was adopted to make it possible to attain sufficiently high extraction efficiency even with a minimal amount of H2O2. The Fenton-like reaction showed 80% of lipid extraction efficiency with 0.5% H2O2, whereas the provision of 16 W UV increased efficiency to 85% and decreased H2O2 consumption to 0.3%. This oxidation-based lipid extraction means have one fortuitous yet beneficial effect to remove chlorophylls, which are known to degrade the quality of the final product like biodiesel. The UV-Fenton-like reaction was found to eliminate 77% of chlorophylls. Such oxidation-based lipid extraction approaches as the Fenton-like reaction appear to have the sure application potential; and it is more so with the help of UV.

Enhancement of non-invasive trans-membrane drug delivery using ultrasound and microbubbles during physiologically relevant flow.

Sonoporation has been associated with drug delivery across cell membranes and into target cells, yet several limitations have prohibited further advancement of this technology. Higher delivery rates were associated with increased cellular death, thus implying a safety-efficacy trade-off. Meanwhile, there has been no reported study of safe in vitro sonoporation in a physiologically relevant flow environment. The objective of our study was not only to evaluate sonoporation under physiologically relevant flow conditions, such as fluid velocity, shear stress and temperature, but also to design ultrasound parameters that exploit the presence of flow to maximize sonoporation efficacy while minimizing or avoiding cellular damage. Human umbilical vein endothelial cells (EA.hy926) were seeded in flow chambers as a monolayer to mimic the endothelium. A peristaltic pump maintained a constant fluid velocity of 12.5 cm/s. A focused 0.5 MHz transducer was used to sonicate the cells, while an inserted focused 7.5 MHz passive cavitation detector monitored microbubble-seeded cavitation emissions. Under these conditions, propidium iodide, which is normally impermeable to the cell membrane, was traced to determine whether it could enter cells after sonication. Meanwhile, calcein-AM was used as a cell viability marker. A range of focused ultrasound parameters was explored, with several unique bioeffects observed: cell detachment, preservation of cell viability with no membrane penetration, cell death and preservation of cell viability with sonoporation. The parameters were then modified further to produce safe sonoporation with minimal cell death. To increase the number of favourable cavitation events, we lowered the ultrasound exposure pressure to 40 kPapk-neg and increased the number of cavitation nuclei by 50 times to produce a trans-membrane delivery rate of 62.6% ± 4.3% with a cell viability of 95% ± 4.2%. Furthermore, acoustic cavitation analysis showed that the low pressure sonication produced stable and non-inertial cavitation throughout the pulse sequence. To our knowledge, this is the first study to demonstrate a high drug delivery rate coupled with high cell viability in a physiologically relevant in vitro flow system.

Sebum, inflammasomes and the skin: current concepts and future perspective.

Increasing evidence has identified ultraviolet radiation (UVR) as the skins most potent mutagen as over exposure results in sunburn, inflammation and DNA damage, thus contributing to a photo-ageing phenotype and possibly skin carcinogenesis. The lipid-rich sebum secreted onto the surface of the skin plays an important physiological role in protecting the skin against external challenges. When skin is photosensitised by UVR, the lipid constituents of sebum are easily oxidised, generating several lipid photo-oxidative products (e.g. squalene peroxides). These photo-oxidative products have been shown to exert diverse toxicological, biological and immunological effects in the skin and have therefore been implicated in several detrimental skin alterations including premature skin ageing. The involvement of lipid peroxidation products in UVR-induced inflammatory responses has been inadequately studied and highly controversial. Furthermore, it is unclear to what extent these oxidative products contribute to the underlying mechanisms of skin photo-ageing. Therefore, this viewpoint essay will discuss the current knowledge on the effect of UVR exposure on skin surface lipids and how these may mediate UVR-induced inflammatory responses which may be key contributors to photo-damage in skin. This essay will also examine the potential role of inflammasomes (innate immune complexes) in the inflammatory response associated with UVR-induced lipid peroxidation. Limited evidence is available on the interactions between sebaceous lipids, downstream mediators and concomitant immune response in sun-exposed skin and clearer elucidation may lead to novel biomarkers of photo-ageing and the incorporation of new molecules into current skin therapies which better target oxidised lipids and or downstream mediators/pathways.

Lipid oxidation in the skin.

Skin is the largest organ of the body and exerts several physiological functions such as a protective barrier against moisture loss and noxious agents including ultraviolet irradiation. Oxidation of skin may impair such functions and induce skin disorders including photoaging and skin cancer. Skin surface lipids, a mixture of sebaceous and epidermal lipids, have unique species and fatty acid profile. The major unsaturated lipids are squalene, sebaleic aicd, linoleic acid, and cholesterol. Singlet oxygen and ozone as well as free radicals and enzymes are important oxidants for skin lipids. Squalene is the major target for singlet oxygen, giving rise to twelve regio-isomeric squalene hydroperoxides. Ultraviolet radiation activates lipoxygenase and cyclooxygenase, inducing specific enzymatic oxidation of lipids. Free radical mediated lipid peroxidation gives multiple oxidation products. Lipid oxidation products produced by these mechanisms are observed in human skin and induce various skin diseases, but in contrast to plasma and other tissues, identification and quantitative measurement of lipid oxidation products in skin are scarce and should be the subjects of future studies.