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Local delivery of antimicrobials for otitis media treatment would maximize therapeutic efficacy while minimizing side effects. However, drug transport across the tympanic membrane in the absence of a delivery system is challenging. In this study, the MSlys endolysin was encapsulated in deformable liposomes for a targeted treatment of S. pneumoniae, one of the most important causative agents of otitis media. MSlys was successfully encapsulated in liposomes composed of l-alpha-lecithin and sodium cholate (5:1) or l-alpha-lecithin and PEG2000 PE (10:1), with encapsulation efficiencies of about 35%. The PEGylated and sodium cholate liposomes showed, respectively, mean hydrodynamic diameters of 85 and 115 nm and polydispersity indices of 0.32 and 0.42, both being stable after storage at 4 °C for at least one year. Both liposomal formulations showed a sustained release of MSlys over 7 days. Cytotoxicity studies against fibroblast and keratinocyte cell lines revealed the biocompatible nature of both MSlys and MSlys-loaded liposomes. Additionally, the encapsulated MSlys showed prompt antipneumococcal activity against planktonic and biofilm S. pneumoniae, thus holding great potential for transtympanic treatment against S. pneumoniae otitis media.
Maria Daniela Silva; Juan L. Paris; Francisco Miguel Gama; Bruno F. B. Silva; Sanna Sillankorva. Sustained Release of a Streptococcus pneumoniae Endolysin from Liposomes for Potential Otitis Media Treatment. ACS Infectious Diseases 2021, 1 .
AMA StyleMaria Daniela Silva, Juan L. Paris, Francisco Miguel Gama, Bruno F. B. Silva, Sanna Sillankorva. Sustained Release of a Streptococcus pneumoniae Endolysin from Liposomes for Potential Otitis Media Treatment. ACS Infectious Diseases. 2021; ():1.
Chicago/Turabian StyleMaria Daniela Silva; Juan L. Paris; Francisco Miguel Gama; Bruno F. B. Silva; Sanna Sillankorva. 2021. "Sustained Release of a Streptococcus pneumoniae Endolysin from Liposomes for Potential Otitis Media Treatment." ACS Infectious Diseases , no. : 1.
The dynamics of two different fluorescent dyes labelling DNA and cationic liposomes is monitored through Fluorescence Cross‐Correlation Spectroscopy (FCCS). Measuring the extent of correlation between the flickering of the two dyes as they diffuse in and out of overlapping confocal volumes, the association of DNA and liposomes to form lipoplexes is quantified. This was achieved analysing the correlation with non 1:1 stoichiometric sample description. Further details can be found in the article by Ana I. Gómez‐Varela, Ricardo Gaspar, Adelaide Miranda, Juliane L. Assis, Rafael H.F. Valverde, Marcelo Einicker‐Lamas, Bruno F. B. Silva, and Pieter A.A. De Beule (e202000200).
Ana I. Gómez‐Varela; Ricardo Gaspar; Adelaide Miranda; Juliane L. Assis; Rafael H.F. Valverde; Marcelo Einicker‐Lamas; Bruno F. B. Silva; Pieter A.A. De Beule. Front Cover. Journal of Biophotonics 2021, 14, 1 .
AMA StyleAna I. Gómez‐Varela, Ricardo Gaspar, Adelaide Miranda, Juliane L. Assis, Rafael H.F. Valverde, Marcelo Einicker‐Lamas, Bruno F. B. Silva, Pieter A.A. De Beule. Front Cover. Journal of Biophotonics. 2021; 14 (1):1.
Chicago/Turabian StyleAna I. Gómez‐Varela; Ricardo Gaspar; Adelaide Miranda; Juliane L. Assis; Rafael H.F. Valverde; Marcelo Einicker‐Lamas; Bruno F. B. Silva; Pieter A.A. De Beule. 2021. "Front Cover." Journal of Biophotonics 14, no. 1: 1.
Cancer is an extremely complex disease, typically caused by mutations in cancer-critical genes. By delivering therapeutic nucleic acids (NAs) to patients, gene therapy offers the possibility to supplement, repair or silence such faulty genes or to stimulate their immune system to fight the disease. While the challenges of gene therapy for cancer are significant, the latter approach (a type of immunotherapy) starts showing promising results in early-stage clinical trials. One important advantage of NA-based cancer therapies over synthetic drugs and protein treatments is the prospect of a more universal approach to designing therapies. Designing NAs with different sequences, for different targets, can be achieved by using the same technologies. This versatility and scalability of NA drug design and production on demand open the way for more efficient, affordable and personalized cancer treatments in the future. However, the delivery of exogenous therapeutic NAs into the patients’ targeted cells is also challenging. Membrane-type lipids exhibiting permanent or transient cationic character have been shown to associate with NAs (anionic), forming nanosized lipid-NA complexes. These complexes form a wide variety of nanostructures, depending on the global formulation composition and properties of the lipids and NAs. Importantly, these different lipid-NA nanostructures interact with cells via different mechanisms and their therapeutic potential can be optimized to promising levels in vitro. The complexes are also highly customizable in terms of surface charge and functionalization to allow a wide range of targeting and smart-release properties. Most importantly, these synthetic particles offer possibilities for scaling-up and affordability for the population at large. Hence, the versatility and scalability of these particles seem ideal to accommodate the versatility that NA therapies offer. While in vivo efficiency of lipid-NA complexes is still poor in most cases, the advances achieved in the last three decades are significant and very recently a lipid-based gene therapy medicine was approved for the first time (for treatment of hereditary transthyretin amyloidosis). Although the path to achieve efficient NA-delivery in cancer therapy is still long and tenuous, these advances set a new hope for more treatments in the future. In this review, we attempt to cover the most important biophysical and physicochemical aspects of non-viral lipid-based gene therapy formulations, with a perspective on future cancer treatments in mind.
Ricardo Gaspar; Filipe Coelho; Bruno Silva. Lipid-Nucleic Acid Complexes: Physicochemical Aspects and Prospects for Cancer Treatment. Molecules 2020, 25, 5006 .
AMA StyleRicardo Gaspar, Filipe Coelho, Bruno Silva. Lipid-Nucleic Acid Complexes: Physicochemical Aspects and Prospects for Cancer Treatment. Molecules. 2020; 25 (21):5006.
Chicago/Turabian StyleRicardo Gaspar; Filipe Coelho; Bruno Silva. 2020. "Lipid-Nucleic Acid Complexes: Physicochemical Aspects and Prospects for Cancer Treatment." Molecules 25, no. 21: 5006.
In this study, we developed a system for the transdermal delivery and controlled release of the hydrophobic immunosuppressive drug rapamycin, foreseeing an application in psoriasis treatment. To do so, rapamycin was encapsulated in phytantriol-based cubosome-like liquid crystalline nanoparticles stabilized with pluronic F127. The final mass percent composition of the lipid nanoparticles was 0.25% phytantriol, 0.1% pluronic F127, 4.75% ethanol and 94.9% water. These particles showed a rapamycin encapsulation efficiency above 95% and a sustained in vitro drug release profile throughout 14 days. Subsequently the rapamycin-carrying particles were incorporated into rapidly dissolving microneedle patches composed of a polymeric matrix of poly(vinylpyrrolidone) and poly(vinyl alcohol). Confocal microscopy allowed to infer the preferential distribution of the cubosome-like particles at the tip and baseplate of the microneedles. The fabricated microneedles showed successful piercing and deposition of the loaded cubosome-like particles on a skin-mimicking agarose gel. Finally, the rapamycin-loaded cubosome-like particles showed antiproliferative activity in natural killer cells in vitro. The results here presented show the potential of the developed system to deliver cubosome-like particles into the skin and promote the sustained release of rapamycin in the context of immunomodulation.
Ana Ramalheiro; Juan L. Paris; Bruno F.B. Silva; Liliana R. Pires. Rapidly dissolving microneedles for the delivery of cubosome-like liquid crystalline nanoparticles with sustained release of rapamycin. International Journal of Pharmaceutics 2020, 591, 119942 .
AMA StyleAna Ramalheiro, Juan L. Paris, Bruno F.B. Silva, Liliana R. Pires. Rapidly dissolving microneedles for the delivery of cubosome-like liquid crystalline nanoparticles with sustained release of rapamycin. International Journal of Pharmaceutics. 2020; 591 ():119942.
Chicago/Turabian StyleAna Ramalheiro; Juan L. Paris; Bruno F.B. Silva; Liliana R. Pires. 2020. "Rapidly dissolving microneedles for the delivery of cubosome-like liquid crystalline nanoparticles with sustained release of rapamycin." International Journal of Pharmaceutics 591, no. : 119942.
The development of non‐viral gene delivery vehicles for therapeutic applications requires methods capable of quantifying the association between the genes and their carrier counterparts. Here we investigate the potential of Fluorescence Cross‐Correlation Spectroscopy to characterize and optimize the assembly of non‐viral Cationic Liposome‐DNA complexes based on a cationic liposome formulation consisting of the cationic lipid DOTAP and zwitterionic lipid DOPC. We use a DNA plasmid for lipoplex loading encoding the Oct4 gene, critically involved in reprogramming somatic cells into induced pluripotent stem cells. We demonstrate that FCCS is able to quantitatively determine the extent of the association between DNA and the liposomes and assess its loading capacity. We also establish that the cationic lipid fraction, being proportional to the liposome membrane charge density, as well as charge ratio between the cationic liposomes and anionic DNA play an important role in the degree of interaction between the liposomes and DNA. This article is protected by copyright. All rights reserved.
Ana I. Gómez‐Varela; Ricardo Gaspar; Adelaide Miranda; Juliane L. Assis; Rafael R.H.F. Valverde; Marcelo Einicker‐Lamas; Bruno F. B. Silva; Pieter A.A. De Beule. Fluorescence cross‐correlation spectroscopy as a valuable tool to characterize cationic liposome‐DNA nanoparticle assembly. Journal of Biophotonics 2020, 14, 1 .
AMA StyleAna I. Gómez‐Varela, Ricardo Gaspar, Adelaide Miranda, Juliane L. Assis, Rafael R.H.F. Valverde, Marcelo Einicker‐Lamas, Bruno F. B. Silva, Pieter A.A. De Beule. Fluorescence cross‐correlation spectroscopy as a valuable tool to characterize cationic liposome‐DNA nanoparticle assembly. Journal of Biophotonics. 2020; 14 (1):1.
Chicago/Turabian StyleAna I. Gómez‐Varela; Ricardo Gaspar; Adelaide Miranda; Juliane L. Assis; Rafael R.H.F. Valverde; Marcelo Einicker‐Lamas; Bruno F. B. Silva; Pieter A.A. De Beule. 2020. "Fluorescence cross‐correlation spectroscopy as a valuable tool to characterize cationic liposome‐DNA nanoparticle assembly." Journal of Biophotonics 14, no. 1: 1.
Complexes combining nucleic acids with lipids and polymers (lipopolyplexes) show great promise for gene therapy since they enable compositional, physical and functional versatility to be optimized for therapeutic efficiency. When developing lipopolyplexes for gene delivery, one of the first evaluations performed is an in vitro transfection efficiency experiment. Many different in vitro models can be used, and the effect of the model on the experiment outcome has not been thoroughly studied. The objective of this work was to compare the insights obtained from three different in vitro models, as well as the potential limitations associated with each of them. We have prepared a series of lipopolyplex formulations with three different cationic polymers (poly-l-lysine, bioreducible poly-l-lysine and polyethyleneimine), and assessed their in vitro biological performance in 2D monolayer cell culture, 3D spheroid culture and microdroplet-based single-cell culture. Lipopolyplexes from different polymers presented varying degrees of transfection efficiency in all models. The best-performing formulation in 2D culture was the polyethyleneimine lipopolyplex, while lipoplexes prepared with bioreducible poly-l-lysine were the only ones achieving any transfection in microdroplet-enabled cell culture. None of the prepared formulations achieved significant gene transfection in 3D culture. All of the prepared formulations were well tolerated by cells in 2D culture, while at least one formulation (poly-l-lysine polyplex) delayed 3D spheroid growth. These results highlight the need for selecting the appropriate in vitro model depending on the intended application.
Juan L Paris; Filipe Coelho; Alexandra Teixeira; Lorena Diéguez; Bruno F. B. Silva; Sara Abalde-Cela. In Vitro Evaluation of Lipopolyplexes for Gene Transfection: Comparing 2D, 3D and Microdroplet-Enabled Cell Culture. Molecules 2020, 25, 3277 .
AMA StyleJuan L Paris, Filipe Coelho, Alexandra Teixeira, Lorena Diéguez, Bruno F. B. Silva, Sara Abalde-Cela. In Vitro Evaluation of Lipopolyplexes for Gene Transfection: Comparing 2D, 3D and Microdroplet-Enabled Cell Culture. Molecules. 2020; 25 (14):3277.
Chicago/Turabian StyleJuan L Paris; Filipe Coelho; Alexandra Teixeira; Lorena Diéguez; Bruno F. B. Silva; Sara Abalde-Cela. 2020. "In Vitro Evaluation of Lipopolyplexes for Gene Transfection: Comparing 2D, 3D and Microdroplet-Enabled Cell Culture." Molecules 25, no. 14: 3277.
Elesclomol (ELC) is an anticancer drug inducing mitochondria cytotoxicity through reactive oxygen species. Here, for the first time, we encapsulate the poorly water soluble ELC in monoolein-based cubosomes stabilized with Pluronic F127. Cellular uptake and nanocarrier accumulation close to the mitochondria with sub-micrometer distance is identified via three-dimensional (3D) confocal microscopy and edge-to-edge compartment analysis. To monitor the therapeutic effect of the ELC nanocarrier, we apply for the first time, label-free time-lapse multi-photon fluorescence lifetime imaging microscopy (MP-FLIM) to track NAD(P)H cofactors with sub-cellular resolution on live cells exposed to an anticancer nanocarrier. Improved in vitro cytotoxicity is verified when loading the pre-complexed ELC with copper (ELC-Cu). Importantly, for equivalent copper concentration, cubosomes loaded with ELC-Cu show higher cytotoxicity compared to the free drug. The novel nanocarrier shows promising features for systemic ELC-Cu administration, and furthermore we establish the MP-FLIM technique for the assessment of anticancer drug delivery systems. Open image in new window
Ana Rita Faria; Oscar Silvestre; Christian Maibohm; Ricardo Adão; Bruno Silva; Jana B. Nieder. Cubosome nanoparticles for enhanced delivery of mitochondria anticancer drug elesclomol and therapeutic monitoring via sub-cellular NAD(P)H multi-photon fluorescence lifetime imaging. Nano Research 2018, 12, 991 -998.
AMA StyleAna Rita Faria, Oscar Silvestre, Christian Maibohm, Ricardo Adão, Bruno Silva, Jana B. Nieder. Cubosome nanoparticles for enhanced delivery of mitochondria anticancer drug elesclomol and therapeutic monitoring via sub-cellular NAD(P)H multi-photon fluorescence lifetime imaging. Nano Research. 2018; 12 (5):991-998.
Chicago/Turabian StyleAna Rita Faria; Oscar Silvestre; Christian Maibohm; Ricardo Adão; Bruno Silva; Jana B. Nieder. 2018. "Cubosome nanoparticles for enhanced delivery of mitochondria anticancer drug elesclomol and therapeutic monitoring via sub-cellular NAD(P)H multi-photon fluorescence lifetime imaging." Nano Research 12, no. 5: 991-998.
Miniaturized magnetic cytometer featuring an adaptable lateral and vertical hydrodynamic focusing which increases cell detection of magnetically labeled cells.
Alexandre Chicharo; Marco Martins; Lester C. Barnsley; Amal Taouallah; João Fernandes; Bruno F. B. Silva; Susana Cardoso; Lorena Diéguez; Begoña Espiña; Susana Cardoso De Freitas; Espiña Begoña. Enhanced magnetic microcytometer with 3D flow focusing for cell enumeration. Lab on a Chip 2018, 18, 2593 -2603.
AMA StyleAlexandre Chicharo, Marco Martins, Lester C. Barnsley, Amal Taouallah, João Fernandes, Bruno F. B. Silva, Susana Cardoso, Lorena Diéguez, Begoña Espiña, Susana Cardoso De Freitas, Espiña Begoña. Enhanced magnetic microcytometer with 3D flow focusing for cell enumeration. Lab on a Chip. 2018; 18 (17):2593-2603.
Chicago/Turabian StyleAlexandre Chicharo; Marco Martins; Lester C. Barnsley; Amal Taouallah; João Fernandes; Bruno F. B. Silva; Susana Cardoso; Lorena Diéguez; Begoña Espiña; Susana Cardoso De Freitas; Espiña Begoña. 2018. "Enhanced magnetic microcytometer with 3D flow focusing for cell enumeration." Lab on a Chip 18, no. 17: 2593-2603.
An understanding of the mechanism of action of antimicrobial peptides is fundamental to the development of new and more active antibiotics. In the present work, we use a wide range of techniques (SANS, SAXD, DSC, ITC, CD, and confocal and electron microscopy) in order to fully characterize the interaction of a cecropin A-melittin hybrid antimicrobial peptide, CA(1-7)M(2-9), of known antimicrobial activity, with a bacterial model membrane of POPE/POPG in an effort to unravel its mechanism of action. We found that CA(1-7)M(2-9) disrupts the vesicles, inducing membrane condensation and forming an onionlike structure of multilamellar stacks, held together by the intercalated peptides. SANS and SAXD revealed changes induced by the peptide in the lipid bilayer thickness and the bilayer stiffening in a tightly packed liquid-crystalline lamellar phase. The analysis of the observed abrupt changes in the repeat distance upon the phase transition to the gel state suggests the formation of an Lγ phase. To the extent of our knowledge, this is the first time that the Lγ phase is identified as part of the mechanism of action of antimicrobial peptides. The energetics of interaction depends on temperature, and ITC results indicate that CA(1-7)M(2-9) interacts with the outer leaflet. This further supports the idea of a surface interaction that leads to membrane condensation and not to pore formation. As a result, we propose that this peptide exerts its antimicrobial action against bacteria through extensive membrane disruption that leads to cell death.
Tânia Silva; Bárbara Claro; Bruno F. B. Silva; Nuno Vale; Paula Gomes; Maria Salomé Gomes; Sérgio S. Funari; José Teixeira; Daniela Uhríková; Margarida Bastos. Unravelling a Mechanism of Action for a Cecropin A-Melittin Hybrid Antimicrobial Peptide: The Induced Formation of Multilamellar Lipid Stacks. Langmuir 2018, 34, 2158 -2170.
AMA StyleTânia Silva, Bárbara Claro, Bruno F. B. Silva, Nuno Vale, Paula Gomes, Maria Salomé Gomes, Sérgio S. Funari, José Teixeira, Daniela Uhríková, Margarida Bastos. Unravelling a Mechanism of Action for a Cecropin A-Melittin Hybrid Antimicrobial Peptide: The Induced Formation of Multilamellar Lipid Stacks. Langmuir. 2018; 34 (5):2158-2170.
Chicago/Turabian StyleTânia Silva; Bárbara Claro; Bruno F. B. Silva; Nuno Vale; Paula Gomes; Maria Salomé Gomes; Sérgio S. Funari; José Teixeira; Daniela Uhríková; Margarida Bastos. 2018. "Unravelling a Mechanism of Action for a Cecropin A-Melittin Hybrid Antimicrobial Peptide: The Induced Formation of Multilamellar Lipid Stacks." Langmuir 34, no. 5: 2158-2170.
Microfluidic devices allow actuation on the microscale, while in situ SAXS allows visualization of these effects in relevant systems.
Bruno F. B. Silva. SAXS on a chip: from dynamics of phase transitions to alignment phenomena at interfaces studied with microfluidic devices. Physical Chemistry Chemical Physics 2017, 19, 23690 -23703.
AMA StyleBruno F. B. Silva. SAXS on a chip: from dynamics of phase transitions to alignment phenomena at interfaces studied with microfluidic devices. Physical Chemistry Chemical Physics. 2017; 19 (35):23690-23703.
Chicago/Turabian StyleBruno F. B. Silva. 2017. "SAXS on a chip: from dynamics of phase transitions to alignment phenomena at interfaces studied with microfluidic devices." Physical Chemistry Chemical Physics 19, no. 35: 23690-23703.
Bruno Silva; Carlos Rodriguez-Abreu; Neus Vilanova. Recent advances in multiple emulsions and their application as templates. Current Opinion in Colloid & Interface Science 2016, 25, 98 -108.
AMA StyleBruno Silva, Carlos Rodriguez-Abreu, Neus Vilanova. Recent advances in multiple emulsions and their application as templates. Current Opinion in Colloid & Interface Science. 2016; 25 ():98-108.
Chicago/Turabian StyleBruno Silva; Carlos Rodriguez-Abreu; Neus Vilanova. 2016. "Recent advances in multiple emulsions and their application as templates." Current Opinion in Colloid & Interface Science 25, no. : 98-108.
Endosomal entrapment is known to be a major bottleneck to successful cytoplasmic delivery of nucleic acids (NAs) using cationic liposome–NA nanoparticles (NPs). Quantitative measurements of distributions of NPs within early endosomes (EEs) have proven difficult due to the sub-resolution size and short lifetime of wildtype EEs. In this study we used Rab5–GFP, a member of the large family of GTPases which cycles between the plasma membrane and early endosomes, to fluorescently label early endosomes. Using fluorescence microscopy and quantitative image analysis of cells expressing Rab5–GFP, we found that at early time points (t < 1 h), only a fraction (≈ 35%) of RGD-tagged NPs (which target cell surface integrins) colocalize with wildtype EEs, independent of the NP's membrane charge density. In comparison, a GTP-hydrolysis deficient mutant, Rab5–Q79L, which extends the size and lifetime of EEs yielding giant early endosomes (GEEs), enabled us to resolve and localize individual NPs found within the GEE lumen. Remarkably, nearly all intracellular NPs are found to be trapped within GEEs implying little or no escape at early time points. The observed small degree of colocalization of NPs and wildtype Rab5 is consistent with recycling of Rab5–GDP to the plasma membrane and not indicative of NP escape from EEs. Taken together, our results show that endosomal escape of PEGylated nanoparticles occurs downstream of EEs i.e., from late endosomes/lysosomes. Our studies also suggest that Rab5–Q79L could be used in a robust imaging assay which allows for direct visualization of NP interactions with the luminal membrane of early endosomes.
Ramsey N. Majzoub; Chia-Ling Chan; Kai K. Ewert; Bruno F.B. Silva; Keng S. Liang; Cyrus R. Safinya. Fluorescence microscopy colocalization of lipid–nucleic acid nanoparticles with wildtype and mutant Rab5–GFP: A platform for investigating early endosomal events. Biochimica et Biophysica Acta (BBA) - Biomembranes 2015, 1848, 1308 -1318.
AMA StyleRamsey N. Majzoub, Chia-Ling Chan, Kai K. Ewert, Bruno F.B. Silva, Keng S. Liang, Cyrus R. Safinya. Fluorescence microscopy colocalization of lipid–nucleic acid nanoparticles with wildtype and mutant Rab5–GFP: A platform for investigating early endosomal events. Biochimica et Biophysica Acta (BBA) - Biomembranes. 2015; 1848 (6):1308-1318.
Chicago/Turabian StyleRamsey N. Majzoub; Chia-Ling Chan; Kai K. Ewert; Bruno F.B. Silva; Keng S. Liang; Cyrus R. Safinya. 2015. "Fluorescence microscopy colocalization of lipid–nucleic acid nanoparticles with wildtype and mutant Rab5–GFP: A platform for investigating early endosomal events." Biochimica et Biophysica Acta (BBA) - Biomembranes 1848, no. 6: 1308-1318.
In this work we investigate the interplay between flow and boundary condition effects on the orientation field of a thermotropic nematic liquid crystal under flow and confinement in a microfluidic device. Two types of experiments were performed using synchrotron small-angle X-ray-scattering (SAXS). In the first, a nematic liquid crystal flows through a square-channel cross section at varying flow rates, while the nematic director orientation projected onto the velocity/velocity gradient plane is measured using a 2D detector. At moderate-to-high flow rates, the nematic director is predominantly aligned in the flow direction, but with a small tilt angle of ∼±11° in the velocity gradient direction. The director tilt angle is constant throughout most of the channel width but switches sign when crossing the center of the channel, in agreement with the Ericksen-Leslie-Parodi (ELP) theory. At low flow rates, boundary conditions begin to dominate, and a flow profile resembling the escaped radial director configuration is observed, where the director is seen to vary more smoothly from the edges (with homeotropic alignment) to the center of the channel. In the second experiment, hydrodynamic focusing is employed to confine the nematic phase into a sheet of liquid sandwiched between two layers of Triton X-100 aqueous solutions. The average nematic director orientation shifts to some extent from the flow direction toward the liquid boundaries, although it remains unclear if one tilt angle is dominant through most of the nematic sheet (with abrupt jumps near the boundaries) or if the tilt angle varies smoothly between two extreme values (∼90 and 0°). The technique presented here could be applied to perform high-throughput measurements for assessing the influence of different surfactants on the orientation of nematic phases and may lead to further improvements in areas such as boundary lubrication and clarifying the nature of defect structures in LC displays.
Bruno F. B. Silva; Miguel Zepeda-Rosales; Neeraja Venkateswaran; Bretton J. Fletcher; Lester G. Carter; Tsutomu Matsui; Thomas M. Weiss; Jun Han; Youli Li; Ulf Olsson; Cyrus R. Safinya. Nematic Director Reorientation at Solid and Liquid Interfaces under Flow: SAXS Studies in a Microfluidic Device. Langmuir 2014, 31, 4361 -4371.
AMA StyleBruno F. B. Silva, Miguel Zepeda-Rosales, Neeraja Venkateswaran, Bretton J. Fletcher, Lester G. Carter, Tsutomu Matsui, Thomas M. Weiss, Jun Han, Youli Li, Ulf Olsson, Cyrus R. Safinya. Nematic Director Reorientation at Solid and Liquid Interfaces under Flow: SAXS Studies in a Microfluidic Device. Langmuir. 2014; 31 (14):4361-4371.
Chicago/Turabian StyleBruno F. B. Silva; Miguel Zepeda-Rosales; Neeraja Venkateswaran; Bretton J. Fletcher; Lester G. Carter; Tsutomu Matsui; Thomas M. Weiss; Jun Han; Youli Li; Ulf Olsson; Cyrus R. Safinya. 2014. "Nematic Director Reorientation at Solid and Liquid Interfaces under Flow: SAXS Studies in a Microfluidic Device." Langmuir 31, no. 14: 4361-4371.
Steric stabilization of cationic liposome–DNA (CL–DNA) complexes is required for in vivo applications such as gene therapy. PEGylation (PEG: poly(ethylene glycol)) of CL–DNA complexes by addition of PEG2000-lipids yields sterically stabilized nanoparticles but strongly reduces their gene delivery efficacy. PEGylation-induced weakening of the electrostatic binding of CL–DNA nanoparticles to cells (leading to reduced uptake) has been considered as a possible cause, but experimental results have been ambiguous. Using quantitative live-cell imaging in vitro, we have investigated cell attachment and uptake of PEGylated CL–DNA nanoparticles with and without a custom synthesized RGD-peptide grafted to the distal ends of PEG2000-lipids. The RGD-tagged nanoparticles exhibit strongly increased cellular attachment as well as uptake compared to nanoparticles without grafted peptide. Transfection efficiency of RGD-tagged PEGylated CL–DNA NPs increases by about an order of magnitude between NPs with low and high membrane charge density (σM; the average charge per unit area of the membrane; controlled by the molar ratio of cationic to neutral lipid), even though imaging data show that uptake of RGD-tagged particles is only slightly enhanced by high σM. This suggests that endosomal escape and, as a result, transfection efficiency of RGD-tagged NPs is facilitated by high σM. We present a model describing the interactions between PEGylated CL–DNA nanoparticles and the anionic cell membrane which shows how the PEG grafting density and membrane charge density affect adhesion of nanoparticles to the cell surface.
Ramsey N. Majzoub; Chia-Ling Chan; Kai K. Ewert; Bruno F.B. Silva; Keng S. Liang; Erica L. Jacovetty; Bridget Carragher; Clinton S. Potter; Cyrus R. Safinya. Uptake and transfection efficiency of PEGylated cationic liposome–DNA complexes with and without RGD-tagging. Biomaterials 2014, 35, 4996 -5005.
AMA StyleRamsey N. Majzoub, Chia-Ling Chan, Kai K. Ewert, Bruno F.B. Silva, Keng S. Liang, Erica L. Jacovetty, Bridget Carragher, Clinton S. Potter, Cyrus R. Safinya. Uptake and transfection efficiency of PEGylated cationic liposome–DNA complexes with and without RGD-tagging. Biomaterials. 2014; 35 (18):4996-5005.
Chicago/Turabian StyleRamsey N. Majzoub; Chia-Ling Chan; Kai K. Ewert; Bruno F.B. Silva; Keng S. Liang; Erica L. Jacovetty; Bridget Carragher; Clinton S. Potter; Cyrus R. Safinya. 2014. "Uptake and transfection efficiency of PEGylated cationic liposome–DNA complexes with and without RGD-tagging." Biomaterials 35, no. 18: 4996-5005.
Cationic liposome–DNA (CL–DNA) complexes, are regarded as promising materials for safe and efficient delivery of genes for therapeutical applications. In order to be used in vivo, these complexes may be coated with a hydrophilic polymer (e.g. polyethylene-glycol, PEG) that provides steric stabilization towards adhesion of proteins and removal by the immune system. In this work we study the influence of the initial salt concentration (Cs) – which modulates the electrostatic interaction between oppositely charged vesicles and DNA – on the structure and stability of PEGylated CL–DNA particles. Previous small-angle X-ray scattering has shown that if non-PEGylated or PEGylated CL–DNA lamellar complexes are prepared in water, their structure is well defined with a high number of lipid membrane–DNA layers (larger than 20). Here we show that if these complexes are transferred to saline media (150 mM NaCl or DMEM, both near physiological conditions), this structure remains nearly unchanged. Conversely, if PEGylated complexes are prepared in saline media, their lamellar structure is much looser, with fewer number of layers. This pathway dependent behavior of PEGylated complex formation in brine is modulated by the liposome membrane charge density and the mole fraction of PEG 2000 in the membranes, with the average number of layers decreasing with increasing Cs and in going from 5 mol% to 10 mol% PEG-lipid. Each of these structures (high and low number of layers) is stable with time, suggesting that despite complex formation being thermodynamically favored, the complexation process in PEGylated membranes, which determines the number of layers per particle, is kinetically controlled. In the extreme case (when polymer repulsions from 10 mol% PEG-lipid are maximized and electrostatic attraction between PEGylated CLs and DNA are minimized at low membrane charge density) complex formation is suppressed at high Cs = 150 mM.
Bruno F.B. Silva; Ramsey N. Majzoub; Chia-Ling Chan; Youli Li; Ulf Olsson; Cyrus R. Safinya. PEGylated cationic liposome–DNA complexation in brine is pathway-dependent. Biochimica et Biophysica Acta (BBA) - Biomembranes 2013, 1838, 398 -412.
AMA StyleBruno F.B. Silva, Ramsey N. Majzoub, Chia-Ling Chan, Youli Li, Ulf Olsson, Cyrus R. Safinya. PEGylated cationic liposome–DNA complexation in brine is pathway-dependent. Biochimica et Biophysica Acta (BBA) - Biomembranes. 2013; 1838 (1):398-412.
Chicago/Turabian StyleBruno F.B. Silva; Ramsey N. Majzoub; Chia-Ling Chan; Youli Li; Ulf Olsson; Cyrus R. Safinya. 2013. "PEGylated cationic liposome–DNA complexation in brine is pathway-dependent." Biochimica et Biophysica Acta (BBA) - Biomembranes 1838, no. 1: 398-412.
Thermotropic liquid crystal formation by salt-free catanionic surfactants (alkyltrimethylammonium alkylsulfonates, herein designated as TAmSon) has been investigated as a function of chain length mismatch (asymmetry). Previous studies on these compounds have revealed an unusual and rich asymmetry-dependent lyotropic phase behavior. Herein, phase transition temperatures and transition enthalpies/entropies were determined by differential scanning calorimetry, while mesophases were assigned by polarized light microscopy. Three series of compounds were investigated, namely: the TA16Son series, where n=6-10; the TAmSo8 series, where m=12-16; and a constant m+n series, TAmSon where m+n=22. Typically, several solid phases and two smectic mesophases are found prior to isotropization to the liquid phase. As asymmetry decreases, two somewhat counterintuitive tendencies emerge: a general decrease in enthalpy/entropy for solid-solid and solid-first mesophase transitions, and an increase in solid-first mesophase transition temperatures. Yet, solid phases are seen to be more stable for the most asymmetric compounds, while the second mesophase is more stable for the least asymmetric ones, in what appears to be a more complex behavior than expected. The results are globally interpreted in terms of subtle differences in chain interdigitation and packing, and odd-even chain effects.
Marta R.A. Matos; Bruno Silva; Eduardo Marques. Chain length mismatch and packing effects on the thermotropic phase behavior of salt-free catanionic surfactants. Journal of Colloid and Interface Science 2013, 405, 134 -144.
AMA StyleMarta R.A. Matos, Bruno Silva, Eduardo Marques. Chain length mismatch and packing effects on the thermotropic phase behavior of salt-free catanionic surfactants. Journal of Colloid and Interface Science. 2013; 405 ():134-144.
Chicago/Turabian StyleMarta R.A. Matos; Bruno Silva; Eduardo Marques. 2013. "Chain length mismatch and packing effects on the thermotropic phase behavior of salt-free catanionic surfactants." Journal of Colloid and Interface Science 405, no. : 134-144.
Bruno F.B. Silva; Miguel Z. Rosales; Joanna Deek; Ulf Olsson; Youli Li; Cyrus R. Safinya. Microfluidics with In-Situ Small-Angle X-Ray Scattering: A Tool to Investigate the Neurofilament Self-Assembly Mechanism. Biophysical Journal 2013, 104, 141a .
AMA StyleBruno F.B. Silva, Miguel Z. Rosales, Joanna Deek, Ulf Olsson, Youli Li, Cyrus R. Safinya. Microfluidics with In-Situ Small-Angle X-Ray Scattering: A Tool to Investigate the Neurofilament Self-Assembly Mechanism. Biophysical Journal. 2013; 104 (2):141a.
Chicago/Turabian StyleBruno F.B. Silva; Miguel Z. Rosales; Joanna Deek; Ulf Olsson; Youli Li; Cyrus R. Safinya. 2013. "Microfluidics with In-Situ Small-Angle X-Ray Scattering: A Tool to Investigate the Neurofilament Self-Assembly Mechanism." Biophysical Journal 104, no. 2: 141a.
In this study we report on instability phenomena in a solution where shear induces multilamellar vesicles (MLVs) from a lamellar phase. A shear-thickening regime has been observed for hexadecyl tetraethylene glycol ether (C16E4) dissolved in D2O at 40 °C. In this regime, unstable temporal viscosity behavior, i.e. periodic oscillations, has been observed at 2, 5 and 10 s−1. Moreover at a shear rate of 10 s−1 shear banding manifests itself as the occurrence of transparent and turbid bands stacked along the vorticity direction. We perform time-resolved-rheo-small angle neutron scattering (rheo-SANS) experiments to understand the nature of the viscosity oscillations and spatial-resolved experiments to obtain a structural characterization of vorticity bands.
Luigi Gentile; Bruno F. B. Silva; Sebastian Lages; Kell Mortensen; Joachim Kohlbrecher; Ulf Olsson. Rheochaos and flow instability phenomena in a nonionic lamellar phase. Soft Matter 2013, 9, 1133 -1140.
AMA StyleLuigi Gentile, Bruno F. B. Silva, Sebastian Lages, Kell Mortensen, Joachim Kohlbrecher, Ulf Olsson. Rheochaos and flow instability phenomena in a nonionic lamellar phase. Soft Matter. 2013; 9 (4):1133-1140.
Chicago/Turabian StyleLuigi Gentile; Bruno F. B. Silva; Sebastian Lages; Kell Mortensen; Joachim Kohlbrecher; Ulf Olsson. 2013. "Rheochaos and flow instability phenomena in a nonionic lamellar phase." Soft Matter 9, no. 4: 1133-1140.
Salt-free catanionic surfactants form in water binary systems, thus differing from pseudo-ternary equimolar catanionic mixtures, where salt is present. A miscibility gap, an unusual phenomenon in binary systems, is observed for the lamellar phase of the catanionic surfactant hexadecyltrimethylammonium octylsulfonate. Experimental data show the coexistence of a swollen and a collapsed lamellar phase in a wide two-phase region, while linear swelling is observed for each phase. This phase behavior is suggested to stem mainly from a concentration dependence of the charge density of catanionic bilayer, driven by the much higher solubility of the short chain ionic counterpart (octylsulfonate). Thus, a theoretical cell model based on combined DLVO and short range repulsive potentials is presented in order to provide physical insight into the miscibility gap. Furthermore, the surfactant forms at high dilution a solution phase and exhibits a very low critical micelle concentration (0.0035 wt%). The dilute lamellar phase is in equilibrium with the isotropic solution, and small vesicles can also be observed, apparently as a dispersion of the swollen lamellae in the solution. Upon temperature increase, a vesicle-to-micelle transition occurs. These unusual equilibria can also be qualitatively rationalized by the short chain solubility model.
Bruno F.B. Silva; Eduardo Marques; Ulf Olsson; Bidyut K Paul; Satya P Moulik. Unusual Phase Behavior in a Two-Component System Catanionic Surfactant-Water: From Lamellar-Lamellar to Vesicle-Micelle Coexistence. Multimedia Information Extraction and Digital Heritage Preservation 2012, 12, 69 -84.
AMA StyleBruno F.B. Silva, Eduardo Marques, Ulf Olsson, Bidyut K Paul, Satya P Moulik. Unusual Phase Behavior in a Two-Component System Catanionic Surfactant-Water: From Lamellar-Lamellar to Vesicle-Micelle Coexistence. Multimedia Information Extraction and Digital Heritage Preservation. 2012; 12 ():69-84.
Chicago/Turabian StyleBruno F.B. Silva; Eduardo Marques; Ulf Olsson; Bidyut K Paul; Satya P Moulik. 2012. "Unusual Phase Behavior in a Two-Component System Catanionic Surfactant-Water: From Lamellar-Lamellar to Vesicle-Micelle Coexistence." Multimedia Information Extraction and Digital Heritage Preservation 12, no. : 69-84.
Environmentally responsive materials (i.e., materials that respond to changes in their environment with a change in their properties or structure) are attracting increasing amounts of interest. We recently designed and synthesized a series of cleavable multivalent lipids (CMVLn, with n = 2-5 being the number of positive headgroup charges at full protonation) with a disulfide bond in the linker between their cationic headgroup and hydrophobic tails. The self-assembled complexes of the CMVLs and DNA are a prototypical environmentally responsive material, undergoing extensive structural rearrangement when exposed to reducing agents. We investigated the structural evolution of CMVL-DNA complexes at varied complex composition, temperature, and incubation time using small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS). A related lipid with a stable linker, TMVL4, was used as a control. In a nonreducing environment, CMVL-DNA complexes form the lamellar (L(α)(C)) phase, with DNA rods sandwiched between lipid bilayers. However, new self-assembled phases form when the disulfide linker is cleaved by dithiothreitol or the biologically relevant reducing agent glutathione. The released DNA and cleaved CMVL headgroups form a loosely organized phase, giving rise to a characteristic broad SAXS correlation profile. CMVLs with high headgroup charge also form condensed DNA bundles. Intriguingly, the cleaved hydrophobic tails of the CMVLs reassemble into tilted chain-ordered L(β') phases upon incubation at physiological temperature (37 °C), as indicated by characteristic WAXS peaks. X-ray scattering further reveals that two of the three phases (L(βF), L(βL), and L(βI)) constituting the L(β') phase coexist in these samples. The described system may have applications in lipid-based nanotechnologies.
Rahau S. Shirazi; Kai Ewert; Bruno Silva; Cecilia Leal; Youli Li; Cyrus R. Safinya. Structural Evolution of Environmentally Responsive Cationic Liposome–DNA Complexes with a Reducible Lipid Linker. Langmuir 2012, 28, 10495 -10503.
AMA StyleRahau S. Shirazi, Kai Ewert, Bruno Silva, Cecilia Leal, Youli Li, Cyrus R. Safinya. Structural Evolution of Environmentally Responsive Cationic Liposome–DNA Complexes with a Reducible Lipid Linker. Langmuir. 2012; 28 (28):10495-10503.
Chicago/Turabian StyleRahau S. Shirazi; Kai Ewert; Bruno Silva; Cecilia Leal; Youli Li; Cyrus R. Safinya. 2012. "Structural Evolution of Environmentally Responsive Cationic Liposome–DNA Complexes with a Reducible Lipid Linker." Langmuir 28, no. 28: 10495-10503.