Polymer Film Dewetting by Water/Surfactant/Good-Solvent Mixtures: A Mechanistic Insight and Its Implications for the Conservation of Cultural Heritage

Aqueous nanostructured fluids (NSFs) have been proposed to remove polymer coatings from the surface of works of art; this process usually involves film dewetting. The NSF cleaning mechanism was studied using several techniques that were employed to obtain mechanistic insight on the interaction of a methacrylic/acrylic copolymer (Paraloid B72) film laid on glass surfaces and several NSFs, based on two solvents and two surfactants. The experimental results provide a detailed picture of the dewetting process. The gyration radius and the reduction of the Tg of Paraloid B72 fully swollen in the two solvents is larger for propylene carbonate than for methyl ethyl ketone, suggesting higher mobility of polymer chains for the former, while a nonionic alcohol ethoxylate surfactant was more effective than sodium dodecylsulfate in favoring the dewetting process. FTIR 2D imaging showed that the dewetting patterns observed on model samples are also present on polymer-coated mortar tiles when exposed to NSF

Methylene blue-containing liposomes as new photodynamic anti-bacterial agents

Novel cationic liposomes containing the photo-activatable drug methylene blue (MB) strongly enhance the antibacterial activity of MB towards Gram-negative bacteria and improve biofilm penetration.</p

Inorganic nanoparticles as potential regulators of immune response in dendritic cells

Aim: The spontaneous adsorption of proteins on nanoparticles (NPs) in biological media is exploited to prepare complexes of NPs and proteins from cancer cells’ lysates for application in cancer immunotherapy. Materials &amp; methods: Gold (Au) and silica NPs were synthesized, incubated with cancer cells’ lysates and characterized. Dendritic cells (DCs) were challenged with protein-coated NPs, their maturation, viability and morphology were evaluated and lymphocytes T proliferation was determined. Results: Silica and Au NPs bound different pools of biomolecules from lysates, and are therefore promising selective carriers for antigens. When incubated with immature DCs, NPs were efficiently endocytosed without cytotoxicity. Finally, protein-coated AuNPs promoted DC maturation and DC-mediated lymphocyte proliferation, at variance with lysate alone and protein-coated silica NPs, that did not promote DCs maturation. Conclusion: These results demonstrate that the spontaneous formation of protein coronas on NPs represents a possible approach to fast, easy, cost-effective DCs stimulation. </jats:p

Lipid Cubic Mesophases Combined with Superparamagnetic Iron Oxide Nanoparticles: A Hybrid Multifunctional Platform with Tunable Magnetic Properties for Nanomedical Applications

Hybrid materials composed of superparamagnetic iron oxide nanoparticles (SPIONs) and lipid self-assemblies possess considerable applicative potential in the biomedical field, specifically, for drug/nutrient delivery. Recently, we showed that SPIONs-doped lipid cubic liquid crystals undergo a cubic-to-hexagonal phase transition under the action of temperature or of an alternating magnetic field (AMF). This transition triggers the release of drugs embedded in the lipid scaffold or in the water channels. In this contribution, we address this phenomenon in depth, to fully elucidate the structural details and optimize the design of hybrid multifunctional carriers for drug delivery. Combining small-angle X-ray scattering (SAXS) with a magnetic characterization, we find that, in bulk lipid cubic phases, the cubic-to-hexagonal transition determines the magnetic response of SPIONs. We then extend the investigation from bulk liquid-crystalline phases to colloidal dispersions, i.e., to lipid/SPIONs nanoparticles with cubic internal structure (“magnetocubosomes”). Through Synchrotron SAXS, we monitor the structural response of magnetocubosomes while exposed to an AMF: the magnetic energy, converted into heat by SPIONs, activates the cubic-to-hexagonal transition, and can thus be used as a remote stimulus to spike drug release “on-demand”. In addition, we show that the AMF-induced phase transition in magnetocubosomes steers the realignment of SPIONs into linear string assemblies and connect this effect with the change in their magnetic properties, observed at the bulk level. Finally, we assess the internalization ability and cytotoxicity of magnetocubosomes in vitro on HT29 adenocarcinoma cancer cells, in order to test the applicability of these smart carriers in drug delivery applications

Role of Curvature-Sensing Proteins in the Uptake of Nanoparticles with Different Mechanical Properties

Nanoparticles of different properties, such as size, charge, and rigidity, are used for drug delivery. Upon interaction with the cell membrane, because of their curvature, nanoparticles can bend the lipid bilayer. Recent results show that cellular proteins capable of sensing membrane curvature are involved in nanoparticle uptake; however, no information is yet available on whether nanoparticle mechanical properties also affect their activity. Here liposomes and liposome-coated silica are used as a model system to compare uptake and cell behavior of two nanoparticles of similar size and charge, but different mechanical properties. High-sensitivity flow cytometry, cryo-TEM, and fluorescence correlation spectroscopy confirm lipid deposition on the silica. Atomic force microscopy is used to quantify the deformation of individual nanoparticles at increasing imaging forces, confirming that the two nanoparticles display distinct mechanical properties. Uptake studies in HeLa and A549 cells indicate that liposome uptake is higher than for the liposome-coated silica. RNA interference studies to silence their expression show that different curvature-sensing proteins are involved in the uptake of both nanoparticles in both cell types. These results confirm that curvature-sensing proteins have a role in nanoparticle uptake, which is not restricted to harder nanoparticles, but includes softer nanomaterials commonly used for nanomedicine applications.</p

Cationic liposomal vectors incorporating a bolaamphiphile for oligonucleotide antimicrobials

Antibacterial resistance has become a serious crisis for world health over the last few decades, so that new therapeutic approaches are strongly needed to face the threat of resistant infections. Transcription factor decoys (TFD) are a promising new class of antimicrobial oligonucleotides with proven in vivo activity when combined with a bolaamphiphilic cationic molecule, 12-bis-THA. These two molecular species form stable nanoplexes which, however, present very scarce colloidal stability in physiological media, which poses the challenge of drug formulation and delivery. In this work, we reformulated the 12-bis-THA/TFD nanoplexes in a liposomal carrier, which retains the ability to protect the oligonucleotide therapeutic from degradation and deliver it across the bacterial cell wall. We performed a physical-chemical study to investigate how the incorporation of 12-bis-THA and TFD affects the structure of POPC- and POPC/DOPE liposomes. Analysis was performed using dynamic light scattering (DLS), ζ-potential measurements, small-angle x-ray scattering (SAXS), and steady-state fluorescence spectroscopy to better understand the structure of the liposomal formulations containing the 12-bis-THA/TFD complexes. Oligonucleotide delivery to model Escherichia coli bacteria was assessed by means of confocal scanning laser microscopy (CLSM), evidencing the requirement of a fusogenic helper lipid for transfection. Preliminary biological assessments suggested the necessity of further development by modulation of 12-bis-THA concentration in order to optimize its therapeutic index, i.e. the ratio of antibacterial activity to the observed cytotoxicity. In summary, POPC/DOPE/12-bis-THA liposomes appear as promising formulations for TFD delivery

Cationic liposomal vectors incorporating a bolaamphiphile for oligonucleotide antimicrobials

Antibacterial resistance has become a serious crisis for world health over the last few decades, so that new therapeutic approaches are strongly needed to face the threat of resistant infections. Transcription factor decoys (TFD) are a promising new class of antimicrobial oligonucleotides with proven in vivo activity when combined with a bolaamphiphilic cationic molecule, 12-bis-THA. These two molecular species form stable nanoplexes which, however, present very scarce colloidal stability in physiological media, which poses the challenge of drug formulation and delivery. In this work, we reformulated the 12-bis-THA/TFD nanoplexes in a liposomal carrier, which retains the ability to protect the oligonucleotide therapeutic from degradation and deliver it across the bacterial cell wall. We performed a physical-chemical study to investigate how the incorporation of 12-bis-THA and TFD affects the structure of POPC- and POPC/DOPE liposomes. Analysis was performed using dynamic light scattering (DLS), ζ-potential measurements, small-angle x-ray scattering (SAXS), and steady-state fluorescence spectroscopy to better understand the structure of the liposomal formulations containing the 12-bis-THA/TFD complexes. Oligonucleotide delivery to model Escherichia coli bacteria was assessed by means of confocal scanning laser microscopy (CLSM), evidencing the requirement of a fusogenic helper lipid for transfection. Preliminary biological assessments suggested the necessity of further development by modulation of 12-bis-THA concentration in order to optimize its therapeutic index, i.e. the ratio of antibacterial activity to the observed cytotoxicity. In summary, POPC/DOPE/12-bis-THA liposomes appear as promising formulations for TFD delivery