8 research outputs found
Magnetic Surfactants and Polymers with Gadolinium Counterions for Protein Separations
New magnetic surfactants, (cationic
hexadecyltrimethlyammonium
bromotrichlorogadolinate (CTAG), decyltrimethylammonium bromotrichlorogadolinate
(DTAG), and a magnetic polymer (polyÂ(3-acrylamidopropyl)Âtrimethylammonium
tetrachlorogadolinate (APTAG)) have been synthesized by the simple
mixing of the corresponding surfactants and polymer with gadolinium
metal ions. A magnetic anionic surfactant, gadolinium triÂ(1,4-bisÂ(2-ethylhexoxy)-1,4-dioxobutane-2-sulfonate)
(GdÂ(AOT)<sub>3</sub>), was synthesized via metathesis. Both routes
enable facile preparation of magnetically responsive magnetic polymers
and surfactants without the need to rely on nanocomposites or organic
frameworks with polyradicals. Electrical conductivity, surface tensiometry,
SQUID magnetometry, and small-angle neutron scattering (SANS) demonstrate
surface activity and self-aggregation behavior of the magnetic surfactants
similar to their magnetically inert parent analogues but with added
magnetic properties. The binding of the magnetic surfactants to proteins
enables efficient separations under low-strength (0.33 T) magnetic
fields in a new, nanoparticle-free approach to magnetophoretic protein
separations and extractions. Importantly, the toxicity of the magnetic
surfactants and polymers is, in some cases, lower than that of their
halide analogues
Antiviral Properties of Polymeric Aziridine- and Biguanide-Modified CoreâShell Magnetic Nanoparticles
Polycationic superparamagnetic nanoparticles (âŒ150â250
nm) were evaluated as virucidal agents. The particles possess a coreâshell
structure, with cores consisting of magnetite clusters and shells
of functional silica covalently bound to polyÂ(hexamethylene biguanide)
(PHMBG), polyethyleneimine (PEI), or PEI terminated with aziridine
moieties. Aziridine was conjugated to the PEI shell through cationic
ring-opening polymerization. The nanometric coreâshell particles
functionalized with biguanide or aziridine moieties are able to bind
and inactivate bacteriophage MS2, herpes simplex virus HSV-1, nonenveloped
infectious pancreatic necrosis virus (IPNV), and enveloped viral hemorrhagic
septicaemia virus (VHSV). The virusâparticle complexes can
be efficiently removed from the aqueous milieu by simple magnetocollection
Mobility of Water and Polymer Species and Rheological Properties of Supramolecular Polypseudorotaxane Gels Suitable for Bone Regeneration
The
aim of this work was to prepare polypseudorotaxane-based supramolecular
gels combining αCD with two temperature-responsive copolymers
of different architecture (i.e., linear poloxamer P and X-shaped poloxamine
T), at the lowest concentration as possible to form syringeable depots,
and to shed light on the self-diffusion and spatial closeness of all
components (including water) which in turn may determine the cooperative
self-assembly phenomena and the performance of the gels at the macroscopic
level. The exchange rate between bound water and bulk water was measured
with a novel NMR experiment Water Diffusion Exchange-Diffusion Optimized
Spectroscopy (WDE-DOSY). Polypseudorotaxane formation caused opposite
effects on the mobility of αCD species (decreased) and internal
water (increased) but did not affect PPO-water interaction. Consequently,
designed ternary P/T/αCD supramolecular gels exhibited in situ
gelling at body temperature could host large amounts of PLA/PLGA microspheres
and behaved as porous 3D-scaffolds for mesenchymal stem cells (MSCs)
supporting their osteogenic differentiation. Interestingly, the gels
withstood freeze-drying and reconstitution with minor changes in inner
structure and rheological properties. The gathered information may
help to understand better the supramolecular gels and provide tools
for the rational design of syringeable bone scaffolds that can simultaneously
accommodate cells and drug microcarriers for efficient tissue regeneration
Superhydrophobic Chips for Cell Spheroids High-Throughput Generation and Drug Screening
We
suggest the use of biomimetic superhydrophobic patterned chips produced
by a benchtop methodology as low-cost and waste-free platforms for
the production of arrays of cell spheroids/microtissues by the hanging
drop methodology. Cell spheroids have a wide range of applications
in biotechnology fields. For drug screening, they allow studying 3D
models in structures resembling real living tissues/tumors. In tissue
engineering, they are suggested as building blocks of bottom-up fabricated
tissues. We used the wettability contrast of the chips to fix cell
suspension droplets in the wettable regions and evaluated on-chip
drug screening in 3D environment. Cell suspensions were patterned
in the wettable spots by three distinct methods: (1) by pipetting
the cell suspension directly in each individual spot, (2) by the continuous
dragging of a cell suspension on the chip, and (3) by dipping the
whole chip in a cell suspension. These methods allowed working with
distinct throughputs and degrees of precision. The platforms were
robust, and we were able to have static or dynamic environments in
each droplet. The access to cell culture media for exchange or addition/removal
of components was versatile and opened the possibility of using each
spot of the chip as a mini-bioreactor. The platformsâ design
allowed for samples visualization and high-content image-based analysis
on-chip. The combinatorial analysis capability of this technology
was validated by following the effect of doxorubicin at different
concentrations on spheroids formed using L929 and SaOs-2 cells
Targeted Combinatorial Therapy Using Gold Nanostars as Theranostic Platforms
This paper reports the development
of a multimodal therapy nanoplatform
based on gold nanostars (Au NS) as core particles. These NS were functionalized
with the chemotherapeutic drug doxorubicin (DOXO), which was conjugated
to the NS surface by means of a cleavable heterobifunctional cross-linker
(sulfo-LC-SPDP) to allow its release under the action of reducing
enzymes. To ensure a specific delivery of the chemotherapeutic drug,
the nanoplatform was additionally functionalized with folic acid (FA)
as targeting ligand and cellular uptake adjuvant. By synthetically
modifying the plasmon band of Au NS to the near-infrared (NIR) region
of the electromagnetic spectrum, the present nanoplatform was able
to simultaneously combine the capability of photothermal therapy (PTT)
through the conversion of absorbed light energy into localized heat
and chemotherapy, enabling their monitoring by means of optical fluorescence
imaging thanks to DOXOâs autofluorescence. Cellular uptake
was observed to be enhanced when the Au NPs were decorated with the
targeting ligand. In addition, the therapeutic efficiency of the nanoplatform
tested in HeLa cells demonstrated the larger cytotoxicity efficiency
of the combined therapy if compared to individual ones
Materials with Fungi-Bioinspired Surface for Efficient Binding and Fungi-Sensitive Release of Antifungal Agents
Materials with fungi-bioinspired
surface have been designed to
host ergosterol-binding polyene antibiotics and to release them via
a competitive mechanism only when fungi are present in the medium.
Silicone rubber (SR) surfaces were endowed with selective loading
and fungi-triggered release of polyene antifungal agents by means
of a two-step functionalization that involved the grafting of glycidyl
methacrylate (GMA) via a Îł-ray preirradiation method (9â21.3%
wt grafting) and the subsequent immobilization of ergosterol (3.9â116.8
mg/g) to the epoxy groups of polyGMA. The functionalized materials
were characterized using FTIR and Raman spectroscopy, thermogravimetric
analysis (TGA), and fluorescence, scanning electron microscopy (SEM),
and atomic force microscopy (AFM) image analyses. Specific interactions
between natamycin or nystatin and ergosterol endowed SR with ability
to take up these polyene drugs, while immobilization of ergosterol
did not modify the loading of antifungal drugs that did not interact
in vivo with ergosterol (e.g., miconazole). In a buffer medium, polyene-loaded
ergosterol-immobilized slabs efficiently retained the drug (<10%
released at day 14), while in the presence of ergosterol-containing
liposomes that mimic fungi membranes the release rate was 10-to-15-fold
enhanced due to a competitive displacement of the drug from the ergosterol-immobilized
slab to the ergosterol-containing liposomes. Release in the presence
of cholesterol liposomes was slower due to a weaker interaction with
polyene agents. The fungi-responsive release was demonstrated for
both polyene drugs tested and for slabs prepared with a wide range
of amounts of immobilized GMA and ergosterol, demonstrating the robustness
of the approach. Nystatin-loaded functionalized slabs were challenged
with Candida albicans and showed improved
capability to inhibit biofilm formation compared to nystatin-soaked
pristine SR, confirming the performance of the bioinspired materials
Spermidine Cross-Linked Hydrogels as a Controlled Release Biomimetic Approach for Cloxacillin
The
intrinsic ability of albumin to bind active substances in the
physiological fluids has been explored to endow hydrogels with improved
capability to regulate drug release. To develop such biomimetic-functional
hydrogels, it is critical that albumin conformation is not altered
and that the protein remains retained inside the hydrogel keeping
its conformational freedom, i.e., it should be not chemically cross-linked.
Thus, the hydrogels were prepared with various proportions of albumin
by physical cross-linking of anionic polysaccharides (gellan gum and
chondroitin sulfate) with the cationic endogen polyamine spermidine
under mild conditions in order to prevent albumin denaturation. Texture
and swelling properties of hydrogels with various compositions were
recorded, and the effect of the preparation variables was evaluated
applying neurofuzzy logic tools for hydrogels prepared with and without
albumin and associating the antibiotic cloxacillin. Developed hydrogel
systems were extensively analyzed by means of nuclear magnetic resonance
(NMR) to determine weak-to-medium and strong binding modes and the
equilibrium constants of the albuminâcloxacillin association.
NMR techniques were also employed to demonstrate the successful modulation
of the cloxacillin release from the albumin-containing hydrogels. <i>In vitro</i> microbiological tests carried out with <i>Staphylococcus aureus</i> and <i>Staphylococcus epidermidis</i> confirmed the interest of the albumin-containing hydrogels as efficient
platforms for cloxacillin release in its bioactive form
Antimicrobial Properties and Osteogenicity of Vancomycin-Loaded Synthetic Scaffolds Obtained by Supercritical Foaming
Advanced porous synthetic
scaffolds are particularly suitable for regeneration of damaged tissues,
but there is the risk of infections due to the colonization of microorganisms,
forming biofilms. Supercritical foaming is an attractive processing
method to prepare bone scaffolds, regulating simultaneously the porosity
and loading of bioactive compounds without loss of activity. In this
work, scaffolds made of poly-Δ-caprolactone (50 kDa), containing
chitosan and an antimicrobial agent (vancomycin), were processed by
supercritical CO<sub>2</sub> foaming for bone regeneration purposes.
The obtained scaffolds showed a suitable combination of morphological
(porosity, pore size distribution, and interconnectivity), time-dependent
in vitro vancomycin release behavior and biological properties (cell
viability and proliferation, osteodifferentiation, and tissue-scaffold
integration). The scaffolds sustained vancomycin release for more
than 2 weeks. Finally, the antimicrobial activity of the scaffolds
was tested against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria after 24 h of incubation with full growth inhibition for S. aureus