2D fibrillar osteoid niche mimicry through inclusion of visco-elastic and topographical cues in gelatin-based networks

Given the clinical need for osteoregenerative materials incorporating controlled biomimetic and biophysical cues, a novel highly-substituted norbornene-modified gelatin was developed enabling thiol-ene crosslinking exploiting thiolated gelatin as cell-interactive crosslinker. Comparing the number of physical crosslinks, the degree of hydrolytic degradation upon modification, the network density and the chemical crosslinking type, the osteogenic effect of visco-elastic and topographical properties was evaluated. This novel network outperformed conventional gelatin-based networks in terms of osteogenesis induction, as evidenced in 2D dental pulp stem cell seeding assays, resulting from the presentation of both a local (substrate elasticity, 25-40 kPa) and a bulk (compressive modulus, 25-45 kPa) osteogenic substrate modulus in combination with adequate fibrillar cell adhesion spacing to optimally transfer traction forces from the fibrillar ECM (as evidenced by mesh size determination with the rubber elasticity theory) and resulting in a 1.7-fold increase in calcium production (compared to the gold standard gelatin methacryloyl (GelMA)).

Good's Buffer Based Highly Biocompatible Ionic Liquid Modified PLGA Nanoparticles for the Selective Uptake in Cancer Cells

Achieving safe and efficacious drug delivery is still an outstanding challenge. Herein we have synthesized 20 biocompatible Good's buffer-based ionic liquids (GBILs) with a range of attractive properties for drug delivery applications. The synthesized GBILs were used to coat the surface of poly(lactic-co-glycolic acid) (PLGA) by nanoprecipitation-sonication and characterized by dynamic light scattering (DLS) and proton nuclear magnetic resonance (1H NMR) spectroscopy. The GBIL-modified PLGA NPs were then tested for their interaction with bio-interfaces such as serum proteins (using SDS-PAGE and LCMS) and red blood cells (RBCs) isolated from human and BALB/c mouse blood. In this report, we show that surface modification of PLGA with certain GBILs led to modulation of preferential cellular uptake towards human triple-negative breast cancer cells (MDA-MB-231) compared to human normal healthy breast cells (MCF-10A). For example, cholinium N,N-bis(2-hydroxyethyl)-2-aminoethane sulfonate (CBES) coated PLGA NPs were found to be selective for MDA-MB-231 cells (60.7 ± 0.7 %) as compared to MCF-10A cells (27.3 ± 0.7 %). In this way, GBIL-coatings have increased PLGA NP uptake in the cancer cells by 2-fold while decreasing the uptake towards normal healthy breast cells. Therefore, GBIL-modified nanoparticles could be a versatile platform for targeted drug delivery and gene therapy applications, as their surface properties can be tailored to interact with specific cell receptors and enhance cellular uptake. This formulation technique has shown promising results for targeting specific cells, which could be explored further for other cell types to achieve site-specific and efficient delivery of therapeutic agents.

Green-step assembly of the supramolecular amphiphile constructed by sodium carboxymethyl cellulose and calixarene for facile loading of hydrophobic food bioactive compounds

The use of biologically active compounds is often limited due to their poor aqueous solubility, which generally reduces their bioavailability and useful efficacy. In this regard, a wide search is currently underway for colloidal systems capable of encapsulating these compounds. In the creation of colloidal systems, long-chain molecules of surfactants and polymers are mainly used, which in an individual state do not always aggregate into homogeneous and stable nanoparticles. In the present work, cavity-bearing calixarene was used for the first time to order polymeric molecules of sodium carboxymethyl cellulose. A set of physicochemical methods demonstrated the spontaneous formation of spherical nanoparticles by non-covalent self-assembly contributed by macrocycle and polymer, and formed nanoparticles were able to encapsulate hydrophobic quercetin and oleic acid. The preparation of nanoparticles by supramolecular self-assembly without use of organic solvents, temperature and ultrasound effects can be an effective strategy for creating water-soluble forms of lipophilic bioactive compounds.

Influence of protic ionic liquids on hydration of glycine based peptides

The structure of water, especially around the solute is thought to play an important role in many biological and chemical processes. Water-peptide and cosolvent-peptide interactions are crucial in determining the structure and function of protein molecules. In this work, we present the H-bonding analysis for model peptides like glycyl-glycine (gly-gly), glycine-ւ-valine (gly-val), glycyl-ւ-leucine (gly-leu) and triglycine (trigly) and triethylammonium based carboxylate protic ionic liquids (PILs) in aqueous solutions as well as for peptides in ∼0.2 mol·L^-1 of aqueous PIL solutions in the spectral range of 7800-5500 cm^-1 using Fourier transform near-infrared (FT-NIR) spectroscopy at 298.15 K. The hydration numbers for peptides and PILs were obtained using NIR method of simultaneous estimation of hydration spectrum and hydration number of a solute dissolved in water. The H-bond of water molecules around peptides and PILs are found to be stronger and shorter than those in pure liquid water. We observe that the hydration shell around zwitterions is a clathrate-like cluster of water in which ions entrap. Watery network analysis confirms that singly H-bonded species or NHBs changes to partial or distorted ice-like structures of water in the hydration shell of PILs. The overall water H-bonding in the hydration sphere of PILs increases in the order TEAF < TEAA < TEAG < TEAPy ≈ TEAP < TEAB. The influence of PILs on hydration behavior of peptides is explored in terms of H-bonding, cooperativity, hydrophobicity, water structural changes, ionic interactions etc.

Synergistic interactions of ionic liquids and antimicrobials improve drug efficacy

Combinations of ionic liquids (ILs) with antimicrobial compounds have been shown to produce synergistic activities in model liposomes. In this study, imidazolium chloride-based ILs with alkyl tail length variations are combined with commercially available, small-molecule antimicrobials to examine the potential for combinatorial and synergistic antimicrobial effects on P. aeruginosa, E. coli, S. aureus, and S. cerevisiae. The effects of these treatments in a human cell culture model indicate the cytotoxic limits of ILs paired with antimicrobials. The analysis of these ILs demonstrates that the length of the alkyl chain on the IL molecule is proportional to both antimicrobial activity and cytotoxicity. Moreover, the ILs which exhibit synergy with small-molecule antibiotics appear to be acting in a membrane permeabilizing manner. Collectively, results from these experiments demonstrate an increase in antimicrobial efficacy with specific IL + antimicrobial combinations on microbial cultures while maintaining low cytotoxicity in a mammalian cell culture model.

Aqueous colloidal systems of bovine serum albumin and functionalized surface active ionic liquids for material transport

Physicochemical and computational investigation of complexation between BSA and SAILs with application in material transport.

Correlating Lipid Membrane Permeabilities of Imidazolium Ionic Liquids with their Cytotoxicities on Yeast, Bacterial, and Mammalian Cells

Alkyl-imidazolium chloride ionic liquids (ILs) have been broadly studied for biochemical and biomedical technologies. They can permeabilize lipid bilayer membranes and have cytotoxic effects, which makes them targets for drug delivery biomaterials. We assessed the lipid-membrane permeabilities of ILs with increasing alkyl chain lengths from ethyl to octyl groups on large unilamellar vesicles using a trapped-fluorophore fluorescence lifetime-based leakage experiment. Only the most hydrophobic IL, with the octyl chain, permeabilizes vesicles, and the concentration required for permeabilization corresponds to its critical micelle concentration. To correlate the model vesicle studies with biological cells, we quantified the IL permeabilities and cytotoxicities on different cell lines including bacterial, yeast, and ovine blood cells. The IL permeabilities on vesicles strongly correlate with permeabilities and minimum inhibitory concentrations on biological cells. Despite exhibiting a broad range of lipid compositions, the ILs appear to have similar effects on the vesicles and cell membranes.

Heme Dissociation from Myoglobin in the Presence of the Zwitterionic Detergent N,N-Dimethyl-N-Dodecylglycine Betaine: Effects of Ionic Liquids

We have investigated myoglobin protein denaturation using the zwitterionic detergent Empigen BB (EBB, N,N-Dimethyl-N-dodecylglycine betaine). A combination of absorbance, fluorescence, and circular dichroism spectroscopic measurements elucidated the protein denaturation and heme dissociation from myoglobin. The results indicated that Empigen BB was not able to fully denature the myoglobin structure, but apparently can induce the dissociation of the heme group from the protein. This provides a way to estimate the heme binding free energy, ΔG_dissociation. As ionic liquids (ILs) have been shown to perturb the myoglobin protein, we have investigated the effects of the ILs 1-butyl-3-methylimidazolium chloride (BMICl), 1-ethyl-3-methylimidazolium acetate (EMIAc), and 1-butyl-3-methylimidazolium tetrafluoroborate (BMIBF₄) in aqueous solution on the ΔG_dissociation values. Absorbance experiments show the ILs had minimal effect on ΔG_dissociation values when compared to controls. Fluorescence and circular dichroism data confirm the ILs have no effect on heme dissociation, demonstrating that low concentrations ILs do not impact the heme dissociation from the protein and do not significantly denature myoglobin on their own or in combination with EBB. These results provide important data for future studies of the mechanism of IL-mediated protein stabilization/destabilization and biocompatibility studies.

Colloidal systems of surface active ionic liquids and sodium carboxymethyl cellulose: physicochemical investigations and preparation of magnetic nano-composites

Carboxymethyl cellulose-surface active ionic liquid colloidal formulations for preparation of magnetic nano-composites.

Synergistic effects of polymyxin and ionic liquids on lipid vesicle membrane stability and aggregation

Ionic liquids (ILs) have been investigated for potential antibacterial and antibiotic applications due to their ability to destabilize and permeabilize the lipid bilayers in cell membranes. Bacterial assays have shown that combining ILs with antibiotics can provide a synergistic enhancement of their antibacterial activities. We have characterized the mechanism by which the conventional ILs 1-butyl-3-methylimidazolium chloride (BMICl) and 1-butyl-3-methylimidazolium tetrafluoroborate (BMIBF₄) enhance the lipid membrane permeabilization of the well-known antibiotic polymyxin B (PMB). We studied the sizes and membrane permeabilities of multilamellar and unilamellar lipid bilayer vesicles in the presence of ILs alone in aqueous solution, PMB alone, and ILs combined together with PMB. Light scattering-based experiments show that vesicle sizes dramatically increase when ILs are combined with PMB, which suggests that the materials combine to synergistically enhance lipid membrane disruption leading to vesicle aggregation. Lipid bilayer leakage experiments using tris (2,2'-bipyridyl) ruthenium (II) (Ru(bpy)₃²⁺) trapped in lipid vesicles, in which the trapped Ru(bpy)₃²⁺ fluorescence lifetime increases when it leaks out of the vesicle, show that combining BMIBF₄ and PMB together permeabilize the membrane significantly more than with PMB or the IL alone. This demonstrates that ILs can assist in antibiotic permeabilization of lipid bilayers which could explain the increased antibiotic activities in the presence of ILs in solution.