Biodegradable Chitosan-Based Films as an Alternative to Plastic Packaging.

The impact of synthetic packaging on environmental pollution has been observed for years. One of the recent trends of green technology is the development of biomaterials made from food processing waste as an alternative to plastic packaging. Polymers obtained from some polysaccharides, such as chitosan, could be an excellent solution.

The solvent-free mechano-chemical grinding of a bifunctional P25-graphene oxide adsorbent-photocatalyst and its configuration as porous beads.

Owing to their use in water-cleaning technology, titanium-dioxide-based nanomaterials have dominated the photocatalysis scene, with so-called Degussa (P25) being the most promising under UV light. However, this is not the case under visible light, where it is necessary to combine titanium dioxide with other photosensitising nanomaterials. Unfortunately, most of the strategies aimed in this direction are chemically non-facile, energy-intensive, economically expensive, and not suitable for large-scale production.

Glassy-like Metal Oxide Particles Embedded on Micrometer Thicker Alginate Films as Promising Wound Healing Nanomaterials.

Micrometer-thicker, biologically responsive nanocomposite films were prepared starting from alginate-metal alkoxide colloidal solution followed by sol-gel chemistry and solvent removal through evaporation-induced assembly. The disclosed approach is straightforward and highly versatile, allowing the entrapment and growth of a set of glassy-like metal oxide within the network of alginate and their shaping as crake-free transparent and flexible films. Immersing these films in aqueous medium triggers alginate solubilization, and affords water-soluble metal oxides wrapped in a biocompatible carbohydrate framework.

Insight into Factors Influencing Wound Healing Using Phosphorylated Cellulose-Filled-Chitosan Nanocomposite Films.

Marine polysaccharides are believed to be promising wound-dressing nanomaterials because of their biocompatibility, antibacterial and hemostatic activity, and ability to easily shape into transparent films, hydrogels, and porous foams that can provide a moist micro-environment and adsorb exudates. Current efforts are firmly focused on the preparation of novel polysaccharide-derived nanomaterials functionalized with chemical objects to meet the mechanical and biological requirements of ideal wound healing systems. In this contribution, we investigated the characteristics of six different cellulose-filled chitosan transparent films as potential factors that could help to accelerate wound healing.

Antimicrobial Effect of Chitosan Films on Food Spoilage Bacteria.

Synthetic materials commonly used in the packaging industry generate a considerable amount of waste each year. Chitosan is a promising feedstock for the production of functional biomaterials. From a biological point of view, chitosan is very attractive for food packaging.

Chitosan-Functionalized Graphene Nanocomposite Films: Interfacial Interplay and Biological Activity.

Graphene oxide () has recently captured tremendous attention, but only few functionalized graphene derivatives were used as fillers, and insightful studies dealing with the thermal, mechanical, and biological effects of graphene surface functionalization are currently missing in the literature. Herein, reduced graphene oxide (), phosphorylated graphene oxide (), and trimethylsilylated graphene oxide () were prepared by the post-modification of . The electrostatic interactions of these fillers with chitosan afforded colloidal solutions that provide, after water evaporation, transparent and flexible chitosan-modified graphene films.

Aldehyde-conjugated chitosan-graphene oxide glucodynamers: Ternary cooperative assembly and controlled chemical release.

Simultaneous condensation of aromatic aldehydes (ArCHO; x = 1-4) on chitosan biopolymer (CS) affords, after water-evaporation, structurally-conjugated aryl-functionalized CS-Ar-f films. Similarly, cooperative assembly of two-dimensional nanometric graphene oxide (GO), aromatic aldehyde and chitosan provides transparent, flexible and crack-free aldehyde-functionalized, ternary-reinforced CS-Ar-GO-f nanocomposite films. Homogenous films were obtained using ortho-hydroxybenzaldehyde Ar while the para-hydroxybenzaldehyde Ar was prone to packing inside.

Palladium Supported on Porous Chitosan-Graphene Oxide Aerogels as Highly Efficient Catalysts for Hydrogen Generation from Formate.

Adsorption of Pd(NH) in preformed chitosan-graphene oxide (CS-GO) beads and their subsequent reduction with NaBH afford well-dispersed, high dispersion (~21%) of uniformly sized Pd nanoparticles (~1.7 nm). The resulting Pd/CS-GO exhibits interesting catalytic activity for hydrogen generation by ammonium formate decomposition.

Supramolecular Chemistry-Driven Preparation of Nanostructured, Transformable, and Biologically Active Chitosan-Clustered Single, Binary, and Ternary Metal Oxide Bioplastics.

Aside from their economical cost and resource depletion, petroleum-based plastics generate annually a substantial amount of waste with a negative and extremely alarming impact on the environment and public health. Consequently, rising interest was devoted to search for biobased materials to find sustainable alternatives. Herein, we report a new and straightforward method to incorporate endogenous nano-objects (exemplified herein by metal oxide clusters) within polysaccharide-based films.

Interfacial complexation driven three-dimensional assembly of cationic phosphorus dendrimers and graphene oxide sheets.

High content nitrogen, sulfur and phosphorus heteroatoms assembled in tree-like dendrimers (DG ) are confined within the galleries of two-dimensional graphene oxide (GO). The presence of the ternary diethyl--ethyl-ammonium groups on the dendrimer peripheries ensures the exfoliation of graphene sheets thereby affording interfacially bridged, three-dimensional heteroatom-enriched graphene-based hybrid nanostructures (DG -GO). Dendrimer generation (from 1 to 4) that reflects the bulkiness of these conceived nano-trees impacts increasingly the degree of dispersion-exfoliation and sheet desordering.

Aldehyde-functionalized chitosan-montmorillonite films as dynamically-assembled, switchable-chemical release bioplastics.

Temporal release of synergistic and/or complementary chemicals (e.g.: drugs) is recognized as extremely challenging because of their frequently intertwined kinetic delivery and presently, straightforward concepts enabling to circumvent this bottleneck are missing in the open literature.

Ternary cooperative assembly--polymeric condensation of photoactive viologen, phosphonate-terminated dendrimers and crystalline anatase nanoparticles.

Photoactive viologen fragments were covalently embedded within the material framework during the self-assembly and sol-gel polymerisation of phosphonate-terminated dendrimers and soluble titanium-oxo-species. The resulting porous anisotropic phosphonate-bridged-crystalline anatase materials serve as new hosts to disperse and stabilize small gold nanoparticles.

Biological Activity of Mesoporous Dendrimer-Coated Titanium Dioxide: Insight on the Role of the Surface-Interface Composition and the Framework Crystallinity.

Hitherto, the field of nanomedicine has been overwhelmingly dominated by the use of mesoporous organosilicas compared to their metal oxide congeners. Despite their remarkable reactivity, titanium oxide-based materials have been seldom evaluated and little knowledge has been gained with respect to their "structure-biological activity" relationship. Herein, a fruitful association of phosphorus dendrimers (both "ammonium-terminated" and "phosphonate-terminated") and titanium dioxide has been performed by means of the sol-gel process, resulting in mesoporous dendrimer-coated nanosized crystalline titanium dioxide.

Organophosphonate bridged anatase mesocrystals: low temperature crystallization, thermal growth and hydrogen photo-evolution.

The sol-gel co-condensation of organo-phosphonates to titanium alkoxides enables access to novel organic-inorganic hybrids based on phosphonate-bridged titanium dioxide. In this contribution, we bring new perspectives to the long established sol-gel mineralization of titanium alkoxide species, by harnessing the virtues of the well-designed phosphonate-terminated phosphorus dendrimers as reactive amphiphilic nanoreactor, confined medium and cross-linked template to generate discrete crystalline anatase nanoparticles at low temperature (T = 60 °C). An accurate investigation on several parameters (dendrimer generation, dendrimer-to-titanium alkoxide ratio, precursor reactivity, temperature, solvent nature, salt effect) allows a correlation between the network condensation, the opening porous framework and the crystalline phase formation.

Haemolytic activity and cellular toxicity of SBA-15-type silicas: elucidating the role of the mesostructure, surface functionality and linker length.

In this contribution, amorphous silica (a-SiO), native SBA-15 silica as well as four functional SBA-15-type silicates modified with aminopropyl (SBA-NH), mercaptopropyl (SBA-SH), ethylcarboxylic (SBA-COOH) and undecenoic acid (SBA-FA-COOH) were prepared by the co-condensation route under similar self-assembly and sol-gel conditions. Next, the impact of these materials on red blood cells was evaluated by studying cell haemolysis and haemoglobin adsorption. Moreover, the influence of the presence of human serum albumin (HSA) on erythrocyte haemolysis and cytotoxicity toward B14 Chinese fibroblasts were investigated.

Synthesis of onion-peel nanodendritic structures with sequential functional phosphorus diversity.

The preparation of novel families of phosphorus-based macromolecular architectures called "onion peel" phosphorus nanodendritic systems is reported. This construct is based on the versatility of methods of synthesis using several building blocks and on the capability of these systems to undergo regioselective reactions within the cascade structure. Sustainable metal-free routes such as the Staudinger reaction or Schiff-base condensation, involving only water and nitrogen as byproducts, allow access to several dendritic macromolecules bearing up to seven different phosphorus units in their backbone, each of them featuring specific reactivity.

Oleochemical-tethered SBA-15-type silicates with tunable nanoscopic order, carboxylic surface, and hydrophobic framework: cellular toxicity, hemolysis, and antibacterial activity.

Novel silicates were prepared by using silylated natural fatty acids (derived from triglyceride renewable oils) as co-condensing reagents in presence of tetraethyl orthosilicate (TEOS) and the triblock copolymer, pluronic P123, as a structure directing agent. A series of carboxylic acid functionalized SBA-15-type mesoporous silicates were obtained with tunable nanoscopic order and reactive functional groups that allow the conjugation of amino probes by peptide coupling. Photophysical studies of the covalently linked aminopyrene substantiated that the internal framework of these materials have pronounced hydrophobicity.

Viologen-based dendritic macromolecular asterisks: synthesis and interplay with gold nanoparticles.

The viologen-skeleton reacts with a hydrazine-terminated cyclotriphosphazene core to provide novel dendritic macromolecular asterisks that efficiently exchange, deliver and stabilize gold nanoparticles for up to eight months.

Promising low-toxicity of viologen-phosphorus dendrimers against embryonic mouse hippocampal cells.

A new class of viologen-phosphorus dendrimers (VPDs) has been recently shown to possess the ability to inhibit neurodegenerative processes in vitro. Nevertheless, in the Central Nervous Systems domain, there is little information on their impact on cell functions, especially on neuronal cells. In this work, we examined the influence of two VPD (VPD1 and VPD3) of zero generation (G0) on murine hippocampal cell line (named mHippoE-18).

Viologen-phosphorus dendrimers exhibit minor toxicity against a murine neuroblastoma cell line.

Dendrimers containing viologen (derivatives of 4,4'-bipyridyl) units in their structure have been demonstrated to exhibit antiviral activity against human immunodeficiency virus (HIV-1). It has also recently been revealed that novel dendrimers with both viologen units and phosphorus groups in their structure show different antimicrobial, cytotoxic and hemotoxic properties, and have the ability to influence the activity of cholinesterases and to inhibit α-synuclein fibrillation. Since the influence of viologen-phosphorus structures on basic cellular processes had not been investigated, we examined the impact of such macromolecules on the murine neuroblastoma cell line (N2a).

Phosphorus-based fatty acid methyl esters.

With the aim of designing novel transformable fatty acid diesters, various strategies for introducing phosphorus arms to the fatty backbone have been examined. While lithiated phosphine reacts classically to brominated fatty esters to afford the mono-addition product, the synthesis of phosphorylated diesters was found to be difficult, a fact related to the bulkiness of fatty acids and phosphine reagents. A base-induced dehydrochlorination reaction using ArPCl2 and hydroxy-terminated fatty esters resulted in metastable diester for which hydrolytic cleavage undergo phosphine oxidation and expulsion of one fatty chain.

Low temperature synthesis of ordered mesoporous stable anatase nanocrystals: the phosphorus dendrimer approach.

The scarcity of low temperature syntheses of anatase nanocrystals prompted us to explore the use of surface-reactive fourth generation phosphorus-dendrimers as molds to control the nucleation and growth of titanium-oxo-species during the sol-gel mineralization process. Unexpectedly, the dendritic medium provides at low temperature, discrete anatase nanocrystals (4.8 to 5.

Viologen-Phosphorus Dendrimers Inhibit α-Synuclein Fibrillation.

Inhibition of α-synuclein (ASN) fibril formation is a potential therapeutic strategy in Parkinson's disease and other synucleinopathies. The aim of this study was to examine the role of viologen-phosphorus dendrimers in the α-synuclein fibrillation process and to assess the structural changes in α-synuclein under the influence of dendrimers. ASN interactions with phosphonate and pegylated surface-reactive viologen-phosphorus dendrimers were examined by measuring the zeta potential, which allowed determining the number of dendrimer molecules that bind to the ASN molecule.

Effect of viologen-phosphorus dendrimers on acetylcholinesterase and butyrylcholinesterase activities.

The inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) is the first step in checking whether new compounds can be considered as drugs for treating neurodegenerative diseases. The effect of viologen-phosphorus dendrimers on AChE and BChE activities was studied. The results show that the effects on the cholinesterase activities depend on dendrimer type and size.